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PubMed1997

Simultaneous use of an implanted defibrillator and ventricular assist device.

A left ventricular assist device was placed as a bridge to cardiac transplantation in a 51-year-old man with cardiogenic shock. Placement of the left ventricular assist device occurred 5 years after implantation of an implantable cardioverter/defibrillator. The implantable cardioverter/defibrillator discharged appropriately during ventricular assist device support to terminate episodes of sustained ventricular tachycardia without causing malfunction of the ventricular assist device.

Defibrillators, Implantable↗
PubMed2001

Lead configuration for defibrillator implantation in a patient with congenital heart disease and a mechanical prosthetic tricuspid valve.

The authors devised a nonthoracotomy defibrillation system for a patient with a prosthetic tricuspid valve using existing technology and previously established implantation techniques. Their lead configuration deviates substantially from existing designs in its primary use of a coronary sinus defibrillation coil and a left-sided subcutaneous array to distribute current across the ventricular myocardium.

Adult↗
PubMed2003

Implantable defibrillator therapy.

Sudden cardiac death (SCD) is the most important cause of death in the industrialised world. Treatment with antiarrhythmic drugs (AAD), however, proved disappointing in preventing SCD. From drugs with electrophysiological properties, only treatment with beta-blockers has been shown to improve clinical outcome. This lack of efficiency of AADs heralded a new era of secondary and primary prevention trials, comparing implantable cardioverterdefibrillator (ICD) with drug therapy. Three large randomised secondary prevention trials were conducted in patients with prior myocardial infarction who where resuscitated from VT or VF. Meta-analysis of these three studies show consistent ICD benefit. This ICD benefit is also observed in three large randomised primary prevention trials in patients with a prior myocardial infarction and left ventricular dysfunction. The beneficial effect of ICD therapy proves to be significantly more pronounced in patients with the lowest left ventricular ejection fraction (26-30%). In patients with nonischaemic dilated cardiomyopathy and low ejection fractions, however, currently the only evidence-based indication for ICD implantation is secondary prevention.

Anti-Arrhythmia Agents↗
PubMed2000

Debate: Do all patients with heart failure require automatic implantable defibrillators for the prevention of sudden death?

Recent clinical trials indicate that approximately two-thirds of patients in New York Heart Association (NYHA) class II and III, who comprise almost 90% of patients with heart failure, die suddenly. Patients in NYHA class IV usually die of progressive heart failure. Implantation of implantable cardioverters defibrillators (ICDs) in this population would represent a huge logistic problem and economic expense. Clinical trials have recently demonstrated that beta-blocker therapy with carvedilol, bisoprolol, and toprol XL decrease the sudden death rate by almost 50%, in addition to impacting significantly on death due to worsening heart failure. This medical approach is beneficial to all patients, and should be our major therapy. However, it is reasonable to attempt to identify that subpopulations of heart failure patients who could benefit from an ICD.

Journal Article↗
PubMed1988

Lithium/silver vanadium oxide batteries for implantable defibrillators.

Lithium/silver vanadium oxide (SVO) batteries have been under development in these laboratories since 1980. The system consists of a lithium anode, a liquid organic electrolyte, a cathode composed of conductive additives, a binder, and silver vanadium oxide, a vanadium oxide bronze produced by the thermal decomposition of vanadium oxide and silver nitrate. High rate batteries for implantable cardiac defibrillators based on this chemistry have been under development since 1984. The first Li/SVO defibrillator battery introduced was the Model 8512 with a theoretical capacity of 5.5 Ah and dimensions of 52 mm X 33 mm X 13.5 mm. Later, the Model 8615 was introduced. This cell has a theoretical capacity of 3.0 Ah and dimensions of 52 mm X 21 mm X 13.5 mm. Two other cells which are proprietary have also been introduced. All of the cells can deliver pulses of up to 2.0 amps from a microampere background. The self-discharge of the cells has been shown to be less than 2% per year. In addition, the silver vanadium oxide chemistry provides a discharge curve whose voltage decreases with depth of discharge. This feature can be used as a state-of-charge indicator. The cells have been subjected to rigorous environmental and abuse testing and have been found to have characteristics suitable for implantable applications.

Electric Countershock↗
PubMed2002

Implantable defibrillator use for de novo ventricular tachyarrhythmias encountered after cardiac surgery.

De novo postoperative life-threatening ventricular arrhythmias are poorly understood. Long-term benefits of, and need for, treatment is uncertain. To assess the therapeutic advantage of ICD to manage new-onset, life-threatening ventricular tachyarrhythmias after cardiac surgery. Patients included were those with an ICD implanted for de novo life-threatening ventricular tachyarrhythmias encountered 48 hours or more after cardiac surgery. Primary endpoints were total survival, time to first ICD therapy, and appropriateness of ICD therapy. Mean projected survival and projected time to first ICD therapy were calculated by the Kaplan-Meier method. Twenty-seven postoperative patients (left ventricular ejection fraction 0.22 +/- 0.07) were followed for 26 +/- 17.6 months. The index arrhythmia was sustained monomorphic ventricular tachycardia in 17 (63%) and ventricular fibrillation in 10 (37%). Electrophysiological study was positive in 22 (81%) of 27. Total survival and mean projected survival after ICD implant were 22 (81%) of 27 and 25.6 months, respectively, to end of follow-up. The majority received ICD therapy (21/27 [78%]), 20 (74%) of 27 receiving appropriate therapy. The mean time to first ICD therapy and mean projected time to first ICD therapy was 5.6 +/- 7.8 months and 10.5 months, respectively. De novo postoperative ventricular arrhythmias are associated with a high probability of late recurrence. The ICD is useful for these patients.

