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2,100 | The use of implantable cardioverter-defibrillators in pediatric patients awaiting heart transplantation. | This multicenter study evaluated experience with implantable cardioverter defibrillators (ICD) as a bridge to orthotopic heart transplantation (OHT) in children.</AbstractText>The application of ICD therapy continues to expand in pediatric populations, due in part to improved technology and new indications, including the prevention of sudden death while awaiting OHT.</AbstractText>We performed a retrospective review of ICD databases at 9 pediatric transplant centers.</AbstractText>Twenty-eight patients (16 males) underwent implantation or had a preexisting ICD while awaiting OHT between 1990 and 2002. The median age at implant was 14.3 years (11 months to 21 years) with a median weight of 49 kg (11.7-88 kg). Diagnoses included cardiomyopathy (n=22), and congenital heart disease (n=6). Indications for ICD implantation included ventricular tachycardia/fibrillation (n=23), syncope (n=5), aborted sudden death with no documentation of rhythm disturbance (n=5), ventricular ectopy (n=1), and poor function (n=5). Of the 28 ICDs, 23 were implanted by a transvenous approach and 5 by epicardial route. There were 55 defibrillator discharges in 17 patients, 47 (85%) of which (in 13 patients) were appropriate. The 8 inappropriate discharges (in 6 patients) were triggered by sinus tachycardia, inappropriate sensing, and atrial flutter. The mean time from implantation to first appropriate shock was 6.9 months (1 day to 2.6 years). Twenty-one patients underwent transplantation during the study period, whereas 2 died while awaiting a donor. Morbidity included a lead fracture, 3 episodes of electromechanical dissociation, and 1 episode of electrical storm.</AbstractText>ICD implantation represents an effective bridge to transplantation in pediatric patients. The complication rate is low, with inappropriate device discharge due primarily to sinus tachycardia or atrial flutter. There is a high incidence of appropriate ICD therapy for malignant ventricular arrhythmias in this highly selected group of patients.</AbstractText> |
2,101 | [Cardiac insufficiency in the African cardiology milieu]. | The aim of this study is to determine the frequency, the aetiologies and the hospital mortality of heart failure in African developing countries.</AbstractText>A prospective study rolled over six months in African urban hospital including 170 patients, middle age 50 years old suffering from heart failure. They underwent clinical, paraclinical cardiac examination.</AbstractText>Heart failure represented 37.7%. Main cardiac failure risks were: hypertension: 76 cases (45%), diabetes mellitus: 20 cases (11.8%). General heart failure is noted at the entrance in 67.6% with cerebral attack in 5%. EKG showed left ventricle hypertrophy in 108 patients (63.5%) and atrial fibrillation in 28 patients (16.6%). Valvular heart diseases and hypertension are the main aetiologies respectively: 76 cases (45%) and 58 cases (34%). In 10 cases (6%) the aetiology is unspecified. Hospital mortality concerned 44 patients (25.9%).</AbstractText>Heart failure is grave and frequent in developing countries where there is no cardiac surgery. Prevention is possible: fighting against articular rheumatism and control hypertension.</AbstractText> |
2,102 | Cardiac arrest and resuscitation epidemiology in Singapore (CARE I study). | To describe the epidemiology of out-of-hospital cardiac arrest (OHCA) in Singapore, the emergency medical services (EMS) response, and to identify possible areas for improvement.</AbstractText>This prospective observational study constitutes phase I of the Cardiac Arrest and Resuscitation Epidemiology (CARE) project. Included were all patients with nontraumatic OHCA conveyed by the national emergency ambulance service. Patient characteristics, cardiac arrest circumstances, EMS response, and outcomes were recorded according to the Utstein style.</AbstractText>From October 1, 2001, to April 30, 2002, 548 patients were enrolled into the study. Mean (standard deviation [SD]) age was 62.2 (17.9) years, with a male predominance (65.6%). A total of 59.8% of collapses occurred at home, 35.3% of arrests were not witnessed, and bystander cardiopulmonary resuscitation was present for 20.6%. Mean (SD) time from collapse to call received by EMS was 10.6 (13.1) minutes. Mean (SD) EMS response time was 10.2 (4.3) minutes. Mean (SD) time from call to defibrillation was 16.7 (7.2) minutes. Mean (SD) on-scene time was 9.9 (4.5) minutes. First presenting rhythm at the scene was asystole in 54.5%, pulseless electrical activity 22.9%, ventricular fibrillation 19.6%, and ventricular tachycardia 0.4%. Of all cardiac arrests, 351 had resuscitation attempted and were of cardiac origin. Among these patients, 17.9% had return of spontaneous circulation, 8.5% survived to hospital admission, and 2.0% survived to discharge.</AbstractText>CARE I establishes the baseline for the evaluation of incremental introduction of prehospital Advanced Cardiac Life Support interventions planned for future phases. Continuing efforts should be made to strengthen all chains of survival. This represents the most comprehensive OHCA study yet conducted in Singapore.</AbstractText> |
2,103 | Adverse prognosis of patients with hypertrophic cardiomyopathy who have epicardial coronary artery disease. | Adult patients with hypertrophic cardiomyopathy (HCM) may develop concomitant atherosclerotic coronary artery disease (CAD). There is a paucity of data on the clinical outcomes of HCM patients who have CAD.</AbstractText>We examined the outcome of 433 adult patients with HCM according to the presence and severity of CAD. All patients were aged > or =21 years, had a left ventricular ejection fraction of > or =50%, and were without a history of prior surgical revascularization (mean age, 63 years; 212 men). Compared with HCM patients with mild-to-moderate or no CAD, those with severe CAD demonstrated markedly reduced survival. Ten-year overall survival was 46.1%, 70.5%, and 77.1% for patients with severe, mild-to-moderate, and no CAD, respectively (unadjusted P=0.0001; adjusted P=0.0006). For the end point of cardiac death, this survival was 62.3%, 81.0%, and 80.9% (unadjusted P=0.009; adjusted P=0.004). For the end point of sudden cardiac death, this survival was 77.4%, 93.2%, and 90.3% (unadjusted P=0.01; adjusted P=0.01). The presence of severe CAD also was highly predictive of these events (risk ratio for respective event: 2.31, 2.15, and 2.77) in multivariate models that additionally identified age, prior stroke, hyperlipidemia, and atrial fibrillation as significant covariates.</AbstractText>Among adult patients with HCM who undergo coronary angiography, those who have concomitant severe CAD are at increased risk of death. This risk far exceeds historical death rates of CAD patients with normal left ventricular function.</AbstractText> |
2,104 | Calcitonin gene-related peptide protects against whole body ischemia in a porcine model of cardiopulmonary resuscitation. | The present study was designed to investigate the protective effects of calcitonin gene-related peptide (CGRP) in a porcine model of cardiopulmonary resuscitation (CPR). Twelve pigs were anesthetized, paralyzed, mechanically ventilated with oxygen, and were monitored for electrocardiograph (ECG), arterial pressure, right atrial pressure, airway pressure. Ventricular fibrillation (VF) was induced in all animals by the application of 30 V of alternating current (60 Hz) across the heart, and remained untreated for 3 min, followed by conventional CPR with pneumatic piston device (Thumper) for 15 min. At 18 min of VF a single dose of vasopressin was given, and followed by defibrillation attempts. Two groups were studied. Group 1: Six pigs were used as saline control. Group 2: 0.3 nmol/kg CGRP was given 15 min prior to induction of VF. All animals in the CGRP pretreated group achieved a return of spontaneous circulation (ROSC) and survived more than 2 h (100%), whereas none of the saline control animals achieved ROSC. Blood gases were not significantly different between the groups. However, CGRP group had significantly higher arterial blood pressure and coronary perfusion pressure than control group during CPR. Pretreatment with CGRP affords a cardioprotective effect in this model of whole body ischemia. |
2,105 | Management of ventricular fibrillation or unstable ventricular tachycardia in patients with congenital long-QT syndrome: a suggested modification to ACLS guidelines. | Prolongation of the QT interval is a known risk factor for syncope, seizures and sudden cardiac death. Most patients with QT prolongation have an acquired cause, but congenital forms of QT prolongation are being increasingly recognized. However, existing advanced cardiac life support (ACLS) treatment algorithms for prolonged QT mediated ventricular fibrillation pertains to acquired long-QT syndrome (LQTS). Here, a young patient with out-of-hospital cardiac arrest secondary to congenital LQTS illustrates critical exceptions to the current ACLS treatment algorithms for ventricular fibrillation and unstable ventricular tachycardia when QT prolongation is congenital in origin. A clarified ACLS algorithm is proposed. |
2,106 | Cardiac arrest survival as a function of ambulance deployment strategy in a large urban emergency medical services system. | This study examines the effect of paramedic deployment strategy on witnessed ventricular fibrillation (VF) cardiac arrest outcomes. Our null hypothesis was that there is no difference in survival between an EMS system using targeted response (TR) and one using a uniform or all advanced life support (ALS) response (UR) model. We define targeted response as a system where paramedics are sent to critical incidents while ambulances staffed with basic EMTs are sent to less critical incidents. A secondary outcome measure was paramedic skill proficiency between the systems.</AbstractText>We conducted a retrospective review of all 1997 VF arrests in a large urban EMS system. The majority of the city is a busy, urban area that uses TR. Outlying areas of the city are suburban and are served by a UR model. All areas have first responders equipped with automated external defibrillators. Outcomes are compared using Utstein criteria.</AbstractText>Patient populations were well matched. There were 181 patients in the TR group and 24 in the UR group. Units in the TR area were able to demonstrate shorter response and time to defibrillation intervals than in the UR area. Rates for return of spontaneous circulation (ROSC), admission to the ward/intensive care unit (ICU), survival to discharge and survival to 1 year were all better in the cohort of patients cared for in the TR area than those in the UR area. Rates for successful intubation and IV initiation were also better in the TR areas than in the UR areas.</AbstractText>This study shows improved outcomes for a subset of patients with cardiac arrest when they are cared for in an area that uses TR compared to an area that uses a UR EMS system.</AbstractText> |
2,107 | Fatal cardiac arrest following blunt chest trauma 17 years after a Senning operation. | Although frequent in patients who have undergone Senning or Mustard operations, cardiac arrhythmias after blunt chest trauma have not been reported. We report the case of a 17-year-old boy with ventricular fibrillation after a minor blow to the chest. |
2,108 | [Clinical case of the month. Rapid atrial fibrillation causing ventricular tachycardia and syncope]. | We report a rare case of rapid atrial fibrillation triggering an episode of ventricular tachycardia. We review the literature and discuss the potential mechanisms of the ventricular arrhythmia. |
2,109 | Implantable cardioverter-defibrillator placement in patients with mild-to- moderate left ventricular dysfunction: hemodynamics and recovery profile with two different anesthetics used during deep sedation. | To compare the effects of thiopental and propofol during defibrillation threshold testing (DFT) on hemodynamics and recovery profile in patients requiring automatic internal cardioverter-defibrilator placement.</AbstractText>Prospective clinical investigation.</AbstractText>University hospital.</AbstractText>Thirty-four adult patients.</AbstractText>After administration of midazolam, 0.025 mg/kg, and fentanyl, 0.5 to 1 mug/kg, surgery was performed under topical infiltration with 1% lidocaine. In group I (GI) (n = 17), patients received thiopental by slow injection and patients in group II (GII) (n = 17) received propofol before induction of ventricular fibrillation (VF).</AbstractText>Patients received 4.1 +/- 1.4 mg of midazolam, 114 +/- 34 mug of fentanyl, and 280 +/- 78 mg of thiopental in GI; and 4.6 +/- 1.7 mg of midazolam, 119 +/- 62 mug of fentanyl, and 147 +/- 40 mg of propofol in GII (p > 0.05). Hemodynamics did not show significant differences between the groups at any recording time. Average time needed to regain the pretest sedation level was 16.4 +/- 8.8 minutes in GI and 10.9 +/- 5.5 minutes in GII (p = 0.03). Time required to achieve a score of 10 using a modified Aldrete score was 26.4 +/- 9.3 minutes in GI and 17.4 +/- 4.9 in GII (p = 0.001). Seven patients in GII (41%) and 1 patient in GI (6%) became hypotensive after DFT (p = 0.04).</AbstractText>Deepening the sedation level by slow injection of thiopental or propofol before DFT provided satisfactory conditions during brief episodes of VF. Delay in recovery of arterial pressure after DFT with propofol and delay in arousal and discharge of patients with thiopental are major disadvantages of the regimens.</AbstractText> |
2,110 | [Acute hemodynamic effects of biventricular and left ventricular pacing in chronic pacemaker-dependent patients with advanced heart failure]. | The beneficial hemodynamic effects of cardiac resynchronization in patients with intraventricular conduction delay have been demonstrated. The potential hemodynamic effects of cardiac resynchronization to compensate the pacing-induced left ventricular conduction delay in chronically paced heart failure patients are not as well established. The aim of the study was to evaluate the acute hemodynamic effects of biventricular and left ventricular pacing in chronically paced patients with advanced heart failure. Fourteen consecutive pacemaker or defibrillator patients with permanent atrial fibrillation and AV block (11 male, 3 woman, mean age: 68 +/- 7 years) were enrolled in this study. There were 5 ischemic (36%) and 9 nonischemic (64%) patients (mean left ventricular ejection fraction: 19 +/- 5%; mean end-diastolic left ventricular diameter: 71 +/- 11 mm). In all patients a right ventricular and left ventricular (via coronary sinus) pacing lead was placed. The aortic and left ventricular hemodynamic measurements were performed using a two-channel micro-tip catheter. The measurements of the aortic pulse pressure (APP) and (dP/ dtmax) were performed during right ventricular apical pacing (RVP), left ventricular (LVP), and biventricular pacing (BVP) (70 bpm). Compared to RVP, LVP and BVP increased APP and dP/dtmax (35.8 +/- 4.2 vs 43.3 +/- 4.5 and 41.2 +/- 4 mmHg; p < 0.001) and (758 +/- 56 vs 967 +/- 60 and 961 +/- 62 mmHg/s; p < 0.001). LVP and BVP showed a comparable hemodynamic response. The hemodynamic effects were not related to the width of the paced QRS complex. Every patient showed improved hemodynamics during LVP and BVP unrelated to the underlying heart disease and to the baseline level of left ventricular dysfunction. BVP and LVP pacing acutely improve contractile left ventricular function in chronically paced patients with advanced heart failure. |
2,111 | Biphasic response of action potential duration to sudden sympathetic stimulation in anesthetized cats. | Although certain roles of the sympathetic nervous system have been suggested as possible mechanisms of life-threatening arrhythmias and sudden cardiac death, the dynamic electrophysiological response to sympathetic activation remains unclear. The aim of this study was to investigate the dynamic response of action potential duration (APD) to sudden sympathetic stimulation (SYM) using monophasic action potential (MAP) recording. In 10 anesthetized cats, MAPs were continuously recorded from the right ventricular endocardium under constant pacing. The dynamic response of the APD to SYM (3 Hz) were examined before and after the administration of propranolol (0.5 mg/kg i.v.) (n=5) or phentolamine (1.0 mg/kg i.v.) (n=5). In response to SYM, the APD was transiently prolonged by 5.5+/-3.2 ms at 7.0+/-1.3 s, and monotonically shortened toward a steady-state level (-14.5+/-6.9 ms). Propranolol almost abolished both the transient prolongation (6.6+/-4.5 to 0.2+/-0.4 ms, p<0.05) and the steady-state shortening (-13.7+/-3.6 to -1.1+/-2.4 ms, p<0.005), whereas phentolamine did not have a significant effect on the response of APD to SYM. These findings might partly account for the propensity of ventricular arrhythmias to occur immediately after sudden sympathetic activation. |
2,112 | Diabetes influences the cardiac symptoms related to atrial fibrillation. | It is well known that diabetes mellitus (DM) masks the cardiac symptoms during an ischemic heart attack, but there have not been reports of whether DM influences the subjective symptoms of atrial fibrillation (AF). The present study retrospectively assessed 65 patients who were revealed to be in sinus rhythm at their first visit to hospital and who had experienced episodes of AF (or paroxysmal AF) during the follow-up period. Compared with non-DM cases (n=50), DM patients (n=15) had a tendency to a more rapid heart rate in sinus rhythm (73+/-4 vs 66+/-2, p=0.07) and higher averaged ventricular response at the first-recorded episode of AF (111+/-7 vs 99+/-3, p=0.10). However, the ratio of symptomatic cases at first-recorded AF tended to be lower in DM cases (33% vs 58%, p=0.08). When patients with beta-blockers or other antiarrhythmic agents were excluded, the ratio of symptomatic patients at first-recorded AF was significantly lower in the DM cases (25% vs 61%, p=0.04), although there was not a significant difference in averaged ventricular response at first-recorded AF (112+/-8 vs 106+/-5). The prevalence of DM neuropathy was significantly higher in asymptomatic patients (70% vs 0%, p=0.01). DM may mask the cardiac symptoms of the first-recorded episode of AF, possibly because of DM neuropathy. |
2,113 | Ischemia-induced translocation of protein kinase C-epsilon mediates cardioprotection in the streptozotocin-induced diabetic rat. | The present study investigated the role of translocation of protein kinase C (PKC) during ischemia/reperfusion in cardioprotection in the streptozotocin (STZ)-induced diabetic rat. Twelve weeks after injection of STZ or vehicle, male Wister-King rat hearts were isolated and perfused in the presence or absence of 50 nmol/L staurosporine or 2 mumol/L chelerythrine using a Langendorff apparatus. Thirty minutes of global ischemia was followed by the same period of reperfusion. The time to onset of contracture was determined during ischemia. The recovery of left ventricular function, incidence of ventricular tachycardia/fibrillation (VT/VF), and amount of released creatine kinase (CK) were determined during the reperfusion period. Translocation of the PKC-alpha, -beta, -delta and -epsilon isoforms was determined by immunoblotting. Development of contracture was delayed, the recovery of left ventricular function was greater, and the incidence of VT/VF and amount of released CK were lower in diabetic than in control hearts. Ischemia caused an increase in the particulate/cytosolic fraction ratio of the PKC- epsilon isoform in the diabetic and control hearts. However, this translocation of PKC-epsilon during ischemia was transient in the control heart, but was persistent in the diabetic heart. The ischemia-induced translocation of PKC-epsilon was abolished by chelerythrine perfusion. These results suggest that persistent translocation of PKC-epsilon during ischemia plays a major role in cardioprotection against ischemia/reperfusion injury in STZ-induced diabetic rats. |
