Showing papers on "Implantable cardioverter-defibrillator published in 2000"
TL;DR: A 20% relative risk reduction occurred in all-cause mortality and a 33% reduction occur in arrhythmic mortality with ICD therapy compared with amiodarone; this reduction did not reach statistical significance.
Abstract: Background—Patients surviving ventricular fibrillation (VF) or sustained ventricular tachycardia (VT) are at a high risk of death due to a recurrence of arrhythmia. The implantable cardioverter defibrillator (ICD) terminates VT or VF, but it is not known whether this device prolongs life in these patients compared with medical therapy with amiodarone. Methods and Results—A total of 659 patients with resuscitated VF or VT or with unmonitored syncope were randomly assigned to treatment with the ICD or with amiodarone. The primary outcome measure was all-cause mortality, and the secondary outcome was arrhythmic death. A total of 328 patients were randomized to receive an ICD. A thoracotomy was done in 33, no ICD was implanted in 18, and the rest had a nonthoracotomy ICD. All 331 patients randomized to amiodarone received it initially. At 5 years, 85.4% of patients assigned to amiodarone were still receiving it at a mean dose of 255 mg/day, 28.1% of ICD patients were also receiving amiodarone, and 21.4% of am...
1,554 citations
TL;DR: The classic fixed effects meta-analysis showed that the estimates of ICD benefit from the three studies were consistent with each other, and there is a 28% reduction in the relative risk of death with the ICD that is due almost entirely to a 50% reduced in arrhythmic death.
Abstract: Aims Three randomized trials of implantable cardioverter defibrillator (ICD) therapy vs medical treatment for the prevention of death in survivors of ventricular fibrillation or sustained ventricular tachycardia have been reported with what might appear to be different results. The present analysis was performed to obtain the most precise estimate of the efficacy of the ICD, compared to amiodarone, for prolonging survival in patients with malignant ventricular arrhythmia.
Methods and Results Individual patient data from the Antiarrhythmics vs Implantable Defibrillator (AVID) study, the Cardiac Arrest Study Hamburg (CASH) and the Canadian Implantable Defibrillator Study (CIDS) were merged into a master database according to a pre-specified protocol. Proportional hazard modelling of individual patient data was used to estimate hazard ratios and to investigate subgroup interactions. Fixed effect meta-analysis techniques were also used to evaluate treatment effects and to assess heterogeneity across studies. The classic fixed effects meta-analysis showed that the estimates of ICD benefit from the three studies were consistent with each other ( P heterogeneity=0·306). It also showed a significant reduction in death from any cause with the ICD; with a summary hazard ratio (ICD:amiodarone) of 0·72 (95% confidence interval 0·60, 0·87; P =0·0006). For the outcome of arrhythmic death, the hazard ratio was 0·50 (95% confidence interval 0·37, 0·67; P <0·0001). Survival was extended by a mean of 4·4 months by the ICD over a follow-up period of 6 years. Patients with left ventricular ejection fraction ≤35% derived significantly more benefit from ICD therapy than those with better preserved left ventricular function. Patients treated before the availability of non-thoracotomy ICD implants derived significantly less benefit from ICD therapy than those treated in the non-thoracotomy era.
Conclusion Results from the three trials of the ICD vs amiodarone are consistent with each other. There is a 28% reduction in the relative risk of death with the ICD that is due almost entirely to a 50% reduction in arrhythmic death.
1,026 citations
TL;DR: At variance with current views, asymptomatic patients are at lower risk for sudden death and programmed electrical stimulation identifies only a fraction of individuals at risk, and sodium channel blockade fails to unmask most silent gene carriers.
Abstract: Background—The ECG pattern of right bundle branch block and ST-segment elevation in leads V1 to V3 (Brugada syndrome) is associated with high risk of sudden death in patients with a normal heart. Current management and prognosis are based on a single study suggesting a high mortality risk within 3 years for symptomatic and asymptomatic patients alike. As a consequence, aggressive management (implantable cardioverter defibrillator) is recommended for both groups. Methods and Results—Sixty patients (45 males aged 40±15 years) with the typical ECG pattern were clinically evaluated. Events at follow-up were analyzed for patients with at least one episode of aborted sudden death or syncope of unknown origin before recognition of the syndrome (30 symptomatic patients) and for patients without previous history of events (30 asymptomatic patients). Prevalence of mutations of the cardiac sodium channel was 15%, demonstrating genetic heterogeneity. During a mean follow-up of 33±38 months, ventricular fibrillation o...
