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High-volume hemofiltration after out-of-hospital cardiac arrest: a randomized study.

The study examined the effect of isovolumic high-volume hemofiltration (HF) alone or combined with mild hypothermia (HT) on survival after out-of-hospital cardiac arrest (OHCA) with initial ventricular fibrillation or asystole.</AbstractText>Global inflammation in response to whole-body ischemia-reperfusion is common after OHCA and may worsen the overall prognosis.</AbstractText>Sixty-one patients admitted between May 2000 and March 2002 in the intensive care units of two hospitals in France were randomized to one of three groups: control, HF (200 ml/kg/h over 8 h) or HF+HT (32 degrees C for 24 h) induced by cooling the HF substitution fluid. Standard supportive care was provided in all three groups. The primary end point was survival with a follow-up time of six months. The effect of HF on death by intractable shock was the secondary end point.</AbstractText>The six-month survival curves of the three groups were significantly different, with better survival in the HF group (p = 0.026) and in the HF+HT group (p = 0.018). After adjustment on baseline characteristics of cardiac arrest, HF (with or without HT) was associated with improved survival (logistic regression odds ratio, 4.4; 95% confidence interval [CI], 1.1 to 16.6). Compared to control group, the relative risk of death by intractable shock was 0.29 (95% CI, 0.09 to 0.91) in the HF+HT group and 0.21 (95% CI, 0.05 to 0.85) in the HF group.</AbstractText>The HF may improve the overall prognosis after resuscitation from OHCA. Combination of HF with mild HT is feasible and should be evaluated in larger trials.</AbstractText>

Pacemaker spikes misleading the diagnosis of ventricular fibrillation.

Pacemakers are used more and more in modern cardiology, because of the increasing age of patients and the increasing number of cases of congestive heart failure treated with biventricular stimulation. Twelve lead ECG traces of electro-stimulated patients normally can be interpreted correctly, but in emergency circumstances where only a three lead ECG trace is available (i.e. the usual monitoring setting in the pre-hospital arena or intensive care unit) recognition of the underlying baseline rhythm may be difficult. The case described illustrates how differentiation between true asystole and fine ventricular fibrillation in the presence of some confounding elements (e.g. pacemaker meditated spikes) can be challenging for the physician and life-threatening for the patient. Therefore, after selecting the best diagnostic ECG trace, direct current defibrillation should be used in the presence of a persistent but uncertain cardiac rhythm, even if it may be thought to be asystole or pulse-less electrical activity.

Decreasing the time to defibrillation: a comparative study of defibrillator electrode designs.

Time to defibrillation (T(defib)) is the most important modifiable factor affecting survival from cardiac arrest. Mortality increases by approximately 7--10% for each minute of defibrillation delay. The purpose of this study was to determine whether defibrillator electrode design complexity affects T(defib).</AbstractText>This was a randomized sequential design study utilizing a standardized ventricular fibrillation cardiac arrest model for CPR mannequins. We evaluated two common types of defibrillator electrode models: a single connector design and a double connector design that requires an adaptor. We compared the time required by cardiac arrest team leaders to apply the two types of defibrillator electrodes to a manikin, connect them to a defibrillator, and then deliver a first defibrillatory shock. The primary outcome was time to defibrillation. The secondary outcome was difficulty of application as perceived by the physician participants on a 10 cm visual analog scale.</AbstractText>Thirty-two residents performed a sequential assessment of both electrodes. The average T(defib) for the double connector model was 42.9s longer than that of the single connector model (87.5s versus 44.6s, p&lt;0.001). As evaluated by the study participants, the single connector model was significantly easier to apply then the double connector model (1.3 cm versus 4.4 cm, p&lt;0.001).</AbstractText>The single connector defibrillator electrode design was associated with a significantly shorter T(defib) than the double connector design. It also was judged to be easier to apply in this model. Ergonomic design of defibrillator electrodes can significantly impact time to defibrillation.</AbstractText>

Phase 2 reentry in man.

Ventricular extrasystoles are characterized by a fixed coupling interval to the last QRST complex preceding it.</AbstractText>We hypothesized that this QRST complex differed from QRST complexes of other sinus beats not followed by ventricular extrasystoles. Further, we investigated whether phase 2 reentry, demonstrated in animal experiments to initiate ventricular extrasystoles, ventricular tachycardia, and ventricular fibrillation, also plays a role in humans.</AbstractText>We examined 18 patients with ventricular extrasystoles and/or ventricular tachycardia by signal averaging of the ECG (group A) or by single-beat analysis of intracardiac electrograms (group B). Group A consisted of six patients without structural heart disease and one patient with the Brugada syndrome. Six of the seven patients had right ventricular outflow tract ventricular extrasystoles. Group B consisted of 11 patients undergoing radiofrequency ablation. Eight of the 11 patients had right ventricular outflow tract extrasystoles.</AbstractText>In six of the seven patients in group A, we demonstrated significant ST-elevation and/or T-wave changes in the sinus beat preceding ventricular extrasystoles compared with the second last sinus beat in one or more of the three orthogonal leads X, Y, and Z. In 9 of the 11 patients in group B, single-beat analysis of unipolar and bipolar electrograms recorded close to successful ablation sites demonstrated similar changes, that is, ST-elevation (median peak voltage gradient 150 muV, range 0-1,700) and T-wave changes in the sinus beat prior to ventricular ectopy. In addition, J-point elevation was demonstrated in several cases. In total, significant changes were demonstrated in 15 of the 18 patients studied (83%).</AbstractText>J-point elevation, ST-elevation, and T-wave changes documented in the last sinus beat prior to ventricular extrasystoles are in agreement with phase 2 reentry, suggesting that this may be the responsible mechanism for ventricular extrasystoles and ventricular tachycardia/fibrillation. The phenomenon has been demonstrated in only animal experiments to date.</AbstractText>

Atrioventricular node ablation and permanent ventricular pacemaker implantation without fluoroscopy: use of an electroanatomic navigation system.

Non-fluoroscopy AV ablation and pacemaker implantation. Fluoroscopic guidance is the standard tool used for transvenous pacemaker implantations and for electrophysiological and ablation procedures. It implies X-ray exposure, occasionally with high dose of radiation for the patient and operator. We describe the case of a 47-year-old man with uncontrollable permanent atrial fibrillation to whom ablation of the AV conduction and a permanent ventricular pacemaker implantation were successfully performed under the guidance of an electroanatomic navigation EnSite NavX system and with no use of fluoroscopy. This case illustrates the stand-alone use of one of the new non-fluoroscopic navigation systems for a complete procedure such as AV ablation and pacemaker implantation.

Mechanism for atrial tachyarrhythmia in chronic volume overload-induced dilated atria.

Mechanism of chronic volume overload-induced AT.</AbstractText>Atrial dilatation associated with chronic volume overload (CVO) plays an important role in the development of atrial fibrillation (AF). However, the underlying mechanisms are unknown.</AbstractText>CVO-induced atrial dilatation was created in Japanese white rabbits using arteriovenous shunt formation for 6 weeks. Epicardial action potentials were measured from both atria in Langendorff-perfused sham-operated control hearts (n=8) and in CVO hearts (n=8) using high-resolution optical mapping techniques. The left atrial diameter was greater in CVO hearts (16.0+/-0.4 mm) compared to control hearts (11.0+/-0.8 mm). During steady-state pacing, right and left atrial conduction velocities were significantly lower in CVO hearts compared to control hearts (P&lt;0.01). Rapid atrial pacing did not induce atrial tachyarrhythmia (AT) in any control hearts. However, in seven of eight CVO hearts 16 episodes of AT were induced, of which 9 exhibited a single reentrant circuit. The remaining 7 episodes exhibited a focal pattern of excitation without evidence of reentry. Interestingly, the activation rate was higher during reentry (16.1+/-1.5 Hz) compared to focal AT (9.8+/-1.0 Hz). In addition, 15 of 16 episodes occurred in the posterior left atrium (PLA). In all seven CVO hearts, AT was self-sustained for more than 10 minutes.</AbstractText>CVO caused atrial dilatation, conduction slowing, and AT associated with reentrant and focal excitation originating from the PLA. These results suggest that the PLA may play an important role in AT induction associated with CVO-induced atrial dilation.</AbstractText>

TRIad: foundation for proarrhythmia (triangulation, reverse use dependence and instability).

There exist both safe and dangerous prolongations of the QT interval. Proarrhythmia can be induced by triangulation of the cardiac action potential, reverse use dependence and instability, a set of three features termed TRIad. TRIad leads to dispersion (spatial, transmural and temporal), stalling of fast repolarization or even early after-depolarization (EAD). EAD can progress to Torsade de Pointes (TdP) especially in the presence of prolonged APD; as the QT interval shortens (e.g. by reverse use-dependence), the cardiac wavelength shortens and TdP can progress to ventricular fibrillation (VF). In the absence of TRIad and QT prolongation, chemicals exhibit on average neither pro- nor anti-arrhythmia. However, QT prolongation in the absence of TRIad becomes antiarrhythmic. Furthermore, this desirable effect increases as TRIad components are replaced by squaring of the action potential, use-dependent prolongation of APD and stabilization of the action potential. It is concluded that proarrhythmic characteristics of drugs can readily be recognized and that hope exists for an effective and safe class III antiarrhythmic agent after all.

Cellular mechanisms of Torsade de Pointes.

Torsade de Pointes (TdP) is a life-threatening arrhythmia closely linked to abnormal cardiac repolarization. It has been demonstrated that cardiac ion channel alterations underlying cellular repolarization results in the phenotypic expression of long QT syndrome, which is closely associated with TdP. However, the mechanisms by which prolonged repolarization leads to TdP remain controversial. Prolonged repolarization is associated with triggered activity, and multiple foci of triggered activity can underlie a TdP phenotype. Action potential shortening associated with rapid ventricular rhythms, in theory, removes conditions for triggered activity. Therefore, while triggered activity may initiate TdP, another mechanism may be responsible for the maintenance of TdP. Re-entrant arrhythmias can also give rise to a TdP phenotype. In intact myocardium significant inhomogeneities of repolarization are manifest in the presence of IKr blockade. Large repolarization gradients between subepicardial and midmyocardial cells formed zones of conduction block responsible for sustained reentrant TdP. Gap junction proteins responsible for intercellular coupling between subepicardial and midmyocardial cells are reduced in normal myocardium which may maintain arrhythmogenic gradients of repolarization. Therefore, the mechanism of TdP is multi-factorial and related to triggered activity and spatial inhomogeneities of ion channel expression combined with regional expression patterns of gap junctions.

Brugada-like electrocardiographic pattern induced by an episode of anemia.

The mechanisms responsible for the undulating pattern of ST-segment elevations in the Brugada syndrome are still a matter of discussion. This report describes a young man with a Brugada-like electrocardiographic pattern. The specific ST-segment elevations were unmasked during an episode of anemia due to a duodenal ulcer.

Euro heart failure survey. Medical treatment not in line with current guidelines.

It was the aim of the Euro Heart Survey on Heart Failure to assess whether patients are being treated according to current guidelines.</AbstractText>In Germany, patients were screened in 7 medical centers if their discharge diagnoses were myocardial infarction, a new episode of atrial fibrillation, or diabetes mellitus. Patients were enrolled if at least one additional criterion was fulfilled: (1) clinical diagnosis of heart failure, (2) hospital admission due to heart failure within the last 3 years, (3) therapy with loop diuretic, (4) medication for heart failure or ventricular dysfunction documented by echocardiography within the past 24 hours prior to death.</AbstractText>2166 patients were screened of whom 747 were included in the study (478 men, 269 women). 93% of the patients suffered from heart failure. Despite the high number of patients with known heart failure (ischemic heart failure in 71%), only 72% received ACE inhibitors and 62% beta-blockers. Average daily dose met recommendations in only 63% of patients on ACE inhibitors and 54% on beta-blockers. 74% of the patients received diuretics (furosemide 36%, thiazide 34%, spironolactone 17%).</AbstractText>An inadequately low number of patients with heart failure receives medical therapy according to guidelines, despite all the overwhelming evidence for improved morbidity and mortality. Awareness of physicians needs to be improved.</AbstractText>

Correlates of left atrial size in Nigerian hypertensives.

Left atrial (LA) enlargement is a common finding in systemic hypertension and is a risk factor for the development of atrial fibrillation and stroke. We determined the correlates of LA enlargement in a Nigerian hypertensive population.</AbstractText>A total of 361 hypertensives were recruited for echocardiography. Enlarged left atrium was defined as LA diameter &gt; 4.2 cm in men or &gt; 3.8 cm in women.</AbstractText>Enlarged LA was found in 15.8% of the hypertensives (19.2% in females and 12.5% males). Compared with those without dilated LA, subjects with dilated LA had higher age, body mass index, left ventricular end diastolic diameter, left ventricular wall thickness, lower ejection fraction and fractional shortening. In multivariate analysis, body mass index and left ventricular (LV) mass were the major predictors of LA size, whereas dilated LA was related to age, female gender and LV mass or the presence of left ventricular hypertrophy in logistic regression analysis.</AbstractText>Left atrial size in Nigerian hypertensives is influenced by age, female gender, left ventricular mass and body mass index.</AbstractText>

Hepatocyte growth factor gene therapy reduces ventricular arrhythmia in animal models of myocardial ischemia.

It was recently reported that gene therapy using hepatocyte growth factor (HGF) has the potential to preserve cardiac function after myocardial ischemia. We speculated that this HGF gene therapy could also prevent ventricular arrhythmia. To investigate this possibility, we examined the antiarrhythmic effect of HGF gene therapy in rat acute and old myocardial infarction models. Myocardial ischemia was induced by ligation of the left descending coronary artery. Hemagglutinating virus of Japan (HVJ)-coated liposome containing HGF genes were injected directly into the myocardium fourteen days before programmed pacing. Ventricular fibrillation (VF)was induced by programmed pacing. The VF duration was reduced and the VF threshold increased after HGF gene therapy ( p&lt; 0.01). Histological analyses revealed that the number of vessels in the ischemic border zone was greatly increased after HGF gene injection. These findings revealed that HGF gene therapy has an anti-arrhythmic effect after myocardial ischemia.

Out-of hospital cardiac arrest in Okayama city (Japan): outcome report according to the "Utsutein Style".

The purpose of this study was to evaluate the outcomes for out-of-hospital cardiac arrest (OHCA) and cardiopulmonary resuscitation (CPR) in the city of Okayama, Japan, during a 1-year period after the reorganization of defibrillation by Emergency Life-Saving Technicians (ELSTs) with standing orders of CPR. The data were collected prospectively according to an Utstein style between June 1, 2003 and May 31, 2004; OHCA was confirmed in 363 patients. Cardiac arrest of presumed cardiac etiology (179) was witnessed by a bystander in 62 (34.6%) cases. Of this group, ventricular fibrillation (VF) was documented in 20 cases (32.3%), and 1 patient (5%) was discharged alive without severe neurological disability. This outcome is average in Japan, but it is quite low level compared with Western countries because there is less VF in Japan. The Utstein style revealed that we must try to detect VF before the rhythm changes and to provide defibrillation as soon as possible in order to improve outcomes. Further research will be required to accurately evaluate OHCA in Okayama city.

Effects of atrial arrhytmias on the regurgitation of a monoleaflet prosthetic heart valve.

Many patients who receive a prosthetic heart valve also have or acquire cardiac arrhythmias. However, most in vitro studies of prosthetic valves examine them under normal rhythms. In this study, a monoleaflet prosthetic heart valve was tested in vitro under conditions that simulated normal sinus rhythm, first degree atrioventricular heart block, and atrial fibrillation (fixed and variable ventricular rates). Atrial contraction was simulated by an active atrial chamber. The timing between the atrium and ventricle was adjusted to simulate various types of arrhythmias. The closing, leakage, and total regurgitant volumes and fractions increased for each type of atrial arrhythmia when compared to normal sinus rhythm. The peak regurgitant flow increased for first degree atrioventricular heart block and atrial fibrillation with a fixed ventricular rate compared to normal sinus rhythm.

Keeping current with biphasic defibrillation waveforms.

In recent years, defibrillators that use a biphasic waveform instead of the traditional monophasic waveform have become increasingly common. In fact, since we last published on this topic in 2001, most defibrillator suppliers have begun concentrating solely on developing and marketing biphasic defibrillators while phasing out their monophasic models. Healthcare facilities are wondering if they should do the same. ECRI believes that the time has come for healthcare facilities to begin making the switch to biphasic models. That's not to say, however, that immediate replacement is required. Continuing to use a monophasic device that is in proper working condition is certainly acceptable, and replacing all models at once would be a large--and we believe unnecessary--financial burden. Rather, ECRI recommends that healthcare facilities implement a plan to phase out their monophasic defibrillators over the next few years. We discuss why, and offer recommendations to facilitate a safe and smooth transition, on the pages that follow.

[Use of levosimendan after cardiac arrest by ventricular fibrillation: a case report].

We describe the case of a patient admitted in intensive care, after cardiac arrest by ventricular fibrillation treated by electrical defibrillation, that showed a serious deficit of the cardiac index and increase of the systemic vascular resistances. The patient was treated by levosimendan (Simdax): a starter dose of 12 microg/Kg in ten minutes and then a continuous perfusion of 0.1 microg/Kg/min. for 24 hours. He had a continuous amelioration of the clinical conditions and of the hemodynamics parameters. In the fifth day the patient was transferred to the Cardiology department and after 20 days he was discharged from hospital.

Clamikalant (Aventis).