2,114 | Refractoriness and conduction interaction during modulation of non-ischemic ventricular fibrillation by flecainide. | To study refractoriness and conduction interaction during modulation of non-ischemic ventricular fibrillation (VF) by flecainide.</AbstractText>Isolated feline and rabbit hearts were used. (a) In the feline hearts (n = 8), electrophysiological parameters were measured before and after flecainide administration (0.6, 1.2 x 10(-6) M). During pacing the parameters were: epicardial conduction time, refractoriness and 1:1 pacing/response capture. During 8 min of electrically-induced tachyarrhythmias they included heart rate and normalized entropy reflecting the degree of organization. (b) In rabbit hearts (n = 4), three-dimensional mapping was performed before and after flecainide administration (2 x 10(-6) M). To follow changes in organization, local RR-intervals and differences in activation time between adjacent epicardial electrodes were measured immediately and 80 sec after VF induction.</AbstractText>In feline hearts with flecainide, fibrillation was more difficult to induce, more frequently terminated spontaneously and was slower and more organized; conduction time was markedly lengthened, and refractoriness less than 1:1 capture, was moderately prolonged. An inverse correlation was observed between arrhythmia properties, rate and organization, and changes in refractoriness and conduction time. In rabbit, the number of wave fronts was reduced, RR-intervals were prolonged but at the same time activation time differences between adjacent electrodes were smaller following flecainide administration.</AbstractText>It is suggested that flecainide modulation of VF properties is associated with conduction suppression and refractoriness prolongation, which act in a synergistic, additive way.</AbstractText> |
2,115 | Clinical results with catheter ablation: AV junction, atrial fibrillation and ventricular tachycardia. | With the limitations of pharmacologic and device therapies for atrial fibrillation and ventricular tachycardia, catheter ablation is assuming a larger role in the management of patients with these common arrhythmias. Multiple case series and clinical trials have helped to define the evolving role of these techniques for ablation of the atrioventricular node, atrial fibrillation, and ischemic ventricular tachycardia. Based on very low complication rates, excellent efficacy and proven outcomes with radiofrequency ablation of the atrioventricular node, this approach with permanent pacing should play a larger role in the treatment of symptomatic patients with permanent atrial fibrillation. While linear ablation of atrial fibrillation has limited clinical utility for the treatment of this common arrhythmia, the results of multiple case series of focal atrial fibrillation ablation indicate the potential for an expanding role of this curative technique. Catheter ablation techniques for ventricular tachycardia in the setting of coronary artery disease have a role as supplemental therapy to the implantable cardioverter defibrillator in patients with recurrent pharmacologically refractory ventricular arrhythmias requiring frequent device interventions. |
2,116 | Rationale and patient selection for "hybrid" drug and device therapy in atrial and ventricular arrhythmias. | Three quite different forms of direct antiarrhythmic therapy are available for the treatment of cardiac arrhythmias: antiarrhythmic drugs, cardiac ablation and implantable devices (pacemakers and defibrillators). None of these therapies is fully effective and consequently they are increasingly combined. This combination therapy is often described as "hybrid" a term that implies fundamental different qualities of treatment which together provide some form of synergism. The mechanisms for the initiation and perpetuation of most cardiac arrhythmias are complex and multiple. It is therefore not surprising that single therapies are not completely effective. Theoretically the use of multiple different therapies allows more specific mechanisms of arrhythmia to be directly addressed. However, this is largely a theoretical concept that has only been strictly evaluated in a small number of studies. Studies of multiple therapies are difficult to perform unless the combination therapy is regarded as a strategy which can be compared to baseline, conventional treatment or one or more single constituent therapies from the combination. Despite the lack of formal studies there is a very substantial clinical experience which testifies to the value of hybrid therapy for the management of both atrial fibrillation and ventricular tachycardia/fibrillation. |
2,117 | Advances in devices for cardiac resynchronization in heart failure. | Patients with advanced heart failure have a high mortality and morbidity despite medical therapy. Depending on the underlying heart disease and severity of heart failure, 3.7 to 52.8% of patients have a QRS complex > or =120 ms who may have interventricular and intraventricular dyssynchrony correctible by cardiac resynchronization therapy (CRT). The latter is usually achieved with biventricular pacing, with the left ventricular lead placed in a tributary of the coronary sinus (CS), with a reported success rate between 88-92%. The technical advances for implantation include preformed guide sheaths to cannulate the CS, over the wire leads with passive fixation mechanism, and surgical placement methods. Device-specific CRT features include optimizing heart failure through insurance of a high percentage of pacing, heart failure monitoring, atrioventricular and interventricular timing, and avoiding double ventricular sensing. Furthermore, arrhythmic co-morbidities of heart failure such as atrial fibrillation and ventricular tachyarrhythmias can also be managed. Recent prospective trials suggest that there is a 30% reduction in heart failure hospitalization with CRT, and preliminary results suggest a survival benefit with CRT and implantable cardioverter defibrillator over optimal medical therapy. |
2,118 | Toward an understanding of the molecular mechanisms of ventricular fibrillation. | A major goal of basic research in cardiac electrophysiology is to understand the mechanisms responsible for ventricular fibrillation (VF). Here we review recent experimental and numerical results, from the ion channel to the organ level, which might lead to a better understanding of the cellular and molecular mechanisms of VF. The discussion centers on data derived from a model of stable VF in the Langendorff-perfused guinea pig heart that demonstrate distinct patterns of organization in the left (LV) and right (RV) ventricles. Analysis of optical mapping data reveals that VF excitation frequencies are distributed throughout the ventricles in clearly demarcated domains. The highest frequency domains are usually found on the anterior wall of the LV, demonstrating that a high frequency reentrant source (a rotor) that remains stationary in the LV is the mechanism that sustains VF in this model. Computer simulations predict that the inward rectifying potassium current (IK1) is an essential determinant of rotor stability and rotation frequency, and patch-clamp results strongly suggest that the outward component of the background current (presumably IK1) of cells in the LV is significantly larger in the LV than in the RV. These data have opened a new and potentially exciting avenue of research on the possible role played by inward rectifier channels in the mechanism of VF and may lead us toward an understanding of its molecular basis and hopefully lead to new preventative approaches. |
2,119 | Clinical review of radiofrequency catheter ablation for cardiac arrhythmias. | Clinical tachycardias are a major cause of morbidity with detrimental effects on quality of life, physical activity and health care costs. Catheter ablation delivered by radiofrequency energy (RFA) has gradually expanded as a therapeutic modality for cure or palliation and is being adapted to address the most difficult to treat tachycardias. The purpose of this paper is to inform decision makers about the current evidence base of RFA through a comprehensive literature review. Of the 968 citations identified through the literature search strategy, 111 studies (11%) met the inclusion criteria. Only 10 of these studies (9%) were randomized, controlled trials. RFA of paroxysmal supraventricular tachycardia, atrial flutter and focal atrial tachycardias are all procedures associated with high procedural success rates and sustained clinical improvement within two years of follow-up. Limited evidence also demonstrates that elimination of these tachycardias improves symptoms and quality of life. RFAs of atrial fibrillation and ventricular tachycardia secondary to underlying structural heart disease are currently considered experimental procedures because there remains insufficient published data to draw conclusions about their clinical efficacy and safety profile. For all of the ablation procedures, there is a paucity of high-quality outcome studies comparing ablation with alternative therapeutic approaches and this provides the opportunity for future research. |
2,120 | Predictors of left atrial appendage stunning after electrical cardioversion of non-valvular atrial fibrillation. | To identify predictors of left atrial appendage stunning after the use of electrical cardioversion to restore sinus rhythm in patients with non-valvular atrial fibrillation.</AbstractText>A total of 68 consecutive patients (45 men, 23 women, 60.5 +/- 8.7 years of age) with non-valvular atrial fibrillation undergoing electrical cardioversion were enlisted in this study. Clinical and echocardiographic variables were analyzed by univariate regression and multivariate logistic regression to investigate the relationship between occurrences of left atrial appendage stunning and these factors.</AbstractText>Univariate analysis revealed that, in comparing patients without and with left atrial appendage stunning, there were significant differences in the duration of atrial fibrillation > 8 weeks (32.3% vs 75.5%, P < 0.001), left atrial diameter > 50 mm (29.0% vs 54.1%, P < 0.05), left atrial emptying fraction (31.5% +/- 7.8% vs 27.1% +/- 8.5%, P < 0.05), left ventricular ejection fraction < 50% (38.7% vs 67.6%, P < 0.05), maximum electrical energy (96.8 J +/- 65.8 J vs 156.8 J +/- 100.8 J, P < 0.01), cumulative electrical energy 146.8 J +/- 142.6 J vs 290.5 J +/- 242.1 J, P < 0.01) and number of electrical cardioversion shocks (1.7 +/- 0.9 vs 2.43 +/- 1.20, P < 0.05). However, backward stepwise multivariate logistic regression analysis identified as significant and independent predictors of left atrial appendage stunning only duration of atrial fibrillation > 8 weeks (OR = 7.249, 95% CI = 1.998 - 26.304, P < 0.01), left atrial diameter > 50 mm (OR = 3.896, 95% CI = 1.105 - 13.734, P < 0.05), left ventricular ejection fraction < 50% (OR = 4.465, 95% CI = 1.51713.140, P < 0.01) and cumulative energy of electrical cardioversion (OR = 1.004, 95% CI = 1.000 - 1.008, P < 0.05).</AbstractText>Duration of atrial fibrillation > 8 weeks, left atrial diameter > 50 mm, left ventricular ejection fraction < 50%, and cumulative energy of electrical cardioversion are independent predictors of left atrial appendage stunning. Anticoagulation treatment should be individualized for patients undergoing electrical cardioversion to reduce the risk of both cardioversion-related thromboembolic events and hemorrhagic complications caused by warfarin treatment.</AbstractText> |
2,121 | Rising rates of hospital admissions for atrial fibrillation. | Atrial fibrillation is a common arrhythmia associated with excess morbidity and mortality. We studied temporal changes in hospital admission rates for atrial fibrillation using data from a prospective population-based cohort study spanning 2 decades (the Copenhagen City Heart Study).</AbstractText>The study included baseline data collected in 1981 through 1983 on 10,955 persons age 40 to 79 years and baseline data collected in 1991 through 1994 on 7212 persons age 40 to 79 years. We used hospital diagnosis data from the Danish National Hospital Discharge Register to determine the rate of first hospital admission for atrial fibrillation during 7 years following each of the 2 baseline data collecting periods. Changes in admission rates were analyzed using Cox proportional hazard models.</AbstractText>During the 2 7-year periods, 379 subjects were admitted with a hospital diagnosis of atrial fibrillation. The rate of hospital admissions for atrial fibrillation increased among both men and women from the first to the second period (relative risk = 1.6; 95% confidence interval = 1.3-1.9 [adjusted for age, sex, prior myocardial infarction, arterial hypertension, diabetes mellitus, electrocardiographic left ventricular hypertrophy, decreased lung function, smoking, height, and weight]).</AbstractText>During the latest 10 to 20 years, there has been a 60% increase in hospital admissions for atrial fibrillation independent of changes in known risk factors. This increase could result from changes in admission threshold or coding practices, or it could reflect a genuine increase in the population incidence of atrial fibrillation.</AbstractText> |
2,122 | Anatomic stereotactic catheter ablation on three-dimensional magnetic resonance images in real time. | Targets for radiofrequency (RF) ablation of atrial fibrillation, atrial flutter, and nonidiopathic ventricular tachycardia are increasingly being selected on the basis of anatomic considerations. Because fluoroscopy provides only limited information about the relationship between catheter positions and cardiac structures and is associated with radiation risk, other approaches to mapping may be beneficial.</AbstractText>An electromagnetic catheter positioning system was superimposed on 3D MR images using fiducial markers. This allowed the dynamic display of the catheter position on the true anatomy of previously acquired MR images in real time. In vitro accuracy and precision during catheter navigation were assessed in a phantom model and were 1.11+/-0.06 and 0.30+/-0.07 mm (mean+/-SEM), respectively. Left and right heart catheterization was performed in 7 swine without the use of fluoroscopy, yielding an in vivo accuracy and precision of 2.74+/-0.52 and 1.97+/-0.44 mm, respectively. To assess the reproducibility of RF ablation, RF lesions were created repeatedly at the identical anatomic site in the right atrium (n=8 swine). Average distance of the repeated right atrial ablations was 3.92+/-0.5 mm. Straight 3-point lines were created in the right and left ventricles to determine the ability to facilitate complex ablation procedures (n=6 swine). The ventricular lesions deviated 1.70+/-0.24 mm from a straight line, and the point distance differed by 2.25+/-0.63 mm from the pathological specimen.</AbstractText>Real-time display of the catheter position on 3D MRI allows accurate and precise RF ablation guided by the true anatomy. This may facilitate anatomically based ablation procedures in, for instance, atrial fibrillation or nonidiopathic ventricular tachycardia and decrease radiation times.</AbstractText> |
2,123 | Comparison of standard cardiopulmonary resuscitation versus the combination of active compression-decompression cardiopulmonary resuscitation and an inspiratory impedance threshold device for out-of-hospital cardiac arrest. | Active compression-decompression (ACD) CPR combined with an inspiratory impedance threshold device (ITD) improves vital organ blood flow during cardiac arrest. This study compared survival rates with ACD+ITD CPR versus standard manual CPR (S-CPR).</AbstractText>A prospective, controlled trial was performed in Mainz, Germany, in which a 2-tiered emergency response included early defibrillation. Patients with out-of-hospital arrest of presumed cardiac pathogenesis were sequentially randomized to ACD+ITD CPR or S-CPR by the advanced life support team after intubation. Rescuers learned which method of CPR to use at the start of each work shift. The primary end point was 1-hour survival after a witnessed arrest. With ACD+ITD CPR (n=103), return of spontaneous circulation and 1- and 24-hour survival rates were 55%, 51%, and 37% versus 37%, 32%, and 22% with S-CPR (n=107) (P=0.016, 0.006, and 0.033, respectively). One- and 24-hour survival rates in witnessed arrests were 55% and 41% with ACD+ITD CPR versus 33% and 23% in control subjects (P=0.011 and 0.019), respectively. One- and 24-hour survival rates in patients with a witnessed arrest in ventricular fibrillation were 68% and 58% after ACD+ITD CPR versus 27% and 23% after S-CPR (P=0.002 and 0.009), respectively. Patients randomized > or =10 minutes after the call for help to the ACD+ITD CPR had a 3 times higher 1-hour survival rate than control subjects (P=0.002). Hospital discharge rates were 18% after ACD+ITD CPR versus 13% in control subjects (P=0.41). In witnessed arrests, overall neurological function trended higher with ACD+ITD CPR versus control subjects (P=0.07).</AbstractText>Compared with S-CPR, ACD+ITD CPR significantly improved short-term survival rates for patients with out-of-hospital cardiac arrest. Additional studies are needed to evaluate potential long-term benefits of ACD+ITD CPR.</AbstractText> |
2,124 | Sevoflurane reduces dysrhythmias during reperfusion in the working rat heart. | The effects of sevoflurane on myocardial reperfusion injury have not been well studied. The purpose of this study was to determine the effects of sevoflurane on myocardial function, arrhythmia, and metabolism during reperfusion in an isolated working rat heart model.</AbstractText>Thirty-two hearts were divided into four groups according to the timing of 2.5% sevoflurane administration: group I, control, no sevoflurane; group II, sevoflurane administered only before ischemia; group III, sevoflurane only during reperfusion; group IV, sevoflurane during the whole study period. Myocardial contractility, myocardial ATP, lactate, and glycogen levels were assessed in the reperfusion period following global heart ischemia of 15 min duration. The incidence and duration of ventricular fibrillation were also observed in the reperfusion period.</AbstractText>There was no difference in cardiac output and left ventricular dP/ dt max among the four groups at 10, 15, and 20 min after reperfusion. There was no difference in myocardial ATP, lactate and glycogen contents between the groups. The incidences of ventricular fibrillation during reperfusion were 100%, 63%, 100%, and 25% (P < 0.05 vs control), and the durations of ventricular fibrillation during reperfusion were 375 +/- 269, 104 +/- 98 (P < 0.05 vs control), 303 +/- 189, and 93 +/- 245 (P < 0.05 vs control) in groups I, II, III, and IV, respectively (mean +/- SD).</AbstractText>The administration of sevoflurane prior to reperfusion appears to provide myocardial protection, as assessed by reduced dysrhythmias during reperfusion.</AbstractText> |
2,125 | Gender-related differences in morbidity and mortality during combined valve and coronary surgery. | Gender-related differences in morbidity and mortality are well described for coronary artery bypass grafting but are not well understood for combined valve and bypass surgery.</AbstractText>We reviewed retrospectively the morbidity and mortality of 1570 consecutive patients who underwent combined valve and bypass procedures at the Toronto General Hospital between January 1990 and October 2000.</AbstractText>There were 1073 men (68%) and 497 women (32%). The mean ages (+/- 1 SD) of women and men were 69 +/- 9 and 68 +/- 9 years, respectively (P =.02). Of the 1570 total patients, 973 patients (62%) underwent aortic valve and coronary bypass surgery, 481 patients (31%) had mitral valve and coronary bypass operations, and 116 (7%) patients had double or triple valve and coronary bypass operations. Preoperative hypertension (P =.002), diabetes (P =.001), and atrial fibrillation (P =.001) were seen more frequently in women. Body surface area was significantly lower in women (P =.0001). At presentation, more women were in congestive heart failure (69% vs 58%, P =.001) and in New York Heart Association functional class III or IV (25% vs 19%, P =.001). Although there was no difference in the number of women with three or more diseased vessels (32% vs 38%), only 35% of women received three or more grafts compared with 44% of men (P =.001). The use of left internal thoracic grafts, although uncommon in the whole study population (36%), was less common in women than in men (26% vs 41%, P =.001). Multivariable logistic analyses for morbidity and mortality showed female gender to be an independent risk factor. Mitral valve replacement, age, left ventricular dysfunction, New York Heart Association classes III and IV, and association of tricuspid valve disease, diabetes, peripheral vascular disease, and preoperative renal failure were found to be independent risk factors for mortality.</AbstractText>Female gender is an independent risk factor for combined morbidity and mortality during and after combined valve and coronary bypass surgery. As with isolated coronary artery bypass grafting, women undergoing combined procedures have more premorbid conditions, are more often in heart failure, had an equal incidence of triple vessel disease but received fewer grafts than men, and, therefore, were more frequently incompletely revascularized.</AbstractText> |