468 citations
TL;DR: In patients with standard ICD indications who also have CHF, LV dysfunction, and an intraventricular conduction delay, ICD therapy is less common with BV pacing; the mechanism for this improvement is unclear but may be related to hemodynamic improvement in CHF.
238 citations
TL;DR: Adjunctive treatment with amiodarone reduced J wave amplitude, preventing ventricular fibrillation and ICD shocks, and may serve as an important diagnostic sign to detect high‐risk individuals with a history of unexplained syncope.
Abstract: Recurrent ventricular fibrillation was observed in a 29-year-old Vietnamese man who did not exhibit structural heart disease. The patient's ECG showed prominent J (Osborn) waves and ST segment elevation in the inferior leads that were not associated with hypothermia, serum electrolyte disturbance, or myocardial ischemia. Rate-dependent change in the amplitude of J waves and ST segment elevation also were observed. An implantable cardioverter defibrillator (ICD) was implanted. Adjunctive treatment with amiodarone reduced J wave amplitude, preventing ventricular fibrillation and ICD shocks. Prominent J waves and ST segment elevation in the inferior leads may serve as an important diagnostic sign to detect high-risk individuals with a history of unexplained syncope. ICD implantation plus amiodarone is the treatment of choice.
227 citations
TL;DR: In CIDS, patients at highest risk of death benefited most from ICD therapy, and can be identified easily on the basis of age, poor ventricular function, and poor functional status.
Abstract: Background—Patients with resuscitated ventricular tachyarrhythmias (ventricular tachycardia/ventricular fibrillation) benefit from implantable cardioverter-defibrillators (ICDs) compared with medical therapy. We hypothesized that the patients who benefit most from an ICD are those at greatest risk of death. Methods and Results—In the Canadian Implantable Defibrillator Study (CIDS), 659 patients with resuscitated ventricular tachyarrhythmias were randomly assigned to receive an ICD or amiodarone and were then followed for a mean of 3 years. There were 98 and 83 deaths in the amiodarone and ICD groups, respectively. We used multivariate Cox analysis to assess the impact of baseline parameters on the mortality in the amiodarone group. Reduced left ventricular ejection fraction, advanced age, and poor NYHA status identified high-risk patients (P=0.0001 to 0.0009). Quartiles of risk were constructed, and the mortality reduction associated with ICD treatment in each quartile was assessed. There was a significan...
213 citations
TL;DR: A new ICD detects AT/AF accurately and continuously and permits successful pacing therapy for a significant fraction of AT, and therapy may be programmed for long-duration At/AF, with a low risk of underdetection.
Abstract: Background—To distinguish prolonged episodes of atrial fibrillation (AF) that require cardioversion from self-terminating episodes that do not, an atrial implantable cardioverter-defibrillator (ICD) must be able to detect AF continuously for extended periods. The ICD should discriminate between atrial tachycardia/flutter (AT), which may be terminated by antitachycardia pacing, and AF, which requires cardioversion. Methods and Results—We studied 80 patients with AT/AF and ventricular arrhythmias who were treated with a new atrial/dual-chamber ICD. During a follow-up period lasting 6±2 months, we validated spontaneous, device-defined AT/AF episodes by stored electrograms in all patients. In 58 patients, we performed 80 Holter recordings with telemetered atrial electrograms, both to validate the continuous detection of AT/AF and to determine the sensitivity of the detection of AT/AF. Detection was appropriate in 98% of 132 AF episodes and 88% of 190 AT episodes (98% of 128 AT episodes with an atrial cycle le...
151 citations
TL;DR: Spontaneous episodes of VF in patients with Brugada syndrome were triggered by specific PVCs, and electrocardiographic features obtained from stored electrograms of ICDs and/or ECG monitoring may provide important insights into the pathophysiological mechanisms causing VF.
140 citations
TL;DR: The era of the clinical use of the implantable cardioverter defibrillator (ICD) therapy began just 20 years ago, and progress in the field since that time has been astounding.
Abstract: At times, our clinical intuition may lead us down the wrong path, but the scientific method helps direct us back to the proper course. In 1970, Mirowski et al1 published their first experience with the standby automatic defibrillator in animals, but their innovative approach to prevent sudden cardiac death was not initially accepted by the cardiac community. Concerns about the practicality of the implanted defibrillator to save lives stimulated Mirowski and colleagues to perform additional investigations; this culminated in their 1980 publication documenting life-saving internal defibrillation with an implantable device in 3 patients.2 The era of the clinical use of the implantable cardioverter defibrillator (ICD) therapy began just 20 years ago, and progress in the field since that time has been astounding.