Clamikalant is a cardioselective blocker of the ATP-dependent potassium channel (KATP) which is under development by Aventis Pharma (formerly Hoechst Marion Roussel) for the potential treatment of cardiac arrhythmia. The sodium salt, HMR-1098, is in phase II trials. Aventis plans for an iv preparation of the drug to be launched in 2004, and an oral preparation to be available in 2005. Clamikalant prevented ischemia-induced reductions in refractory period in dogs with ventricular fibrillation without significant hemodynamic effects or alteration in blood glucose levels. HMR-1883 exerted an anti-arrhythmic effect in a model of isolated hearts from male White New Zealand rabbits, and indicated and did not interfere with post-ischemic hyperemia.

An uncommon coronary artery fistula causing survived sudden cardiac death in a young woman.

Although most patients suffering from a coronary artery fistula remain asymptomatic during childhood and adolescence, many of them develop complications in adulthood due to volume overload, endocarditis or ischemia. Here we present a young woman surviving a sudden cardiac death due to myocardial ischemia with subsequent ventricular fibrillation caused by thrombosis of a coronary artery fistula deriving from the left main coronary artery. Parts of the thrombus had been embolized into the circumflex artery causing posterior myocardial infarction. The thrombosis might have been initiated by local compression from a round extracardiac mass of 3 cm with liquid and solid content located between the vena cava superior and the ascending aorta. This structure was suspected to be a hematoma which had been caused by a blunt thoracic trauma while playing soccer 2 weeks before.

Automated external defibrillators: to what extent does the algorithm delay CPR?

Maximizing cardiopulmonary resuscitation (CPR) during resuscitation may improve survival. Resuscitation protocols stack up to 3 shocks to achieve defibrillation, followed by an immediate postdefibrillation pulse check. The purpose of this study is to evaluate outcomes of rhythm reanalyses immediately after shock, stacked shocks, and initial postshock pulse checks in relation to achieving a pulse and initiating CPR.</AbstractText>We conducted an observational study of patients with ventricular fibrillation treated by first-tier emergency medical services (EMS). We collected data from EMS, dispatch, and hospital records. Additionally, we analyzed automatic external defibrillator recordings to determine the proportion of cardiac arrest victims who were defibrillated and achieved a pulse according to shock number (single versus stacked shock), proportion of victims with a pulse during the initial postdefibrillation pulse check, and interval from initial shock to CPR.</AbstractText>The study included 481 cardiac arrest subjects. Automatic external defibrillators terminated ventricular fibrillation with the initial shock in 83.6% (n=402) of cases. A second shock terminated ventricular fibrillation in an additional 7.5% (n=36) of cases, and a third shock terminated ventricular fibrillation in 4.8% (n=23) of cases. The initial sequence of 3 shocks failed to terminate ventricular fibrillation in 4.1% (n=20) of cases. In total, automatic external defibrillators performed 560 rhythm reanalyses during the initial shock sequence and delivered 122 "stacked" shocks. Termination of ventricular fibrillation was not synonymous with return of a pulse. The initial shock produced a pulse that was eventually detected in 21.8% (105/481) of cases. Stacked shocks produced a pulse in 10.7% (13/122) of cases. For the 24.5 % (n=118) of cases in which a pulse returned, the pulse was detected during the initial postshock pulse check only 12 times, or 2.5% of all cases. The median interval from initial shock until CPR was 29 (23,41) seconds.</AbstractText>Rhythm reanalyses, stacked shocks, and postshock pulse checks had low yield for achieving or detecting return of a pulse. CPR was not initiated until 29 seconds after the initial shock.</AbstractText>

Effects of a high dose intravenous bolus amiodarone in patients with atrial fibrillation and a rapid ventricular rate.

Amiodarone, given as intravenous bolus has not yet been studied in patients with atrial fibrillation and a high ventricular rate.</AbstractText>One hundred consecutive patients with atrial fibrillation and a ventricular rate above 135 bpm were randomized to receive either 450 mg amiodarone or 0.6 mg digoxin given as a single bolus through a peripheral venous access. If the ventricular rate exceeded 100 bpm after 30 min, another 300 mg amiodarone or 0.4 mg digoxin were added. Primary endpoints of the study were the ventricular rate and the occurrence of sinus rhythm after 30 and 60 min. Secondary endpoints were blood pressure during the first hour after drug administration, and safety regarding drug induced hypotension, and phlebitis at the infusion site.</AbstractText>Baseline heart rate was 144+/-19 in the amiodarone group and 145+/-15 in the digoxin group (p=0.72). Following amiodarone, heart rate was 104+/-25 after 30 min compared to 116+/-23 in the digoxin group (p=0.02) and 94+/-22 versus 105+/-22 after 60 min (p=0.03). After 30 min, sinus rhythm was documented in 14 (28%) patients following amiodarone compared to 3 (6%) patients in the digoxin group (p=0.003), and after 60 min in 21 (42%) versus 9 (18%) patients (p=0.012). Asymptomatic hypotension was observed in 4 amiodarone treated patients, and superficial phlebitis in 1 patient.</AbstractText>Amiodarone, given as an intravenous bolus is relatively safe and more effective than digoxin for heart rate control and conversion to sinus rhythm in patients with atrial fibrillation and a rapid ventricular rate.</AbstractText>

German origin clusters for high cardiovascular risk in an Italian enclave.

Mortality and morbidity appear to be higher in a Cimbrian population representing an enclave of people who migrated from medieval Germany to the secluded Leogra valley in Italy. A population-based study was organized, recruiting 881 elderly subjects of Cimbrian origin and comparing them with a standard control population (SCP, n = 3,282) having comparable general characteristics and lifestyle. Serum lipids and glucose, blood pressure, heart rate, respiratory function, ECG abnormalities, and historical events were used as risk indicators. Age-adjusted systolic and pulse pressure were higher in the Cimbrians than in the SCP, while diastolic blood pressure was comparable. The prevalences of arterial hypertension, isolated systolic hypertension, and pulse hypertension were significantly more represented among Cimbrians than SCP. The prevalences of diabetes, hypercholesterolemia, and hypertriglyceridemia were higher among the former than the latter. The ratio between apolipoproteins B and A1 was also higher, while the HDL fraction was significantly lower in Cimbrians than in the SCP. In Cimbrians, the relative risk (RR) for ischemic heart disease was 1.92 (1.57-2.34) in women, 2.30 (1.54-3.43) in men and 1.03 (1.00-1.06) in women for stroke, 2.43 (1.54-3.83) in men and 1.45 (1.01-1.12) in women for atrial fibrillation, 3.85 (2.83-5.24) in men and 1.39 (1.20-1.60) in women for respiratory disease, 1.97 (1.32-2.94) in men and 6.81 (4.38-10.60) in women for intermittent claudication, and 3.31 (2.44-4.50) in men and 2.30 (1.76-3.01) in women for left ventricular hypertrophy. The subjects living in the secluded Leogra valley are at higher cardiovascular risk than the standard controls. Whether this depends on genetic factors, lifestyle, or both will need to be clarified by further analysis.

Predictors of congestive heart failure mortality in elderly people from the general population.

Congestive heart failure (CHF) is highly prevalent in the elderly. The aim of this study was to identify the predictors of CHF mortality in patients over 65 years of age who were free of CHF at initial screening. A total of 3,282 elderly subjects were recruited in a population-based frame and 12-year events were recorded. Continuous items were divided into tertiles and for each tertile adjusted the relative risk (RR) with 95% confidence intervals (CI) was derived in both genders from multivariate Cox analysis of CHF mortality. Age &gt; or = 72 years ([RR]: 2.24; 95% CI 1.56 - 3.24), male gender ([RR]: 1.4; 95%CI 1.02 - 1.76), clinical history of coronary artery disease ([RR]: 1.25; 95% CI 1.02 - 1.76), pulse pressure &gt; or = 79 mmHg ([RR]: 1.33; 95% CI 1.03 - 1.87), heart rate &gt; or = 81 bpm ([RR]: 1.32; 95% CI 1.10 - 1.96), atrial fibrillation ([RR]: 1.82; 95% CI 1.18 - 2.81), left ventricular hypertrophy ([RR]: 1.42; 95% CI 1.01 - 2.02), diabetes ([RR]: 1.35; 95% CI 1.02 - 1.78), vital capacity &lt; or = 81% of the theoretical value ([RR]: 2.50; 95% CI 1.88 - 3.32), forced expiratory volume in 1 second &lt; or = 72% of the theoretical value ([RR]: 2.02; 95% CI 1.55 - 2.72) and serum sodium level &lt; or = 139 mmol/L ([RR]: 1.95; 95% CI 1.44 - 2.63) predicted CHF mortality. This model is able to identify elderly people at increased risk of death from CHF.

Detection of repolarization alternans with an implantable cardioverter defibrillator lead in a porcine model.

Mechanistic links have been suggested between repolarization alternans (RPA) and the onset of ventricular tachycardia (VT) and/or fibrillation. Endocardial detection of RPA may, therefore, be an important step in future device-based treatments of arrhythmias. Here, we investigate if RPA could be detected during acute ischemia using an implantable cardioverter defibrillator (ICD) lead (tip to distal coil) located in the right ventricular apex. In 18 pigs, the right coronary (n = 10) or left anterior descending coronary (n = 8) artery was occluded for 10 min using a balloon catheter, followed by reperfusion for 30 min, and re-occlusion for 30 min. RPA magnitude, computed using the modified moving average (MMA) method, showed a sharp increase in all 18 animals, from a mean baseline level of 1.9 +/- 1.3 mV to 3.0 +/- 1.3 mV during first occlusion (p &lt; 0.001). RPA magnitude showed a prominent increase in 10 animals during re-occlusion, from a mean baseline level of 1.7 +/- 1.0 mV to 3.3 +/- 1.5 mV (p &lt; 0.001). The protocol was terminated during the first two stages of occlusion and reperfusion for the remaining 8 animals due to the occurrence of ventricular fibrillation (VF). These results confirm that RPA increases under ischemic conditions and that it is possible to detect and track RPA dynamics with an ICD lead that is positioned in a clinically realistic location. Such an approach may be useful in formulating improved arrhythmia detection and control algorithms.

Ventricular tachycardia ablation in patients with coronary heart disease: beyond the reentry circuit.

Patients with coronary heart disease and left ventricular dysfunction are at increased risk for the development of ventricular tachycardia (VT) related to areas of myocardial fibrosis. Although the mechanism and the circuit of this arrhythmia are well understood, little is known about the triggers that precipitate VT episodes. Purkinje fiber potentials may be responsible for idiopathic VT, and recent studies have related them to polymorphic VT and ventricular fibrillation.</AbstractText>Between January 2002 and December 2003, we performed ablation in 10 patients with coronary heart disease, left ventricular systolic dysfunction and VT refractory to pharmacological therapy. All patients had implantable cardioverter-defibrillators. Electroanatomical activation and voltage mapping (CARTO) and electrophysiological criteria (premature activation during VT, pace mapping, and presence of diastolic potentials) were used to define scar regions, slow conduction areas and the reentry circuit isthmuses.</AbstractText>Spike potentials were recorded in the scars of three patients. These potentials were almost fused with the ventricular electrogram during sinus rhythm, and were more premature during VT, probably reflecting local activation of Purkinje fibers. During ablation, we were able to dissociate the spike from the ventricular electrogram, thus terminating the VT. In the cases with conduction recovery, ventricular; ectopic beats recurred, preceded by a spike and degenerating into short runs of VT. The ablation strategy was not modified since persistence of the VT required the isthmus.</AbstractText>The results suggest that residual Purkinje fibers may be present in scar regions and that the activity of these fibers may trigger VT in pre-established circuits.</AbstractText>

Sinus node dysfunction concomitant with Brugada syndrome.

A genetic correlation between Brugada syndrome (BS) and sinus node dysfunction (SND) has been proposed, although the clinical and electrophysiologic characteristics of this concomitant condition are unknown.</AbstractText>The study comprised 5 patients with symptomatic BS (4 with spontaneous episodes of ventricular fibrillation (VF) and 1 with syncope) of whom 3 had a documented sinus pause &gt; 3 s (a 42- and 62-year-old man, and a 49-year-old woman). Only 1 of them had a family history of sudden death; 2 of them had also had an episode of atrial fibrillation or flutter. Electrophysiologic study demonstrated prolonged sinus node recovery time in 2 patients (2.6 s and &gt; 5 s), in whom a cardiac pacemaker had been implanted before the diagnosis of BS was made after episodes of VF. Finally, all 3 patients received an implantable cardioverter defibrillator, including 2 upgrades from pacemaker.</AbstractText>SND is not a rare concomitant disorder in BS and there is a possible genetic connection.</AbstractText>

What is the normal range for N-terminal pro-brain natriuretic peptide? How well does this normal range screen for cardiovascular disease?

To define the N-terminal pro-brain natriuretic peptide (NTpBNP) normal range, assessing its cardiovascular screening characteristics in general population and higher risk subjects.</AbstractText>A total of 2320 subjects (1392 general population and 928 high-risk) &gt; or =45 years old, selected randomly from seven community practices, were invited to undergo clinical assessment and echocardiography and to assess NTpBNP serum levels. Of these, 1205 attended. The NTpBNP normal range was calculated and its cardiovascular screening characteristics were assessed. Age (P&lt;0.0001) and female gender (P&lt;0.0001) independently predicted NTpBNP levels in normal subjects. In the general population, age- and gender-stratified normal NTpBNP levels gave a negative-predictive value (NPV) of 99% in excluding left ventricular systolic dysfunction, atrial fibrillation, and valvular heart disease, and a positive predictive value of 56% in detecting any cardiovascular disease assessed. In high-risk subjects, these values were 98 and 62%, respectively. Ninety-five per cent of subjects with NTpBNP levels over four times the normal had significant cardiovascular disease with the others having renal dysfunction.</AbstractText>Normal NTpBNP levels should be stratified by age and gender. Normal NTpBNP levels give high NPV in excluding significant cardiovascular disease. Most subjects with raised NTpBNP levels and almost all subjects with NTpBNP levels over four times the normal have significant cardiovascular disease.</AbstractText>

Modulation of I(Kr) inactivation by mutation N588K in KCNH2: a link to arrhythmogenesis in short QT syndrome.

Short QT syndrome (SQTS) is characterized by ventricular arrhythmias and sudden death. One form of SQTS is caused by mutation N588K in human ether-a-go-go-related gene (HERG). In this study we sought to determine the potential role of N588K in arrhythmias.</AbstractText>We measured the characteristics of HERG current generated by wild-type (WT) KCNH2 and the N588K mutant channel expressed in mammalian TSA201 cells.</AbstractText>Whole-cell patch-clamp recordings of WT HERG currents showed the usual rapid onset of inactivation (rectification) at potentials more positive than +10 mV. In contrast, N588K currents rectified at potentials over +80 mV. Over the physiological range of potentials, N588K currents do not inactivate. During an action potential clamp, WT currents displayed a "hump" like waveform with slow activation kinetics and a rapid increase during phase 3 repolarization. In contrast, N588K currents were proportional to the amplitude of the action potential and displayed a dome-like configuration and a much larger current during the initial phases in the ventricle. Purkinje cell action potentials display a more negative phase 2 repolarization than the ventricle and elicited much smaller WT and N588K currents of similar amplitudes.</AbstractText>Physiologically the N588K mutation abolishes rectification of HERG currents and specifically increases I(Kr) in the ventricle with minimal effects on the Purkinje fiber action potential duration. Such preferential prolongation may explain the separation of the T and U waves observed in the ECG of SQTS patients and lead to re-excitation of the ventricle endocardium.</AbstractText>

Minimally invasive midaxillary muscle sparing thoracotomy for atrial septal defect closure in prepubescent patients.

Partial sternotomy, as well as posterolateral or anterolateral right-sided thoracotomy, are used for correction of selected cardiac lesions in children. However, in female patients impaired breast development after an anterolateral thoracotomy is reported, and for both the posterolateral and the anterolateral approach, partial transection of large muscle groups is required. The midaxillary approach may help to avoid these side effects and improve the cosmetic result.</AbstractText>Beginning in April 2003, our institutional policy changed toward a midaxillary approach in prepubescent patients with an atrial septal defect, in whom criteria for catheter closure were not fulfilled. Thoracotomy was performed after a horizontal midaxillary incision and mobilization of the latissimus dorsi and splitting of the serratus anterior. Aorta and caval veins were cannulated directly. The atrial septal defect was closed during electrically induced fibrillation of the heart.</AbstractText>Until August 2004, this technique was applied in 36 patients (30 girls, 6 boys), with no need for conversions to another approach. Mean patient age was 6.9 +/- 2.6 years (range, 4 to 14 years), with a mean weight of 23.8 +/- 11.2 kg (range, 15 to 69 kg). Skin incision ranged from 4.5 to 6.0 cm. Mean cardiopulmonary bypass time was 31 +/- 13 minutes (range, 13 to 73 minutes), with a mean ventricular fibrillation time of 21.2 +/- 7.4 minutes (range, 10 to 42 minutes). In 28 of 36 patients a patch was used. No phrenic nerve damage occurred.</AbstractText>The midaxillary approach is a safe alternative to lateral thoracotomies frequently used in cardiac surgery for atrial septal defect closure. It helps to improve the cosmetic result in the prepubescent patient group. We believe that its application should not be expanded to include repair of more complex lesions or to patients below the age of 3 to 4 years. For these, variations of cosmetically favorable partial sternotomy techniques should be applied.</AbstractText>

Effect of nitric oxide synthase modulation on resuscitation success in a swine ventricular fibrillation cardiac arrest model.