2,126 | Clinical logistics in 24-hour ambulatory electrocardiographic monitoring. | In total, 493 ambulatory ECG recordings were studied. Women were preponderant (62.3% vs 37.7%). The average age of women and men patients was 66.9 and 64.7 years, respectively. Of the ECGs studied, 71.4% showed abnormalities and 28.6% appeared completely normal. Urgent abnormalities were noted in 1.4% of the recordings and significant abnormalities were present in 14.6%. Subjective complaints were noted in their logbooks by 18.8% of patients, but correlation of complaints with the electrocardiographic abnormalities was noted in only 1.2% of cases. The attending cardiologist concluded that 23.9% of the tests supported reasons of valid necessity for performance. Two hundred seventy-three recordings were classified as electrocardiographically abnormal (55.4%) but were clinically insignificant. General practitioners requested 59.8% of the tests versus 40.2% by specialists. Preponderant abnormalities included premature atrial and ventricular contractions, supraventricular tachycardia, and atrial fibrillation. Less frequent abnormalities included ventricular tachycardia (4.6%), atrial flutter, atrioventricular block, artificial pacemaker rhythm, nodal rhythm, and intermittent bundle branch block. |
2,127 | A neural mechanism for sudden death after myocardial infarction. | By monitoring efferent cardiac sympathetic nerve activity (CSNA) directly in a conscious animal we observed, for the first time, that ventricular fibrillation (VF) following myocardial infarction (MI) was preceded by a paroxysm of CSNA which was not baroreflexmodulated. This observation has potential therapeutic implications. |
2,128 | Cardiac resynchronization therapy for the treatment of heart failure in patients with intraventricular conduction delay and malignant ventricular tachyarrhythmias. | This study was conducted to assess the safety and effectiveness of cardiac resynchronization therapy (CRT) when combined with an implantable cardioverter defibrillator (ICD).</AbstractText>Long-term outcome of CRT was measured in patients with symptomatic heart failure (HF), intraventricular conduction delay, and malignant ventricular tachyarrhythmias (ventricular tachycardia/ventricular fibrillation [VT/VF]) requiring therapy from an ICD.</AbstractText>Patients (n = 490) were implanted with a device capable of providing both CRT and ICD therapy and randomized to CRT (n = 245) or control (no CRT, n = 245) for up to six months. The primary end point was progression of HF, defined as all-cause mortality, hospitalization for HF, and VT/VF requiring device intervention. Secondary end points included peak oxygen consumption (VO(2)), 6-min walk (6 MW), New York Heart Association (NYHA) class, quality of life (QOL), and echocardiographic analysis.</AbstractText>A 15% reduction in HF progression was observed, but this was statistically insignificant (p = 0.35). The CRT, however, significantly improved peak VO(2) (0.8 ml/kg/min vs. 0.0 ml/kg/min, p = 0.030) and 6 MW (35 m vs. 15 m, p = 0.043). Changes in NYHA class (p = 0.10) and QOL (p = 0.40) were not statistically significant. The CRT demonstrated significant reductions in ventricular dimensions (left ventricular internal diameter in diastole = -3.4 mm vs. -0.3 mm, p < 0.001 and left ventricular internal diameter in systole = -4.0 mm vs. -0.7 mm, p < 0.001) and improvement in left ventricular ejection fraction (5.1% vs. 2.8%, p = 0.020). A subgroup of patients with advanced HF (NYHA class III/IV) consistently demonstrated improvement across all functional status end points.</AbstractText>The CRT improved functional status in patients indicated for an ICD who also have symptomatic HF and intraventricular conduction delay.</AbstractText> |
2,129 | The hemodynamic effects of acute myocardial ischemia and reperfusion in Clawn miniature pigs. | Acute myocardial ischemia was induced by occluding the LAD in Clawn miniature pigs. Eight pigs (group 1) were subjected to 6 h ischemia and nine pigs (group 2) were subjected to 20 min ischemia, followed by reperfusion for 340 min. Three animals of the group 1 died due to ventricular fibrillation after occlusion and in group 2, four animals died due to the arrhythmia after reperfusion. Though the ischemic area of group 2 (15.6% of the ventricle) was narrower than that of group 1 (21.7%), the survival rate was lower. We supposed that ischemia-reperfusion injuries were strongly connected with the hemodynamics of group 2. Clawn miniature pigs are useful experimental animals for myocardial ischemic researches. |
2,130 | Rhythm control versus rate control in patients with persistent atrial fibrillation. Results of the HOT CAFE Polish Study. | Patients with atrial fibrillation (AF) can be managed either by maintaining sinus rhythm using antiarrhythmic drugs and/or electrical cardioversion, or by leaving patients in AF and controlling ventricular rate without attempts to restore sinus rhythm. Which of these two strategies is superior, has not yet been definitively established.</AbstractText>HOT CAFE Polish Study (How To Treat Chronic Atrial Fibrillation) was designed to evaluate in a randomised, multicentre and prospective manner the risks and advantages of two therapeutical strategies - rate control or rhythm control, in patients with persistent AF.</AbstractText>The study group consisted of 205 patients (71 females and 134 males; mean age 60.8+/-11.2 years) with a mean time of AF duration of 273.7+/-112.4 days; 101 patients were randomly assigned to rate control (Group I) whereas 104 patients were randomised to sinus rhythm (SR) restoration by DC cardioversion (CV) and subsequent antiarrhythmic drug treatment (Group II). At the end of follow-up (12 months) SR was present in 75% of patients.</AbstractText>The incidence of hospital admissions was higher in group II in comparison to group I (12% vs 74%; p<0.001). Mortality was similar in both groups (1.0% versus 2.9%, NS). In both groups a significant improvement of heart failure symptoms was observed during the first 2 months (p<0.02 and p<0.001). In group II exercise tolerability measured by maximal workload during treadmill test significantly improved compared with baseline (5.2+/-5.1 vs 7.6+/-3.3 MET; p<0.0001). In patients in whom SR was restored, the left ventricular function improved and an increase in the shortening fraction was observed (29+/-7% vs 31+/-7%; p<0.01). No thromboembolic complications were observed in patients left with AF. Three patients from group II suffered ischaemic stroke; in two cases stroke was associated with CV whereas in the third patient - with late AF recurrence.</AbstractText>The HOT CAFE Polish Study did not reveal significant differences in mortality between the two treatment strategies in patients with persistent AF. Although patients with SR had better improvement in some haemodynamical parameters, the hospitalisation rate was higher and the incidence of stroke was not reduced compared with the rate control group.</AbstractText> |
2,131 | Factors determining long-term maintenance of sinus rhythm after cardioversion of persistent atrial fibrillation. | Long-term maintenance of sinus rhythm (SR) after successful cardioversion (CV) of persistent atrial fibrillation (AF) carries a low risk of stroke and may avoid the risks associated with anticoagulation.</AbstractText>To determine the clinical and echocardiographic predictors of maintaining SR during one-year follow-up.</AbstractText>The initial study group consisted of 205 patients with persistent AF of whom 104 (33 females, 71 males, mean age 60.4+/-7.4 years) were randomised to SR restoration and maintenance. The results of transthoracic echocardiography, obtained before CV, were compared between patients who remained in SR and those in whom AF recurred during a one-year follow-up period, using the linear and logistic regression analysis.</AbstractText>SR was present in 63.5% of patients at the end of the follow-up period. Of several analysed echocardiographic parameters, an increased left atrial area (<28 cm(2)) (p<0.02; RR 1.72, OR 1.09-2.71) and an increase in the fractional shortening of the left ventricle (range 25-40%, p<0.05, RR 1.2, OR 1.01-1.44) were significantly associated with SR maintenance during a 12-month follow-up period.</AbstractText>Left atrial area and left ventricular fractional shortening are the independent predictors of the maintenance of SR after successful CV in patients with persistent AF.</AbstractText> |
2,132 | Admissions with atrial fibrillation in a multiracial population in Kuala Lumpur, Malaysia. | There are established differences in cardiovascular disease in different racial groups. Worldwide, the literature regarding the clinical epidemiology of atrial fibrillation in non-white populations is scarce.</AbstractText>To document the prevalence of atrial fibrillation (AF) in the multiracial population of Malaysia, and to describe the clinical features and management of these patients.</AbstractText>Busy city centre general hospital in Kuala Lumpur, Malaysia, over a 1-month period.</AbstractText>One-thousand four hundred and thirty-five acute medical admissions, of whom 40 patients (2.8%) had AF.</AbstractText>Of 1435 acute medical admissions to Kuala Lumpur General Hospital over the 4-week study period, 40 had AF (21 male, 19 female; mean age 65 years). Of these, 18 were Malay, 16 Chinese and six Indian. Nineteen patients had previously known AF (seven with paroxysmal AF) and 21 were newly diagnosed cases. The principal associated medical conditions were ischaemic heart disease (42.5%), hypertension (40%) and heart failure (40%). Dyspnoea was the commonest presentation, whilst stroke was the cause of presentation in only two patients. Investigations were under-utilised, with chest X-ray and echocardiography in only 62.5% of patients and thyroid function checked in 15%. Only 16% of those with previously diagnosed AF were on warfarin, with a further three on aspirin. Anticoagulant therapy was started in 13.5% of patients previously not on warfarin, and aspirin in 8%. Records of contraindications to warfarin were unreliable, being identified in only 25%. For those with known AF, 58% were on digoxin. For new onset AF, digoxin was again the most common rate-limiting treatment, initiated in 38%, whilst five patients with new onset AF were commenced on amiodarone. DC cardioversion was not used in any of the patients with new onset AF.</AbstractText>Amongst acute medical admissions to a single centre in Malaysia the prevalence of AF was 2.8%. Consistent with previous similar surveys in mainly western (caucasian) populations, standard investigations in this Malaysian cohort were also inadequate and there was underuse of anticoagulation, medication for ventricular rate control and cardioversion to sinus rhythm.</AbstractText> |
2,133 | Communitywide trends in the use and outcomes associated with beta-blockers in patients with acute myocardial infarction: the Worcester Heart Attack Study. | Despite the benefits associated with beta-blocker therapy in patients with acute myocardial infarction (AMI), limited recent data are available describing the extent of use of this therapy and the associated hospital and long-term outcomes, particularly from the perspective of a population-based study. Data are also limited about the characteristics of patients with AMI who do not receive beta-blockers. This study examines more than 2 decades of trends in the use of beta-blockers in hospitalized patients with AMI.</AbstractText>Communitywide study of 10,374 patients hospitalized with confirmed AMI in all metropolitan Worcester hospitals during 12 annual periods between 1975 and 1999.</AbstractText>There was a marked increase in the use of beta-blockers in hospitalized patients between 1975 (11%) and 1999 (82%). Older patients, women, and patients with comorbidities were significantly less likely to be treated with beta-blockers. After controlling for other prognostic factors, patients treated with beta-blockers were less likely to develop heart failure (adjusted odds ratio [OR], 0.58; 95% confidence interval [CI], 0.53-0.63), cardiogenic shock (OR, 0.46; 95% CI, 0.39-0.54), and primary ventricular fibrillation (OR, 0.84; 95% CI, 0.65-1.08) and were less likely to die (OR, 0.26; 95% CI, 0.22-0.29) during hospitalization than were patients who did not receive this therapy. Patients who used beta-blockers during hospitalization had significantly lower death rates after hospital discharge.</AbstractText>The results of this observational study demonstrate encouraging trends in the use of beta-blockers in hospitalized patients with AMI and document the benefits to be gained from this treatment.</AbstractText> |
2,134 | The high incidence of left atrial appendage thrombosis in patients on maintenance haemodialysis. | The incidence of intracardiac thrombosis in haemodialysis patients has not been studied. Here we determined the incidence in end-stage renal disease patients on maintenance haemodialysis.</AbstractText>Transoesophageal echocardiography was performed in 215 patients (125 males, 90 females; mean age 60 +/- 9 years). Any potential candidate with current or past chronic or intermittent atrial fibrillation or with cardiovascular diseases was excluded from the study.</AbstractText>Thrombi were found in the left atrial appendages in 71 out of 215 subjects (33%). Based on multiple logistic regression analyses, the probability of finding a thrombus was found to be increased in patients on chronic antiplatelet therapy (odds ratio 4.268) and in those with diabetes mellitus and a low haematocrit (</=0.3; odds ratio 7.173). Other clinical parameters, including gender, age, duration of haemodialysis, blood pressure, left ventricular dimension, smoking habit or type of anticoagulation during dialysis, were not associated with the incidence of left atrial appendage thrombosis.</AbstractText>Maintenance haemodialysis patients have a high incidence of left atrial appendage thrombosis. Either chronic use of antiplatelet drugs or the background conditions requiring antiplatelet therapy, and the concomitant presence of diabetes mellitus and a low haematocrit may be involved in left atrial appendage thrombosis.</AbstractText> |
2,135 | A brief history of sudden cardiac death and its therapy. | At the end of the 19th century, there was both experimental and clinical evidence that coronary artery obstruction causes ventricular fibrillation and sudden death and that fibrillation could be terminated by electric shocks. The dominant figure at that time was McWilliam, who in 1923 complained that "little attention was given to the new view for many years." This remained so for many decades. It was not until the 1960s that the medical profession became aware of the magnitude of the problem of sudden death and began to install coronary care units where arrhythmias could be monitored and prompt defibrillation could be delivered. This approach was pioneered by Julian in 1961. Milestones that allowed this development were open-chest defibrillation by Beck, closed-chest defibrillation by Zoll, cardiac massage by Kouwenhoven et al., and development of the DC defibrillator by Lown. In 1980, Mirowski et al. implanted the first implantable cardioverter defibrillator (ICD) in a patient. Thereafter, the use of the ICD increased exponentially. Several randomized trials, largely in patients with coronary artery disease and left ventricular dysfunction or in patients with documented lethal arrhythmias, showed beyond doubt that the ICD is superior to antiarrhythmic drug therapy in preventing sudden death, although a number of trials showed no effect. Trials on antiarrhythmic drugs were disappointing. Sodium channel blockers and "pure" potassium channel blockers actually increase mortality, calcium channel blockers have no effect, and, although amiodarone reduces arrhythmic death, it had no effect on total mortality in the 2 largest trials. Only the beta-blockers have been proven to reduce the incidence of sudden death, but their effect appears not to be related to the suppression of arrhythmias but rather to the reduction in sinus rate. Drugs that prevent ischemic events, or lessen their impact, such as anticoagulants, statins, angiotensin-converting enzyme inhibitors, and aldosteron antagonists, all reduce the incidence of sudden death. |
2,136 | Cardiac arrest due to ventricular fibrillation as a complication occurRing during rigid bronchoscopic laser therapy. | Laser bronchoscopy is a usually well tolerated procedure for the treatment of obstructive lesions on the tracheobronchial tree, with a very low morbidity and mortality rate. Cardiovascular complications, including atrial and ventricular arrhythmias, and myocardial ischemia, have only rarely been reported during laser bronchoscopy. Cardiac arrhythmias during such a procedure are usually well tolerated but occasionally may be life threatening. Here we report a case of a young, female patient affected by Pulmonary Tuberculosis with a cicatricial stenosis of the left main bronchus who developed an episode of prolonged cardiac arrest due to ventricular fibrillation (and no signs of acute myocardial ischemia) during rigid broncoscopic laser-therapy. Underlying Coronary Artery Disease and other cardiac abnormalities were also excluded by subsequent cardiovascular examination. The clinical implications are also discussed. |
2,137 | [Cardiac arrest and implantation of a cardioverter-defibrillator in a pregnant woman]. | During pregnancy increased incidence of maternal cardiac arrhythmias is observed. We reported a 31 year old primipara after two incidents of cardiac arrest due to ventricular fibrillation during pregnancy at 10th and 16th week of gestation. The implantable cardioverter defibrillator was implanted at the 19th week of gestation. There was no complication after ICD implantation. A healthy child was born by cesarean section at 38th week of gestation. |
2,138 | A candidate locus approach identifies a long QT syndrome gene mutation. | Long QT syndrome is an inherited disorder that results in lengthened cardiac repolarization. It can lead to sudden onset of torsades de pointes, ventricular fibrillation, and death. The authors obtained a family history, performed electrocardiograms, and drew blood for DNA extraction and genotyping from 15 family members representing 4 generations of an affected family. Seven individuals demonstrated prolonged QT intervals. The authors used polymorphic short tandem repeat markers at known LQTS loci, which indicated linkage to chromosome 11p15.5 where the potassium channel, KCNQ1, is encoded. Polymerase chain reaction was used to amplify the coding region of KCNQ1. During survey of the KCNQ1 coding region, a G-to-A transition (G502A) was identified. DNA from all clinically affected but from none of the clinically unaffected family members carried the G-to-A transition. The candidate locus approach allowed an efficient mechanism to uncover the potassium channel mutation causing LQTS in this family. |
2,139 | Cariporide is cardioprotective after iatrogenic ventricular fibrillation in the intact swine heart. | We sought to introduce sodium-hydrogen exchange inhibition as prophylaxis against the development of ventricular dysfunction in the setting of implantable cardioverter defibrillator insertion in high-risk patients. Cariporide, shown to be safe in humans, was used to reproduce previous results in our laboratory that demonstrated that sodium-hydrogen exchange inhibition preserves left ventricular (LV) function after ventricular fibrillation (VF) and reperfusion.</AbstractText>Twelve pigs (weight, 35 to 55 kg) were divided into two groups of six. Baseline ventricular function studies were based on echocardiography, conductance, aortic flow, and LV pressure. Animals were given vehicle (control) or cariporide (3 mg/kg intravenously). Ten minutes later, hearts underwent 80 seconds of VF. After reperfusion for 40 minutes, function studies were repeated.</AbstractText>Postmortem examination included measuring passive pressure-volume curves and myocardial water content. Systolic indices, including preload recruitable stroke work and ejection fraction, were significantly depressed from baseline after VF and reperfusion for control animals (preload recruitable stroke work, 30.13 +/- 0.59 [standard error of the mean] versus 43.85 +/- 2.60 mm Hg; ejection fraction, 25.7% +/- 2.4% versus 33.5% +/- 3.0%) but not for those in the cariporide group (preload recruitable stroke work, 38.36 +/- 1.87 versus 40.86 +/- 1.45 mm Hg; ejection fraction, 33.9% +/- 3.5% versus 32.8% +/- 3.9%). In vivo diastolic indices demonstrated trends toward diminished ventricular compliance in control animals but not in the cariporide group after VF and reperfusion. Control animals had significantly increased postmortem LV stiffness, myocardial water content, and normalized LV mass.</AbstractText>Cariporide preserves LV function after 80 seconds of VF and 40 minutes of reperfusion. Cariporide may prove useful in patients with severe LV dysfunction undergoing VF for implantable cardioverter defibrillator testing.</AbstractText> |