A series of randomized ICD trials began in the early 1990s. When my colleagues and I were designing the Multicenter Automatic Defibrillator Implantation Trial (MADIT), the general attitude was that the ICD might prolong life for only a short time in patients with advanced coronary disease. Although the ICD had already been shown to be effective in terminating acute ventricular fibrillation, it was assumed that defibrillation in patients with chronic coronary disease would only be a temporizing measure, with early occurrence of death due to heart failure. This was not the case. The results of MADIT were published in 1996,3 and those of the Multicenter UnSustained Tachycardia Trial (MUSTT) in 1999.4 These 2 primary prevention trials substantiated improved survival with ICD therapy in coronary patients with nonsustained ventricular tachycardia. Two secondary prevention trials that focused on patients with aborted cardiac arrest or life-threatening cardiac arrhythmias have also been completed; these are the Antiarrhythmics Versus Implantable Defibrillators (AVID) study5 and the Canadian Implantable …
135 citations
TL;DR: This is the first observation that the use of lipid lowering drugs is associated with a reduction of recurrences of VA in patients with CAD and ICD implants.
120 citations
TL;DR: There is a lack of data concerning the association of AF and ventricular tachyarrhythmias, but there is a need to investigate this link more fully.
Abstract: Atrial Fibrillation and Appropriate ICD Therapy. Introduction: Atrial fibrillation(AF) is associated with significant morbidity and mortality that may be related to heniodynamic Impairment, thromboembolic events, or enhanced electrical instability of the ventricular myocardium. There is, however, a lack of data concerning the association of AF and ventricular tachyarrhythmias.
Methods and Results: Consecutive patients with indication for an implantable cardioverter defibrillator (ICD) were classified for the presence or absence of persistent AF at the time of device implantation. Incidence of device therapy, stored electrograms, and clinical events during follow-up were evaluated prospectively. Two hundred fifty patients were included. During follow-up (20 ± 14 months), patients in AF experienced appropriate device therapy for recurrent ventricular arrhythmias more frequently compared with patients in sinus rhythm (SR) (63% vs 38%, P = 0.01). On multivariate analysis, AF was an independent predictor of appropriate ICD therapy (relative risk 1.8; 95% confidence interval [CI] 1.2 to 2.9) and in appropriate device therapy (relative risk 2,3; 95% CI 1,2 to 4.5). Predefined clinical events (cluster endpoint: death, syncope, and hospitalizations) were observed more frequently in AF than in SR patients (55% vs 31%. P = 0.01). Analysis of device-stored electrograms revealed a higher incidence of short-long-short cycles preceding ventricular arrhythmias in AF compared with SR patients (50% vs 16%, P = 0.002), Baseline heart rate preceding ventricular arrhythmias did not differ between the two groups.
Conclusion: AF is an independent predictor of recurrent ventricular arrhythmias in ICD recipients. The underlying electrophysiologic mechanism seems to be irregular rather than rapid ventricular activation, with a high incidence of short-long-short sequences preceding ventricular tachyarrhythmias in AF patients.
TL;DR: In a patient population with symptomatic heart failure and ventricular arrhythmias, BV pacing does not appear to be associated with excess mortality, and larger and longer studies will be needed to determine if Bv pacing confers a survival benefit.
Abstract: Biventricular (BV) pacing is under clinical investigation for the treatment of heart failure. Its impact on mortality is unknown. Patients with heart failure and ventricular tachyarrhythmias received an implantable cardioverter defibrillator with BV pacing capability. Patients were randomized 1:1 to BV pacing or no pacing, then crossed over to the alternate mode after 3 months. All-cause mortality was measured in each arm up to the point of crossover. Fifteen of 222 patients died between implant and crossover. Five patients died while programmed to BV pacing and 19 died while programmed to no pacing. Survival in the BV pacing arm was 93 +/- 4% versus 86 +/- 6% in the no pacing arm (P = 0.18). In a patient population with symptomatic heart failure and ventricular arrhythmias, BV pacing does not appear to be associated with excess mortality. Larger and longer studies will be needed to determine if BV pacing confers a survival benefit.
TL;DR: Combined oral administration of a β1‐adrenergic agonist, a parasympathetic antagonist, and quinidine has successfully suppressed recurrences of VT or VF for 6 months, and the combination may have the potential to decrease the incidence of VT and VF as an adjunctive therapy with prophylactic placement of an implantable cardioverter defibrillator.