We have demonstrated previously that the nitric oxide synthase (NOS) inhibitor N(G)-nitro-L-arginine (L-NNA) decreases free radical generation and nitrosative injury via peroxynitrite formation after epicardial dc shocks.</AbstractText>Our purpose was to explore the effects of NOS inhibition and NOS donation on cardiopulmonary resuscitation (CPR) success after cardiac arrest of variable duration. We used the non-selective NOS inhibitor L-NNA and the selective neuronal NOS inhibitor ARR-17477, the NOS donor S-nitroso-N-acetylpenicillamine (SNAP) and the vasodilator Enalaprilat, which lowers arterial pressure via a non-NO mechanism.</AbstractText>Part I: 17 pigs undergoing 4 min supported (i.e. with closed-chest compression and ventilation) ventricular fibrillation (VF) were divided into two groups: a no-L-NNA group (n=8) receiving IV saline and an L-NNA group (n=9) receiving IV L-NNA (5 mg/kg) for 8 min before VF was induced. Part II: 35 pigs undergoing 6-8 min VF were randomized to three groups: a no-L-NNA group (n=13) receiving IV saline, an L-NNA group (n=11) receiving IV L-NNA (5 mg/kg) and an ARR17477 group (n=11) receiving IV ARR17477 (5 mg/kg) before VF. All animals in Part II underwent unsupported VF (no chest compression or ventilation) for 6 min (n=13) or 8 min (n=22); closed-chest compression, ventilation and epinephrine (adrenaline) were employed after defibrillation. Part III: 12 swine were divided into two groups: control (n=6) receiving saline and an LNNA group (n=6) receiving IV LNNA (5 mg/kg). Swine underwent 6 min unsupported VF and 2 min supported VF before defibrillation. Part IV: 25 animals were studied to determine the effect of the NO donor SNAP and the angiotensin-converting enzyme inhibitor Enalaprilat on coronary perfusion pressure (CPP).</AbstractText>In Part I, after defibrillation, with continued ventilation, chest compression and epinephrine, 8/9 L-NNA pigs achieved ROSC versus 4/8 control pigs (p=0.11). After 60 s of CPR, 7/9 pigs in the L-NNA group achieved ROSC versus 2/8 pigs in the no-L-NNA group (p&lt;0.05). Only 2/9 pigs receiving L-NNA required epinephrine (1 mg) after defibrillation, compared to 6/8 pigs requiring at least one dose of epinephrine in the no-L-NNA group (p&lt;0.05). In Part II, there was no significant difference between L-NNA, ARR17477 and control pigs in ROSC. However, control pigs required 6.8+/-1.4S.E. mg epinephrine; L-NNA pigs and ARR17477 pigs required less epinephrine (3.7+/-0.7 and 3.0+/-0.3 mg, both p=0.01). Shorter chest compression was required in the L-NNA group (252+/-38 s, p&lt;0.05) and in ARR17477 group (222+/-15 s, p&lt;0.05) compared to the control group (405+/-77 s). In Part III, L-NNA infusion caused a significant increase in mean blood pressure at baseline, but did not change CPP throughout the experiment. In Part IV, there were no significant differences in the changes of mean blood pressure and CPP between SNAP and Enalaprilat group in all animals throughout the experiment.</AbstractText>NOS inhibition pre-arrest did not improve survival, but did reduce requirements for epinephrine and closed-chest compression in a swine resuscitation model.</AbstractText>

[Dual atrioventricular nodal conduction and arrhythmia with severe hemodynamic alterations during liver retransplantation].

We report the case of a man who developed tachycardia caused by atrioventricular reentry related to dual nodal conduction during liver retransplantation. The hemodynamic alterations were severe. Arrhythmia and altered cardiac conduction are potential complications of liver transplantation. The development of tachyarrhythmias--atrial fibrillation as well as episodes of supraventricular and ventricular tachycardia and bradycardia--have been described. Such arrhythmias tend to occur particularly during reperfusion of the graft. Risk factors implicated are the severe ion imbalances, acid-base imbalance, and hypothermia that accompany the reperfusion of a new organ. A review of the possible pathogenic and etiological mechanisms that lead to arrhythmia in patients with end-stage liver disease is provided.

Intraoperative bypass flow measurement reduces the incidence of postoperative ventricular fibrillation and myocardial markers after coronary revascularisation.

Sudden ventricular fibrillation (VF) and myocardial infarction (MI) are life-threatening complications after coronary artery bypass grafting (CABG). We prospectively analysed the impact of intraoperative bypass flow measurement with the transit time flow Doppler method (TTFD) on the incidence and outcome of postoperative VF and MI.</AbstractText>In 1995 a standardized algorithm for the treatment of postoperative VF was introduced in our institution. The rate of postoperative VF was therefore exactly registered. In 1998 the TTFD method was implemented as a standard in all CABG cases. Whenever insufficient bypass graft flow was detected, anastomoses were redone and technical problems affecting the grafts were excluded. The incidence of postoperative VF and CK/CK-MB fraction was observed prospectively and the new data was compared to the data from 1995 to 1998.</AbstractText>From 1/95 to 7/98 a total of 4321 patients (group A) were operated on with isolated CABG procedures using extracorporeal circulation. In the period from 8/98 to 10/02 a total of 3421 patients (group B) was operated on with isolated CABG procedures under the same conditions, except that the TTFD method was used in every case. The treatment of VF was standardised in both groups according to the algorithm. The most striking effect was the significant reduction of VF from 0.66% to 0.44% when TTFD was introduced and the steep decrease in mortality from 30% to 12.2% in patients with VF when the algorithm and TTFD were routinely applied. Furthermore the rate of insufficient bypass flow detected by angiography was reduced by 66%.</AbstractText>Routinely the use of TTFD significantly reduced the incidence of postoperative VF, postoperative CK/CK-MB fraction, and angiographically detected bypass malfunction. A simultaneously implemented algorithm reduced the mortality with VF after CABG. The consequent use of TTFD intraoperatively reduced the incidence of postoperative anastomosis and technically related complications of bypass surgery and led to a significant reduction of postoperative mortality in CABG procedures.</AbstractText>

Azimilide (Procter &amp; Gamble).

Azimilide is a class III anti-arrhythmic agent under development by Procter &amp; Gamble. In December 1998, the company submitted an NDA with the FDA seeking an indication for the maintenance of sinus heart rhythm in patients with various forms of supraventricular arrhythmia. By November 1997, the drug was being evaluated in clinical trials for its use in patients with implantable cardioverter defibrillators (ICDs). The study was to examine its ability to reduce the frequency and severity of ICD electrical discharges. As of August 1999, azimilide was in phase I development by Tanabe Seiyaku in Japan, for the potential treatment of arrhythmia. Results of a pivotal clinical trial, presented at the annual meeting of the Society for Neuroscience in November 1998, demonstrated azimilide to prolong the arrythmia-free period in patients suffering from atrial fibrillation. Phase III clinical trials so far have involved patients with supraventricular and ventricular arrhythmias. Trial results from the ASAP (Azimilide Supraventricular Arrhythmia Program Trial), showed that azimilide significantly prolonged the arrythmia-free period in patients suffering from atrial fibrillation. There were three deaths in the azimilide group compared to one in the placebo group. The safety and efficacy of azimilide in 6000 patients who have suffered a heart attack is currently under study in the phase III ALIVE (azimilide post-infarct survival evaluation) multicenter trial, which commenced in centers in the US and Europe in October 1997.

Presentation and survival of prehospital apparent sudden infant death syndrome.

Prehospital providers are often involved in the resuscitation of apparent sudden infant death syndrome (SIDS) victims; however, data are few on the presentation and outcome of these patients.</AbstractText>To describe the presentation and determine the survival rate of infants who have an unwitnessed, prehospital arrest consistent with SIDS (apparent SIDS), and to compare the presentation of infants with a final diagnosis of SIDS with those who presented as apparent SIDS but had a different final diagnosis.</AbstractText>This was a secondary analysis of data from a controlled trial whose methodology has been previously described. The setting was two large, urban emergency medical services (EMS) systems of Los Angeles and Orange Counties, California. The population included 113 apparent SIDS victims from the original interventional study who had a prehospital, unwitnessed arrest consistent with SIDS, defined by the scenario of an infant aged =12 months being placed to sleep and later found in full arrest (pulseless and apneic). Data collected included ethnicity, gender, arrest etiology, signs of death (lividity, rigor mortis), prehospital interventions, return of spontaneous circulation (ROSC), arrest rhythm, code 3 transport (lights and sirens), and survival to hospital discharge.</AbstractText>One hundred ten of 113 apparent SIDS patients had survival data; 0 of 110 (95% CI 0% to 3.3%) survived, although ROSC was achieved in 5%; for three patients data on survival were missing. Arrest rhythms were determined in 94% of the subjects: asystole 87%, pulseless electrical activity (PEA) 8%, and ventricular fibrillation 4%. Only 50 of 113 (44%) of the EMS records documented code 3 transport; the remainder of the records were ambiguous. SIDS was the final coroner's diagnosis for 79 of 113 (70%) of the cases. Other causes of death in these apparent SIDS victims included respiratory causes (12%), asphyxiation (3%), abuse (2%), congenital heart disease (2%), sepsis (2%), other (4%), and unknown (5%). Apparent SIDS victims with a final diagnosis of SIDS were more likely to show signs of death (27/79, 34% vs. 5/34, 15%, p = 0.035) and were less likely to have a rhythm of PEA (4/77, 5% vs. 5/31, 16%, p = 0.08), although the latter result was not statistically significant.</AbstractText>Apparent SIDS victims have a dismal prognosis; all infants presenting with apparent SIDS died, even the 30% whose final diagnosis was not SIDS. Given that there were no survivors, new prehospital policies are needed governing the use of lights and sirens, resuscitation decisions including termination of resuscitation, provision of grief support to families, and incident stress debriefing for prehospital personnel.</AbstractText>

The role of prophylactic implantable cardioverter defibrillators in heart failure: recent trials usher in a new era of device therapy.

Sudden cardiac death (SCD) manifested as ventricular fibrillation or sustained ventricular tachycardia has been a major focus of cardiovascular research for more than three decades. Although mortality in patients with heart failure (HF) caused by left ventricular systolic dysfunction has declined in recent years through effective pharmacotherapeutic strategies, SCD remains the major cause of death in symptomatic HF, with little improvement by drug therapy. Although it is clear that the implantable cardioverter defibrillator (ICD) is efficacious and should be used to prevent a recurrence of sustained ventricular arrhythmia (secondary prevention) in most patients, the guidelines for prophylactic use of ICDs (primary prevention) are less well defined. The results of recent clinical trials examining the efficacy of prophylactic ICD therapy in HF patients have clarified the role of ICD treatment in this population. This article reviews these trials and summarizes our current approach to the prevention of SCD in HF.

Restitution in mapping models with an arbitrary amount of memory.

Restitution, the characteristic shortening of action potential duration (APD) with increased heart rate, has been studied extensively because of its purported link to the onset of fibrillation. Restitution is often represented in the form of mapping models where APD is a function of previous diastolic intervals (DIs) and/or APDs, A(n+1)=F(D(n),A(n),D(n-1),A(n-1),...), where A(n+1) is the APD following a DI given by D(n). The number of variables previous to D(n) determines the degree of memory in the mapping model. Recent experiments have shown that mapping models should contain at least three variables (D(n),A(n),D(n-1)) to reproduce a restitution portrait (RP) that is qualitatively similar to that seen experimentally, where the RP shows three different types of restitution curves (RCs) [dynamic, S1-S2, and constant-basic cycle length (BCL)] simultaneously. However, an interpretation of the different RCs has only been presented in detail for mapping models of one and two variables. Here we present an analysis of the different RCs in the RP for mapping models with an arbitrary amount of memory. We determine the number of variables necessary to represent the different RCs in the RP. We also present a graphical visualization of these RCs. Our analysis reveals that the dynamic and S1-S2 RCs reside on two-dimensional surfaces, and therefore provide limited information for mapping models with more than two variables. However, constant-BCL restitution is a feature of the RP that depends on higher dimensions and can possibly be used to determine a lower bound on the dimensionality of cardiac dynamics.

Fatal fluoxetine ingestion with postmortem blood concentrations.

A 37-year-old male ingested 12 gm of fluoxetine approximately 2 hours prior to arrival at an emergency department. The patient developed tonic-clonic seizures, which resolved with diazepam and midazolam therapy. The patient then developed profound bradycardia that progressed to ventricular fibrillation and asystole. A postmortem toxicology analysis reported a fluoxetine concentration of 4500 mcg/L and diazepam of 500 mcg/L. No other drugs were detected. We report an unusual case of massive fluoxetine ingestion resulting in neurological and cardiovascular toxicity resulting in death.

Recurrence of symptomatic atrial fibrillation after successful catheter ablation of atrioventricular accessory pathways: a multivariate regression analysis.

The primary aim of this study is to investigate the factors related to the recurrence of atrial fibrillation (AF) after a successful ablation of atrioventricular accessory pathway. Thirty-seven patients with spontaneous AF (study group) were selected from 401 consecutive patients who underwent radiofrequency catheter ablation of atrioventricular accessory pathway. A multivariate regression analysis was used in order to evaluate the relationships between AF recurrence and patients' age, sex, atrial size, left ventricular function, location of accessory pathways, heart rate during atrioventricular re-entrant tachycardia and atrial vulnerability (induction of sustained AF) after a successful ablation. Atrioventricular accessory pathway was abolished in 36 of the study group patients and 351 of the control group patients. During the follow-up of 36 +/- 11 months, four patients (11.1%) from the study group experienced sustained AF. Multivariate regression analysis showed that, in patients with pre-ablation AF, older age and post-ablation atrial vulnerability were the only independent predictive factors for AF recurrence. We concluded that radiofrequency catheter ablation of atrioventricular accessory pathway greatly reduces the risk of AF in patients who had a history of symptomatic AF. Older patients and patients with inducible AF after accessory pathway ablation are at an increased risk of AF recurrence. These patients should be closely monitored after successful ablation of atrioventricular accessory pathways.

Repaired tetralogy of Fallot in the adult.

The majority of persons living with tetralogy of Fallot are now adults and may face a number of long-term cardiac problems that necessitate reoperation. These problems include pulmonary regurgitation, tricuspid regurgitation, ventricular tachycardia, atrial flutter and/or fibrillation, pulmonary artery branch stenoses, right ventricular aneurysms, right ventricular outflow tract obstruction, residual ventricular septal defects, and coronary artery disease. Management approaches to these potential problems are discussed. Issues related to genetics, pregnancy, infective endocarditis, insurability, and employment are also reviewed with specific reference to the individual with repaired tetralogy of Fallot.

Typical ECG changes unmasked by ajmaline in a patient with Brugada syndrome and left bundle branch block.

Brugada syndrome is a channelopathy associated with right bundle branch block and ST segment elevation in the right precordial leads. These electrocardiographic signs may not be apparent most of the time but can be unmasked by certain antiarrhythmic agents. Until now, all of the reports on this syndrome have focused on patients with no significant intraventricular conduction delay at baseline electrograms. In this report, we describe a patient with Brugada syndrome with left bundle branch block at baseline ECG. After intravenous ajmaline, the patient developed right bundle branch block and ST segment elevations in the right precordial leads.

Simulated microgravity induces microvolt T wave alternans.

There are numerous anecdotal reports of ventricular arrhythmias during spaceflight; however, it is not known whether spaceflight or microgravity systematically increases the risk of cardiac dysrhythmias. Microvolt T wave alternans (MTWA) testing compares favorably with other noninvasive risk stratifiers and invasive electrophysiological testing in patients as a predictor of sudden cardiac death, ventricular tachycardia, and ventricular fibrillation. We hypothesized that simulated microgravity leads to an increase in MTWA.</AbstractText>Twenty-four healthy male subjects underwent 9 to 16 days of head-down tilt bed rest (HDTB). MTWA was measured before and after the bed rest period during bicycle exercise stress. For the purposes of this study, we defined MTWA outcome to be positive if sustained MTWA was present with an onset heart rate&lt;or=125 bpm. During various phases of HDTB, the following were also performed: daily 24-hour urine collections, serum electrolytes and catecholamines, and cardiovascular system identification (measure of autonomic function).</AbstractText>Before HDTB, 17% of the subjects were MTWA positive [95%CI: (0.6%, 37%)]; after HDTB, 42% of the subjects were MTWA positive [95%CI: (23%, 63%)] (P=0.03). The subjects who were MTWA positive after HDTB compared with MTWA negative subjects had an increased versus decreased sympathetic responsiveness (P=0.03) and serum norepinephrine levels (P=0.05), and a trend toward higher potassium excretion (P=0.06) after bed rest compared to baseline.</AbstractText>HDTB leads to an increase in MTWA, providing the first evidence that simulated microgravity has a measurable effect on electrical repolarization processes. Possible contributing factors include loss in potassium and changes in sympathetic function.</AbstractText>

The impact of catecholamines in patients with or without beta-blockers on the ventricular fibrillation cycle length and ventricular fibrillation cycle length variability.