2,140 | Patient experiences with atrial fibrillation and treatment with implantable atrial defibrillation therapy. | Patient perspectives about their illness experiences, symptoms, and treatment are essential aspects of quality of life and provide direction for patient and provider decision making regarding innovative therapies such as implantable devices for arrhythmia.</AbstractText>The purpose of this qualitative study was to describe: 1) the experience of patients living with symptomatic, drug-refractory atrial fibrillation (AF) and 2) patient experiences and acceptance of treatment with the implantable cardioverter defibrillator (ICD) with atrial therapies (ICD-AT) including ventricular and atrial defibrillation therapy.</AbstractText>Subjects were 3 women and 8 men, 35 to 80 years of age, who received the Medtronic Jewel AF 7250 ICD-AT as therapy for recurrent, drug-refractory AF, had a history of AF for 3 to 20 years and had experienced multiple treatment modalities including frequent external cardioversion in an effort to control their AF.</AbstractText>A semi-structured interview addressed experiences of symptoms and prior treatment for AF and experiences, concerns, and perceived benefits of the ICD-AT. Interviews were recorded and transcribed verbatim. Narratives were coded and categorized using Atlas Ti(R) software. Qualitative interpretive analysis methods were used to identify key themes.</AbstractText>Before ICD-AT, patient themes focused on AF that was: 1) misdiagnosed, minimized, and poorly treated; 2) distressful because of frequent and intense AF symptoms (fatigue, dizziness, shortness of breath, and anxiety) before ICD-AT; 3) limiting of activities of daily living; 4) associated with distress from enduring previous treatment; and 5) associated with the continuous pursuit of successful treatment and maintenance of normalcy. Decision making regarding ICD-AT therapy included weighing symptom or treatment distress versus anticipated risks or benefits, hope for better outcomes, and lack of options. After ICD-AT, themes included positive perceptions of the device because of AF symptom relief, ability to resume normalcy, and medication tolerance; incorporation of shock experiences into life routines; and patient suggestions regarding preparation and social support.</AbstractText>Symptoms of AF have a major negative impact on overall quality of life. Treatment with the ICD-AT confers a sense of security and reduced symptom distress. Greater provider attention to patient preparation and facilitating social support are important for future ICD-AT patient care.</AbstractText> |
2,141 | Transesophageal cardioversion of atrial flutter and atrial fibrillation using an electric balloon electrode system. | To determine the feasibility and efficiency of terminating atrial flutter (AFL) and atrial fibrillation (AF) using synchronous low-energy shocks delivered through a novel transesophageal electric balloon electrode system.</AbstractText>By using a novel electric balloon electrode system, we attempted 91 transesophageal cardioversions in 52 patients, to treat 53 episodes of AFL and 38 episodes of AF.</AbstractText>Of the 40 patients of AFL that failed to respond to drug therapy, 37 (92.5%) were successfully countershocked to sinus rhythm by transesophageal cardioversion, with a mean energy of (22.70 +/- 4.50) J (20 - 30 J). Of the 19 patients in AF, transesophageal cardioversion was successful in 16 (84.2%) cases, requiring a mean delivered energy of (17.38 +/- 8.58) J (3 - 30 J). There were no complications such as heart block or ventricular fibrillation, and no evidence of esophageal injury.</AbstractText>Transesophageal cardioversion using an electric balloon electrode system is an effective and feasible method for the treatment of AFL and AF. It requires low energy and no anesthesia, leads to less trauma, and shows a high cardioversion success rate that may prove valuable in the management of tachyarrhythmias.</AbstractText> |
2,142 | [Incidence and risk indicators of thromboembolism during the acute phase of single chamber ventricular pacing]. | The incidence of thromboembolism may be higher in single chamber ventricular pacing than in physiological pacing. However, the incidence of thromboembolism during the acute phase of single chamber ventricular pacing (within 14 days) is not known.</AbstractText>The incidence and the risk indicators of thromboembolism were investigated during the acute phase of single chamber ventricular pacing.</AbstractText>Fifty-five consecutive patients (22 males, 33 females, mean age 67 +/- 9 years) who required VVI pacemakers due to brady-tachy sick sinus syndrome (42 patients) or brady atrial fibrillation (13 patients) in the period from April 1975 to December 2000 were retrospectively reviewed. The patients were divided into groups with thromboembolism and without thromboembolism, and the risk indicators for thromboembolism were analyzed.</AbstractText>Seven patients (13%) suffered systemic thromboembolism. Three patients had thromboembolic events during temporary ventricular pacing, and four patients had thromboembolic events just after permanent VVI pacemaker implantation. The following risk indicators were identified in the patients with thromboembolism: hyperlipidemia, hypertension, organic heart disease (p < 0.05, respectively), and diabetes mellitus (p < 0.0005).</AbstractText>Patients with brady-tachy sick sinus syndrome and brady atrial fibrillation have a significant risk of thromboembolism during the acute phase of single chamber ventricular pacing. Effective anticoagulation is needed in these patients.</AbstractText> |
2,143 | Detection of patients with hypertrophic cardiomyopathy at risk for paroxysmal atrial fibrillation during sinus rhythm by P-wave dispersion. | Paroxysmal atrial fibrillation (PAF) in hypertrophic cardiomyopathy (HCM) is associated with poor prognosis. Previous studies have shown good correlation between P-wave dispersion (Pd) and occurrence of PAF. However, Pd in patients with HCM for predicting PAF has not been studied.</AbstractText>The aim of the study was to determine whether Pd could identify patients with HCM who are likely to suffer from PAF.</AbstractText>Twenty-two patients with HCM with a history of PAF (Group 1) and 26 patients with HCM without a history of PAF (Group 2) were studied. Maximum (Pmax) and minimum (Pmin) P-wave durations, as well as P-wave dispersion (Pd = Pmax - Pmin) were calculated from 12-lead surface electrocardiograms (ECG).</AbstractText>P-wave dispersion was significantly different between the groups (Group 1: 55 +/- 6 ms vs. Group 2: 37 +/- 8 ms; p<0.001), while Pmax (Group 1: 134 +/- 11 ms vs. Group 2: 128 +/- 13 ms; p = 0.06) and Pmin (Group 1: 78 +/- 9 ms vs. Group 2: 81 +/- 7 ms; p = 0.07) was not significantly different. Patients with a history of PAF had higher left atrial diameter than the patients without PAF (Group 1: 52 +/- 8 mm vs. Group 2: 48 +/- 10 mm; p = 0.02). A cut-off value of 46 ms for Pd had a sensitivity of 76% and a specificity of 82% in discriminating between patients with and without PAF.</AbstractText>This study suggests that P-wave dispersion could identify patients with HCM who are likely to develop PAF.</AbstractText> |
2,144 | Biventricular support with the Jarvik 2000 axial flow pump: a feasibility study. | Patients with congestive heart failure who are supported with a left ventricular assist device (LVAD) may experience right ventricular dysfunction or failure that requires support with a right ventricular assist device (RVAD). To determine the feasibility of using a clinically available axial flow ventricular assist device as an RVAD, we implanted Jarvik 2000 pumps in the left ventricle and right atrium of two Corriente crossbred calves (approximately 100 kg each) by way of a left thoracotomy and then analyzed the hemodynamic effects in the mechanically fibrillated heart at various LVAD and RVAD speeds. Right atrial implantation of the device required no modification of either the device or the surgical technique used for left ventricular implantation. Satisfactory biventricular support was achieved during fibrillation as evidenced by an increase in mean aortic pressure from 34 mm Hg with the pumps off to 78 mm Hg with the pumps generating a flow rate of 4.8 L/min. These results indicate that the Jarvik 2000 pump, which can provide chronic circulatory support and can be powered by external batteries, is a feasible option for right ventricular support after LVAD implantation and is capable of completely supporting the circulation in patients with global heart failure. |
2,145 | Signal averaged ECG in different patterns of left ventricular hypertrophy and geometry in hypertension. | It is still unknown which factors determine the presence of ventricular late potentials (LP) in hypertension.</AbstractText>To evaluate the prevalence of LP in hypertension in relation to the pattern of left ventricular hypertrophy (LVH) and geometry, and to establish the factors causing signal-averaged ECG abnormalities.</AbstractText>The study group consisted of 109 patients (58 females, 51 males, mean age 49.7 +/-9.1 years) with hypertension and without coronary artery disease. Two-dimensional Echo Doppler, 24-hr ECG Holter, signal-averaged ECG and spectral analysis of heart rate variability (HRV) were performed. Four patterns of LVH and geometry were identified: normal geometry (N; n=30), concentric remodelling (CR; n=24), concentric hypertrophy (CH; n=38) and eccentric hypertrophy (EH; n=17).</AbstractText>LP were more frequently detected in patients with LVH (9.1%), particularly in those with EH, than in patients without LVH (5.6%). Linear regression analysis revealed no correlation between signal-averaged ECG parameters and LV ejection fraction (LVEF) or diastolic LV function indices. None of echocardiographic variables correlated with signalaveraged QRS duration, however, a significant positive correlation between LAS and LV mass (LVM) (r=0.26), LAS and LV end-diastolic volume (EDV) (r=0.2), as well as a significant negative correlation between V40 and LVM (r=-0.22) were noted. A significant positive correlation between LF/HF and signal-averaged QRS (r=0.31) and LAS (r=0.29) as well as a significant negative correlation between LF/HF and V40 (r=-0.21) were found. In the univariate analysis, the presence of EH was significantly related to the occurrence of LP (p<0.01). The reduction of HF power <113 ms(2), indicating a withdrawal of parasympathetic activity, was associated with LP (p<0.05). A ratio of LF 1n/HF 1n >1.28, indicating relative sympathetic overactivity, was a relative risk for LP incidence (p<0.05). In the multivariate analysis, however, all these factors were not independent predictors of the presence of LP.</AbstractText>LP are more frequently detected in hypertensives with LVH, particularly in those with eccentric hypertrophy pattern. Left ventricular structural remodelling and withdrawal of parasympathetic tone are the significant determinants of LP occurrence.</AbstractText> |
2,146 | Heart rate variability in patients with Brugada syndrome in Thailand. | Since patients with Brugada syndrome usually have symptoms at nighttime, we hypothesize that changes in autonomic modulation have an important role in the occurrence of the ventricular fibrillation episodes. The objective of this study was to determine the changes in heart rate variability (HRV) in patients with Brugada syndrome compared to asymptomatic subjects with Brugada ECG and controls.</AbstractText>We studied 17 patients with Brugada syndrome, 10 asymptomatic subjects with Brugada ECG and 45 controls. Patients with Brugada syndrome and asymptomatic subjects with Brugada ECG underwent echocardiography, exercise stress testing, 24-h Holter monitoring, signal-averaged ECG. Patients with Brugada syndrome also underwent coronary angiography and electrophysiologic study. Time domain and frequency domain HRV analysis were performed at daytime and nighttime. The results of this study showed that patients with Brugada syndrome had lower HRV or lower vagal tone at night compared to the controls. They also had lower heart rate during the day and higher during the night compared to asymptomatic subjects and the controls.</AbstractText>Patients with Brugada syndrome had low heart rate variability at night which may predispose to the occurrence of VF episodes.</AbstractText> |
2,147 | Prediction of risk for first age-related cardiovascular events in an elderly population: the incremental value of echocardiography. | We sought to determine if echocardiography enhances prediction of first age-related cardiovascular events.</AbstractText>Whether echocardiographic assessment improves risk stratification for first cardiovascular events is not well known.</AbstractText>This retrospective cohort study included randomly selected residents of Olmsted County, Minnesota, age >/=65 years, who had >/=1 transthoracic echocardiograms at the Mayo Clinic between 1990 and 1998, in sinus rhythm, without valvular or congenital heart disease, and followed through medical records for first myocardial infarction (MI), coronary revascularization, atrial fibrillation (AF), congestive heart failure (CHF), transient ischemic attack (TIA), stroke, or cardiovascular death. Patients were excluded if they had any of these events before the baseline echocardiogram.</AbstractText>Of 1,160 patients (age 75 +/- 7 years; 746 women) followed for a mean of 3.8 +/- 2.7 years, 333 (29%) first events occurred (70 AF, 67 coronary revascularization procedures, 65 CHF, 48 MI, 38 stroke, 25 TIA, and 20 cardiovascular deaths). In a multivariate model, age (p < 0.001), male gender (p < 0.001), diabetes mellitus (p = 0.005), systemic hypertension (p < 0.001), left atrial volume/body surface area >/=32 ml/m(2) (p = 0.003), left ventricular (LV) mass/height >/=120 g/m (p = 0.014), LV systolic dysfunction (p < 0.001), and LV diastolic dysfunction (p = 0.029) were independent predictors. A risk-scoring algorithm was developed and validated for the prediction of first events. The five-year event-free survival was 90%, 74%, and 50% for low-, medium-, and high-risk groups, respectively.</AbstractText>Echocardiography enhanced prediction of first cardiovascular events in this referral-based elderly cohort. Its role in risk stratification for primary prevention of these events in the community warrants further investigations.</AbstractText> |
2,148 | Further evidence that melanocortins prevent myocardial reperfusion injury by activating melanocortin MC3 receptors. | In rats subjected to myocardial ischemia/reperfusion, melanocortin peptides, including gamma(1)-melanocyte-stimulating hormone (gamma(1)-MSH), are able to exert a protective effect by stimulating brain melanocortin MC(3) receptors. A non-melanocortin receptor belonging to a group of receptors for Phe-Met-Arg-Phe-NH(2) (FMRFamide)-like peptides may be involved in some of the cardiovascular effects of the gamma-MSHs. FMRFamide-like peptides and gamma(1)-/gamma(2)-MSH share, among other things, the C-terminal Arg-Phe sequence, which seems to be essential for cardiovascular effects in normal animals. So we aimed to further investigate which receptor and which structure are involved in the protective effects of melanocortins in anesthetized rats subjected to myocardial ischemia by ligature of the left anterior descending coronary artery (5 min), followed by reperfusion. In saline-treated rats, reperfusion induced, within a few seconds, a high incidence of ventricular tachycardia and ventricular fibrillation, and a high percentage of death within the 5 min of observation period. Reperfusion was associated with a massive increase in free radical blood levels and with an abrupt and marked fall in systemic arterial pressure. The i.v. treatment (162 nmol/kg) during the ischemic period with the adrenocorticotropin fragment 1-24 [ACTH-(1-24): the reference protective melanocortin which binds all melanocortin receptors], as well as with both the melanocortin MC(3) receptor agonists gamma(2)-MSH and [D-Trp(8)]gamma(2)-MSH, reduced the incidence of ventricular tachycardia, ventricular fibrillation and death, the increase in free radical blood levels and the fall in arterial pressure. On the contrary, gamma(2)-MSH-(6-12) (a fragment unable to bind melanocortin receptors) was ineffective. Such protective effect was prevented by the melanocortin MC(3)/MC(4) receptor antagonist SHU 9119. In normal (i.e., not subjected to myocardial ischemia/reperfusion) rats, the same i.v. dose (162 nmol/kg) of gamma(2)-MSH, [D-Trp(8)]gamma(2)-MSH and gamma(2)-MSH-(6-12) provoked a prompt and transient increase in arterial pressure; on the other hand, ACTH-(1-24), which lacks the C-terminal Arg-Phe sequence, decreased arterial pressure, but only at higher doses. Heart rate of normal rats was not affected by any of the assayed peptides. The present data confirm and extend our previous findings that melanocortins prevent myocardial reperfusion injury by activating melanocortin MC(3) receptors. Moreover, they further support the notion that, in normal rats, cardiovascular effects of gamma-MSHs are mediated by receptors for FMRFamide-like peptides, for whose activation, but not for that of melanocortin MC(3) receptors, the C-terminal Arg-Phe structure being relevant. |
2,149 | Spatiotemporal correlation between phase singularities and wavebreaks during ventricular fibrillation. | Phase Singularity and Wavebreak.</AbstractText>Phase maps and the detection of phase singularities (PSs) have become a well-developed method for characterizing the organization of ventricular fibrillation (VF). How precisely PS colocalizes with wavebreak (WB) during VF, however, is unknown.</AbstractText>We performed optical mapping of 27 episodes of VF in nine Langendorff-perfused rabbit hearts. A WB is a point where the activation wavefront and the repolarization waveback meet. A PS is a site where its phase is ambiguous and its neighboring pixels exhibit a continuous phase progression from -pi to +pi. The correlation coefficient between the number of WBs and PSs was 0.78 +/- 0.09 for each heart and 0.81 for all VF episodes (P < 0.001), indicating a significant temporal correlation. We then superimposed the WBs and PSs for every 100 frames of each episode. These maps showed a high degree of spatial colocalization. To quantify spatial colocalization, the spatial shifts between the cumulative maps of WBs and PSs in corresponding frames were calculated by automatic alignment to obtain maximum overlap between these two maps. The spatial shifts were 0.04 +/- 0.31 mm on the x-axis and 0.06 +/- 0.27 mm on the y-axis over a 20 x 20 mm2 mapped field, indicating highly significant spatial correlation.</AbstractText>Phase mapping provides a convenient and robust approach to quantitatively describe wave propagation and organization during VF. The close spatiotemporal correlation between PSs and WBs establishes that PSs are a valid alternate representation of WB during VF and further validated the use of phase mapping in the study of VF dynamics.</AbstractText> |
2,150 | Focal origin of atrial tachycardia in dogs with rapid ventricular pacing-induced heart failure. | Mapping and Ablation of Atrial Tachycardia in Heart Failure.</AbstractText>Dogs with rapid ventricular pacing-induced congestive heart failure (CHF) have inducible atrial tachycardia (AT), with a mechanism consistent with delayed afterdepolarization-mediated triggered activity. We assessed the hypothesis that AT has a focal origin.</AbstractText>Twenty-one CHF dogs undergoing 3 to 4 weeks of ventricular pacing at 235 beats/min were studied. Biatrial epicardial mapping of 20 sustained AT episodes (cycle length [CL], 175 +/- 53 msec) in 5 dogs revealed an area of earliest activation in the right atrial (RA) free wall (13 episodes), RA appendage (4 episodes), or between the pulmonary veins (3 episodes). Total epicardial activation time during AT (73 +/- 19 msec) was similar to that during sinus rhythm (72 +/- 13 msec) and on average was <50% of the AT CL. Higher-density mapping of the RA free wall during 30 sustained AT episodes (163 +/- 55 msec) in 9 dogs identified a site of earliest activation along the sulcus terminalis most frequently as a stable, focal activation pattern from a single site. Endocardial mapping of 49 sustained AT episodes (156 +/- 27 msec) in 10 dogs revealed multiple sites of AT origin arising along the crista terminalis and pulmonary veins. Right and left ATs were terminated with discrete radiofrequency ablation, but other ATs remained inducible. A rapid, left AT generating an ECG pattern of atrial fibrillation was ablated inside the pulmonary vein.</AbstractText>AT induced in this CHF model after 3 to 4 weeks of rapid ventricular pacing has an activation pattern consistent with a focal origin. Sites of earliest activation are distributed predominately along the crista terminalis and within or near the pulmonary veins.</AbstractText> |