Abstract: We report a 6-month-old Japanese infant with a malignant form of Brugada syndrome, who had frequent episodes of ventricular fibrillation (VF) and nonsustained polymorphic ventricular tachycardia (VT). To the best of our knowledge, this infant is the youngest patient reported to have Brugada syndrome. Continuous infusion of a beta-adrenergic agonist and intravenous injection of a parasympathetic antagonist suppressed the electrical storm of polymorphic VT and VF. Combined oral administration of a beta1-adrenergic agonist, a parasympathetic antagonist, and quinidine has successfully suppressed recurrences of VT or VF for 6 months, and the combination may have the potential to decrease the incidence of VT or VF as an adjunctive therapy with prophylactic placement of an implantable cardioverter defibrillator.
TL;DR: It is concluded that the new EASYTRAK lead design for transvenous left ventricular lead implantation seems to be a suitable and safe tool for delivering resynchronization therapy to heart failure patients.
Abstract: Several independent studies suggest that resynchronization therapy--achieved by left- or biventricular pacing--improves hemodynamics in heart failure patients with interventricular conduction disturbances. Delivery of this new therapy in an effective and minimally invasive manner presents technical challenges, as transvenous access to the left ventricle is required. Since 1999, a novel over-the-wire approach combining standard pacing lead and angioplasty technology has been evaluated in several European countries. This new left ventricular lead, the EASYTRAK system (Guidant, St. Paul, MN), has been clinically evaluated in 2 phases. The first phase was a clinical investigation to obtain the CE-mark (i.e. European Commission approval). The second phase, which started immediately after the CE-mark was obtained, consisted of a postmarket surveillance called the European registry. This article reports on the results of the pre-CE-mark clinical investigation and the preliminary results of the European registry (first 150 patients). During the pre-CE-mark clinical investigation of the EASYTRAK system, lead performance was assessed in 36 successfully implanted patients. The patients had indications for VVI-pacing, symptoms of heart failure and significant left ventricular dysfunction. The left ventricular lead was implanted in conjunction with a conventional right ventricular lead and a new heart failure device (CONTAK TR, Guidant, Brussels, Belgium). Lead measurements (threshold, sensing, and impedance) were performed at implant and subsequent follow-ups. The stimulation thresholds at 0.5 msec impulse width were acceptable, although (as expected) slightly higher than with standard right ventricular pacing leads: 1.39 +/- 1.15 V at implant, 1.72 +/- 1.26 V at predischarge, 1.54 +/- 0.88 V at 2 weeks, 1.38 +/- 0.80 V at 6 weeks, and 1.24 +/- 0.73 V at 12 weeks. R-wave and impedance measurements were stable over time. A revision of the EASYTRAK lead was required in 3 patients. No perforations were observed. During the second phase of the European registry, 150 implants were attempted in 63 centers from November 1999 to January 2000. The EASYTRAK was implanted with a pulse generator offering, in addition to resynchronization therapy, either tachycardia monitoring (CONTAK TR) or implantable cardioverter defibrillator therapy (CONTAK CD), depending on the patient indication. Over half of the centers involved had not previously implanted the EASYTRAK system. Total implant success rate was 83% (135/150), skin-to-skin duration of the implant was 169 +/- 81 minutes (range, 53-480 minutes), with a clear learning curve. Once the coronary sinus was found, the implant success rate was 92%. One lead dislodgment and 2 cases of phrenic nerve stimulation were reported. We conclude that the new EASYTRAK lead design for transvenous left ventricular lead implantation seems to be a suitable and safe tool for delivering resynchronization therapy to heart failure patients.
TL;DR: Both abnormal autonomic modulation and dynamic patterns of HRV seem to characterize the minutes before arrhythmia onset in patients with implantable cardioverter defibrillators, as well as under control conditions.