To evaluate the impact of epinephrine, norepinephrine, or placebo on the ventricular fibrillation cycle length (VFCL) and the variability of VFCL (cvVFCL) measurements in implantable cardioverter defibrillator (ICD) patients with or without beta-blockers.</AbstractText>Forty-three patients scheduled for their 6-week post-ICD placement noninvasive electrophysiologic study were included in the study at the Arrhythmia Procedure Laboratory at Hartford Hospital, Hartford, CT. This randomized, double-blind, placebo-controlled evaluation was approved by the Hartford Hospital Institutional Review Board.</AbstractText>After 2 seconds of continuous VF, 7 consecutive VFCLs were measured from the ICD device recording printout using a 0.5 mm scale ruler under magnification at baseline and after the infusion of catecholamines (epinephrine or norepinephrine at 2 mcg/min) or matching placebo at steady state. The average VFCL and the cvVFCL were determined for each study phase. Subgroup analysis based on chronic beta-blocker use was performed. No between-group differences were noted for epinephrine, norepinephrine, or placebo group for baseline (P=0.538) or postinfusion VFCL (P=0.749) or for baseline (P=0.561) or postinfusion cvVFCL (P=0.623) Regardless of catecholamine group randomization, longer pre- and postinfusion VFCL were noted in those receiving beta-blockers (P=0.157, P=0.019) but no differences in cvVFCL were noted (P=0.216, P=0.474) versus those without beta-blockers, respectively.</AbstractText>Moderately dosed epinephrine or norepinephrine does not affect either VFCL or the variability of VFCL after short duration of ventricular fibrillation. Chronic cardioselective beta-blockade prolongs VFCL without any impact on coefficient of variation of VFCL.</AbstractText>

[Successful weaning from cardiopulmonary bypass with administration of landiolol hydrochloride in a patient with hypertrophic obstructive cardiomyopathy].

A 14-yr-old boy with hypertrophic obstructive cardiomyopathy, undergoing percutaneous transluminal septal myocardial ablation suffered dissection of the left main coronary artery during the procedure. Sixty minutes after absolute ethanol administration, he was transferred to the operating room for emergency coronary artery bypass grafting, mitral valve replacement and cardiomyectomy. Transesophageal echocardiography (TEE) findings after the induction of anesthesia were: general hypokinesis, mitral regurgitation 1+, left ventricular outflow tract pressure gradient of 11 mmHg and no blood flow in the left anterior descending coronary artery. On aorta declamping, ECG showed ventricular fibrillation and ventricular tachycardia, and the sinus rhythm was restored after 100 mg lidocaine i.v. and DC conversion. TEE revealed severe hypokinesis in antero-septal and hypokinesis in posterolateral wall, respectively. Since supraventricular tachycardia (HR 130 140 bpm) disabled the intraaortic balloon pump (IABP) synchronization, HR was maintained 90-100 bpm with landiolol hydrochloride (10-40 micrograms x kg(-1) min(-1)) and synchronization was obtained. Systolic BP was maintained 90-120 mmHg with norepinephrine (0.2-0.3 micrograms x kg(-1) x min(-1)) and the patient could be successfully weaned from CPB with cardiac index 2.0 and mixed venous oxygen saturation 59%. On the 2nd postoperative day (POD), he was weaned from IABP and ventilator. On the 6 th POD, he was discharged from the ICU.

Radiofrequency catheter ablation of accessory pathways during pre-excited atrial fibrillation: acute success rate and long-term clinical follow-up results as compared to those patients undergoing successful catheter ablation during sinus rhythm.

The onset of recurrent or sustained atrial fibrillation (AF) is common during electrophysiological (EP) studies of accessory pathways (AP). We report our experience in patients with Wolff-Parkinson-White (WPW) syndrome in whom AF with rapid antegrade conduction over the AP occurred during an EP study and mapping and ablation were done during sustained AF, as compared to patients ablated during sinus rhythm. The study group consisted of 18 patients (group 1) with WPW syndrome who underwent catheter ablation during pre-excited AF. Two hundred and sixty-three patients, comparable for clinical characteristics, whose manifest APs were ablated under sinus rhythm formed the control group (group 2). Bipolar electrogram criteria recorded from the ablation catheter showing early ventricular activation relative to the delta wave on the surface ECG and AP potentials preceding the onset of ventricular activation were used as targets for ablation. Clinically documented atrial fibrillation was significantly more frequent and antegrade ERP of AP was significantly shorter in group 1 than in group 2 (39% vs 14%, P=0.014 and 268+/-37 vs 283+/-16, P&lt;0.001, respectively). Procedure-related variables, acute success rates (17/18 [94%] in group 1, 251/263 [95%] in group 2; P&gt;0.05) and late recurrence rates (0/18 [0%] in group 1 vs 5/263 [2%] in group 2; P&gt;0.05) during a mean follow-up of 25+/-9 months (range 8-52 months) did not differ significantly. Our results show that both right- and left-sided accessory pathways can be mapped and ablated safely during pre-excited AF without delay, and that acute success and recurrence rates and long-term follow-up results are similar to those of pathways ablated during sinus rhythm.

Cholestatic liver disease modulates susceptibility to ischemia/reperfusion-induced arrhythmia, but not necrosis and hemodynamic instability: the role of endogenous opioid peptides.

<AbstractText Label="BACKGROUND/AIMS" NlmCategory="OBJECTIVE">Acute cholestasis is associated with cardiovascular complications, which mainly manifest during stressful conditions. The goal of this study is to evaluate susceptibility of 7-day bile duct-ligated rats to ischemia/reperfusion-induced injury.</AbstractText>Sham-operated and cholestatic rats, treated with daily normal saline, L-NAME (a non-selective NO synthase inhibitor) naltrexone, or both L-NAME and naltrexone were subjected to 30 min of ischemia followed by 2 h of reperfusion.</AbstractText>Cholestatic rats demonstrated significant bradycardia, hypotension (P &lt; 0.01), and QT prolongation (P &lt; 0.001). The incidence of premature ventricular contractions (P &lt; 0.01), incidence and duration of ventricular tachycardia (P &lt; 0.05), but not ventricular fibrillation, were significantly lower in cholestatic rats. There was no significant difference in hemodynamic instability and infarct size between the groups. L-NAME corrected QT prolongation in cholestatic rats (P &lt; 0.05), with no effect on heart rate, blood pressure and arrhythmia. Naltrexone restored normal heart rate (P &lt; 0.05), blood pressure (P &lt; 0.05) and susceptibility to arrhythmia (P &lt; 0.05) in cholestatic animals, with no significant effect on QT interval. L-NAME and naltrexone co-administration corrected bradycardia (P &lt; 0.05), hypotension (P &lt; 0.05), QT prolongation (P &lt; 0.05) and abolished resistance of cholestatic rats against arrhythmia (P &lt; 0.05).</AbstractText>This study suggests that short-term cholestasis is associated with resistance against ischemia/reperfusion-induced arrhythmia, which depends on availability of endogenous opioids.</AbstractText>

QRS duration does not predict occurrence of ventricular tachyarrhythmias in patients with implanted cardioverter-defibrillators.

The aim of this study was to determine whether QRS duration (QRSd) correlates with occurrence of ventricular arrhythmia in patients with coronary disease (CAD) receiving implantable cardioverter-defibrillators (ICDs).</AbstractText>A QRSd measured on a standard electrocardiograph (ECG) correlates with total mortality risk in CAD patients at high risk for sudden death; however, the relationship between QRSd and risk of ventricular tachyarrhythmias (ventricular tachycardia/ventricular fibrillation [VT/VF]) is unclear.</AbstractText>PainFREE Rx II was a randomized trial, comparing efficacy of antitachycardia pacing versus shock therapy for VT/VF in patients receiving ICDs. We retrospectively correlated the QRSd and specific ECG conduction abnormalities on the 12-lead ECG at study entry with occurrence of VT/VF in 431 patients with CAD enrolled in the trial.</AbstractText>The QRSd was &lt; or =120 ms in 291 of 431 (68%) patients. Left bundle branch block (LBBB) was present in 65 patients, right bundle branch block (RBBB) in 48 patients, and nonspecific intraventricular conduction delay (IVCD) was present in 124 patients. Over 12 months' follow-up, VT/VF occurred in 95 (22%) patients (22% of patients with QRSd &lt; or =120 ms vs. 23% of patients with QRSd &gt;120 ms, p = NS). Patients with LBBB were less likely to experience at least one VT/VF episode than patients with QRSd &lt;120 ms. Patients with RBBB and nonspecific IVCD did not differ from patients with narrow QRS complexes with regard to occurrence of tachycardias.</AbstractText>The QRSd and ECG conduction abnormalities are not useful to predict ICD benefit in patients having the characteristics of our study population. The utility of QRSd to predict VT/VF events in patients with CAD requires further prospective evaluation.</AbstractText>

[Analysis of arrhythmias in immediate post-operative period of cardiovascular surgery].

Cardiac arrhythmias are one of the most frequent complications in the immediate post-operatory period of cardiac surgery with extracorporeal circulation, this occurring in between 35% and 50% of the patients subjected to this therapeutic intervention. Among the causal factors, electrolytic alterations, direct surgical aggression on the heart tissue and alterations secondary to ischemic cell damage that is produced in the myocardial during extracorporeal circulation are found. Due to the frequency of appearance of arrhythmias, we decided to study them and know them in depth. Thus, the objective of our study was to know the incidence and prevalence of arrhythmias during the immediate post-operatory period of cardiovascular surgery. Out of all those admitted to the unit, all the patients who had undergone valvular and coronary surgery with a stay in the intensive care unit of the University Hospital Marques de Valdecilla that did not exceed 7 days were selected. This means 258 patients, the most frequent alterations during the post-operative period being right branch blockage (16%), atrial fibrillation (12%), ventricular tachycardy (7%), atrial ventricular block (4%), among other rhythm and conduction alterations. As conclusions, we stress that the most frequent alterations during the immediate post-operative period were branch blocks, arrhythmia being more prevalent than atrial fibrillation. A total of 85% of the patients undergoing valvular replacement and 89% of those operated on for coronary derivation plus valvular replacement had more arrhythmia episodes than the rest.

[Management of cardiac arrest in a German soccer stadium. Structural, process and outcome quality].

In Germany there is a lack of data about the quality of emergency medical care in mass gatherings. The following report reflects our experience with management of cardiac arrest events as an example for the most critical medical emergency in a soccer stadium.</AbstractText>The Fritz-Walter Stadium is a well-known soccer arena with a crowd capacity of 46,600. Emergency medical care is provided by a 2-tiered system consisting of 3 emergency physicians and 65 ambulance personnel and paramedics. Resuscitation was conducted according to the guidelines of the European Resuscitation Council and American Heart Association.</AbstractText>Within 80 months, 13 witnessed cardiac arrests occurred, all in males. In each case the initial rhythm was ventricular fibrillation, 6 patients collapsed before or after the match. Basic life support was usually provided within 2 min, defibrillation and advanced life support within 4 min, 77% regained spontaneous circulation, and 62% survived without neurologic deficits.</AbstractText>Cardiac arrest is a relatively frequent event in a soccer stadium. Due to a well organised response system, the survival rate exceeded by far the corresponding figures reported by public health systems.</AbstractText>

An autopsy case of isolated eosinophilic coronary periarteritis: a limited form of Churg-Strauss syndrome or a new entity?

A 52-year-old man without a history of asthma or allergic diseases died of ventricular fibrillation early in the morning. His autopsy revealed no significant findings, except for a mild mural-thickening localized at the proximal region of the right coronary artery. Microscopic examination showed periarteritis with infiltration of numerous eosinophils in the adventitia. No significant vasculitis was found in any other organs. Based on the findings this seems to be the second reported case of isolated eosinophilic coronary periarteritis.

Successful radiofrequency catheter ablation of idiopathic ventricular fibrillation presented as recurrent syncope and diagnosed by an implanted loop recorder.

As a palliative therapy, an implantable cardioverter-defibrillator (ICD) could not prevent the occurrence of ventricular tachycardia or fibrillation (VT, VF), but only suppress it by overdrive pacing or direct current shocks. Recurrent VT or VF followed by frequent ICD shocks might thus put patients in a painful disaster. We presented a case of recurrent syncope diagnosed as recurrent VF by an implanted loop recorder (ILR). The VF was eliminated by radiofrequency catheter ablation (RFCA) of triggering ventricular premature complexes (VPCs).

The effects of pulsatile versus non-pulsatile extracorporeal circulation on the pattern of coronary artery blood flow during cardiac arrest.

In sudden cardiac arrest, the effective maintenance of coronary artery blood flow is of paramount importance for myocardial preservation as well as cardiac recovery and patient survival. The purpose of this study was to directly compare the effects of pulsatile versus non-pulsatile circulation to coronary artery flow and myocardial preservation in a cardiac arrest condition.</AbstractText>A cardiopulmonary bypass circuit was constructed in a ventricular fibrillation model using fourteen Yorkshire swine weighing 25-35 kg each. The animals were randomly assigned to group I (n=7, non-pulsatile centrifugal pump) or group II (n=7, pulsatile T-PLS pump). Extracorporeal circulation was maintained for two hours at a pump flow of 2 L/min. The left anterior descending coronary artery flow was measured with an ultrasonic coronary artery flow measurement system at baseline (before bypass) and at every 20 minutes after bypass. Serologic parameters were collected simultaneously at baseline, 1 hour, and 2 hours after bypass in the systemic arterial and coronary sinus venous blood. The Mann-Whitney U test of STATISTICA 6.0 was used to determine intergroup significances using a p value of &lt;0.05.</AbstractText>The resistance index of the coronary artery was lower in group II and the difference was significant at 40 min, 80 min, 100 min and 120 min (p&lt;0.05). The mean velocity of the coronary artery was higher in group II throughout the study, and the difference was significant from 20 min after starting the pump (p&lt;0.05). The coronary artery blood flow was higher in group II throughout the study, and the difference was significant from 40 min to 120 min (p&lt;0.05) except at 80 min. Serologic parameters showed no differences between the groups at 1 hour and 2 hours after bypass in the systemic and coronary sinus blood (p=NS).</AbstractText>In the cardiac arrest condition, pulsatile extracorporeal circulation provides more blood flow, higher flow velocity and less resistance to coronary artery than non-pulsatile circulation.</AbstractText>

Apical hypertrophic cardiomyopathy: a case of slow flow in lad and malign ventricular arrhythmia.

The coronary slow flow phenomenon is an angiographic finding characterized by delayed distal vessel opacification in the absence of epicardial coronary artery disease. Patients often present with acute coronary syndrome. Histopathologic studies have revealed the existence of fibromuscular hyperplasia and myofibrilar hypertrophy. Apical hypertrophic cardiomyopathy is a benign progressive form of hypertrophic cardiomyopathy, that is rarely observed in western communities. It remains commonly asymptomatic until advanced ages. Syncope, arrhythmia or sudden death may be the first symptom. We report a case of slow coronary arterial flow in a 71-year-old male patient with apical hypertrophic cardiomyopathy who experienced chest pain and sudden cardiac arrest due to ventricular arrhythmia.

Single-chamber versus dual-chamber pacing for high-grade atrioventricular block.

In the treatment of atrioventricular block, dual-chamber cardiac pacing is thought to confer a clinical benefit as compared with single-chamber ventricular pacing, but the supporting evidence is mainly from retrospective studies. Uncertainty persists regarding the true benefits of dual-chamber pacing, particularly in the elderly, in whom it is used less often than in younger patients.</AbstractText>In a multicenter, randomized, parallel-group trial, 2021 patients 70 years of age or older who were undergoing their first pacemaker implant for high-grade atrioventricular block were randomly assigned to receive a single-chamber ventricular pacemaker (1009 patients) or a dual-chamber pacemaker (1012 patients). In the single-chamber group, patients were randomly assigned to receive either fixed-rate pacing (504 patients) or rate-adaptive pacing (505 patients). The primary outcome was death from all causes. Secondary outcomes included atrial fibrillation, heart failure, and a composite of stroke, transient ischemic attack, or other thromboembolism.</AbstractText>The median follow-up period was 4.6 years for mortality and 3 years for other cardiovascular events. The mean annual mortality rate was 7.2 percent in the single-chamber group and 7.4 percent in the dual-chamber group (hazard ratio, 0.96; 95 percent confidence interval, 0.83 to 1.11). We found no significant differences between the group with single-chamber pacing and that with dual-chamber pacing in the rates of atrial fibrillation, heart failure, or a composite of stroke, transient ischemic attack, or other thromboembolism.</AbstractText>In elderly patients with high-grade atrioventricular block, the pacing mode does not influence the rate of death from all causes during the first five years or the incidence of cardiovascular events during the first three years after implantation of a pacemaker.</AbstractText>Copyright 2005 Massachusetts Medical Society.</CopyrightInformation>

Survival of dialysis patients after cardiac arrest and the impact of implantable cardioverter defibrillators.

Sudden cardiac death is the single largest cause of mortality in dialysis patients. There are no published data on the use or survival impact of implantable cardioverter defibrillators (ICDs) in dialysis patients. The objective of this retrospective cohort study was to determine ICD use in dialysis patients and impact on survival.</AbstractText>Dialysis patients hospitalized from 1996 to 2001 for ventricular fibrillation/cardiac arrest, having ICD implantation within 30 days of admission, discharged alive, and surviving at least 30 days from admission were identified from the 100% end-stage renal disease (ESRD) sample of the Medicare database. Long-term survival was estimated by life-table method. Impact of independent predictors on survival was examined in a comorbidity-adjusted Cox model and a propensity model.</AbstractText>There were 460 patients (7.6%) with ICD and 5582 patients (92.4%) without ICD. Estimated 1-, 2-, 3-, 4-, and 5-year survivals after day 30 of admission in the ICD group were 71%, 53%, 36%, 25%, and 22%, respectively; in the no-ICD group, 49%, 33%, 23%, 16%, and 12% (P &lt; 0.0001). ICD implantation was independently associated with a 42% reduction in death risk [relative risk 0.58 (95% CI 0.50, 0.66)]. In the propensity model, the relative risks of death for the lower, middle, and upper third propensity groups were 0.45 (0.26, 0.81), 0.61 (0.45, 0.84), and 0.65 (0.55, 0.76), respectively. The C statistic for the propensity model equaled 0.81.</AbstractText>In dialysis patients, ICD therapy is apparently underused. ICD implantation in cardiac arrest survivors on dialysis is associated with greater survival.</AbstractText>

[Outpatient treatment of recurrent atrial fibrillation with the "pill-in-the-pocket" approach: practical aspects].