2,151 | Effects of cytochalasin D on electrical restitution and the dynamics of ventricular fibrillation in isolated rabbit heart. | Cytochalasin D in Rabbit Ventricle.</AbstractText>Cytochalasin D (cyto-D) has been used as an excitation-contraction uncoupler during optical mapping studies. However, its effects on action potential duration restitution (APDR) and dynamics during ventricular fibrillation (VF) are unclear.</AbstractText>Langendorff-perfused rabbit hearts (N = 6) were immersed in a tissue chamber. Transmembrane potential was recorded using glass microelectrodes. APD measured to 90% repolarization (APD90) was used to construct the APDR curve. During regular pacing at 300-msec cycle length, increasing concentrations of cyto-D resulted in progressively prolonged APD90 (131 +/- 26 msec, 171 +/- 14 msec, and 177 +/- 14 msec) and steepened maximum slope of the APDR curve (1.1 +/- 0.2, 1.3 +/- 0.2, and 1.6 +/- 0.4 for control, 5 micromoles, and 10 micromoles, respectively; P < 0.01). Resting membrane potential, AP amplitude, and maximum dV/dt did not change. Cyto-D lengthened VF cycle length and APD90, and steepened the maximum slope of the APDR curve. However, cyto-D did not significantly change the diastolic interval. The dominant frequency of pseudoelectrocardiogram progressively decreased with increasing concentrations of cyto-D (15.2 +/- 0.6 Hz, 11.1 +/- 2.4 Hz, and 9.8 +/- 3.2 Hz for control, 5 micromoles, and 10 micromoles, respectively; P < 0.01). Sustained (>1 min) VF was repeatedly inducible at baseline and with 5 or 10 micromoles of cyto-D.</AbstractText>Continuous perfusion of cyto-D at 5 or 10 micromoles prolonged APD90, steepened APDR slope, and reduced dominant frequency in rabbit ventricles. Cyto-D at these concentrations allowed induction of sustained VF.</AbstractText> |
2,152 | Clinical significance and contributing factors of long-term variability in induced ventricular tachyarrhythmias. | Long-Term Variability in Induced Tachyarrhythmias.</AbstractText>Ventricular arrhythmias induced during electrophysiologic study (EPS) may vary over time, making arrhythmia induction studies unreliable. The aim of this prospective study was to clarify the clinical significance of long-term variability in induced arrhythmias and to elucidate factors determining this variability.</AbstractText>Three noninvasive EPSs were performed 1, 13, and 25 months after implantation of a cardioverter defibrillator in 40 patients with ventricular tachyarrhythmias, without a change in their antiarrhythmic drug regimens. The induced ventricular arrhythmias were categorized into five grades. Long-term variability, which was defined as a variation in the grades during the three EPSs, was observed in 23 patients (group A) and not in the remaining 17 patients (group B). During the 2-year period, spontaneous sustained ventricular arrhythmias developed in 15 patients (65%) in group A but in only 4 patients (24%) in group B (P = 0.01). Inducibility of sustained tachyarrhythmias was not associated with emergence of spontaneous arrhythmias. All patients also underwent thallium-201 and iodine-123-metaiodobenzylguanidine (MIBG) scans to evaluate the extent of the regions showing normal thallium uptake with reduced MIBG uptake. Group A patients showed greater thallium/MIBG mismatched regions than did group B patients (P = 0.01). Logistic regression analysis revealed that long-term variability (relative risk [RR] 7.55, P = 0.03), amiodarone therapy (RR 0.14, P = 0.04), and left ventricular ejection fraction <35% (RR 6.26, P = 0.04) were independent predictors of spontaneous arrhythmia occurrence.</AbstractText>In patients with ventricular tachyarrhythmias, long-term variability in induced arrhythmias, but not the inducibility of arrhythmias, is associated with a higher incidence of spontaneous arrhythmias. Regional cardiac sympathetic denervation may be an important mechanism of this variability. These results also may explain why inducibility-based antiarrhythmic drug testing does not predict patient prognosis.</AbstractText> |
2,153 | Distal right ventricular coil position reduces defibrillation thresholds. | Distal RV Coil Position Reduces DFTs.</AbstractText>Understanding the factors that affect defibrillation thresholds (DFTs) has important implications both for optimization of defibrillation efficacy and for the design of new transvenous leads. The aim of this prospective study was to test the hypothesis that defibrillation efficacy is improved with the right ventricular (RV) coil in a distal position compared with a more proximal RV coil position.</AbstractText>A novel defibrillation lead with three adjacent RV defibrillation coils (distal 0.8 cm, middle 3.7 cm, proximal 0.8 cm) was used for this study to permit comparison of DFTs with the proximal and distal RV coil positions without lead repositioning. In the distal RV configuration, the distal and middle RV coils were connected electrically as the anode for defibrillation. In the proximal RV configuration, the middle and proximal coils were the anode. A superior vena cava (SVC) coil and active can were connected electrically as the cathode (reversed polarity, RV-->Can+SVC). In each patient, the DFT was measured twice using a binary search protocol with the distal RV and proximal RV configurations, with the order of testing randomized. The study cohort consisted of 31 subjects (mean age 65 +/- 12 years, mean left ventricular ejection fraction 30% +/- 16%, 81% male predominance). The mean delivered energy (8.2 +/- 5.3 J vs 11.2 +/- 6.1 J), leading-edge voltage (335 +/- 109 V vs 393 +/- 118 V), and peak current (11.6 +/- 5.2 A vs 14.9 +/- 7.3 A) at DFT all were significantly lower with the distal RV configuration compared to the proximal RV configuration (P < 0.01 for all comparisons).</AbstractText>DFTs are significantly reduced with the distal RV configuration compared to the proximal RV configuration. Defibrillation leads should be designed with the shortest tip to coil distance that can be achieved without compromising ventricular fibrillation sensing.</AbstractText> |
2,154 | Automated external defibrillation versus manual defibrillation for prolonged ventricular fibrillation: lethal delays of chest compressions before and after countershocks. | We sought to determine whether the delays in chest compressions and defibrillation associated with an automated external defibrillator would adversely affect outcome compared with manual defibrillation in a swine model of out-of-hospital prolonged ventricular fibrillation.</AbstractText>After 8 minutes of untreated ventricular fibrillation, 16 swine (33+/-4 kg) were randomly assigned to automated external defibrillator defibrillation or manual defibrillation with the same biphasic truncated exponential waveform 150-J shock through the same type of pads. Defibrillation with the automated external defibrillator was performed as recommended by the manufacturer, and manual defibrillation was provided per American Heart Association Guidelines. The primary outcome measure was 24-hour survival with good neurologic outcome. Data are described as means+/-SD.</AbstractText>None of 8 animals in the automated external defibrillator group survived for 24 hours, whereas 5 of 8 animals in the manual defibrillation group survived 24 hours, all with good neurologic outcome (P=.027). The time interval from simulated defibrillator arrival to first compressions was 98+/-18 seconds in the automated external defibrillator group versus 68+/-15 seconds in the manual defibrillation group. In particular, the interval from first shock to first chest compressions was 46+/-18 seconds versus 22+/-16 seconds, respectively. The mean percentage of time that chest compressions were performed in the first minute after the first countershock was 15%+/-13% versus 40%+/-15%, respectively. As a result, return of spontaneous circulation within 5 minutes of simulated defibrillator arrival occurred in only 1 of 8 animals in the automated external defibrillator group versus 6 of 8 animals in the manual defibrillation group.</AbstractText>The longer delays in chest compressions with automated external defibrillator defibrillation versus manual defibrillation can worsen the outcome from prolonged ventricular fibrillation.</AbstractText> |
2,155 | Rapid progression of primary cardiac leiomyosarcoma with obstruction of the left ventricular outflow tract and mitral stenosis. | We report a 73-year-old woman with primary cardiac leiomyosarcoma in the left atrium and ventricle. The tumor progressed very rapidly for 2 months after initial clinical evaluation. Obstruction of the left ventricular outflow tract and mitral stenosis were induced by the tumor. Urgent surgical resection was performed because she had cardiogenic shock due to paroxysmal atrial fibrillation. We could not resect the tumor completely because of severe invasion. She refused postoperative chemotherapy and radiotherapy, and died suddenly at home 89 days after surgery. To our knowledge, this is the first observation of mitral stenosis concomitant with obstruction of the left ventricular outflow tract in a patient with primary cardiac leiomyosarcoma. |
2,156 | Electrocardiogram in centenarians. | Electrocardiographic abnormalities in the very elderly have not yet been fully assessed.</AbstractText>To evaluate ECG recordings obtained from centenarians.</AbstractText>ECG tracings recorded at place of residence of 35 subjects aged 100-112 years (mean 101.7 years) were examined using the Minnesota code.</AbstractText>Entirely normal ECG recordings were found in 5.7% of centenarians. The most frequently encountered abnormalities included leftward QRS axis deviation (45.7%), abnormal T wave morphology (42.9%), ST segment depression (34.3%), extrasystolic beats (28.6%), left anterior haemiblock (25.7%) and first degree atrio-ventricular block (17.1%). Other, less frequently present abnormalities, included Q wave or QS complex, atrial fibrillation, right or left bundle branch block, left ventricular hypertrophy or low QRS voltage.</AbstractText>In the majority of centenarians ECG shows numerous but usually benign abnormalities. Only very few centenarians have entirely normal ECG.</AbstractText> |
2,157 | Atrial natriuretic peptide before and after cardioversion of persistent atrial fibrillation. | Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia in clinical practice, affecting many millions of people world-wide. The treatment of AF has improved significantly during the past decade, but most patients suffer from symptoms and recurrences of arrhythmia. Studies on the neurohormonal remodelling in patients with AF are becoming increasingly important because they may improve the treatment of AF.</AbstractText>To determine plasma atrial natriuretic peptide (ANP) concentrations in patients with persistent AF, before and one day after electrical cardioversion of AF.</AbstractText>We attempted cardioversion in 42 consecutive patients (30 men and 12 women), aged 57+/-8 years, with persistent nonvalvular AF of 7+/-6 month duration. The underlying heart disease was systemic hypertension in 20, ischaemic heart disease in 17, dilated cardiomyopathy in 3, and lone AF in 2 patients. All patients had left ventricular ejection fraction >45%. The control group comprised 11 subjects with sinus rhythm and no history of AF who were age-, gender- and concomitant disease-matched with the AF patients. Plasma samples of ANP were obtained at rest the day before and 24 hours after cardioversion.</AbstractText>Cardioversion was successful in 35 patients. Patients with successful or non-successful cardioversion had similar clinical characteristics. The mean baseline ANP level before cardioversion was 59.5+/-15.6 pg/ml and was significantly higher than in the control group - 34.3+/-10.2 pg/ml (p<0.001). In patients in whom sinus rhythm was restored, a significant decrease in the ANP level was observed (59.4+/-16.6 versus 31.4+/-15.0 pg/ml; p<0.01) whereas it did not change in patients with ineffective cardioversion (59.4+/-10.7 versus 60.2+/-10.7 pg/ml, NS).</AbstractText>Plasma ANP concentration in patients with AF was significantly reduced after successful cardioversion and remained stable in those with unsuccessful cardioversion.</AbstractText> |
2,158 | Efficacy of atrial antitachycardia pacing using the Medtronic AT500 pacemaker in patients with congenital heart disease. | Patients with congenital heart disease are vulnerable to atrial tachyarrhythmias, especially after atrial surgeries. We evaluated the efficacy of atrial arrhythmia detection and antitachycardia pacing (ATP) using the Medtronic AT500 pacemaker in 28 patients with congenital heart disease (age 30 +/- 18 years). Of 15 patients with atrial arrhythmias, 14 had atrial tachycardia events that were appropriately detected. ATP was enabled for 167 treatable episodes, successfully converting 90 (54%). Rhythms classified as ventricular tachycardia were detected 127 times, yet most were actually atrial or sinus tachycardia with 1:1 atrioventricular conduction. Atrial tachycardias in congenital heart disease are amenable to ATP algorithms in the AT500 pacemaker. |
2,159 | Usefulness of QRS prolongation in predicting risk of inducible monomorphic ventricular tachycardia in patients referred for electrophysiologic studies. | QRS prolongation on surface electrocardiography has been identified as a marker for increased cardiac mortality. A potential mechanism for increased mortality is ventricular tachycardia (VT). This study aimed to evaluate the relation between bundle branch block and sustained monomorphic VT inducibility in patients referred for electrophysiologic studies. We analyzed a cohort of 777 patients (age 63 +/- 18 years, 67% men, left ventricular [LV] ejection fraction [EF] 45% +/- 16, prior myocardial infarction 41%) referred for electrophysiologic studies between 1994 and 2001 who underwent programmed stimulation for VT. Forty-five percent of patients were referred for syncope or a history of VT and/or ventricular fibrillation. Thirty-one percent of patients had prolonged QRS duration (> or =120 ms). Patients with prolonged QRS duration were older, had lower LVEFs, and were more likely to have a history of myocardial infarction. Prolonged QRS was a significant predictor of sustained monomorphic VT inducibility (p <0.0001). On multivariate analysis correcting for age, sex, LVEF, history of myocardial infarction, medications, and QRS conduction delay proved to be independently associated with sustained monomorphic VT inducibility (relative risk 3.290, 95% confidence interval 2.185 to 4.953 for prolonged vs normal QRS duration). Thus, a prolonged QRS duration on surface electrocardiography is a strong, independent predictor of inducible sustained monomorphic VT. Conduction delay may be an important risk factor, providing a substrate for the development of reentrant monomorphic VT, and furthermore suggests a potential mechanism for the increased mortality observed in patients with prolonged QRS. |
2,160 | QRS duration and prediction of mortality in patients undergoing risk stratification for ventricular arrhythmias. | This study tested the hypothesis that prolonged QRS duration independently predicts long-term mortality in patients who underwent risk stratification and treatment for ventricular arrhythmias. Patients who underwent risk stratification by electrophysiologic study were identified. Electrophysiologic study results were defined as positive if sustained monomorphic ventricular tachycardia was induced. Mortality was the primary end point. Of 915 patients studied, mean left ventricular (LV) ejection fraction (EF) was 35.3 +/- 15.7%, 608 (66.4%) had coronary artery disease, 233 (25.5%) had positive electrophysiologic study findings, 298 (32.6%) received implantable cardioverter-defibrillators, and 174 (19%) died (mean follow-up 35.0 +/- 15.0 months). Cox regression analysis identified older age, coronary artery disease, digoxin use, absence of beta blockers, lower LVEF, and prolonged QRS duration to be independent predictors of mortality. QRS duration > or =130 ms, present in 33.6% of patients, was associated with a twofold increase in mortality (hazard ratio 2.1, 95% confidence interval 1.5 to 2.8; p <0.0001). For every 10 ms increase in QRS duration, mortality rate increased 10%. In a subgroup of patients with coronary artery disease and LVEF < or =30%, prolonged QRS duration remained an independent predictor of mortality (hazard ratio 2.6, 95% confidence interval 1.6 to 4.2; p <0.0001). Thus, prolonged QRS duration is a strong independent marker of long-term mortality in patients who undergo risk stratification for ventricular arrhythmias. Whether QRS duration represents only a marker for mortality or if modification of this factor using resynchronization therapies will impact mortality merits further study. |
2,161 | Endocardial defibrillation lead extraction: an unusual case of entrapment. | Spurious discharges due to late insulation break in an IS-1 pacing/sensing connector prompted ICD lead removal in 65-year-old man. The tip of the lead was easily freed and pulled back into the SVC by the superior approach. After that, the lead became trapped. The distal part of the lead was caught and easily withdrawn by inferior approach. Superior venous angiography showed extravascular location of the entrapped part of the lead due to the unintentional percutaneous puncture of the innominate vein after piercing the subclavian vein. It may be desirable to use contrast venography before intervention of extraction to ensure venous patency and lead location. |
2,162 | Clinical efficacy of a wearable defibrillator in acutely terminating episodes of ventricular fibrillation using biphasic shocks. | The Wearable Cardioverter Defibrillator (WCD) automatically detects and treats ventricular tachyarrhythmias without the need for assistance from a bystander, while at the same time allowing the patient to ambulate freely. It represents an alternative to emergency medical services for outpatient populations with a temporary risk of sudden cardiac death. While the original devices used a monophasic truncated exponential waveform for cardioversion/defibrillation shocks, a new, biphasic shock was developed for the next device generation. In 12 patients undergoing electrophysiological testing for ventricular tachyarrhythmias, termination of electrically induced ventricular fibrillation (VF) was attempted via the WCD. In 22 episodes, induced VF was promptly terminated by the first 70 J (n=12) or 100 J (n=10) biphasic shocks. Time between arrhythmia initiation and shock delivery was 22 +/- 6 seconds (70 J) and 21 +/- 6 seconds (100 J) (P=NS). The measured transthoracic impedance was 71 +/- 5 Ohms (64-79 Ohms) for the 70 J shock and 64 +/- 8 Ohms (47-72 Ohms) for the 100 J shock. The present study demonstrates that a single low energy biphasic shock delivered by the WCD, reliably terminates electrically induced VF (100% of episodes). The results of this study suggest that there is an acceptable safety margin to the maximum output of the device (150 J). Despite our promising data, we recommend that programming all shocks for maximum energy output should be done when using the WCD in ambulatory patients. |
2,163 | Predictors and clinical impact of atrial fibrillation after pacemaker implantation in elderly patients treated with dual chamber versus ventricular pacing. | The Pacemaker Selection in the Elderly (PASE) trial was a prospective, multicenter, single blind, randomized comparison of single chamber, rate adaptive, ventricular pacing (VVIR) with dual chamber, rate adaptive pacing (DDDR) in 407 patients aged > or =65 years(mean 76 +/- 7 years, 60% male)with standard bradycardia indications for dual chamber pacemaker implantation. The incidence, predictors, and clinical consequences of atrial fibrillation (AF) developing after pacemaker implantation in the PASE trial were studied prospectively. During a median follow-up of 18 months, AF developed in 73 (18%) patients. Kaplan-Meier estimated cumulative incidences of AF in patients with sinus node dysfunction (n=176) at 18 months were 28% in the VVIR and 16% in the DDDR groups (P=0.08). After adjustment for other clinical variables using a Cox multivariate regression model, randomization to VVIR compared with DDDR pacing mode among patients with sinus node dysfunction was independently associated with a 2.6-fold increased relative risk (RR) of developing AF after pacemaker implantation (P=0.01). Other independent clinical risk factors for development of postimplant AF included a preimplant history of hypertension (P=0.02) or supraventricular tachyarrhythmias(P<0.04). Patients who developed AF had similar health related quality of life scores and cardiovascular functional status after 18 months of pacing as patients who remained free of AF. The RR of death, stroke, or heart failure hospitalization was not increased in patients who developed AF. Thus, in the elderly patients with sinus node dysfunction requiring permanent pacing, DDDR pacing mode protected against the development of AF. However, development of AF after pacemaker implantation in this population was not associated with a significant impact on quality-of-life, functional status, or other clinical endpoints during 18 months of follow-up. |