Abstract: Time- and frequency-domain analysis of heart rate variability (HRV) has been proven effective in describing alteration of autonomic control mechanisms and in identifying patients with increased cardiac and arrhythmic mortality. Patients with implantable cardioverter defibrillators offer the opportunity to evaluate HRV patterns before ventricular tachycardia (VT) and under control conditions. We therefore analyzed time- and frequency-domain parameters of short-term HRV and power-law behavior of RR interval time series at rest, at 15 to 30 minutes, and immediately before VT. In comparison to control conditions, lower values of mean cycle length duration and total power were observed before VT. Spectral analysis indicated that the low- to high-frequency ratio was significantly higher (5.5 ± 0.6 vs 2.8 ± 0.3) immediately before VT than during rest. Both findings were consistent with the shift of sympathovagal balance toward sympathetic predominance and reduced vagal tone. Before VT, a more negative value of the scaling exponent β of the power-frequency relation (−1.57 ± 0.04 vs −1.33 ± 0.04) also confirmed the presence of an altered HRV pattern in comparison to controls. Thus, both abnormal autonomic modulation and dynamic patterns of HRV seem to characterize the minutes before arrhythmia onset in these patients.
TL;DR: In patients with nonischemic cardiomyopathy and syncope, therapy with an ICD is associated with a reduction in sudden death and an improvement in overall survival.
Abstract: The purpose of this study was to assess whether in patients with syncope and heart failure due to nonischemic cardiomyopathy, treatment with an implantable cardioverter-defibrillator (ICD) compared with conventional medical therapy is associated with a reduction in sudden death and total mortality. Patients with advanced heart failure who have syncope have been shown to be at high risk for sudden death. Further risk stratification has been difficult in patients with nonischemic cardiomyopathy in whom inducibility on electrophysiologic study is not predictive of future risk. Of 639 consecutive patients with nonischemic cardiomyopathy referred for heart transplantation, 147 patients with history of syncope and no prior history of sustained ventricular tachycardia or cardiac arrest were identified. Outcomes were compared for the 25 patients managed with an ICD and 122 patients managed with conventional medical therapy. There were no differences in the baseline variables in the 2 groups of patients, including age, ejection fraction, and medical treatments for heart failure, but patients receiving an ICD were more likely to have had nonsustained ventricular tachycardia (56% vs 15%, p = 0.001). During a mean follow-up of 22 months, there were 31 deaths, 18 sudden, in patients treated with conventional therapy, whereas there were 2 deaths, none sudden, in patients treated with an ICD. An appropriate shock occurred in 40% of the ICD patients. Actuarial survival at 2 years was 84.9% with ICD therapy and 66.9% with conventional therapy (p = 0.04). Thus, in patients with nonischemic cardiomyopathy and syncope, therapy with an ICD is associated with a reduction in sudden death and an improvement in overall survival.
TL;DR: The Defibrillators in Nonischemic Cardiomyopathy Treatment Evaluation (DEFINITE) is a multicenter randomized trial designed to last an estimated 4 years and is expected to reduce mor‐tality by 50%.
Abstract: The Defibrillators in Nonischemic Cardiomyopathy Treatment Evaluation (DEFINITE) is a multicenter randomized trial. Patients will have nonischemic cardiomyopathy (LVEF 10 PVCs/hour or nonsustained ventricular tachycardia defined as 3-15 beats at a rate of > 120 beats/min) on Holter monitor or telemetry within the past 6 months. Patients will be randomized to an implantable cardioverter defibrillator (ICD) versus no ICD. All patients will receive standard oral medical therapy for heart failure including angiotensin converting enzyme inhibitors and beta-blockers (if tolerated). Patients will be followed for 2-3 years. The primary endpoint will be total mortality. Quality-of-life and pharmacoeconomics analyses will also be performed. A registry will track patients who meet basic inclusion criteria but are not randomized. We estimate an annual total mortality of 15% at 2 years in the treatment arm that does not receive an ICD. The ICD is expected to reduce mortality by 50%. Approximately 204 patients will be required in each treatment group. Twenty-five centers will be included in a trial designed to last an estimated 4 years.
Patent•
05 Jun 2000TL;DR: In this paper, an implantable cardioverter defibrillator (ICD) system includes an internal electrode placed in the right ventricle of the heart, and a quasi-Faraday cage (which includes a single or multiple electrodes) placed over a significant portion of heart.
Abstract: An implantable cardioverter defibrillator (ICD) system includes an internal electrode placed in the right ventricle of the heart, and a quasi-Faraday cage (which includes a single or multiple electrodes) placed over a significant portion of the heart. Defibrillation shocks are applied between the internal electrode in the ventricle and the electrode(s) of the quasi-Faraday cage. Because the quasi-Faraday cage surrounds a significant portion of the heart, it functions as a quasi-Faraday cage and is capable of confining a significant portion of the defibrillation shock field to the heart itself so as to reduce pain. Application of shocks is thus less painful to the patient.