In patients with not very frequent episodes of atrial fibrillation (AF), highly symptomatic for palpitation, hemodynamically well tolerated but long enough to require emergency room (ER) intervention, the best outpatient treatment appears to be the "pill-in-the-pocket" approach. In several studies, in-hospital administration of flecainide or propafenone in a single oral loading dose has been shown to be effective and superior to placebo in terminating recent-onset AF. Recently, a multicenter Italian study has been carried out to evaluate the feasibility and the safety of self-administered oral loading of flecainide or propafenone in terminating AF of recent onset outside the hospital. Either flecainide or propafenone were administered orally to restore sinus rhythm in 268 patients with mild heart disease or none, who came to the ER with AF of recent onset that was hemodynamically well tolerated. Of these patients, 21% were excluded from the study because of treatment failure or side effects. During a mean follow-up of 15 months, 94% of the arrhythmic episodes were interrupted by the oral loading of flecainide or propafenone; the mean time to resolution of symptoms was about 2 hours. Adverse effects were reported during one or more arrhythmic episodes by 7% of the patients, including atrial flutter at a rapid ventricular rate in 1 patient. The numbers of monthly visits to the ER and hospitalizations were 90% lower during follow-up than the year before enrollment. These results show that in a selected, risk-stratified population of patients with recurrent AF, the "pill-in-the-pocket" treatment is feasible and safe, with a high rate of compliance by patients, a low rate of adverse effects, and a marked reduction in ER visits. Some recommendations on the practical use of this type of treatment are given.

[Mathematical model of cardiac action potential and its computer simulations].

Malignant arrhythmias and ventricular fibrillation are generally accepted as one of the major causes of death in cardiovascular diseases. Based on the H-H equations, the mathematical model of the cardiac cell action potential consists of the ion channels, pumps, exchangers and transporters that are closely connected with intra- and extra-cellular ion concentrations, the channel's conditions, nerve transductors and drugs. It can build the link between cell electrophysiology and clinical pathophysiology. By altering the cellular environments the computer simulating study on this kind of model can help us look into the electrophysiological changes of the cardiac tissue and even the whole heart and investigate the mechanisms of the cardiac arrhythmias as well. The components of the model and its computer simulating study are introduced in the paper.

[Spontaneous rupture of common iliac artery after hysterectomy for malignant gynecologic tumor].

Authors described a serious, iatrogenic, vessel complications after hysterectomy for uterus sarcoma. After successful abdominal hysterectomy spontaneous rupture of right common iliac artery occurred causing massive exsanguination into intraperitoneal space. During secondary laparotomy procedure large, partial loss of arterial wall was recognized and provided with non-absorbable Prolene 4-0 suture. Subsequently, the injury was replaced by arterial artificial prosthesis gore-tec 8. Intraoperatively, ventricular fibrillation and cardiac arrest took place with subsequent acute respiratory and circulatory distress syndrome. Throughout next several days after reoperation patient was deep unconscious and hospitalized on Intensive Care Unit. She manifested symptoms of damaged extrapyramidal tracts. In spite of further unfavourable prognosis, after almost a month of respiratory therapy, she fully recovered without symptoms of brain damage and visual sequelae.

Dronedarone (Sanofi-Synth&#xe9;labo).

Sanofi-Synthelabo (formerly Sanofi) is developing the class III antiarrhythmic agent, dronedarone, for the potential treatment of atrial fibrillation and ventricular tachycardia [157842]. Phase III trials for the treatment of arrhythmia are planned for 2001 [399945]. By December 1998, phase IIb trials for the treatment of cardiac arrhythmia had been initiated [295681,320585], and the compound was shown to have the same efficacy as, and better tolerability than amiodarone [330073]. By 1997, the compound had entered phase IIa trials in Europe [219077,295681]. In November 1997, Sanofi expected to file for marketing in 2001/2 [270242]. ABN Amro predicted sales of FFR 50 million in 2001, rising to FFR 150 million in 2002 [317536]. Lehman Brothers predicted a 20% chance of the compound reaching market, with a launch anticipated in 2003 and potential peak sales of $200 million in 2011 [346267].

Postmortem anatomy of the coronary sinus pacing lead.

Biventricular pacing nowadays represents a recognized method of nonpharmacological treatment of severe congestive heart failure refractory to medication. A growing number of biventricular implants is likely to bring an increasing demand for the extraction of specially designed coronary sinus (CS) leads for left ventricular pacing. There is a lot of data regarding conventional pacing or defibrillation lead extractions, but only very limited experience with the CS lead extractions. We describe the pathological-anatomical findings of a woman who died after 26 months postimplantation due to refractory ventricular fibrillation with focus on the left ventricular pacing lead course and feasibility of extraction.

Characteristics and relevance of clustering ventricular arrhythmias in defibrillator recipients.

Studies of recurrent ventricular tachycardia and ventricular fibrillation (VT/VF) have been limited to "electrical storms," where recurrent arrhythmias necessitate repeated external cardioversions or defibrillations. Patients with an implantable cardioverter-defibrillator (ICD) may also suffer frequently recurrent arrhythmias. The aim of this study was to analyze the temporal pattern and the clinical relevance of clustering ventricular arrhythmias in ICD recipients.</AbstractText>The incidence and the type of arrhythmias were determined by reviewing stored electrograms. VT/VF clusters were defined as the occurrence of three or more adequate and successful ICD interventions within 2 weeks. Two hundred and fourteen consecutive ICD recipients were followed during an average of 3.3 +/- 2.2 years (698 patient-years).</AbstractText>Fifty-one patients (24%) suffered 98 VT/VF clusters 21 +/- 22 months after ICD implantation, 93% of these clusters consisting of recurrent regular VT. Monomorphic VT as index event leading to ICD implantation was the only factor predicting VT/VF clusters. Kaplan-Meier estimates of the combined end-point of death or heart transplantation showed a 5-year event-free survival of 67% versus 87% in patients with and without clusters, respectively (P = 0.026). Adjusted hazard ratios for death or heart transplantation in the group with arrhythmia clusters was 3.5 (95% confidence interval 1.5-7.9 P = 0.003).</AbstractText>VT/VF clusters are frequent late after ICD implantation particularly in patients who had VT as index-event. As arrhythmias and recurrent ICD interventions are responsible for an important morbidity, there is a possible role for a prophylactic intervention. Furthermore, VT/VF clusters are an independent marker of increased risk of death or need for heart transplantation.</AbstractText>

Effect of concomitant antiarrhythmic therapy on survival in patients with implantable cardioverter defibrillators.

Application of implantable cardioverter defibrillator (ICD) therapy is expanding to include both primary and secondary prevention of sudden cardiac death and has been proven to be superior to conventional antiarrhythmic therapies. Concomitant antiarrhythmic drug therapy in patients with ICD is common. These drugs are potentially proarrhythmic, alter defibrillation thresholds, and may affect response to device therapy. However, the impact of concomitant antiarrhythmic drug therapy on survival in patients with ICD devices is unknown.</AbstractText>We investigated the effect of different antiarrhythmic drugs on survival when given concomitantly in 360 consecutive ICD patients from our university medical center. Mortality data were obtained from the national death index. Survival analysis was performed using the Kaplan-Meier method. Corrections for significant covariates and group differences were made using the Cox regression model.</AbstractText>Patients were followed up for 4.4 +/- 3.7 years. There were 68 deaths over this period with a 5-year survival of 80%. Patient characteristics were: age 62 +/- 13 years, left ventricular (LV) ejection fraction (EF) 33 +/- 17%, ischemic etiology of LV dysfunction 68%, diabetes mellitus 19%, hypertension 49%, atrial fibrillation 23%, digoxin 43%, beta-blocker 46%, amiodarone 28%, and sotalol 9%. The use of beta-blockers was associated with a better survival (P = 0.0005). This effect persisted after correcting for age, heart rate, EF, and ischemic etiology. The beneficial effect of beta-blocker was unrelated to its effect on heart rate. Digoxin use was associated with a lower survival only on univariate analysis (P = 0.006), but not after adjusting for other variables on a Cox regression model (P = 0.093). Amiodarone and sotalol were found to have a neutral effect on survival.</AbstractText>In patients with ICDs, beta-blockers had a favorable effect on survival. Sotalol and amiodarone had a neutral effect on survival. There was a trend toward a deleterious effect with digoxin use. These findings suggest a need for further investigation addressing survival effects of antiarrhythmic drugs when given concomitantly in patients with ICDs.</AbstractText>

Ventricular fibrillation frequency.

Ventricular-fibrillation (VF) wave frequency is known to decrease with prolonged, untreated VF. VF wave frequency is used as an algorithm to identify VF in AEDs and ICDs; yet the nature of the frequency change is not appreciated.</AbstractText>In this study, anesthetized pigs were used and VF was induced electrically. VF wave frequency was measured each second during VF for periods up to 200 sec. Defibrillation was achieved with transchest electrodes. VF wave frequency was plotted for each second during VF. In 2 animals, CPR was applied and VF wave frequency was measured.</AbstractText>In all cases VF wave frequency decreased with increasing duration of VF. At the onset of VF, the VF wave frequency ranged from 5 to 12/sec. A plot of the normalized ratio of VF wave frequency during fibrillation to the VF frequency at induction decreased to between 0.1 and 0.8 of the initial frequency. In one of the animals, VF was initiated, CPR was provided and the VF wave frequency was measured over a 200-second period. Then, the procedure was repeated without CPR. Beyond 130 seconds, the VF frequency with CPR was higher than that without CPR, indicating myocardial oxygenation.</AbstractText>Those who use VF wave frequency to identify the presence of VF should be aware of the nature of the VF wave frequency decrease with the passage of time.</AbstractText>

[Atrial fibrillation during myocardial infarction with and without ST segment elevation].

The occurrence of atrial fibrillation (AF) in the acute phase of myocardial infarction with ST segment elevation is common and responsible for an excess hospital mortality. The aim of this work was to define the incidence, predictive factors, and the prognostic impact of AF during MI with and without raised ST segment in the RICO study.</AbstractText>Between January 2001 and July 2003, 1701 patients were included in this study: 130 (7.6%) had AF in the first 24 hours of management (AF+ group); 1571 (92.4%) remained in sinus rhythm (AF- group).</AbstractText>Among the 1701 patients included in this study, 1197 (70.4%) had MI with raised ST and 504 (29.6%) had MI without raised ST. The incidence of AF was identical whatever the type of MI (7.6% with raised ST versus 7.7% without, p=0.334). The presence of Killip class &gt;2 on admission and chronic obstructive pulmonary disease were independent predictive factors for the occurrence of AF (OR=3.84, p=0.007, and OR=2.47, p=0.014 respectively). The presence of AF was significantly associated with the occurrence of ventricular arrhythmia and/or cardiovascular mortality during admission in the non-selected MI population whatever the type of MI (raised ST ; AF+; 34% and AF-; 18%, p&lt;0.01 versus without raised ST; AF+; 36% and AF-; 16%, p = 0.01).</AbstractText>This study provides evidence that the incidence of AF during the first 24 hours of MI, as well as its poor prognosis, are identical whether or not there is ST segment elevation.</AbstractText>

[Analysis of the intra-hospital attending of ventricular fibrilation/ventricular taquicardia simulated events].

To analyze the time intervals between the beginning of the Ventricular Fibrilation/Ventricular Taquicardia (VF/VT) and the main procedures made.</AbstractText>Twenty VF/VT simulations were performed and filmed in a hospital environment, using a static mannequin, on random days at random times. All teams had the same level of skills. The times (in sec.) related to basic life support (BLS) - arrival of the team (AT), confirmation of the arrest (CAT), beginning of the CPR (IT) and the times related to the advanced life support (ALS) - 1st defibrillation (DT), 1st dose of adrenalin (AT) and orotracheal intubation (OTIT). The variables were analyzed and compared in two groups: intensive care unit (ICU) and wards with telemetry (TLW).</AbstractText>The results in both groups was in that order (GW x ICU ) - AT (70.2+38.7 x 38.6+49.2); CCA (89.4+57.1 x 71+63.9); SC (166.8+81.1 x 142+66.2); FD (282.5+142.8 x 108.4+52.5); FE (401.4+161.7 x 263.3+122.8) e OI (470.3+150.6 x 278.8+98.8). Shows the comparison of the average times between the two groups.</AbstractText>The differences noted in relation to DT, AT and OTIT favorable to ICU are associated to the facility of performance of the ALS maneuvers in such environment. The BLS-related times were similar in both groups, which reinforce the need for the use of semi-automatic defibrillators, even in a hospital environment.</AbstractText>

Canine model of paroxysmal atrial fibrillation and paroxysmal atrial tachycardia.

Both autonomic nerve activity and electrical remodeling are important in atrial arrhythmogenesis. Therefore, dogs with sympathetic hyperinnervation, myocardial infarction (MI), and complete atrioventricular block (CAVB) may have a high incidence of atrial arrhythmias. We studied eight dogs (experimental group) with MI, CAVB, and sympathetic hyperinnervation induced either by nerve growth factor infusion (n = 4 dogs) or subthreshold electrical stimulation (n = 4 dogs) of the left stellate ganglion. Cardiac rhythm was continuously monitored by a Data Sciences International transmitter for 48 (SD 27) days. Three normal control dogs were also monitored. Six additional normal dogs were used for histology control. Paroxysmal atrial fibrillation (PAF) and paroxysmal atrial tachycardia (PAT) were documented in all dogs in the experimental group, with an average of 3.8 (SD 3) episodes/day, including 1.3 (SD 1.6) episodes of PAF and 2.5 (SD 2.2) episodes of PAT. The duration averaged 298 (SD 745) s (range, 7-4,000 s). There was a circadian pattern of arrhythmia onset (P &lt; 0.01). Of 576 episodes of PAF and PAT, 236 (41%) episodes occurred during either sustained or nonsustained ventricular tachycardia (VT). Among these 236 episodes, 53% started before VT, whereas 47% started after the onset of VT. Normal dogs did not have either PAF or PAT. The hearts from the experimental group had a higher density of nerve structures immunopositive (P &lt; 0.01) for three different nerve specific markers in both right and left atria than those of the control dogs. We conclude that the induction of nerve sprouting and sympathetic hyperinnervation in dogs with CAVB and MI creates a high yield model of PAF and PAT.

Inter-atrial conduction time shortens after blood pressure control in hypertensive patients with left ventricular hypertrophy.

Assuming that blood pressure control could induce a shortening of the inter-atrial conduction time and prevent atrial fibrillation occurrence, we studied the inter-atrial conduction time in hypertensive patients with left ventricular hypertrophy.</AbstractText>Sixty-eight (26 male) 58.34+/-8.08-year-old patient participated in the study. All were in sinus rhythm and had abnormal blood pressure (163+/-18/95+/-9 mm Hg). Their cardiac mass index was increased (151+/-43 g/m(2) SC) and their left atrial dimension was normal (3.67+/-0.54 cm). The inter-atrial conduction time was measured in the echocardiogram from the beginning of the electrocardiographic P wave to the beginning of the A wave in the mitral Doppler signal and was corrected for heart rate. Heart rhythm disturbances were monitored clinically and by means of a Holter. Most patients were treated with angiotensin antagonists.</AbstractText>It was found that arterial blood pressure decreased significantly after treatment and that the P-A interval was significantly reduced (71.4+/-14.5 vs. 63.9+/-11.5 ms). During the follow-up, no patient complained of arrhythmia symptoms or exhibited atrial fibrillation in the Holter recording.</AbstractText>In this selected group of patients with hypertensive heart disease (left ventricular hypertrophy), an effective blood pressure control was accompanied by a significant decrease in the inter-atrial conduction time. It is possible that these effects prevent atrial fibrillation.</AbstractText>

Fuzzy logic and continuous cellular automata in warfarin dosing of stroke patients.

"Evidence-based" recommendations for warfarin prescription in patients with history of ischemic stroke limit its use to prevention of stroke due to atrial fibrillation. Warfarin is also prescribed by the authors to prevent thrombosis in stroke patients with thrombophilia and potential cardiac or arterial source for thromboembolism. These potential conditions, in the face of thrombophilia, include, but may not be limited to, dilated cardiomyopathy, decreased left ventricular function, atrial septal aneurysm with or without patent foramen ovale (PFO), PFO with evidence of pelvic or lower extremity deep venous thrombosis or with clear thrombophilia, spontaneous echocardiographic contrast, intracardiac or intra-arterial thrombus, intra-aortic arch thrombus, high degree of stenosis of large- and medium-sized cerebrovascular arteries, and arterial dissection. Commonly diagnosed thrombophilic states in our population currently include protein S or C deficiency, antiphospholipid antibodies, and less commonly ATIII deficiency, factor V Leiden mutation, G20210A PT mutation, and plasminogen activator inhibitor-1 mutation. Thrombophilic states often occur in combination. The occurrence of combined arterial, cardiac, and thrombophilic sources of thromboembolism poignantly describes the complexity of causation of ischemic stroke in any one patient. Our practice of treating the complex interaction of thromboembolic sources is based on scientific evidence, which is not arbitrarily limited to probability-based statistics. Warfarin is well known in the clinical setting to interact with many different contextual factors of the individual patient, making its dosing and response unique to that patient. We have shown why the indications for warfarin use and its dosing cannot be directly extrapolated to the individual patient from the results of large, double-blind, randomized trials. In practice, the unique patient and his or her context must be considered by the expert physician who makes the therapeutic decision. The context includes, but is not limited to, known pathologies that contribute to thrombus formation according to the accepted pathophysiologic model of thrombosis based on Virchow's triad of altered flow, endothelium, and blood components.