2,164 | Coingestion of cyclooxygenase inhibitors can worsen severe paracetamol poisoning by middle-sized and small arteries vasoconstriction. | We report fatal cases of multifocal ischemic injuries occurring in patients awaiting liver transplantation after severe concomitant paracetamol and cyclooygenase inhibitors self-poisoning.</AbstractText>Case report in an intensive care unit.</AbstractText>In addition to signs of acute liver failure with a systemic inflammatory response syndrome, these three previously healthy young women demonstrated cutaneous vasoconstriction. One patient displayed a sudden ST-segment elevation with ventricular fibrillation.</AbstractText>Angiography, plasma endothelin concentrations measurements, and autopsy.</AbstractText>Radiography showed diffuse vasospasm on mesenteric and renal arteries, transiently reversed by vasodilators. We measured tenfold higher plasma endothelin concentrations than in healthy controls. Autopsy revealed no atherosis (including coronary arteries); organs showed multifocal ischemic injuries without thrombosis.</AbstractText>Such injuries subsequent to dramatic vasoconstriction suggest that cyclooygenase inhibition has specific deleterious vascular side effects once systemic inflammatory response syndrome is in progress during paracetamol poisoning.</AbstractText> |
2,165 | [Acquired long QT syndrome with torsade de pointes in a patient with primary hypothyroidism]. | A case of 78 year-old woman with primary hypothyroidism and atrial fibrillation treated with sotalol, complicated with cardiac arrest due to ventricular fibrillation (VF) and torsade de pointes (TdP) is presented. The QT interval was prolonged to 660 msec. Episodes of polymorphic ventricular tachycardia and VF recurred. Lidocaine, tosylate bretylate and betabloker successfully eliminated VF but short-lasting episodes of TdP were still present. Increased doses of hormonal substitution with thyroid hormones successfully eliminated malignant ventricular arrhythmias and normalised QT interval to 430 msec. |
2,166 | Diagnosis of arrhythmogenic right ventricular dysplasia-cardiomyopathy: value of standard ECG revisited. | The diagnostic dilemma in arrhythmogenic right ventricular dysplasia-cardiomyopathy (ARVD/C) is that a single diagnostic test does not exist and that there is a need for broadening diagnostic criteria. As standard ECG contributes significantly to clinical diagnosis and represents a tool for screening in family studies ECG data should be revisited.</AbstractText>In a cohort of 265 patients (159 males, mean age 46.8 years) with ISFC/ESC criteria of ARVD/C ECG features were reevaluated. QRS duration in (V1 + V2 + V3)/(V4 + V5 + V6) > or = 1.2-called localized right precordial QRS prolongation-was present in 261/265 patients (98%) and represents the essential finding. Right precordial epsilon potentials were found in 23% in standard and in 75% in highly amplified and modified recording technique. Right precordial T wave inversions were present in 143 cases (54%) and ST-segment elevation of different types in 66 patients (25%). Localized prolongation of inferior QRS complexes could be found in 58 cases (22%), complete right bundle branch block with T inversions beyond V2 in most cases in 17 patients (6%), incomplete right bundle branch block in 38 cases (14%), pseudo-incomplete right bundle branch block in 8 patients (3%), and right precordial R wave reduction in 14 cases (5%).</AbstractText>With regard to sensitivity and already known specificity an ECG score for the diagnosis of ARVD/C was developed with high probability of ARVD/C in cases with > or =4 points, possibly without the need for an additional imaging technique. Standard ECG with additional highly amplified and modified recording technique represents a single diagnostic test with high value in the clinical diagnosis of ARVD/C and should be used as a first line tool in noninvasive family screening.</AbstractText> |
2,167 | Predictive value of P-wave signal-averaged electrocardiogram for atrial fibrillation in acute myocardial infarction. | Atrial fibrillation (AF) is a common complication of acute myocardial infarction (AMI) with a reported incidence of 7-18%. Recently, P-wave signal-averaged electrocardiogram (P-SAECG) has been used to assess the risk of paroxysmal AF attacks in some diseases. The aim of this study was to determine prospectively whether patients with AMI at risk for paroxysmal AF would be identified by P-SAECG and other clinical variables.</AbstractText>A total of 100 patients (mean age: 59+/-12, 77 male, 23 female) with ST segment elevation AMI were enrolled in this study. Patients with chronic AF were excluded. At entry, all patients underwent standard 12-lead ECG and in the first 24 hours, P-SAECG was taken, and echocardiography and coronary angiography were performed on the patients. Patients are followed for a month in terms of paroxysmal AF attacks and mortality.</AbstractText>AF was determined in 19 patients (19%). In patients with AF, abnormal P-SAECG more frequently occurred than in patients without AF (37% vs 15%, P<0.05). Patients with AF were older (70+/-14 vs 56+/-10, P<0.001) and had lower left ventricular ejection fraction (42%+/-8 vs 49%+/-11, P<0.05). AF was less common in thrombolysis-treated patients (47% vs 74%, P<0.05). Thirty-day mortality was higher in patients with AF (16% vs 2%, P=0.05).</AbstractText>An abnormal P-SAECG may be a predictor of paroxysmal AF in patients with AMI. Advanced age and systolic heart failure were detected as two important clinical risk factors for the development of AF.</AbstractText> |
2,168 | Prevalence of sensing abnormalities in dual chamber implantable cardioverter defibrillators. | The clinical efficacy of ICD therapy depends on accurate sensing of intracardiac signals and sensing algorithms. We investigated the occurrence of sensing abnormalities in patients with dual chamber ICDs.</AbstractText>The study group consisted of all patients with dual chamber ICDs enrolled in the LESS trial and patients implanted with dual chamber ICDs at a single center between January 1997 and July 2000. Electrograms of spontaneous ventricular arrhythmias requiring device intervention were analyzed.</AbstractText>A total of 48 patients met the criteria for enrollment. Among the 244 episodes, 215 (88%) were due to ventricular tachycardia and 29 (12%) were due to ventricular fibrillation. Overall undersensing was infrequent with 12 (20%) patients exhibiting on average 2.2 undersensed beats during 26 episodes of ventricular arrhythmias. There was no delay in therapy due to undersensing. Oversensing occurred in 5 (10%) patients resulting in 13 (2.7%) episodes of inappropriate therapy. None of the patients had any lead abnormalities and oversensing resolved after device reprogramming in 4 patients while 1 patient required a separate rate sensing lead. Among patients with oversensing, 4 out of 5 were pacing before the index event while among patients with no oversensing only 5 out of 42 were pacing (P<0.001).</AbstractText>Dual chamber ICDs demonstrate outstanding accuracy of sensing. However, because of the selection of patient population requiring more frequent pacing, oversensing occurs with a significant frequency. Meticulous evaluation in such patients is necessary to minimize the likelihood of oversensing and inappropriate shocks.</AbstractText> |
2,169 | Management of hypertrophic cardiomyopathy in children. | Hypertrophic cardiomyopathy (HCM) is an inherited cardiac disease characterized by unexplained left ventricular hypertrophy, typically involving the interventricular septum. Hypertrophy may be present in infants, but commonly develops during childhood and adolescence. Management of children with HCM aims to provide symptomatic relief and prevention of sudden death, which is the primary cause of death. Unfortunately, no randomized comparative trials to date have assessed different treatment options in HCM. Medical treatment with negative inotropic agents (beta-adrenoceptor antagonists [beta-blockers], verapamil) is the first therapeutic choice in all symptomatic patients. Beta-blockers also appear to have prognostic merit in children. Surgical myectomy is effective in reducing symptoms in children with left ventricular (LV) obstruction who are unresponsive to medical treatment, although a repeat operation may be needed in a substantial proportion of patients due to relapse of LV obstruction. The recently introduced percutaneous septal ablation can also be regarded as a feasible alternative in this cohort. Technical limitations of both invasive therapeutic options should be carefully considered, preferably in experienced centers. Results of recent randomized trials indicate that dual chamber pacing, once considered a therapeutic option for patients with HCM, should only be used as treatment for conduction abnormalities. Regular clinical risk stratification for sudden death is of vital importance for the prevention of sudden death in young patients. Familial history of sudden death at a young age, LV hypertrophy >3 cm, unexplained syncope, nonsustained ventricular tachycardia in Holter monitoring, and abnormal blood pressure response during exercise are currently considered clinical risk factors for sudden death. Each factor has a low positive predictive accuracy, but patients having two or more of these risk factors are deemed as high risk. Secondary prevention of sudden death in patients successfully resuscitated from cardiac arrest and/or sustained ventricular tachycardia warrants treatment with an implantable cardioverter defibrillator (ICD). Primary prevention of sudden death in patients considered to be at high risk should aim at the management of obvious arrhythmogenic mechanisms (paroxysmal atrial fibrillation, sustained monomorphic ventricular tachycardia, conduction system disease, accessory pathway, myocardial ischemia), and the prevention and/or management of ventricular tachyarrhythmias with amiodarone and/or ICD implantation, respectively. The choice of treatment in children is greatly influenced by technical aspects, such as adverse effects of amiodarone, and ICD implantation difficulties or complications. Amiodarone could also be used as a bridge in children at high risk, until they reach adulthood, possibly achieving a lower risk status, or until their physical growth permits ICD implantation as long-term therapy. |
2,170 | [18-year old patient with anti-epileptic therapy and sudden cardiac death]. | An 18-year old female taking anti-epileptic medication was found unconscious in her bed early in the morning. After documented ventricular fibrillation and successful resuscitation, the patient was admitted to our emergency care unit. According to ECG criteria a long-QT syndrome of the subtype 2 was suspected. A few days later, however, the patient died because of hypoxic brain death. From previous hospital reports it turned out that the patient had repeatedly experienced syncopes in the past, which were interpreted as epileptic seizures. Her 17-year old sister and the female twin of her mother had both recently died from sudden cardiac death of unknown cause. An ECG screening in the family revealed six members with LQTS. A genetic analysis revealed in all of them a previously not described rearrangement mutation (888 delG insAA) in the LQT2 gene ( HERG) that was predicted to cause a protein truncation (360X) in the amino acid chain of the I(Kr)-channel subunit. This casuistic contribution exemplifies some classical aspects of LQTS (typical adrenergic trigger mechanism, classical false diagnosis "epilepsy") and demonstrates the possibility of a genotypic classification guided by phenotypic ECG characteristics. It represents an unusual case of a LQTS with a high degree of malignancy, which requires aggressive therapeutic interventions for the family survivors. |
2,171 | Implantable cardioverter-defibrillators in cardiovascular care: technologic advances and new indications. | Present generation implantable cardioverter-defibrillators (ICD) have become a proven primary therapeutic option in management of symptomatic ventricular arrhythmias and are now being increasingly used for primary prevention. The addition of biventricular pacing and atrial defibrillation to these devices has had an impact on the management of several new patient populations. The widespread application of these devices requires precise knowledge of their potential benefits and factors that could adversely affect device function.</AbstractText>ICD therapy has improved the survival of coronary disease patients with left ventricular dysfunction by reducing sudden death rate. In congestive heart failure patients, ICD therapy and biventricular pacing improves heart failure status thus improving overall survival and quality of life. Atrial defibrillation can establish rhythm control in drug refractory atrial fibrillation usually in a "hybrid therapy" prescription.</AbstractText>Implantable cardioverter defibrillators have proven to be invaluable in the primary and secondary prevention of sudden cardiac death. Incorporation of new technology in these devices has resulted in expanded indications that improve survival and quality of life of new patient populations.</AbstractText> |
2,172 | Arrhythmias in the intensive care patient. | Atrial fibrillation, atrial flutter, AV-nodal reentry tachycardia with rapid ventricular response, atrial ectopic tachycardia, and preexcitation syndromes combined with atrial fibrillation or ventricular tachyarrhythmias are typical arrhythmias in intensive care patients. Most frequently, the diagnosis of the underlying arrhythmia is possible from the physical examination, the response to maneuvers or drugs, and the 12-lead surface electrocardiogram. In all patients with unstable hemodynamics, immediate DC-cardioversion is indicated. Conversion of atrial fibrillation to sinus rhythm is possible using antiarrhythmic drugs. Amiodarone has a conversion rate in atrial fibrillation of up to 80%. However, caution in the use of short-term administration of intravenous amiodarone in critically ill patients with recent-onset atrial fibrillation is absolutely necessary, and the duration of therapy should not exceed 24 to 48 hours. Ibutilide represents a relatively new class III antiarrhythmic agent that has been reported to have conversion rates of 50% to 70%; it seems that ibutilide is even successful when intravenous amiodarone failed to convert atrial fibrillation.</AbstractText>Newer studies compared the outcome of patients with atrial fibrillation and rhythm- or rate-control. Data from these studies (AFFIRM, RACE) clearly showed that rhythm control is not superior to rate control for the prevention of death and morbidity from cardiovascular causes. Therefore, rate-control may be an appropriate therapy in patients with recurrent atrial fibrillation after DC-cardioversion. Acute therapy of atrial flutter in intensive care patients depends on the clinical presentation. Atrial flutter can most often be successfully cardioverted to sinus rhythm with energies less than 50 joules. Ibutilide trials showed efficacy rates of 38-76% for conversion of atrial flutter to sinus rhythm compared with conversion rates of 5-13% when intravenous flecainide, propafenone, or verapamil was administered. In addition, a high dose (2 mg) of ibutilide was more effective than sotalol (1.5 mg/kg) in conversion of atrial flutter to sinus rhythm (70% versus 19%).</AbstractText>There is general agreement that bystander first aid, defibrillation, and advanced life support is essential for neurologic outcome in patients after cardiac arrest due to ventricular tachyarrhythmias. The best survival rate from cardiac arrest can be achieved only when (1) recognition of early warning signs, (2) activation of the emergency medical services system, (3) basic cardiopulmonary resuscitation, (4) defibrillation, (5) management of the airway and ventilation, and (6) intravenous administration of medications occurs as rapidly as possible. Public access defibrillation, which places automatic external defibrillators in the hands of trained laypersons, seems to be an ideal approach in the treatment of ventricular fibrillation. The use of automatic external defibrillators by basic life support ambulance providers or first responder in early defibrillation programs has been associated with a significant increase in survival rates. Drugs such as lidocaine, procainamide, sotalol, amiodarone, or magnesium were recommended for treatment of ventricular tachyarrhythmias in intensive care patients. Amiodarone is a highly efficacious antiarrhythmic agent for many cardiac arrhythmias, ranging from atrial fibrillation to malignant ventricular tachyarrhythmias, and seems to be superior to other antiarrhythmic agents.</AbstractText> |
2,173 | Electrical storm: case series and review of management. | Electrical storm is defined as a recurrent episode of hemodynamically destabilizing ventricular tachyarrhythmia that usually requires electrical cardioversion or defibrillation. We describe three cases presenting with electrical storm under differing circumstances: (1) a 57-year-old man with ST-elevation myocardial infarction within 1 week of a posterior circulation stroke who developed refractory sustained ventricular tachycardia 10 days after an acute myocardial infarction; (2) a 65-year-old man who developed polymorphic ventricular tachycardia and ventricular fibrillation following dobutamine echocardiography; and (3) a 20-year-old woman who developed intractable ventricular fibrillation following an overdose of a weight-reduction pill. The management of electrical storm is discussed, and evolving literature supporting the routine use of intravenous amiodarone and beta-blockers in place of intravenous lidocaine is critically examined. |
2,174 | [Coronary artery bypass graft for patients with ascending aorta atherosclerosis]. | The increasing number of aged patients with severe ascending aorta atherosclerosis who are undergoing coronary artery bypass graft (CABG) present high risk for ascending aortic cannulation, cross-clamping or partial occluding and proximal anastomosis. We reviewed the surgical experience in 22 patients of CABG with ascending aorta atherosclerosis and tried to find the way to minimize the complications.</AbstractText>Twenty-two patients with severe atherosclerotic and calcified ascending aorta underwent CABG in our hospital. Thirteen of them received CABG on beating heart. Nine patients had their CABG with extracorporeal circulation. With deep hypothermia, we reduced the flow rate and intermittently arrested the circulation for the proximal anastomosis on ascending aorta in 5 patients with neither cross-clamping nor partial occluding. The sequential grafts and "Y" type anastomosis between reversed saphenous venous grafts were employed.</AbstractText>Twenty of the patients survived after surgery. One died of inhalation pneumonia in two weeks after surgery. Another died of right hemothorax in ten days after surgery. The complications include: pneumonia 4 patients (18%), angina 2 patients (9%), ventricular fibrillation 1 patients (5%), post-CABG myocardium infarction 1 case (5%) and hemothorax 1 case (5%). There is no neurologic complications or aortic dissection after CABG.</AbstractText>CABG on beating heart with pedicel arterial grafts is the best approach to performing the surgery without touching the diseased ascending aorta. Ventricular fibrillation under mild hypothermia cardiopulmonary bypass and left ventricular suction were employed for quiet and bloodless field while distal anastomosis had no cross-clamping the ascending aorta. Also deep hypothermia and intermittently circulatory arrest offer quiet and bloodless field for the proximal anastomosis on ascending aorta without cross-clamping or partial-occluding. Distal sequential anastomosis and proximal "Y" type anastomosis are the effective approach to minimizing the proximal anastomosis on the ascending aorta.</AbstractText> |