TL;DR: In the 20 years since Michel Mirowski and coworkers implanted an ICD into their first patient, the implantable cardioverter defibrillator (ICD) has become recognized as the therapy of first choice for managing patients at high risk of sudden cardiac death from ventricular tachyarrhythmias.
Abstract: In the 20 years since Michel Mirowski and coworkers implanted an ICD into their first patient, the implantable cardioverter defibrillator (ICD) has become recognized as the therapy of first choice for managing patients at high risk of sudden cardiac death from ventricular tachyarrhythmias. Multiple clinical series and recently completed prospective, randomized trials have shown that ICDs are irrefutably superior to antiarrhythmic drugs in reducing
TL;DR: The purpose of this study was to analyze the pattern of initiation of sustained ventricular arrhythmias in patients with varying types of underlying structural heart disease.
Abstract: Initiation of Sustained Ventricular Arrhythmias. Introduction: The purpose of this study was to analyze the pattern of initiation of sustained ventricular arrhythmias in patients with varying types of underlying structural heart disease.
Methods and Results: The study group consisted of 90 patients with an implantable cardioverter defibrillator. Cardiovascular diagnoses included coronary artery disease in 64 patients (71%). The patients were divided into four groups based on the type and severity of structural heart disease. Two hundred sixty episodes of sustained ventricular arrhythmias were analyzed. The mean coupling interval of the initiating heat of all ventricular arrhythmias was 523 ± 171 msec. The coupling interval of the initiating beat was longer in patients with impaired ventricular function, particularly those with nonischemic dilated cardiomyopathy. The prematurity index was similar regardless of the type of underlying structural heart disease. However, the prematurity index was shorter in patients with polymorphic ventricular tachycardia (VT) compared to those with monomorphic VT. A pause was observed more commonly before the onset of polymorphic VT/ventricular fibrillation than sustained monomorphic VT. Two hundred twenty-two (85%) of the arrhythmia episodes were initiated by a late-coupled premature beat, 33 (13%) were initiated by an early-coupled premature beat, and 5 episodes (2%) were initiated with a short-long-short sequence. The patttern of initiation of the ventricular arrhythmias was similar in all patient groups and for both monomorphic and polymorphic tachycardias.
Conclusion: These findings demonstrate that sustained ventricular arrhythmias typically are initiated by late-coupled ventricular premature depolarizations, regardless of the type or severity of underlying structural heart disease or resultant arrhythmia.
TL;DR: There is growing evidence that patients with sustained VT or a history of resuscitation have the best outcome with ICD therapy regardless of the degree of heart failure, and the implantable cardioverter defibrillator has evolved as a promising therapy for life‐threatening arrhythmias.
Abstract: Arrhythmias in Heart Failure. About one half of deaths in patients with heart failure are sudden, mostly due to ventricular tachycardia (VT) degenerating to ventricular fibrillation or immediate ventricular fibrillation. In severe heart failure, sudden cardiac death also may occur due to bradyarrhythmias. Other dysrhythmias complicating heart failure include atrial and ventricular extrasystoles, atrial fibrillation (AF), and sustained and nonsustained ventricular tachyarrhythmias. The exact mechanism of the increased vulnerability to arrhythmias is not known. Depending on the etiology of heart failure, different preconditions, including ischemia or structural alterations such as fibrosis or myocardial scarring, may he prominent. Reentrant mechanisms around scar tissue, afterdepolarizations, and triggered activity due to changes in calcium metabolism significantly contribute to arrhythmogenesis. Furthermore, alterations in potassium currents leading to action potential prolongation and an increase in dispersion of repolarization play a significant role. Treatment of arrhythmias is necessary either because patients are symptomatic or to reduce the risk for sudden cardiac death. The individual history, left ventricular function, electrophysiologic testing, and the signal-averaged ECG give useful information for identifying patients at risk for sudden cardiac death. The implantable cardioverter defibrillator (ICD) has evolved as a promising therapy for life-threatening arrhythmias. A potential role may exist for antiarrhythmic drugs, mainly amiodarone. There is growing evidence that patients with sustained VT or a history of resuscitation have the best outcome with ICD therapy regardless of the degree of heart failure. Many of these patients require additional antiarrhythmic therapy because of AF or nonsustained VTs that may activate the device. Catheter ablation or map-guided endocardial resection are additional options in selected patients but seldom represent the only therapeutic strategy.