Is there an overlap between Brugada syndrome and arrhythmogenic right ventricular cardiomyopathy/dysplasia?

The Brugada syndrome is a congenital syndrome displaying an autosomal dominant mode of transmission in patients with a structurally normal heart. The disease has been linked to mutations in SCN5A , a gene located on the short arm of chromosome 3 (p21-24) that encodes for the alpha subunit of the sodium channel. The syndrome is characterized by a dynamic ST-segment elevation (accentuated J wave) in leads V 1 to V 3 of the ECG followed by negative T wave. Right bundle-branch block of varying degrees is observed in some patients. The syndrome is associated with syncope and a relatively high incidence of sudden cardiac death secondary to the development of polymorphic ventricular tachycardia that may degenerate into ventricular fibrillation. An acquired form of the Brugada syndrome is also recognized, caused by a wide variety of drugs and conditions that alter the balance of currents active during the early phases of the action potential. Among patients with arrhythmogenic right ventricular cardiomyopathy/dysplasia, there is a subpopulation with a clinical and electrocardiographic pattern similar to that of the Brugada syndrome. These cases of arrhythmogenic right ventricular cardiomyopathy/dysplasia are thought to represent an early or concealed form of the disease. This review examines the overlap between these 2 syndromes.

Diagnostic performance of a computer-based ECG rhythm algorithm.

We examined the accuracy of computer-based rhythm interpretation from one electrocardiograph manufacturer (GE Healthcare Technologies MUSE software 005C) in 4297 consecutive recordings in a university hospital setting. Overreading was performed by either of 2 experienced cardiologists, and all disagreements with the initial computer rhythm statement were reviewed by the second cardiologist to achieve physician consensus used as the "gold standard" for rhythm diagnosis. Overall, 13.2% (565/4297) of computer-based rhythm statements required revision, but excluding tracings with pacemakers, the revision rate was 7.8% (307/3954), including 3.8% involving the primary rhythm diagnosis and 3.9% involving definition of ectopic complexes. The false-negative rate for sinus rhythm was only 1.3%, but a computer diagnosis of sinus rhythm was incorrect in 9.9% of other rhythms. The false-negative rate for atrial fibrillation was 9.2%, whereas a computer diagnosis of atrial fibrillation was incorrect in 1.1% of other rhythms, including sinus. Computer diagnosis of paced rhythms remains problematic, and physician overreading to correct computer-based electrocardiogram rhythm diagnoses remains mandatory.

New model of ventricular fibrillation.

The purpose of this study was to develop a more efficient and stable model of ventricular fibrillation (VF) in the isolated rabbit heart, because there is not a satisfactory model with this animal. We also observed the effects of increasing extracellular calcium in the stability and reversibility of the arrhythmia. After suspending the hearts in a classical Langendorff preparation, VF was induced by burst stimulation (current = 2.0 mA, pulse duration = 3 milliseconds, frequency = 50 Hz, voltage = 10 V, duration of stimulation = 5 minutes). The hearts were then divided into 2 groups, A and B. The hearts in group B were perfused with a modified Krebs-Henseleit solution, which contained twice as much calcium as the solution used in the other group. The rate of success with this model was 100% for both groups. The hearts fibrillated up to 30 minutes in group A and more than 40 minutes in group B, longer then all studies ever published in rabbit hearts. Ventricular fibrillation reverted to sinus rhythm in 100% of the hearts of group A when treated with an antifibrillatory drug, whereas no reversion at all was observed in the hearts of group B. We conclude that high extracellular calcium makes the reversion to sinus rhythm more difficult in this model. Our high rate of success and the exceptionally stable and long-lasting VF turn our model very effective for the study of antiarrhythmic interventions in the isolated rabbit heart.

[Recurrent ventricular tachycardias following myocardial infarction: linear ablation strategy using an electroanatomical mapping system].

The implantable cardioverter defibrillator (ICD) is the therapy of choice for patients with ventricular tachycardia (VT) after myocardial infarction. In some patients frequent ICD shocks occur, often resulting in clinical problems, if antiarrhythmic drugs insufficiently suppress them. Our aim was to describe electro-anatomical mapping and ablation techniques in patients with VTs, in which conventional strategy treatments have failed.</AbstractText>17 patients (69.5 +/- 8 years, 12 male) were included. During 3 months before ablation the number of ICD shocks was 21 +/- 8 (mean +/- SD). Using an electro-anatomical mapping system (CARTO), activation mapping was performed in 12 patients during hemodynamically tolerable, stable VT. In 5 cases with "non-mappable" VT only voltage mapping during sinus rhythm was obtained. The aim was to characterize the underlying scar tissue precisely in order to modify the substrate with an individual strategic linear lesion, thus preventing re-induction of VT.</AbstractText>Procedure time was 184 +/- 9 minutes, fluoroscopy time totalled 19 +/- 9 minutes. Lesion lines were established with 13 +/- 9 ablation pulses. In 15 patients (88 %) acute ablation of the VT was successful. During a follow-up of 8 +/- 7 months, 2 patients had a recurrence of the VT. Two patients developed a VT with a different morphology. In another case ventricular fibrillation occurred. No major complications were observed.</AbstractText>Electro-anatomical mapping combined with an individual linear ablation strategy is a safe and effective method to prevent symptomatic VT in patients after myocardial infarction.</AbstractText>

[Severe intrahepatic cholestasis in a 66-year old male patient with medically treated atrial fibrillation].

A 66-year-old male was admitted to hospital due to painless jaundice. Because of ischemic cardiomyopathy with paroxysmal atrial fibrillation as well as recurrent ventricular tachycardias and fibrillation he was treated with phenprocoumon and amiodarone (200 mg per day) for 2 years. Laboratory tests revealed significant elevation of the parameters of cholestasis and aminotransferase activity. Serological tests excluded infectious, autoimmune or metabolic liver diseases. Abdominal ultrasound and ERCP showed no mechanic cholestasis nor tumor of the pancreas. Cardiac congestive disease was also excluded. Severe intrahepatic cholestasis, consistent with drug-induced hepatotoxic damage, was diagnosed histologically. After discontinuing phenprocoumon the liver enzymes further increased. When amiodarone was stopped, however, laboratory parameters showed a continuous downward tendency. For prevention of malignant cardiac arrhythmia the patient received an atrioventricular defibrillator. Intrahepatic cholestasis is a rare presentation of amiodarone-induced hepatic toxicity. Liver damage can even occur after the drug has been taken for prolonged periods without any problems.

Strain rate imaging for noninvasive functional quantification of the left atrium: comparative studies in controls and patients with atrial fibrillation.

Strain rate (SR) imaging enables quantitative measurement of left ventricular (LV) function independent of cardiac translation. However, whether SR imaging is applicable for detection of left atrial (LA) dysfunction remains unknown. The purpose of this study was to assess the feasibility of measuring LA function by SR imaging, focusing on the effects of aging and LA dilatation during atrial fibrillation (AF). Echocardiographic evaluation including SR imaging was performed in 50 controls (29 males and 21 females; mean age, 41 +/- 14 years) and in 27 patients with AF (15 males and 12 females; mean age, 62 +/- 12 years; 8 with persistent AF and 19 with paroxysmal AF) from 3 apical views and analyzed off-line. Peak SR was measured at each LA segment (septum, lateral, posterior, anterior, and inferior), and mean peak systolic SR (SR-LAs), early diastolic SR (SR-LAe), and late diastolic SR (SR-LAa) were calculated by averaging the results for each segment. LA dimension, peak mitral and pulmonary velocities at late diastole, LA fractional shortening, and atrial filling fraction were calculated as parameters of LA function. Normal values for mean SR-LAs, SR-LAe, and SR-LAa were 3.4 +/- 1.0 s -1 , -3.9 +/- 1.7 s -1 , and -3.1 +/- 1.0 s -1 , respectively, and they were successfully measured in more than 95% of the LA segments. In controls, both mean SR-LAs and mean SR-LAe correlated with age, LA dimension, and early to late diastolic mitral flow velocity ratio. Conversely, mean SR-LAa did not show significant correlation with age or parameters of LA function. In AF patients, mean SR-LAs was correlated inversely with age. The mean SR-LAs was significantly lower in persistent AF patients than in age-matched controls (1.7 +/- 0.8 vs 2.9 +/- 0.9 s -1 ; P &lt; .01). Based on our findings, we conclude that noninvasive quantification of LA function using SR imaging enables evaluation of LA dysfunction due to aging and LA dilatation.

Sympathetic denervation and reinnervation after the maze procedure.

We evaluated serial changes in cardiac sympathetic nerve distribution using 123I-metaiodobenzylguanidine (123I-MIBG) after the Maze procedure. The Maze procedure, in which multiple incisions are made in the atrium, has been concomitantly performed with mitral valve (MV) surgery in an attempt to eliminate atrial fibrillation (AF). Although attenuation of the sinoatrial node response to exercise and a reduction of left ventricular function (left ventricular ejection fraction [LVEF]) in early stages after the Maze procedure have been suggested, factors leading to these changes have not been clarified.</AbstractText>Thirteen patients with MV disease were enrolled in this study. Six of them had undergone MV surgery and the Maze procedure (Maze+), and 7 had undergone MV surgery without the Maze procedure (Maze-). All patients underwent cardiac 123I-MIBG imaging preoperatively and 10 d and 1 y after surgery to assess 123I-MIBG uptake (heart-to-mediastinum count ratio of early planar images [H/M]) and the washout rate (WR). Radionuclide ventriculography was also performed to calculate LVEF 3 d after each 123I-MIBG imaging.</AbstractText>The LVEF of the Maze+ group significantly decreased 10 d after surgery (44.2 +/- 4.8; mean +/- SD) compared with that before surgery (60.3 +/- 6.9; P &lt; 0.05) and significantly increased at 1 y (65.2 +/- 2.9) compared with that at 10 d (P &lt; 0.05). In the Maze- group, there was no significant change 10 d (53.0 +/- 12.3) and 1 y (58.6 +/- 4.8) after surgery compared with that before surgery (60.4 +/- 4.6) (P = not significant, each). In the Maze+ group, the H/M (1.51 +/- 0.18) was significantly lower at 10 d after than that at the preoperative stage (1.90 +/- 0.25; P &lt; 0.05) but significantly recovered at 1 y (2.23 +/- 0.18; P &lt; 0.05) with a similar transient increase in the WR (36.7% +/- 6.1% at preoperative stage; 46.9% +/- 3.4% at 10 d; 39.9% +/- 6.5% at 1 y; P &lt; 0.05, each). On the other hand, the Maze- group did not show a significant change in the H/M (1.94 +/- 0.32, 2.06 +/- 0.18, and 2.13 +/- 0.17, respectively; P = not significant, each) but did exhibit a significant decrease in the WR (40.4% +/- 5.1%, 37.0% +/- 5.1%, and 32.9% +/- 2.5%, respectively; P &lt; 0.05, each). Changes in the H/M of both groups significantly correlated with the change in LVEF (r = 0.82; P &lt; 0.05), and the WR showed a significant inverse correlation with changes in the LVEF (r = -0.81; P &lt; 0.05).</AbstractText>Cardiac sympathetic nerves were denervated at early stage and reinnervated at late stage after the Maze procedure. Such adrenergic nerve changes may be correlated, at least in part, with changes in left ventricular function after this procedure.</AbstractText>

Mitral mechanical replacement in young rheumatic women: analysis of long-term survival, valve-related complications, and pregnancy outcomes over a 3707-patient-year follow-up.

A follow-up study was performed to assess long-term survival, valve-related complications, and pregnancy outcomes in young rheumatic women undergoing isolated mitral mechanical replacement. The influence of prosthetic type on outcomes was also investigated.</AbstractText>Between 1975 and 2003, 267 isolated mitral mechanical prostheses were implanted. Follow-up reached 3707.8 patient-years.</AbstractText>Actuarial survival at 1, 5, 10, 15, 20, and 25 years was 97% +/- 0.01%, 90.4% +/- 0.017%, 85.3% +/- 0.023%, 82.3% +/- 0.025%, 71.7% +/- 0.036%, and 70.2% +/- 0.038%, respectively. At multivariate analysis, atrial fibrillation at follow-up was identified as an independent risk factor for late mortality, whereas left ventricular ejection fraction at 12 postoperative months proved to be a protective factor. Freedom from thromboembolism at 1, 5, 10, 15, 20, and 25 years was 98.1% +/- 0.01%, 94.1% +/- 0.015%, 89.1% +/- 0.021%, 85.9% +/- 0.025%, 81.1% +/- 0.031%, and 75.3% +/- 0.063%, respectively. Atrial fibrillation and Carbomedics device were significantly associated with an increase in thromboembolic events. Freedom from reoperation at 1, 5, 10, 15, 20, and 25 years was 99.2% +/- 0.005%, 95% +/- 0.014%, 91.6% +/- 0.018%, 88.6% +/- 0.022%, and 85.7% +/- 0.041%. Type of prosthesis (tilting disc) was identified as a predictor of reoperation. At the end of the study, 208 patients were still alive: 94.7% were in New York Heart Association class I or II. When receiving warfarin therapy, no patient undertaking pregnancy (n = 35) experienced adverse cardiac or valve-related events. Fetal events were significantly less frequent with a daily warfarin dose less than 5 mg.</AbstractText>Mechanical devices provided excellent performance, safety, and durability. The prognostic role of left ventricular function and atrial fibrillation overwhelmed any differences that might exist between different prosthetic designs. Pregnancies entail virtually no maternal risk and predictable fetal complications.</AbstractText>

Organization of myocardial activation during ventricular fibrillation after myocardial infarction: evidence for sustained high-frequency sources.

Studies of ventricular fibrillation (VF) in small mammals have revealed localized sustained stationary reentry. However, studies in large mammals with surface mapping techniques have demonstrated only relatively short-lived rotors. The purpose of this study was to identify whether sustained high-frequency activation with low beat-to-beat variability was present at intramural sites in a postinfarct ovine model of VF.</AbstractText>VF was induced in 12 sheep 77+/-40 days after anterior myocardial infarction. Electrical activation was recorded with 20 multielectrode transmural plunge needles. Unipolar electrogram frequency content and local cycle duration variability were studied in 30-second recordings beginning 5 seconds after the onset of VF. Higher mean beat frequency was associated with lower SD of the cycle duration intervals (r=-0.91, P&lt;0.001). The mean beat frequency and the SD of cycle duration intervals of the highest-frequency electrode were 8.8+/-2.0 Hz and 17+/-11 ms. In 3 cases, a region with regular activation throughout the recording was identified (SD of the cycle duration interval, 6.0+/-0.7 ms). Two of these sites and 67% of all sites with low local cycle duration variability were intramural. They occurred within regions with a high dominant frequency as determined by fast Fourier transform of the unipolar electrogram.</AbstractText>Regions with the highest frequency of activation during VF were always associated with a low local cycle duration variability and usually intramural in this chronic infarct model. In a minority of cases, a region of stable, rapid, and very regular activation could be identified. These findings support the hypothesis that relatively stable periodic sources form a component of the mechanism of VF in this model.</AbstractText>

[Automated external defibrillators: perspectives and outlook].

In Germany about 80.000 patients die of sudden cardiac death each year with enormous human, social and economic consequences. Most cases of sudden cardiac death are caused by ischemia-triggered ventricular fibrillation. A precondition for survival of the victims is an optimally and fast reacting "chain of survival". One of the central links of this chain is timely defibrillation, which is the only effective therapy for treatment of ventricular fibrillation. Automated external defibrillators proved to be a major step forward in improvement of resuscitation results. It has been convincingly demonstrated, that these devices not only are safe and efficacious in the hands of rescue personnel of different qualification degrees but also in the hands of minimally trained "first responders" and even in the hands of untrained lay people. This story of success was paralleled by the development of a new generation of biphasic defibrillators, which have a superior efficacy, are lightweight and are even cheaper than conventional devices. It must however kept in mind, that progress offered by these new opportunities will only translate in better resuscitation results, when programmes are thoroughly planned, will stay under continuous quality control with regard to performance of devices and rescuers and if new knowledge in resuscitation is adequately incorporated in action protocols.

[Technical requirements for early defibrillation: what are the capabilities of automated external defibrillators].

Modern automated external defibrillators (AEDs) offer a variety of technical improvements which increase the efficacy of early defibrillation, facilitate the application by not or minimally trained persons and improve safety. The development of biphasic shocks allows better myocardial protection, the use of lithium batteries, and a marked decrease of AEDs, in size. Microprocessors realize complex acoustic and visual prompts which lead the user through all steps of cardiopulmonary resuscitation (CPR) according to current guidelines. The design of AEDs has been simplified; many devices provide only a single button which can be used for all active processes. Memory functions record the whole CPR with all details which can be transferred to other computers and analyzed off-line. The introduction of AEDs has reduced the delay between collapse and defibrillation to less than 4 min in several studies thus increasing the success of CPR and the proportion of patients dismissed from hospital alive and without neurological deficit. Up to 93% of untrained volunteers were able to successfully complete defibrillation with the use of an AED, sixth-form pupils without experience in CPR were only few sec slower with an AED than staff of emergency medical services. The ability to perform CPR after defibrillation guided by the AED depends primarily on the clarity of acoustic prompts which have to consider the terms and abbreviations of the respective language. Currently available AEDs surpass performance goals of the AHA. However, all devices exhibit advantages and disadvantages which will be discussed in this review.