Adult↗
PubMed1996

Comparison of three cardioverter defibrillator implantation techniques: initial results with transvenous pectoral implantation.

A total of 121 patients underwent epicardial (n = 32), transvenous abdominal (n = 30), and transvenous pectoral (n = 59) ICD implants. Perioperative complications were defined as those occurring within 30 days after surgery. Hospital costs were calculated with $750 per day as a fixed charge. Duration of surgery was the time between the first skin incision and the last skin suture. Severe perioperative complications that were life-threatening or required surgical intervention occurred in the epicardial (6%) and transvenous (10%) abdominal groups, but not in the pectoral group. Perioperative mortality occurred only in the epicardial abdominal group, predominantly in patients with concomitant surgery (18%), and in 5% of patients without concomitant surgery. The duration of surgery was significantly shorter for transvenous pectoral implantation (58 +/- 15 min, P < 0.05) compared to transvenous abdominal implantation (115 +/- 38 min). Epicardial abdominal ICD implantation had the longest procedure time (154 +/- 31 min). The postimplant hospital length of stay was significantly shorter for pectoral implantation (5 +/- 3 days, P < 0.05) compared to transvenous (13 +/- 5) and epicardial (19 +/- 5) abdominal implantation. Total hospitalization costs significantly decreased in the pectoral implantation group ($4,068 +/- $2,099 for the pectoral group vs $14,887 +/- $4,415 and $9,975 +/- $3,657 for the epicardial and the transvenous abdominal group, respectively, P < 0.05). These initial results demonstrate the advantage of transvenous pectoral ICD implantation in terms of perioperative complications, procedure time, hospital length of stay, and hospitalization costs.

Abdominal Muscles↗
PubMed2003

Are electrophysiological studies needed prior to defibrillator implantation?

At present, patients with documented sustained VT or resuscitated cardiac arrest (CA) are treated with ICDs. The aim of this study was to retrospectively evaluate if a routine electrophysiological study should be recommended prior to ICD implantation. In 462 patients referred for ICD implantation because of supposedly documented VT (n = 223) or CA (n = 239), electrophysiological study was routinely performed. In 48% of the patients with CA, sustained VT or VF was inducible. Electrophysiological study suggested conduction abnormalities (n = 11) or supraventricular tachyarrhythmias (n = 3) in conjunction with severely impaired left ventricular function to have been the most likely cause of CA in 14 (5.9%) of 239 patients. Likewise, sustained VT was only inducible in 48% of patients with supposedly documented VT. Of these inducible VTs, nine were diagnosed as right ventricular outflow tract tachycardia or as bundle branch reentry tachycardia. Supraventricular tachyarrhythmias judged to represent the clinical event were the only inducible arrhythmia in 35 (16%) patients (AV nodal reentrant tachycardia [n = 7], AV reentry tachycardia [n = 4], atrial flutter [n = 19], and atrial tachycardia [n = 5]). Based on findings from the electrophysiological study, ICD implantation was withheld in 14 (5.9%) of 239 patients with CA and in 44 (19.7%) of 223 patients with supposedly documented VT. During electrophysiological study, VT or VF was only reproducible in about 50% of patients with supposedly documented VT or CA. Electrophysiological study revealed other, potentially curable causes for CA or supposedly documented VT in 12.6% (58/462) of all patients, indicating that ICD implantation can potentially be avoided or at least postponed in some of these patients. Based on these retrospective data, routine electrophysiological study prior to ICD implantation seems to be advisable.

Chi-Square Distribution↗
PubMed2006

The high cost of implantable defibrillators.

Increased use of ICDs in patients with cardiac disease has the potential to strain national health care budgets because of the large numbers of eligible patients and the high cost of the ICDs. Randomized trials show ICDs increase life-expectancy in some groups of patients and also increase total medical costs significantly. ICDs exemplify the role of new technology as the main force behind rising health care costs. ICDs have not been used in all eligible patients, in part because of cost, but also because of patient resistance and a shortage of specialists able to implant and manage complex ICDs. The cost-effectiveness of ICDs would be improved by development of simpler and cheaper devices, and by better tools to identify patients who benefit from an ICD.

Arrhythmias, Cardiac↗
PubMed2002

[Implantable defibrillators and prevention of sudden death: clinical and economic implications in the light of the MADIT II study].

The cardioverter-defibrillator is the most effective strategy to prevent sudden death in patients with previous episodes of ventricular tachyarrhythmia (secondary prevention of sudden death). In recent years the possibility of primary prevention of sudden death in selected groups of high risk patients has raised great interest. The MADIT II study highlighted the possibility of preventing sudden death in patients with coronary artery disease. According to this trial, identification of such patients can be performed by means of few clinical data and without expensive screenings (i.e. electrophysiological study). Indeed, patients with a previous myocardial infarction and low left ventricular ejection fraction (< 30%) may benefit from the implant of a cardioverter-defibrillator, with a reduction of the mortality risk by about 31% in the following two years. In the light of these data, implant of a cardioverter-defibrillator should be proposed in such patients, even if the problem of limited economic resources to meet the cost of the devices has to be considered even in the richest country of the world. Despite the positive scientific result, MADIT II has raised the problem of the effective possibility of adopting this therapeutic strategy in clinical practice and this question is still open. Strategies to reduce the theoretically high costs implicated by the MADIT II study include a reduction in the cost of defibrillators through dynamic market forces, the identification of subgroups at higher risk of sudden death, and the use of cheap defibrillators with limited diagnostic and therapeutic options. A long-term evaluation of the cost-effectiveness for western countries of these strategies is necessary to identify in which patient subgroups implant of a cardioverter-defibrillator is acceptable, i.e. cost-effective, in terms of primary prevention.

Clinical Trials as Topic↗