Patent•
11 Apr 2000
TL;DR: An arrhythmia detection system provides automatic detection criteriaadjustment in an implantable cardioverter-defibrillator (30) that applies the terminating electrical energy to a heart responsive to detection of the arrhythmias episode of the heart as discussed by the authors.
Abstract: An arrhythmia detection system provides automatic detection criteria
adjustment in an implantable cardioverter-defibrillator (30) that applies
arrhythmia terminating electrical energy to a heart responsive to detection of the
arrhythmic episode of the heart. A first detector (82) detects arrhythmic
episodes of the heart in accordance with detection criteria. A second detector
(90) confirms the detection of each arrhythmic episode by the first detector (82)
and a detection criteria regulator (100) adjusts the detection criteria of the first
detector responsive to confirmation results provided by the second detector.
TL;DR: This review deals only with pharmacological treatments in chronic heart failure: non-pharmacological measures apply to all patients, whereas surgical and device treatments apply only to specific patient subsets.
Abstract: Heart failure represents a complex clinical syndrome characterised by abnormalities of left ventricular function and neurohormonal regulation, exercise intolerance, shortness of breath, fluid retention, and reduced longevity.1 Despite improvements in treatment the prognosis for patients with heart failure remains poor: the risk of death annually is 5%-10% in patients with mild symptoms and 30%-40% in those with advanced disease.2 3 This condition is also associated with major morbidity and healthcare expenditure, being responsible for about 5% of hospital admissions in the United Kingdom.4
### Box 1: Treatment of heart failure
#### Aims
#### Treatment modalities
Mitral valve surgery
Coronary revascularisation
Surgical ventricular remodelling procedures
Cardiomyoplasty
Dual chamber pacing
Implantable cardioverter defibrillator treatment
Ventricular assist devices
Artificial heart
Heart transplantation
This review deals only with pharmacological treatments in chronic heart failure. Non-pharmacological measures apply to all patients, whereas surgical and device treatments (many still experimental) apply only to specific patient subsets. Patients with clinical symptoms of heart failure but normal or near normal left ventricular systolic function often have impaired left ventricular diastolic function. This heterogeneous group has been generally excluded from heart failure trials. We do not discuss the treatment of diastolic left ventricular dysfunction or acute heart failure syndromes: more comprehensive reviews are available.5
### Summary points
The prognosis for patients with heart failure remains poor
Drugs clearly shown to improve survival in patients with heart failure are ACE inhibitors and βblockers
These drugs should be used in most patients with heart failure but require …
TL;DR: Among patients with cardiomyopathies of different etiologies, those with Chagas' heart disease had the lowest cumulative probability of nonoccurrence of life‐threatening VA, confirming its unfavorable prognosis and the importance of preventive measures against sudden death in this disease.
Abstract: The implantable cardioverter defibrillator (ICD) is highly effective in the treatment of ventricular arrhythmias (VA) responsible for sudden cardiac death. However, the probability of occurrence of these arrhythmic events in presence of cardiomyopathy remains uncertain. The aim of this study was to compare the probability of nonoccurrence of life-threatening VA in ICD recipients with Chagas' versus non-Chagas' heart disease. Over a mean follow-up of 10.5 months, 53 ICD recipients (mean age = 50.1 years, 48 male) were evaluated. Eleven patients had Chagas' heart disease, 19 had idiopathic dilated cardiomyopathy and 23 had ischemic cardiomyopathy. Ventricular tachyarrhythmias with a cycle length < 315 ms were considered life-threatening. The cumulative probability of nonoccurrence of life-threatening VA was examined by Kaplan-Meyer method and the outcomes were submitted to the log rank test. At 2 years, the cumulative probability of life-threatening VA nonoccurrence was 0 in the Chagas' heart disease group versus 40% up to 55 months of follow-up in the non-Chagas' disease group (P = 0.0097). Among patients with cardiomyopathies of different etiologies, those with Chagas' heart disease had the lowest cumulative probability of nonoccurrence of life-threatening VA, confirming its unfavorable prognosis and the importance of preventive measures against sudden death in this disease.
TL;DR: How patients living with an ICD-device in south-western Sweden conceive their life situation is described to illuminate the beneficial as well as intrusive effects of such a device, and emphasize the need for support groups for patients and families aswell as further education for personnel in hospital and primary health care.
Abstract: Patients with implantable cardioverter-defibrillator and their conceptions of the life situation : a qualitative analysis
TL;DR: In a patient with severe congestive heart failure and ischemic disease, frequent episodes of ventricular tachycardia were completely suppressed by an implantable cardioverter defibrillator with biventricular pacing.