[Resuscitation in ventricular fibrillation: what is essential?].

Prognosis of prehospital cardiac arrest due to ventricular fibrillation is dependent on the first minutes, as survival decreases by 10% for each minute by which resuscitation attempts are delayed. Thus, early defibrillation plays a key role in improving outcome of cardiac arrest victims. The effectiveness of automated external defibrillators (AEDs) in this setting has been proven by several clinical trials. There remains controversy with regard to using AEDs in the in-hospital setting, as well as the approach of "public access" defibrillation. Whereas the use of intravenous antiarrhythmic drugs, particularly amiodarone, remains controversial, new data support the use of vasopressine instead of epinephrine as vasopressor drug in cardiac arrest patients. The present review aims to focus on the above mentioned aspects as well as on the changes to the present ILCOR guidelines which have led to modification of the resuscitation guidelines of the European Resuscitation Council (ERC).

Influence of Cheyne-Stokes respiration on ventricular response to atrial fibrillation in heart failure.

In subjects with sinus rhythm, respiration has a profound effect on heart rate variability (HRV) at high frequencies (HF). Because this HF respiratory arrhythmia is lost in atrial fibrillation (AF), it has been assumed that respiration does not influence the ventricular response. However, previous investigations have not considered the possibility that respiration might influence HRV at lower frequencies. We hypothesized that Cheyne-Stokes respiration with central sleep apnea (CSR-CSA) would entrain HRV at very low frequency (VLF) in AF by modulating atrioventricular (AV) nodal refractory period and concealed conduction. Power spectral analysis of R-wave-to-R-wave (R-R) intervals and respiration during sleep were performed in 13 subjects with AF and CSR-CSA. As anticipated, no modulation of HRV was detected at HF during regular breathing. In contrast, VLF HRV was entrained by CSR-CSA [coherence between respiration and HRV of 0.69 (SD 0.22) at VLF during CSR-CSA vs. 0.20 (SD 0.19) at HF during regular breathing, P &lt; 0.001]. Comparison of R-R intervals during CSR-CSA demonstrated a shorter AV node refractory period during hyperpnea than apnea [minimum R-R of 684 (SD 126) vs. 735 ms (SD 147), P &lt; 0.001] and a lesser degree of concealed conduction [scatter of 178 (SD 56) vs. 246 ms (SD 72), P = 0.001]. We conclude that CSR-CSA entrains the ventricular response to AF, even in the absence of HF respiratory arrhythmia, by inducing rhythmic oscillations in AV node refractoriness and the degree of concealed conduction that may be a function of autonomic modulation of the AV node.

Transient complete atrioventricular block following transvenous electrical cardioversion of atrial fibrillation in a horse.

Transvenous electrical cardioversion was attempted in a horse with drug refractory atrial fibrillation. A temporary pacing catheter and two defibrillation catheters were inserted transvenously into the right ventricular apex, the right atrium and the pulmonary artery, respectively. Under general anaesthesia 100, 200, 300 and 360 J monophasic shocks were delivered between both defibrillation catheters but sinus rhythm could not be restored. Immediately after the 200, 300 and 360 J shock, transient third-degree atrioventricular block occurred for a period of, respectively, 15, 40 and 55 s. These periods of profound bradycardia were corrected by temporary right ventricular pacing until spontaneous conduction resumed. It is concluded that temporary right ventricular pacing should be available during electrical cardioversion of atrial fibrillation in horses.

Thoracic lavage in accidental hypothermia with cardiac arrest--report of a case and review of the literature.

Accidental hypothermia resulting in cardiac arrest poses numerous therapeutic challenges. Cardiopulmonary bypass (CPB) should be used if feasible since it optimally provides both central rewarming and circulatory support. However, this modality may not be available or is contraindicated in certain cases. Thoracic lavage (TL) provides satisfactory heat transfer and may be performed by a variety of physicians. This paper presents the physiological rationale, technique, and role for TL in accidental hypothermia with cardiac arrest.</AbstractText>A patient with hypothermic cardiac arrest, treated by the author using TL, serves as the basis for this report. A search of the English language literature using PubMed (National Library of Medicine, Bethesda, Maryland) was conducted from 1966 to 2003 and 13 additional patients were identified. Demographic information, lavage method, rewarming rate, complications, and neurological outcome were analysed.</AbstractText>There were numerous causes for hypothermia, with drug and alcohol intoxication being the most common (n = 4; 28.6%). Patient age ranged from 8 to 72 years (median = 36 years). Mean core temperature was 24.5+/-0.60 degrees C. Most patients were without blood pressure or pulse upon presentation to the Emergency Department and the predominant cardiac rhythm was ventricular fibrillation (VF) (n = 9; 64.3%). Thoracic lavage was accomplished by thoracotomy in seven patients and tube thoracotomy in the remaining seven. Median rewarming rate was 2.95 degrees C/h. Median time until sinus rhythm was restored was 120 min. Median length of hospital stay was 2 weeks. Four (28.6%) patients died. Complications were seen in 12 (85.7%) patients. Among survivors, neurological outcome was normal in 8 (80%) while two were left with residual impairments.</AbstractText>Patients presenting in cardiac arrest from accidental hypothermia may be rewarmed effectively using TL. Among survivors, normal neurological recovery is seen. Thoracic lavage should be strongly considered for these patients if CPB is not available or contraindicated.</AbstractText>

Echocardiographic comparison of cardiopulmonary resuscitation (CPR) using periodic acceleration (pGz) versus chest compression.

This investigation compared the effects of conventional cardiopulmonary resuscitation (CPR) using an automated Thumper chest compression device to periodic acceleration CPR (pGz-CPR) on early post-resuscitation ventricular function assessed by echocardiography, in an adult pig model of CPR.</AbstractText>Whole body periodic acceleration along the spinal axis (pGz) is a new method of cardiopulmonary resuscitation (CPR). Biomechanical forces and biochemical release produced by pGz impart ventilation and increase blood flow. Our laboratory has reported normal neurological and cardiovascular function 48 h after return of spontaneous circulation in animals that have undergone 22 min of pGz-CPR.</AbstractText>Ventricular fibrillation (VF) was induced in 16 animals (25-35 kg). After 3 min of non-interventional period, the animals were randomized to receive either pGz-CPR or Thumper-CPR for 15 min. After 18 min of VF, a single dose of vasopressin and bicarbonate were administered and defibrillation attempted. An echocardiogram was performed at baseline and serially for 6h. Ejection fraction (EF), fractional shortening (FS) and wall motion were assessed by 2D and M-mode echocardiography.</AbstractText>Return of spontaneous circulation to 360 min occurred in 5/8 (62%) of the animals receiving Thumper-CPR and in 7/8 (88%) receiving pGz-CPR. FS and EF were impaired after CPR, but pGz-CPR animals had less impairment than Thumper-CPR animals. Further, wall motion score index (WMSI) was more impaired after Thumper-CPR and remained as such even 6h post-CPR.</AbstractText>pGz holds promise as a new method for CPR with better left ventricular (LV) function post-CPR than the more traditional chest compression method.</AbstractText>

Attenuated pediatric electrode pads for automated external defibrillator use in children.

This post-market, observational study is intended to evaluate reported uses of pediatric pads that reduce the energy delivered by some adult automated external defibrillators (AEDs) so that they may be used with pediatric patients.</AbstractText>Users of the pediatric pads were asked to report any use of the pads, even if no shock was delivered and to provide detailed information about the event, caregiver and the patient.</AbstractText>Reports of the use of pediatric pads have been received and confirmed for 27 patients, age range 0 days to 23 years, median 2 years. Ventricular fibrillation (VF) was reported in eight cases, age range 4.5 months to 10 years, median 3 years. Shocks were delivered to all VF patients, the average shock number was 1.9, range 1-4. All patients had termination of VF, were admitted to the hospital and five survived to hospital discharge. Non-shockable rhythms were reported in 16 patients, and the AED appropriately did not advise a shock. Eleven of these patients had asystole or PEA as their initial rhythm and did not survive to hospital discharge. One report contained no additional information other than that the patient did not survive, and in two other reports, the pads were not applied to patients.</AbstractText>Voluntary reports of the use of attenuated pediatric defibrillation pads indicate the devices performed appropriately. All eight VF patients had termination of VF and five survived to hospital discharge. These data support the rapid deployment of AEDs for young children as well as adolescents and adults. Since the pediatric pads are available and deliver an appropriate dose for children, their use should be strongly encouraged.</AbstractText>

Ventricular fibrillation is not provoked by chest compression during post-shock organized rhythms in out-of-hospital cardiac arrest.

It has been proposed that chest compression (CC) can provoke recurrent ventricular fibrillation (VF) after defibrillation has restored an organized rhythm (OR). If so this would have major implications for proposed changes in resumption of CC after defibrillation, regardless of rhythm. The aim of this study was to examine our defibrillation data for evidence of post-shock CC-induced VF.</AbstractText>In a defibrillation program using police/fire personnel entire electrocardiograms (ECGs) from defibrillator data cards were examined for initial and post-shock rhythms and CC artifact. Successful shock rhythms were defined as either asystole or OR in the first five seconds post-shock, the latter as at least two QRS complexes during this time period. Artifact from CC was assessed for association with recurrent VF during either asystole or OR.</AbstractText>Among 67 patients (pts) defibrillated by police/fire personnel VF recurred at least once in 35 (52%). Entire ECGs were available in 32 of these 35 pts. Chest compression-associated recurrent VF developed in 16 of 32 patients (50%). A total of 78 VF recurrences were observed during the period prior to administration of epinephrine (adrenaline) or other drugs. During post-shock asystole VF recurred 32 times (41% of all recurrent VF episodes); in 19 (59%) VF recurred during CC and in 13 (41%) it was spontaneous. During OR VF recurred 46 times (59% of all recurrent VF episodes); in 36 (78%) VF recurred spontaneously and in only 10 (22%) during CC. Heart rate preceding spontaneous recurrence of VF during OR was 84+/-35 beats/min, and heart rate preceding CC-associated VF recurrence during OR was 46+/-20 beats/min (p &gt; 0.001). There was no statistically significant difference in the width of the QRS complex preceding VF recurrence in the CC-associated and spontaneous VF recurrence groups (p = 0.925).</AbstractText>VF recurred following successful shocks in 52% of pts. With asystole VF recurred frequently during CC. However, during post-shock OR VF recurred unrelated to CC in most instances. Thus, resumption of CC immediately after shocks that restore an OR is unlikely to provoke recurrent VF, and resumption of CC need not be delayed.</AbstractText>

A comparison of low versus high heart rate in patients with atrial fibrillation and advanced chronic heart failure: effects on clinical profile, neurohormones and survival.

Atrial fibrillation is common in chronic heart failure. Long-term restoration of sinus rhythm is generally unsuccessful. It may be speculated that higher heart rates are unfavorable, since this may lead to tachycardiomyopathy, but there are no data which have examined this.</AbstractText>Seventy-seven patients with atrial fibrillation and advanced chronic heart failure, age 70 +/- 7 years, left-ventricular ejection fraction 0.23 +/- 0.08, 61% with ischemic etiology were included. Patients were dichotomized according to the median heart rate (80 bpm) at inclusion (39 patients with "low" heart rate and 38 patients with "high" heart rate). At baseline, both patient groups were remarkably comparable. After a mean follow-up of 3.3 +/- 0.9 years, mortality was comparable (62% versus 55%, p = non-significant). An independent relation was found between lower heart rate and survival, in addition to absence of hypertension, digoxin use, and higher N-ANP, dopamine, and renin levels.</AbstractText>In the present analysis, patients with atrial fibrillation and advanced chronic heart failure with higher heart rates are comparable to those with lower heart rates. Not higher heart rates at baseline but, on the contrary, lower heart rates seem associated with a worse outcome.</AbstractText>

Out-of-hospital cardiac arrest rectilinear biphasic to monophasic damped sine defibrillation waveforms with advanced life support intervention trial (ORBIT).

Although biphasic defibrillation waveforms appear to be superior to monophasic waveforms in terminating VF, their relative benefits in out-of-hospital resuscitation are incompletely understood. Prior comparisons of defibrillation waveform efficacy in out-of-hospital cardiac arrest (OHCA) are confined to patients presenting in a shockable rhythm and resuscitated by first responder (basic life support). This effectiveness study compared monophasic and biphasic defibrillation waveform for conversion of ventricular arrhythmias in all OHCA treated with advance life support (ALS).</AbstractText>This prospective randomized controlled trial compared the rectilinear biphasic (RLB) waveform with the monophasic damped sine (MDS) waveform, using step-up energy levels. The study enrolled OHCA patients requiring at least one shock delivered by ALS providers, regardless of initial presenting rhythm. Shock success was defined as conversion at 5s to organized rhythm after one to three escalating shocks. We report efficacy results for the cohort of patients treated by ALS paramedics who presented with an initially shockable rhythm who had not received a shock from a first responder (MDS: n=83; RLB: n=86). Shock success within the first three ascending energy shocks for RLB (120, 150, 200J) was superior to MDS (200, 300, 360J) for patients initially presenting in a shockable rhythm (52% versus 34%, p=0.01). First shock conversion was 23% and12%, for RLB and MDS, respectively (p=0.07). There were no significant differences in return of spontaneous circulation (47% versus 47%), survival to 24h (31% versus 27%), and survival to discharge (9% versus 7%). Mean 24h survival rates of bystander witnessed events showed differences between waveforms in the early circulatory phase at 4-10 min post event (mean (S.D.) RLB 0.45 (0.07) versus MDS 0.31 (0.06), p=0.0002) and demonstrated decline as time to first shock increased to 20 min.</AbstractText>Shock success to an organized rhythm comparing step-up protocol for energy settings demonstrated the RLB waveform was superior to MDS in ALS treatment of OHCA. Survival rates for both waveforms are consistent with current theories on the circulatory and metabolic phases of out-of-hospital cardiac arrest.</AbstractText>

Refining detection of drug-induced proarrhythmia: QT interval and TRIaD.

QT interval prolongation is so frequently associated with torsades de pointes (TdP) that it has come to be recognized as a surrogate marker of this unique tachyarrhythmia. However, not only does TdP not always follow QT interval prolongation, but TdP can occur even in the absence of a prolonged QT interval. Worse still, even shortening of the QT interval may be associated with serious arrhythmias (particularly ventricular tachycardia [VT] and ventricular fibrillation [VF]). It appears increasingly probable that the distinction between various ventricular tachyarrhythmias may be arbitrary, and drug-induced TdP, polymorphic VT, VT, catecholaminergic polymorphic VT, and VF may represent discrete entities within a spectrum of drug-induced proarrhythmia. Although they are differentiated by the coupling interval and the duration of QT interval, they appear to share a common substrate: a set of disturbances of repolarization characterized by Triangulation, Reverse use dependency, electrical Instability of the action potential, and Dispersion (TRIaD). It is becoming increasingly evident that augmentation of TRIaD, rather than changes in the duration of QT interval, provides the proarrhythmic substrate. In contrast, when not associated with an increase of TRIaD, QT interval prolongation can be an antiarrhythmic property. Electrophysiologically, augmentation of TRIaD can be explained by inhibition of hERG (human ether-a-go-go related gene) channel. Because drug-induced disturbances in repolarization commonly result from inhibition of hERG channels or I(Kr), hERG blockade and the resulting prolongation of QT interval are important properties of a drug to be studied. However, these need only be a concern if associated with TRIaD. More significantly, TRIaD so often precedes prolongation of action potential duration or QT interval and ventricular tachyarrhythmias that it should be considered a marker of proarrhythmia until proven otherwise, even in the absence of QT interval prolongation. Detecting drug-induced augmentation of TRIaD may offer an additional, more sensitive, and accurate indicator of the broader proarrhythmic potential of a drug than may QT interval prolongation alone.

Quantification of activation patterns during ventricular fibrillation in open-chest porcine left ventricle and septum.

A single stationary mother rotor has been hypothesized to be responsible for maintenance of ventricular fibrillation (VF) in the guinea pig. Previous studies have pointed to the ventricular septum as a possible location for a mother rotor in the pig heart.</AbstractText>The purpose of this study was to test the hypothesis that a mother rotor is located in the septum.</AbstractText>In seven open-chest pigs, we mapped the first 20 seconds of electrically induced VF simultaneously from the posterior left ventricle (LV) and right side of the septum with two electrical arrays. Each array contained 504 electrodes (21 x 24) spaced 2 mm apart in the LV and 1.5 mm apart in the septum.</AbstractText>The percentage of VF wavefronts that formed reentrant circuits was significantly lower in the septum (1% +/- 1% [mean +/- SD]) than in the LV (2% +/- 1%). The peak frequency during VF also was significantly smaller in the septum (8.6 Hz +/- 3.0 Hz) than in the LV (10.4 Hz +/- 3.4 Hz). The mean direction of spread of activation of VF wavefronts was away from the region where the posterior LV free wall intersects the posterior septum in both the LV and septum.</AbstractText>The lower incidence of reentry and lower peak frequency in the mapped region of the septum than in the LV indicate that a mother rotor is not present in swine on the RV side of the septum. The mean directions of the VF activation sequences in the LV and septum suggest that if a mother rotor is present during the first 20 seconds of VF, it exists where the posterior LV free wall joins the septum, the region where the posterior papillary muscle inserts.</AbstractText>

Simplified cardiac resynchronization implantation technique involving right access and a triple-guide/single introducer approach.