2,175 | Paroxysms of excitement: sodium channel dysfunction in heart and brain. | Inherited disorders of ion-channels are associated with paroxysmal dysfunction of excitable tissues and manifest as diseases of the brain, heart and skeletal muscle. These so-called channelopathies have now been described for most of the major categories of voltage-dependent ion-channels including those selectively permeable to sodium. Sodium channelopathies affecting the heart and brain are reviewed in this essay. They show striking differences and similarities including, for example, their responsiveness to changes in body temperature and sleep state. They represent a paradigm for efforts to trace disturbed behaviour of physiological systems back to its molecular origins and understanding their molecular basis may provide clues to important health issues such as cardiac side effects of drugs and response to medication used to treat epilepsy. |
2,176 | Impact of cerebral cardiopulmonary resuscitation maneuvers in a general hospital: prognostic factors and outcomes. | To assess survival of patients undergoing cerebral cardiopulmonary resuscitation maneuvers and to identify prognostic factors for short-term survival.</AbstractText>Prospective study with patients undergoing cardiopulmonary resuscitation maneuvers.</AbstractText>The study included 150 patients. Spontaneous circulation was re-established in 88 (58%) patients, and 42 (28%) were discharged from the hospital. The necessary number of patients treated to save 1 life in 12 months was 3.4. The presence of ventricular fibrillation or tachycardia (VF/VT) as the initial rhythm, shorter times of cardiopulmonary resuscitation maneuvers and cardiopulmonary arrest, and greater values of mean blood pressure (BP) prior to cardiopulmonary arrest were independent variables for re-establishment of spontaneous circulation and hospital discharge. The odds ratios for hospital discharge were as follows: 6.1 (95% confidence interval [CI] = 2.7-13.6), when the initial rhythm was VF/VT; 9.4 (95% CI = 4.1-21.3), when the time of cerebral cardiopulmonary resuscitation was < 15 min; 9.2 (95% CI = 3.9-21.3), when the time of cardiopulmonary arrest was < 20 min; and 5.7 (95% CI = 2.4-13.7), when BP was > 70 mmHg.</AbstractText>The presence of VF/VT as the initial rhythm, shorter times of cerebral cardiopulmonary resuscitation and of cardiopulmonary arrest, and a greater value of BP prior to cardiopulmonary arrest were independent variables of better prognosis.</AbstractText> |
2,177 | Pravastatin prevents arrhythmias induced by coronary artery ischemia/reperfusion in anesthetized normocholesterolemic rats. | HMG-CoA reductase inhibitors (statins) have been shown to decrease cardiovascular mortality. Since ventricular tachyarrhythmias are closely related to cardiovascular mortality, we tested effects of the hydrophilic statin pravastatin and the lipophilic statin fluvastatin in a rat arrhythmia model of ischemia/reperfusion and simultaneously measured serum total cholesterol level. Anesthetized rats were subjected to 5-min ischemia and 10-min reperfusion after chronic administration of oral pravastatin (0.02, 0.2, or 2 mg/kg), fluvastatin (0.2, 2, or 4 mg/kg), or vehicle for 22 days, once daily. The acute effect of pravastatin (0.2 or 2 mg/kg, once orally) was also observed. Chronically administrated pravastatin significantly reduced the incidence of ischemia-induced ventricular tachycardia (VT) from 70% (control) to 9% at 2 mg/kg, and it reduced the incidence of reperfusion-induced lethal ventricular fibrillation (VF) from 90% (control) to 20% at 0.2 mg/kg. Acute pravastatin and chronically administrated fluvastatin had no significant effect on these arrhythmias. There were no significant changes in blood pressure, heart rate, QT interval, and serum cholesterol among pravastatin-, fluvastatin-, and vehicle-treated groups. Hydrophilic pravastatin prevented reperfusion-induced lethal VF in anesthetized rats by chronic administration independent of its cholesterol lowering effect. This may be a new beneficial role of pravastatin in decreasing cardiovascular mortality. |
2,178 | Kv1.5 is an important component of repolarizing K+ current in canine atrial myocytes. | Although the canine atrium has proven useful in several experimental models of atrial fibrillation and for studying the effects of rapid atrial pacing on atrial electrical remodeling, it may not fully represent the human condition because of reported differences in functional ionic currents and ion channel subunit expression. In this study, we reassessed the molecular components underlying one current, the ultrarapid delayed rectifier current in canine atrium [IKur(d)], by evaluating the mRNA, protein, immunofluorescence, and currents of the candidate channels. Using reverse transcriptase-polymerase chain reaction, we found that Kv1.5 mRNA was expressed in canine atrium whereas message for Kv3.1 was not detected. Western analysis on cytosolic and membrane fractions of canine tissues, using selective antibodies, showed that Kv3.1 was only detectable in the brain preparations, whereas Kv1.5 was expressed at high levels in both atrial and ventricular membrane fractions. Confocal imaging performed on isolated canine atrial myocytes clearly demonstrated the presence of Kv1.5 immunostaining, whereas that of Kv3.1 was equivocal. Voltage- and current-clamp studies showed that 0.5 mmol/L tetraethylammonium had variable effects on sustained K+ currents, whereas a compound with demonstrated selectivity for hKv1.5 versus Kv3.1, hERG or the sodium channel, fully suppressed canine atrial IKur tail currents and depressed sustained outward K+ current. This agent also increased action potential plateau potentials and action potential duration at 20% and 50% repolarization. These results suggest that in canine atria, as in other species including human, Kv1.5 protein is highly expressed and contributes to IKur. |
2,179 | The hemodynamic and metabolic effects of shivering during acute normovolemic hemodilution. | To assess the hemodynamic and metabolic effects of shivering during extreme normovolemic hemodilution, we anesthetized 16 pigs with fentanyl-midazolam-pancuronium. Mild hypothermia (36.5 degrees +/- 0.1 degrees C) was induced by surface cooling, and the animals were randomized to either a control group (hemoglobin 118 +/- 3 g/L) or a hemodilution group (hemoglobin 52 +/- 2 g/L). In the latter group, blood was replaced with an isotonic Ringer's acetate/dextran 70 solution. Shivering was allowed to occur by a controlled decrease in the infusion rate of pancuronium. Shivering increased oxygen consumption (VO(2)) in both groups (P < 0.001). Initially, this was predominantly compensated for by an increased oxygen extraction ratio (ER), but when VO(2) was 2.3 +/- 0.2 times baseline, critical levels of mixed venous oxygenation (SVO(2) = 18% +/- 2%; PVO(2) = 22.5 +/- 1.5 mm Hg) and ER (82% +/- 3%) were recorded in anemic animals. Control animals did not reach critical levels until VO(2) was maximal (3.7 +/- 0.3 times baseline). Maximal attained VO(2) was less (2.9 +/- 0.1 times baseline) in the anemic animals (P = 0.01), and at this stage two of these pigs had myocardial lactate production, one of which died in ventricular fibrillation. Coronary perfusion pressure was significantly less (P < 0.001) in the anemic animals. We conclude that in this experimental model, maximal shivering as measured by VO(2) was limited in hemodiluted animals, and left ventricular oxygen balance was marginal, as evidenced by a decreased lactate uptake and extraction.</AbstractText>The effect of acute increases in oxygen consumption (shivering) on severely anemic individuals has not been evaluated. In this experimental model, left ventricular oxygen balance was marginal, as evidenced by decreased lactate extraction.</AbstractText> |
2,180 | Anesthetic management for implantation of the Jarvik 2000 left ventricular assist system. | The Jarvik 2000 Heart(TM) is a left ventricular assist device that produces continuous nonpulsatile axial flow by means of a single, rotating, vaned impeller. Anesthetic and perioperative considerations of the Jarvik 2000 Heart(TM) differ from those of conventional assist devices. The Jarvik 2000 is implanted within the left ventricle through a left thoracotomy, which is aided by left lung isolation. A brief period of cardiopulmonary bypass and induced ventricular fibrillation facilitate implantation. Transesophageal echocardiography is essential to assure proper intraventricular positioning of the device and aortic outflow, confirmed by observation of aortic valve opening in the presence of adequate left ventricular volume. Because continuous flow devices function best in the presence of lower systemic and pulmonary vascular resistance, milrinone was preferentially used as an inotropic drug. In the first group of 10 patients to receive the Jarvik 2000, the pump provided a cardiac output of up to 8 L/min, depending on preload, afterload, and pump speed. There were no early perioperative deaths. The average support duration was 81.2 days; the range was 13-214 days. Seven of the 10 patients survived to transplantation. Survivors underwent complete physical rehabilitation during pump support.</AbstractText>The Jarvik 2000 is a left ventricular assist device that produces continuous nonpulsatile axial flow by means of a rotating, vaned impeller. Because the anesthetic considerations differ from those of conventional left ventricular assist devices, we report the perioperative management of the first 10 patients who participated in a bridge-to-transplantation feasibility study of the Jarvik 2000.</AbstractText> |
2,181 | 2-aryl-3-phenylamino-4,5-dihydro-2h-benz[g]indazoles with analgesic activity. | A series of 2-aryl-3-phenylamino-4,5-dihydro-2H-benz[g]indazoles was synthesized and tested for antiarrhythmic, local anaesthetic and analgesic activity. The title compounds showed a good antinociceptive activity. |
2,182 | Esmolol versus diltiazem in atrial fibrillation following coronary artery bypass graft surgery. | Atrial fibrillation (AF) is the most common arrhythmic complication following coronary artery bypass graft surgery (CABG). The efficacy and safety of esmolol and diltiazem were compared in patients with post-CABG AF.</AbstractText>This study was a retrospective medical record review of consecutive patients with post-CABG AF > or =15 min in duration with a ventricular rate > or =110 b.p.m. who received either i.v. esmolol (n = 59) or i.v. diltiazem (n = 48) with or without concomitant digoxin therapy at a single university-affiliated teaching hospital. Treatment success was defined as either cardioversion to sinus rhythm or a reduction in the ventricular rate to < or =90 b.p.m. at 24 h after the start of therapy. Time to treatment success and the occurrence of adverse effects were considered secondary outcomes.</AbstractText>A total of 107 patients with post-CABG AF were treated with i.v. esmolol (n = 59) or i.v. diltiazem (n = 48). The mean maximum dose of esmolol and diltiazem were 115 +/- 38 microg/kg/min and 11.2 +/- 3.5 mg/h, respectively. The average duration of the esmolol and diltiazem infusions were 19.3 +/- 8.5 h and 20.1 +/- 11.3 h, respectively. Based on the combined efficacy endpoint of cardioversion or ventricular rate control, esmolol was significantly more effective than diltiazem (90% vs 77%; p = 0.038). Time to treatment success was significantly better for esmolol than diltiazem at all time points (1, 2, 4, 6, 12, and 24 h post-treatment). The overall incidence of adverse effects was 44% with esmolol and 60% with diltiazem (p = 0.04). Rates of drug discontinuance for adverse effects were significantly less for esmolol (20%) compared with diltiazem (38%) (p = 0.04).</AbstractText>Esmolol is significantly more effective than diltiazem in the management of post-CABG AF. More patients converted to sinus rhythm with esmolol as compared to diltiazem. Esmolol was associated with fewer adverse effects than diltiazem, including adverse effects leading to drug discontinuance. Due to study design limitations (retrospective data collection), an adequately powered randomised, controlled trial is needed to confirm these preliminary findings.</AbstractText> |
2,183 | [Implantable automatic defibrillator]. | Automatic defibrillators which can be implanted have developed into a major advancement to treat patients suffering from cardiac arrhythmias, and especially cases of ventricular tachy-arrhythmias, which degenerate into ventricular fibrillation and can lead to cardiac arrest. Since tachy-arrhythmias can cause sudden, unexpected death, is it necessary to identify high risk patients who do not show any clinical signs. The authors describe the history of automatic defibrillators which can be implanted, how they are implanted, the models available and their indicated usage. |
2,184 | A report of a surgical case of papillary fibroelastoma in the left ventricular outflow tract. | While a 74-year-old man with a past history of cerebral infarction was undergoing surface echocardiography due to transient atrial fibrillation, an unstable, pedunculated tumor was detected in the left ventricular outflow tract. As the results of transesophageal echocardiography suggested a left ventricular tumor, semi-emergency surgery was performed. Based on pathological findings, the tumor was diagnosed as papillary fibroelastoma. This tumor mainly affects the cardiac valves and is often discovered during open-heart surgery or autopsy. This report presents a very rare case of preoperatively identified papillary fibroelastoma in the left ventricular outflow tract. |
2,185 | Effect of left ventricular function on long-term left ventricular pacing and sensing threshold. | The effect of left ventricular (LV) systolic function on the long-term left ventricular pacing and sensing threshold is unclear.</AbstractText>We studied the effect of LV ejection fraction (LVEF) on the LV pacing and sensing threshold in 56 patients (mean age: 70.2 +/- 10.5 years) underwent permanent LV pacing using a self-retaining coronary sinus lead (Model 1055 K, St Jude Medical, USA). In 49 patients, the LV lead was implanted for conventional pacemaker indication (sick sinus syndrome = 14, heart block = 26 or slow atrial fibrillation = 9). The remaining 7 patients were implanted for congestive heart failure. The LV pacing and sensing threshold, and lead impedance were compared between patients with LVEF <40% (Group 1, n = 28) and LVEF >40% (Group 2, n = 28) during implant and at 3-month follow up. The LV pacing lead was successfully implanted in all patients without any lead dislodgement on follow-up. At implant, Group 1 patients had a significant lower R wave amplitude, but similar LV pacing threshold and lead impedance as compared to Group 2. However, at 3-month follow-up, Group 1 patients had a significantly higher LV pacing threshold compared to Group 2 patients. There were no significant differences in the sensing threshold and lead impedance between the two groups. Furthermore, there was also a significant interval increase in LV pacing threshold in Group 1 patients (0.94 +/- 0.12 V) after 3 months, but not in Group 2 patients (0.16 +/- 0.08 V, p < 0.01).</AbstractText>The results of this study suggest that the LV systolic function has a significant impact on the long-term LV pacing threshold. The long-term left ventricular pacing threshold in patients with left ventricular systolic dysfunction increased after implant and was higher than patients with normal left ventricular systolic function.</AbstractText> |
2,186 | Effectiveness of ibutilide in cardioversion of persistent atrial fibrillation in patients with dual chamber stimulation. | To evaluate the effectiveness of Ibutilide in cardioversion of persistent atrial fibrillation in patients with sinus node disease wearing a dual chamber pacemaker and to assess the potential role of overdrive ventricular pacing in prevention of drug related proarrhythmia.</AbstractText>Fifty-three sinus node disease patients (35 males; mean age 75 +/- 9.5 years), implanted with a dual chamber pacing system, with persistent atrial fibrillation, lasting for 328 +/- 416 days, received 1-2 mg of intravenous Ibutilide. Pacing mode was programmed in VVI at 90 ppm, in order to suppress spontaneous ventricular activity. All patients were monitored for 4 hours. Late occurrence of ventricular arrhythmias was evaluated using the pacemaker memory. Ventricular pacing threshold, spontaneous electrogram amplitude and pacing impedance were measured before and after Ibutilide infusion. Cardioversion to sinus rhythm occurred in twenty-two patients (41.5%). Treatment success was significantly related to shorter atrial fibrillation duration. Paced QT interval duration increased from 412 +/- 36 ms to 481 +/- 40 ms (p < 0.0001), without differences between responders and non responders; QRS width did not change significantly (from 152 +/- 25 ms to 161 +/- 25 ms; p = n.s.). No early or late episodes of sustained or non sustained polymorphic ventricular tachycardia were observed. Pacing and sensing threshold did not show any significant variation.</AbstractText>Ibutilide showed a good effectiveness in treating persistent atrial fibrillation in paced patients. Overdrive ventricular pacing may have played a role in preventing drug induced ventricular proarrhythmia. No adverse effect on pacing threshold was observed.</AbstractText> |
2,187 | QRS duration: a simple marker for predicting cardiac mortality in ICD patients with heart failure. | Patients resuscitated from ventricular tachyarrhythmias benefit from implantable cardioverter-defibrillators (ICDs) as opposed to medical treatment. Patients with increased QRS duration receiving an ICD in the presence of heart failure are at greatest risk of cardiac death and benefit most from ICD therapy.</AbstractText>To determine whether an increased QRS duration predicts cardiac mortality in ICD recipients.</AbstractText>Consecutive patients with heart failure in New York Heart Association functional class III were grouped according to QRS duration (< 150 ms, n = 139, group 1; v > or = 150 ms, n = 26, group 2) and followed up for (mean (SD)) 23 (20) months.</AbstractText>165 patients were studied (80% men, 20% women); 73% had coronary artery disease and 18% had dilated cardiomyopathy. Their mean age was 62 (10) years and mean ejection fraction (EF) was 33 (14)%. They presented either with ventricular tachycardia (VT) or ventricular fibrillation (VF).</AbstractText>Overall and cardiac mortality; recurrence rates of VT, fast VT, or VF.</AbstractText>Mean left ventricular EF did not differ between group 1 (33 (13)%) and group 2 (31 (15)%). Forty patients died (34 cardiac deaths). There was no difference in survival between patients with EF > 35% and < or = 35%. Cardiac mortality was significantly higher in group 2 than in group 1 (31.3% at 12 months and 46.6% at 24 months, v 9.5% at 12 months and 18.2% at 24 months, respectively; p = 0.04). The recurrence rate of VT was similar in both groups.</AbstractText>Within subgroups at highest risk of cardiac death, QRS duration-a simple non-invasive index-predicts outcome in ICD recipients in the presence of heart failure.</AbstractText> |
2,188 | Metastatic squamous cell carcinoma of the skin in chronic myeloid leukaemia: complication of hydroxyurea therapy. | Hydroxyurea is a ribonucleotide diphosphate reductase inhibitor used in the treatment of patients with myeloproliferative disorders. Hydroxyurea has some dermatological side-effects. It has recently been recognized that hydroxyurea can induce squamous cell and basal cell carcinomas of skin. We present the case of an elderly man with chronic myeloid leukaemia who was treated with hydroxyurea for 4 years, with good control of his disease. However, in addition to the appearance of various skin lesions and cutaneous squamous cell carcinoma after 3 years of therapy, he was found to have a metastatic squamous cell carcinoma after 4 years. Hydroxyurea was discontinued, and he underwent surgery and radiotherapy. The patient subsequently died of ventricular fibrillation. We present this case to draw attention to the association between hydroxyurea and secondary skin cancers and to emphasize the need for dermatological examination before and during the course of hydroxyurea therapy. |