Abstract: GARRIGUE, S., et al.: Treatment of Drug Refractory Ventricular Tachycardia by Biventricular Pacing. In a patient with severe congestive heart failure and ischemic disease, frequent episodes of ventricular tachycardia were completely suppressed by an implantable cardioverter defibrillator with biventricular pacing
TL;DR: In this paper, the authors showed the survival benefit of an implantable cardioverter defibrillator (ICD) in patients with previous myocardial infarction, left ventricular ejection fraction < or = 0.40, and nonsustained ventricular tachycardia (VT), and who have had sustained VT induced at electrophysiology study.
Abstract: MUSTT and MADIT have clearly shown the survival benefit of an implantable cardioverter defibrillator (ICD) in patients with previous myocardial infarction, left ventricular ejection fraction < or = 0.40, and nonsustained ventricular tachycardia (VT), and who have had sustained VT induced at electrophysiology study. Progress in primary prevention of sudden cardiac death (SCD) depends on a concerted effort by clinicians to identify and appropriately treat MUSTT/MADIT-type patients; further research to more precisely define patient subgroups at risk for SCD and the willingness of industry to develop a lower priced ICD for prophylactic use are needed.
TL;DR: A case of failure to detect an episode of indueed ventricular tachycardia by a dual cbamber ICD, due to abbreviation of ventricular detection window secondary to programmed pacing parameters and a rate‐smoothing algorithm is reported.
Abstract: Intradevice Interaction in Dual Chamber ICD. Failure to detect ventricular tachycardia and/or ventricular fibrillation by implantable cardioverter defibrillators (ICDs) is a rare but serious problem. We report a case of failure to detect an episode of indueed ventricular tachycardia by a dual cbamber ICD, due to abbreviation of ventricular detection window secondary to programmed pacing parameters and a rate-smoothing algorithm. In this patient, the intradevice interaction was corrected by programming rate-smoothing off. This report highlights the potentially lethal consequences of critical timing relationships among the pacing function, arrhythmia detection, and the characteristics of the arrhythmia when using a modern dual chamber ICD. Physicians responsible for patients with ICDs must be aware of such interactions.
TL;DR: Dual Chamber Arrhythmia Detection hy ICD extended ICD therapy to more than termination of hemodynamicaly unstable ventricular tachyarrhythmias and created the basis for dual chamber arrhythmoa management.
Abstract: INTRODUCTION Dual chamber implantable cardioverter defibrillator (ICD) technology extended ICD therapy to more than termination of hemodynamically unstable ventricular tachyarrhythmias. It created the basis for dual chamber arrhythmia management in which dependable detection is important for treatment and prevention of both ventricular and atrial arrhythmias. METHODS AND RESULTS Dual chamber detection algorithms were investigated in two Medtronic dual chamber ICDs: the 7250 Jewel AF (33 patients) and the 7271 Gem DR (31 patients). Both ICDs use the same PR Logic algorithm to interpret tachycardia as ventricular tachycardia (VT), supraventricular tachycardia (SVT), or dual (VT+ SVT). The accuracy of dual chamber detection was studied in 310 of 1,367 spontaneously occurring tachycardias in which rate criterion only was not sufficient for arrhythmia diagnosis. In 78 episodes there was a double tachycardia, in 223 episodes SVT was detected in the VT or ventricular fibrillation zone, and in 9 episodes arrhythmia was detected outside the boundaries of the PR Logic functioning. In 100% of double tachycardias the VT was correctly diagnosed and received priority treatment. SVT was seen in 59 (19%) episodes diagnosed as VT. The causes of inappropriate detection were (1) algorithm failure (inability to fulfill the PR
TL;DR: A patient with Parkinson's disease treated with two pectorally implanted neurostimulators (NSs) who presented with a life‐threatening ventricular tachyarrhythmia in whom an abdominal ICD was implanted showed that the NS did not affect the bipolar sensing of the ICD.
Abstract: We report a patient with Parkinson's disease treated with two pectorally implanted neurostimulators (NSs) who presented with a life-threatening ventricular tachyarrhythmia in whom an abdominal ICD was implanted. Testing during implantation showed that the NS did not affect the bipolar sensing of the ICD, even when the NSs were set at a frequency of 130 pulses/s with an output of 5 V and pulse width of 0.21 ms in a bipolar and a unipolar configuration. The ICD shock, however, did affect both NSs: there was a reset to the output Off state and there was a reset of the electrode polarities.