Biventricular pacing is useful for patients with congestive heart failure but has the disadvantage of being a long, user-dependent, highly technical procedure.</AbstractText>The purpose of this study was to simplify the procedure. The simplified technique consists of sinus (CS) venography prior to implantation, direct coronary access for the left ventricular (LV) lead without use of a left-heart delivery system, and triple-guide/one introducer cephalic vein access as the first approach in patients presenting in sinus rhythm.</AbstractText>A cephalic cutdown was performed, and a steerable hydrophilic guidewire was introduced in the cephalic vein. A 9Fr introducer was advanced over the guidewire, and two other guides were inserted through the introducer. This technique allowed for insertion of a right ventricular lead, an LV lead, and an atrial lead.</AbstractText>One hundred three patients were evaluated from January 2002 to September 2004. Four implants failed (3.9%). The 7Fr LV lead was successfully placed in 99 of 103 patients (96.1%) directly via the 9Fr introducer, without use of a dedicated left-heart delivery system. The final position was lateral in 59 patients, posterolateral in 33, posterior in 4, and anterolateral in 3. Sixty patients were in sinus rhythm, 13 were in atrial fibrillation, and 26 had a previous pacemaker (n = 21) or defibrillator (n = 5). Triple cephalic vein access was possible in 48 of the patients in sinus rhythm (80%). Procedure parameters were as follows: LV threshold 0.9 +/- 0.7 V, LV wave amplitude 15 +/- 8 mV, LV impedance 790 +/- 232 Omega, skin-to-skin procedure time 76 +/- 33 minutes, and fluoroscopy time 23 +/- 19 minutes. Ten complications (10.1%) occurred: 7 lead dislodgments (3 within 48 hours and 4 within 6 months) requiring repositioning (7.1%), 1 subacute local infection requiring explantation (1%), 1 phrenic nerve stimulation (1%), and 1 pneumothorax (1%). The long-term success of biventricular pacing was 93.1%.</AbstractText>This study demonstrates that cardiac resynchronization therapy implantation can be simplified with the combined use of a steerable hydrophilic guidewire, three guides, and one introducer via a right cephalic vein, without use of a left-heart delivery system. The triple cephalic vein approach yields an 80% implant success rate for patients in sinus rhythm. The long-term success of biventricular pacing was 93.1%.</AbstractText>

Mechanisms of pain associated with internal defibrillation shocks: results of a randomized study of shock waveform.

Shock pain has limited the acceptance of the implantable atrial cardioverter and is a complication of ventricular implantable cardioverter-defibrillator therapy. Rounding off of the peak of a shock waveform reduces pain. Whether the pain reduction results from reduction in the peak voltage or from the rounding has not been established. In other words, does reducing the extreme dV/dt (voltage derivative) of the conventional truncated exponential capacitive discharge waveform reduce pain?</AbstractText>The purpose of this study was to compare the relative contributions of peak voltage and waveform shape to pain.</AbstractText>We compared rounded and conventional waveforms with equal peak voltages. Eighty-five shocks of 50 to 500 V were delivered to 10 patients requiring atrial cardioversion for persistent atrial fibrillation. The patient touched an analog pain scale (0-15 cm) and orally reported a pain score on a scale from 0 to 5. An observer scored thoracic contractions on a scale from 0 to 5.</AbstractText>No differences between the rounded and conventional waveform on any scale were noted for either univariate or multivariate analyses. However, all three response scales were strongly predicted by voltage with r(2) = 0.77 (oral), r(2) = 0.86 (analog), and r(2) = 0.85 (contraction) after correcting for patient variability and including a log voltage term.</AbstractText>Patient pain perception was determined primarily by waveform peak voltage and not by the rounding, per se.</AbstractText>

Asymptomatic atrial fibrillation: demographic features and prognostic information from the Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) study.

Atrial fibrillation (AF) may occur without symptoms. Little is known about demographic features and prognostic information in patients with asymptomatic AF.</AbstractText>In the AFFIRM study, 4060 patients were randomized to either rhythm or rate control. At baseline, patients were identified as asymptomatic if they answered "no" to a 15-item questionnaire related to cardiac symptoms during AF in the 6 months before study entry.</AbstractText>There were 481 (12%) asymptomatic patients at baseline. Compared with symptomatic patients, asymptomatic patients were more often men and had a lower incidence of coronary artery disease and congestive heart failure, but had more cerebrovascular events. Asymptomatic patients had a longer duration of AF, a lower maximum heart rate, and better left ventricular function. They received fewer cardiac medications and fewer therapies to maintain sinus rhythm. At 5 years, there was a trend for better survival in asymptomatic patients (81% vs 77%, P = .058), and they were more likely to be free from disabling stroke or anoxic encephalopathy, major bleeding, and cardiac arrest (79% vs 67%, P = .024). However, mortality and major events were similar after correction for baseline differences.</AbstractText>Patients with asymptomatic AF have less serious heart disease but more cerebrovascular disease. Asymptomatic patients receive different therapies than symptomatic patients. However, the absence of symptoms and the differences in treatment does not confer a more favorable prognosis when differences in baseline clinical parameters are considered. Anticoagulation should be considered in these patients.</AbstractText>

Clinical factors that influence response to treatment strategies in atrial fibrillation: the Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) study.

The AFFIRM Study was a randomized multicenter comparison of 2 treatment strategies, rate-control versus rhythm-control, in high-risk patients with atrial fibrillation (AF). The primary outcome of the trial showed no overall difference in survival between strategies. However, there may be important patient subgroups for which there are identifiable differences in outcome with 1 of the 2 strategies.</AbstractText>Subgroups that were prespecified for analysis from the main AFFIRM Study were age, sex, coronary artery disease (CAD), hypertension, congestive heart failure (CHF), left ventricular ejection fraction (LVEF), rhythm at randomization, first episode of AF, and duration of the qualifying episode of AF. Baseline characteristics were analyzed for each subgroup. Adjusted hazard ratios for each subgroup and for each stratum were generated using Cox models, and these models were used to determine whether treatment strategy affected overall survival differentially by subgroup. Adjusted survival was worse for patients &gt; or =65 years and for patients with a history of CHF, CAD, or an abnormal LVEF. In the adjusted analyses, the effect of treatment strategy was similar within all of the prespecified subgroups. When each subgroup stratum was analyzed separately, patients &gt; or =65 years and patients without a history of CHF had significantly better outcome with rate-control therapy (each P &lt; .01).</AbstractText>Overall, treatment effect for rate control versus rhythm control was the same within each subgroup. However, certain selected patient categories may have better survival with one particular strategy for management of AF.</AbstractText>

The immediate future for the medical treatment of atrial fibrillation.

Atrial fibrillation is the most commonly sustained cardiac arrhythmia and a common reason for mortality and morbidity. Atrial fibrillation causes disease for three reasons: i) the ventricular rate is often high, which leads to symptoms ranging from discomfort to life threatening heart failure; ii) the rhythm causes loss of atrioventricular synchrony, which reduces diastolic filling and may lead to heart failure; and iii) atrial contraction is lost leading to stagnant blood that again may lead to atrial thrombi and peripheral embolism. Thus, the treatment of atrial fibrillation is focused on the maintenance of sinus rhythm, rate control and prevention of embolism. For the maintenance of sinus rhythm, all drugs under current development are potassium channel blockers; the so-called class III anti-arrhythmic drugs. Those which have been further investigated appear to be valuable for maintenance of sinus rhythm but all carry a significant risk of pro-arrhythmia, in particular Torsade de Pointe ventricular tachycardia. Rate control has been a focus of treatment for many years and several very old drugs, including digoxin, are used for this. There is, to the author's knowledge, no current effort for evaluating new drugs for this indication. Prevention of embolism has for many years been obtained with vitamin K antagonists for which the clinical evidence is overwhelming. Previous attempts to replace vitamin K antagonists with aspirin have not been fruitful. A large number of newer anticoagulation regimes are in development, but to the author's knowledge only a single thrombin inhibitor is actively being developed for atrial fibrillation.

Dynamics of inflammation parameters prior to tachyarrhythmias in critically ill patients.

The aim of this study was to assess the dynamics of inflammation parameters prior to a tachyarrhythmic event in critically ill patients. We evaluated the course of inflammation parameters over 48 hours before the occurrence of tachyarrhythmias.</AbstractText>Prospective observational study conducted at a cardiologic medical-postoperative tertiary intensive care unit at the Vienna university hospital. Between November 1996 and July 1999 all consecutive patients (n = 756) were screened for the occurrence of arrhythmias. Patients with sustained tachyarrhythmias (n = 119) form the basis of the report. The tachyarrhythmia episodes were related to the evolution of C-reactive protein, leukocytes and fibrinogen during the 48 hours before the arrhythmic event.</AbstractText>A total of 278 tachyarrhythmia episodes was identified (wide QRS complex tachycardia, n = 168; narrow QRS complex tachycardia, n = 108; ventricular fibrillation, n = 2). The body temperature on the day of arrhythmia was 37.4 +/- 1 degrees C. Overall, there was no statistically significant change in any inflammation parameter within 48 hours prior to tachyarrhythmias (C-reactive protein: 17.4 +/- 12 [-48 h], 16.2 +/- 11 [-24 h], 15.2 +/- 12 [0 h] mg/dl, p = 0.2). When stratifying for different levels of C-reactive protein on the day of arrhythmia, the trend was inhomogenous. For lower strata, values were significantly decreasing towards arrhythmias; for higher strata, an increase in C-reactive protein was observed (stratum A: 8.5 +/- 7.2 [-48 h], 6.6 +/- 4.9 [-24 h], 4.8 +/- 2.9 mg/dl [0 h], p = 0.0001; stratum B: 16.0 +/- 7.1 [-48 h], 13.8 +/- 6.0 [-24 h], 14.4 +/- 2.6 mg/dl [0 h], p = 0.09; stratum C: 21.2 +/- 7.4 [-48 h], 21.5 +/- 7.5 [-24 h], 24.9 +/- 3.0 mg/dl [0 h], p = 0.008; stratum D: 34.3 +/- 13.4 [-48 h], 35.7 +/- 9.0 [-24 h], 39.7 +/- 5.5 mg/dl [0 h], p = 0.13).</AbstractText>In this group of critically ill patients inflammation parameters did not change significantly during the 48 hours prior to the arrhythmic event. For different levels of C-reactive protein at the time of arrhythmia, no clear dynamics of inflammatory signs were observed.</AbstractText>

[Ischemic postconditioning of the myocardium: a new method of heart protection against reperfusion damage].

To examine effects of ischemic postconditioning on persistent ventricular fibrillation (VF) induced by reperfusion on the model of isolated rat heart.</AbstractText>Isolated by Langendorf hearts (n = 46) were ischemized for 30 min with following reperfusion. Hearts with persisting VF (n = 11) persisting to reperfusion minute 15 were randomized into two groups: control (n = 6)--reperfusion without interventions, study group on postconditioning (n = 5)--2 min global ischemia followed by reperfusion. Left ventricular pressure, heart rate, coronary blood flow were registered continuously.</AbstractText>VF converted to a regular rhythm in all the hearts exposed to postconditioning. Regular contractions were made by all the postconditioned hearts in the course of further reperfusion. None of the control hearts had normal rhythm in the end of the experiment. In the end of reperfusion pulse left ventricular pressure of the postconditioned hearts was lower than that in hearts without persistent VF.</AbstractText>Ischemic postconditioining exerts an arrhythmic effect in relation to persistent reperfusion ventricular tachyarrhythmias. Postconditioning may serve a new strategy for myocardial protection.</AbstractText>

Thyrotoxicosis and the cardiovascular system.

Thyrotoxicosis is associated with increased cardiovascular morbidity and mortality, primarily due to heart failure and thromboembolism. Palpitations, caused by sinus tachycardia and occasionally by atrial fibrillation, are the most frequent cardiovascular symptom. As atrial fibrillation may be the only manifestation of thyrotoxicosis, thyroid hormone excess should routinely be excluded in patients with this rhythm disturbance. Heart failure occurs mostly in the presence of underlying heart disease or tachycardia-induced cardiomyopathy in patients with long-standing atrial fibrillation. On occasion, long-standing hyperthyroidism may lead to heart failure even in the absence of concomitant cardiac conditions. Beta-blockers offer symptomatic relief and at the same time slow the ventricular response in patients with atrial fibrillation. Amiodarone, and occasionally iodinated contrast agents, may cause iodine-induced thyrotoxicosis. Clinical suspicion is essential in the diagnosis of amiodarone-induced thyrotoxicosis (AIT), because the antiadrenergic effect of the drug may conceal symptoms. AIT should be considered in any patient on amiodarone in the presence of new-onset or recurrent atrial arrhythmias or unexplained weight loss. Beyond discontinuation of amiodarone, treatment options include propylthiouracil or methimazole, potassium perchlorate, steroids, lithium and, if pharmacological treatment fails, surgery. Amiodarone may potentially be used less frequently in the future since recent studies have shown that this drug is inferior to implantable cardioverter defibrillators in prevention of sudden cardiac death in patients with severe heart failure. In addition, non-iodinated amiodarone analogues are currently in advanced phase of clinical testing.

Idiopathic premature ventricular contractions arising from the pulmonary artery: importance of mapping in the pulmonary artery in left bundle branch block-shaped ventricular arrhythmias.

A patient underwent radiofrequency (RF) catheter ablation of symptomatic idiopathic ventricular contractions (PVCs). RF energy applications at 2 sites in the right ventricular outflow tract (RVOT), where both the earliest ventricular activation and near-perfect pace mapping were obtained, did not abolish the PVC but resulted in changes in the QRS morphology of the PVC. Complete elimination of the PVC was achieved with RF energy application at a site within the pulmonary artery 13 mm above the pulmonary valve, which was greater than 20 mm away from the failed ablation sites within the RVOT.

Beneficial effects of biatrial pacing on cardiac function in patients with bradycardia -- tachycardia syndrome.

Biatrial (BiA) pacing prevents atrial fibrillation. By an unknown mechanism. The purpose of this study was to use Doppler echocardiography to evaluate the hemodynamic effects during BiA pacing.</AbstractText>The subjects were 7 patients with bradycardia - tachycardia syndrome with an implanted pacemaker. Atrial pacing sites were the right atrial appendage (RAA) and coronary sinus. P wave duration during BiA pacing (123 +/-16 ms) was significantly shorter than during either RAA pacing (167+/-19 ms, p&lt;0.05) or sinus rhythm (148+/-12 ms, p&lt;0.05). Doppler echocardiography revealed a greater cardiac output during BiA pacing than during RAA pacing (4.1+/-1.1 vs 3.5+/-0.7 L/min, p=0.042). The Doppler waveform of transmitral flow indicated that the left ventricular contraction interrupted the atrial filling wave during RAA pacing. The interval between the end of the atrial filling wave of transmitral flow and the mitral valvular closing sound was significantly increased by BiA pacing compared with RAA pacing (56+/-65 vs 40+/-57 ms, p=0.047).</AbstractText>Cardiac hemodynamics were improved by BiA pacing and reduction of left atrial load may be one of the mechanisms.</AbstractText>

Tako-tsubo-like left ventricular dysfunction: clinical presentation, instrumental findings, additional cardiac and non-cardiac diseases and potential pathomechanisms.

Tako-tsubo-like left ventricular dysfunction phenomenon (TTP) has primarily been described in Japan and is characterized by transient left ventricular apical ballooning in the absence of coronary artery disease, associated with chest symptoms, electrocardiographic changes and minimal cardiac enzymes release. Aim of the present review is to summarize the current knowledge about TTP. TTP has been described predominantly in females. TTP occurs also outside Japan. Clinical symptoms comprise anginal chest pain, dyspnea and syncope. TTP occurs frequently after acute emotional or physical stress. Electrocardiographic ST- elevations may be present only for several hours. Then, normalization of the ST-segment occurs, followed by negative T waves, which persist for months. Arterial hypertension in TTP is found in up to 76%, hyperlipidaemia in up to 57%, diabetes mellitus in up to 12% and smoking in up to 18% of the patients. Several pathomechanisms have been proposed: myocardial stunning due to increased catecholamine levels, coronary vasospasm, atherosclerotic plaques rupture, myocarditis, catecholamine-induced hyperkinesis of the basal left ventricular segments and genetic. Patients with TTP should be monitored like patients with myocardial infarction. Care should be taken in the application of catecholamines and nitrates. Betablockers should be given in the acute and chronic phase, and possibly indefinitely to prevent recurrences. The prognosis of TTP is assumed to be good, but in the acute phase there are deaths due to multisystem organ failure, cardiogenic shock, ventricular fibrillation and ventricular rupture. The long term prognosis of TTP patients is largely unknown.

Complex-periodic spiral waves in confluent cardiac cell cultures induced by localized inhomogeneities.

Spatiotemporal wave activities in excitable heart tissues have long been the subject of numerous studies because they underlie different forms of cardiac arrhythmias. In particular, understanding the dynamics and the instabilities of spiral waves have become very important because they can cause reentrant tachycardia and their subsequent transitions to fibrillation. Although many aspects of cardiac spiral waves have been investigated through experiments and model simulations, their complex properties are far from well understood. Here, we show that intriguing complex-periodic (such as period-2, period-3, period-4, or aperiodic) spiral wave states can arise in monolayer tissues of cardiac cell culture in vitro, and demonstrate that these different dynamic states can coexist with abrupt and spontaneous transitions among them without any change in system parameters; in other words, the medium supports multistability. Based on extensive image data analysis, we have confirmed that these spiral waves are driven by their tips tracing complex orbits whose unusual, meandering shapes are formed by delicate interplay between localized conduction blocks and nonlinear properties of the culture medium.