2,189 | Ventricular fibrillation in acute myocardial infarction in Spanish patients: Results of the ARIAM database. | The aim of this study has been to investigate the factors predisposing to primary or secondary ventricular fibrillation (VF) and the prognosis in Spanish patients with acute myocardial infarction (AMI) during their admission to the intensive care unit or the coronary care unit.</AbstractText>A retrospective, observational study.</AbstractText>The intensive care units and coronary care units of 119 Spanish hospitals.</AbstractText>A retrospective cohort study including all the AMI patients listed in the ARIAM registry (Analysis of Delay in Acute Myocardial Infarction), a Spanish multicenter study. The study period was January 1995 to January 2001.</AbstractText>Factors associated with the onset of VF were studied by univariate analysis. Multivariate analysis was used to evaluate the independent factors for the onset of VF and for mortality. A total of 17,761 patients with AMI were included in the study; 964 (5.4%) developed VF (primary in 735 patients, secondary in 229). In multivariate analysis, the variables that continued to show an association with the development of VF were the Killip and Kimball class, peak creatine kinase, APACHE II score, age, and time from the onset of symptoms to the initiation of thrombolysis. The mortality in the patients with any VF was 31.8% (27.8% in patients with primary VF and 49.1% in patients with secondary VF). The development of VF is an independent predictive factor for mortality in patients with AMI, with a crude odds ratio of 5.12 (95% confidence interval, 4.41-5.95) and an adjusted odds ratio of 2.73 (95% confidence interval, 2.12-3.51).</AbstractText>Despite the considerable improvement in the treatment of AMI in recent years, the onset of either primary or secondary VF is associated with a poor prognosis. It is usually accompanied by extensive necrosis.</AbstractText> |
2,190 | Release of neuron-specific enolase and S100 after implantation of cardioverters/defibrillators. | Repeated induction of ventricular fibrillation with ensuing alterations in electroencephalogram and jugular venous oxygen saturation is common practice during insertion of transvenous implantable cardioverters/defibrillators. We investigated whether these functional changes are also associated with cerebral injury.</AbstractText>Prospective study.</AbstractText>University hospital.</AbstractText>We studied 45 patients undergoing implantable cardioverter/defibrillator insertion. Eleven patients with cardiac pacemaker implantation, which was performed in the same manner yet without the necessity to induce ventricular fibrillation, served as controls.</AbstractText>Serum neuron-specific enolase and S100 were determined before, immediately postoperatively, and 2 hrs postoperatively. In a randomly composed subgroup, neuron-specific enolase was also determined 6 and 24 hrs after surgery. Implantable cardioverter/defibrillator patients only showed an increase of both markers postoperatively. Median neuron-specific enolase values climbed from a preoperative 9.9 to 12.3 and 14.4 microg/L at 2 and 24 hrs after surgery, respectively. This increase was associated with the number of shocks and the cumulative time in circulatory arrest. The highest median S100 level (0.075 microg/L) was reached 2 hrs after the procedure. Neuron-specific enolase and S100 were extremely elevated (13.7 and 0.970 microg/L, respectively) in one patient after an extended episode of ventricular fibrillation. Plasma hemoglobin levels were in the normal range in implantable cardioverter/defibrillator patients throughout the observation period.</AbstractText>Apparently, even brief successive periods of global cerebral ischemia cause neuronal damage without obvious severe neurologic deficits. However, they may be related to subtle postoperative neurologic or cognitive dysfunctions that a number of implantable cardioverter/defibrillator patients exhibit after implantation.</AbstractText> |
2,191 | Effect of lunar cycle on temporal variation in cardiopulmonary arrest in seven emergency departments during 11 years. | To determine the effect of the phase of the full and new moon on the variation in the number of daily cardiopulmonary resuscitations.</AbstractText>A retrospective analysis of a computerized billing database of emergency department visits in a cohort of seven northern New Jersey (USA) emergency departments.</AbstractText>Consecutive patients seen by emergency department physicians over an 11-year period (1 January 1988 to 31 December 1998). We determined the timing of full and new moon days from the National Oceanographic and Aeronautic Administration website.</AbstractText>Time series regression estimated the independent effect of full and new moon days on the daily variation in cardiopulmonary resuscitations. Tests of statistical significance were made at alpha=0.05.</AbstractText>A total of 2 370 233 emergency department visits were made during the 4018-day period of study. A total of 6827 had an emergency department diagnosis of cardiopulmonary resuscitation. We found no significant difference in the occurrence of cardiopulmonary resuscitations during the full moon (P=0.97). On average there were 6.5% fewer cardiopulmonary resuscitations during new moon days (P=0.02; 95% confidence interval 1.3-11.7%).</AbstractText>Contrary to the traditional belief that more cardiopulmonary resuscitations occur during the full moon, we were unable to identify a significant effect during full moon days. However, there were on average 6.5% fewer cardiopulmonary resuscitations during new moon days than other days.</AbstractText> |
2,192 | Midterm results after stentless mitral valve replacement. | To analyze the midterm clinical results after stentless mitral valve (SMV) replacement.</AbstractText>Fifty one patients (68.3+/-8.4 years, 35 female) with severe mitral valve disease (stenosis 25, incompetence 17, mixed lesion 9) received a chordally supported SMV (Quattro, St. Jude Medical Inc.) since August 1997. Preoperative New York Heart Association class was 3.1+/-0.6; left ventricular ejection fraction 64+/-13%, and cardiac index 2.1+/-0.8 l/min/m2. Additional intraoperative ablation therapy was performed on 19 patients with chronic atrial fibrillation. Mean follow-up is 35.4+/-19.2 months (range 5 to 63). SMV implantation was performed using a conventional (32) or a minimally invasive (19) approach, valve size was 29+/-1.5 mm, cross-clamp duration was 81+/-33 minutes. Atrial rhythm was reestablished in 16 of 19 patients. Five patients required reoperation early in this series, two for paravalvular leakage, two for functional stenosis, and one with underlying rheumatoid disease. Mortality was one perioperative (1.96%, non-valve-related), one after reoperation as a result of multiple organ failure (MOF), and five during late follow-up (30+/-7 months postoperatively) for noncardiac causes. Regular echocardiographic control revealed good SMV function (Vmax 1.7+/-0.2m/s, P(mean) 3.9+/-1.2 mm Hg) and well-preserved ejection fraction postoperatively and at most recent follow-up.</AbstractText>Midterm results after SMV implantation are promising. Preservation of the annuloventricular continuity leads to stable left ventricular function and combined with ablation therapy to physiological hemodynamics. Long-term durability remains to be proven.</AbstractText> |
2,193 | Results of the introduction of an automated external defibrillation programme for non-medical personnel in Galicia. | To describe the plan and development of a programme for the introduction of automated external defibrillation for non medical personnel and to report the results of the first 10 months of activity in a community which is predominently rural, such as Galicia.</AbstractText>The plan for introduction of the project included aspects of logistics, training and control. We studied cardiac arrests, that were treated in basic life support ambulances (BLS-A) equipped with automated external defibrillators (AEDs), from 1st March to 31st December 2001.</AbstractText>Our community benefits from pioneering legislation in Spain. During the 10 months of study, 28 AEDs were in service, mostly in urban areas. In all cases, a thorough control of the quality of the service in which AEDs was used was carried out. 12% of the patients, who were victims of sudden cardiac death (SCD) and were found in ventricular fibrillation (VF), survived and were discharged from hospital. However, the percentage of patients found in VF is only around 26%. This is due to long assistance intervals (from the call to the arrival on site), and an important delay from the moment when circulatory collapse takes place until the emergency service 061 is called, more than 5 min in half the cases.</AbstractText>The programme followed for the introduction of AEDs in Galicia was adapted to the socio-demographic characteristics of the population. The prehospital emergency assistance model was developed, executed and controlled by the Public Emergency Health Foundation of Galicia 061 (PEHF-061). The overall results of our first 10 months experience with the automated external defibrillation programme were as to be expected. In general, they are comparable to other published reports; however, ways of shortening the times from the point of collapse to defibrillation must be found, mainly by training the population and through the extension of automated external defibrillation provision to other first responders.</AbstractText> |
2,194 | Causes and prognosis of cardiac arrest in a population admitted to a general hospital; a diagnostic and therapeutic problem. | The purpose of this study was to determine the causes and the prognosis of consecutive patients resuscitated from cardiac arrest occurring in a general hospital. We assessed 28 females and 94 males (aged 13-82 years) who were resuscitated from cardiac arrest not attributable to acute myocardial infarction. Ventricular fibrillation (VF) was documented in 97. Non-cardiac causes were excluded. Non-invasive studies (24 h Holter monitoring, 2D echocardiogram, signal-averaged ECG, exercise testing, magnetic resonance imaging) and invasive studies (right and left ventricular angiography, coronary angiography and complete electrophysiologic study (EPS) were performed.</AbstractText>An underlying cardiac disease was found in 107 patients (88%). Patients were followed for a period ranging from 6 months to 10 years (mean 4+/-5 years). Several causes for cardiac arrest were identified and treated specifically. The prognosis was variable. Among surviving patients the following causes of cardiac arrest were found: Wolff-Parkinson-White syndrome (n=2), rapid supraventricular tachycardia (n=6), acquired or congenital long QT syndrome (n=7), complete atrioventricular block (n=3), proarrhythmic effect of an antiarrhythmic drug (n=5), vasospastic angina (normal coronary arteries) (n=5). Among ten patients with VF related to cardiac ischaemia two died suddenly. Ventricular tachycardia (VT) or VF was the main cause leading to resuscitation after cardiac arrest (n=64). The risk of recurrence of arrest is confirmed in the present study particularly in patients in whom VT/VF could not be suppressed by antiarrhythmic drug therapy (n=45) and in those where an ICD was not implanted (18 cardiac deaths (nine sudden cardiac deaths (SCD's)). The cause of cardiac arrest was not elucidated in 20 patients (16%). The prognosis of these patients differed according to the documentation of VF at the time of cardiac arrest: of those with documented VF (n=12), six patients died suddenly (one with an ICD); of those without documented VF (n=8), all are alive.</AbstractText>To determine the precise cause of cardiac arrest was the first problem; the diagnosis of cardiac arrest clearly was erroneous in 8 of 122 patients (6.5%). In other patients, a ventricular tachyarrhythmia was identified as the cause for cardiac arrest in half of the population; the indication for an ICD is evident in this group. In 31% of patients with proven cardiac arrest, another arrhythmia requiring specific treatment was identified and ICD implantation was avoided; these patients had a survival of 92% at 3 years. In patients without an identified cause of cardiac arrest and negative EPS, the prognosis was unfavorable only in those with documented VF.</AbstractText> |
2,195 | Factors at resuscitation and outcome among patients suffering from out of hospital cardiac arrest in relation to age. | To describe various factors at resuscitation and outcome among patients suffering from out-of-hospital cardiac arrest in relation to age.</AbstractText>All patients included in the Swedish Cardiac Arrest Registry during the period 1990-1999. The registry covers about 60% of all ambulance organisations in Sweden.</AbstractText>All patients reached by the ambulance crew and in whom resuscitative efforts were attempted. Crew witnessed cases were excluded. Only patients aged over 18 years were included. Patients were divided into three age groups: less than 65 years (n=7810), 65-75 years (n=7261) and over 75 years (n=8390).</AbstractText>The proportion of cases with a cardiac aetiology increased with increasing age (P<0.0001). The proportion of witnessed cases increased with increasing age among those with a non-cardiac aetiology (P<0.0001) and decreased with increasing age among cases with a cardiac aetiology (P=0.02). The proportion of patients exposed to bystander CPR decreased with increasing age (P<0.0001). The proportion of patients found in ventricular fibrillation (VF) decreased with increasing age among patients with a cardiac aetiology (P<0.0001) but was not related to age in those with a non-cardiac aetiology. The proportion of patients being alive after 1 month in the three age groups (youngest first) were: 4.5, 3.2 and 2.5% (P<0.0001). The corresponding figures for patients with a cardiac aetiology found in VF were: 10.7, 7.6 and 6.6% (P<0.0001). After multiple regression analysis controlling for other factors increasing age was still associated with decreased survival to 1 month (odds ratio 0.85; 95% confidence limits 0.80-0.91).</AbstractText>Among patients suffering from out-of-hospital cardiac arrest various factors at resuscitation, including initial rhythm, aetiology and bystander CPR, are strongly related to age. The chance of survival diminishes with increasing age. When correcting for the dissimilarities in terms of factors at resuscitation, age is still significantly associated with survival, being lower among the elderly.</AbstractText> |
2,196 | Cardiopulmonary resuscitation of adults in the hospital: a report of 14720 cardiac arrests from the National Registry of Cardiopulmonary Resuscitation. | The National Registry of Cardiopulmonary Resuscitation (NRCPR) is an American Heart Association (AHA)-sponsored, prospective, multisite, observational study of in-hospital resuscitation. The NRCPR is currently the largest registry of its kind. The purpose of this article is to describe the NRCPR and to provide the first comprehensive, Utstein-based, standardized characterization of in-hospital resuscitation in the United States. All adult (>/=18 years of age) and pediatric (<18 years of age) patients, visitors, employees, and staff within a facility (including ambulatory care areas) who experience a resuscitation event are eligible for inclusion in the NRCPR database. Between January 1, 2000, and June 30, 2002, 14720 cardiac arrests that met inclusion criteria occurred in adults at the 207 participating hospitals. An organized emergency team is available 24 h a day, 7 days a week in 86% of participating institutions. The three most common reasons for cardiac arrest in adults were (1) cardiac arrhythmia, (2) acute respiratory insufficiency, and (3) hypotension. Overall, 44% of adult in-hospital cardiac arrest victims had a return of spontaneous circulation (ROSC); 17% survived to hospital discharge. Despite the fact that a primary arrhythmia was one of the precipitating events in nearly one half of adult cardiac arrests, ventricular fibrillation (VF) was the initial pulseless rhythm in only 16% of in-hospital cardiac arrest victims. ROSC occurred in 58% of VF cases, yielding a survival-to-hospital discharge rate of 34% in this subset of patients. An automated external defibrillator was used to provide initial defibrillation in only 1.4% of patients whose initial cardiac arrest rhythm was VF. Neurological outcome in discharged survivors was generally good. Eighty-six percent of patients with Cerebral Performance Category-1 (CPC-1) at the time of hospital admission had a postarrest CPC-1 at the time of hospital discharge. |
2,197 | EMS defibrillation-first policy may not improve outcome in out-of-hospital cardiac arrest. | Early defibrillation using automated external defibrillators (AEDs) has been advocated to improve survival in witnessed out-of-hospital cardiac arrest (OHCA) due to pulseless ventricular tachycardia (VT) and ventricular fibrillation (VF). However, when VT/VF is untreated and prolonged for more than a few minutes, defibrillation using AEDs may fail.</AbstractText>This retrospective study reviewed the charts from local emergency medical service (EMS) between the years 1993 to 2001 to evaluate the value of the AED after its introduction into our EMS. All witnessed OHCA due to VT/VF were analysed; cases of collapse witnessed by EMS were excluded. The primary endpoint was defined as survival to hospital discharge and at 1-year follow-up, and the secondary endpoint as survival without major neurological deficit. A total of 76 patients were treated for witnessed VT/VF before the implementation of the AED and 92 patients after its implementation.</AbstractText>Before the introduction of paramedic AED defibrillation, physician defibrillation was performed at 15.6 min (+/-5.5, S.D.). After the introduction of AED defibrillation, paramedic defibrillation was performed at 5.7 min (+/-2.4, S.D.); the mean response interval from the call to defibrillation was shortened significantly (P<0.001). At the same time, survival to hospital discharge decreased from 23.7% (18/76 patients) to 14.1% (13/92) (P=0.112) and at 1-year follow-up from 17.1% (13/76) to 9.8% (9/92) (P=0.161). Favourable neurological outcome at 1-year follow-up also decreased from 14.5% (11/76) to 8.7% (8/92) (P=0.239).</AbstractText>Implementation of the AED did not improve survival or a favourable neurological outcome in patients with OHCA due to VF/VT. However, with 5.7 min time to defibrillation, our EMS did not meet the criteria for early defibrillation. For prolonged periods of VT/VF, initial basic life support (BLS) may be superior to immediate AED. If response times of <4 min cannot be attained by the emergency systems, reconsidering of resuscitation algorithms seems to be advisable.</AbstractText> |
2,198 | The critical importance of minimal delay between chest compressions and subsequent defibrillation: a haemodynamic explanation. | Outcome after prehospital defibrillation remains dire. The aim of the present study was to elucidate the pathophysiology of cardiac arrest and to suggest ways to improve outcome. Ventricular fibrillation (VF) was induced in air-ventilated pigs, after which ventilation was withdrawn. After 6.5 min of VF, ventilation with 100% oxygen was initiated. In six pigs (group I), defibrillation was the only treatment carried out. In another six pigs (group II), mechanical chest compression-decompression CPR (mCPR) was carried out for 3.5 min followed by a 40-s hands-off period before defibrillation. If unsuccessful, mCPR was resumed for a further 30 s before a second or a third, 40-s delayed, shock was given. In a final six pigs (group III) mCPR was applied for 3.5 min after which up to three shocks (if needed) were given during on-going mCPR. Return of spontaneous circulation (ROSC) occurred in none of the pigs in group I (0%), in 1 of six pigs in group II (17%) and in five of six pigs in group III (83%). During the first 3 min of VF arterial blood was transported to the venous circulation, with the consequence that the left ventricle emptied and the right ventricle became greatly distended. It took 2 min of mCPR to establish an adequate coronary perfusion pressure, which was lost when the mCPR was interrupted. During 30 s of mCPR coronary perfusion pressure was negative, but a carotid flow of about 25% of basal value was obtained. In this pig model, VF caused venous congestion, an empty left heart, and a greatly distended right heart within 3 min. Adequate heart massage before and during defibrillation greatly improved the likelihood of return of spontaneous circulation (ROSC). |
2,199 | Management of unexpected coronary artery spasm in an asymptomatic patient during anaesthesia. | We report a case of life-threatening arrhythmia that was not predicted before surgery. Pulse-less ventricular tachycardia and ventricular fibrillation occurred during surgery without any changes in heart rate and blood pressure, and cardiac massage was required to maintain circulation. Although no organic stenosis was found in either the right or left coronary arteries, post-surgical angiographic examination revealed severe vasospastic angina induced by intra-luminal administration of acetylcholine. Anaesthesia with a high dose of fentanyl and vasodilators prevented the recurrence of life-threatening arrhythmia. Vasospastic angina attacks are difficult to predict with the preoperative examination routinely employed. |
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