Cardiac defibrillator

Cuvillier E (2009) Handbook of leads for pacing, defibrillation cardiac resynchronization. Eric Cuvillier, Juana Diaz... 

An implantable medical device (IMD) operates inside the body to monitor certain physiological parameters. Based on the power requirements of the device, IMDs are divided into two categories (i) active (the devices that need power) and (ii) passive (those that do not require power). Examples of passive IMDs are artificial joints and vascular grafts, whereas active IMDs may include cardiac defibrillators, cardiac pacemakers, neurostimulators, drug pumps, cochlear implants, and retinal implants. The need to broaden the assortment of effectively active IMDs is constantly increasing. 

Implantable cardioverter-defibrillators are more effective than antiarrhythmic drugs for reduction in the risk of sudden cardiac death due to VT or VF. 

In patients who have experienced VT and are at risk for sudden cardiac death, implantation of an implantable cardioverter-defibrillator (ICD) is the treatment of choice.44 An ICD is a device that provides internal electrical cardioversion of VT or defibril -lation of VF the ICD does not prevent the patient from developing the arrhythmia, but it reduces the risk that the patient will die of sudden cardiac death as a result of the arrhythmia. Whereas in the past ICD implantation required a thoracotomy, these devices now may be implanted transvenously, similarly to pacemakers, markedly reducing the complication rate. 

Unlabeled uses Bretylium is a second-line agent following lidocaine in the protocol for advanced cardiac life support during CPR. For resistant VF and VT (after lidocaine, defibrillation, and procainamide failures), give bretylium 5 to 10 mg/kg IV repeat as needed up to 30 mg/kg use a bolus every 15 to 30 minutes, infusion 1 to 2 mg/min. For life-threatening arrhythmia use an undiluted infusion of 1 g/250 mL. 

Abstract Two thirds of the nearly half a million deaths per year in the United States due to sudden cardiac death (SCD) is attributed to coronary artery disease (CAD) and most commonly results from untreated ventricular tachyarrhythmias. Patients with ischemic cardiomyopathy and left ventricular dysfunction are at highest risk for SCD, but this still defines only a small subset of patients who will suffer SCD. Multiple lines of evidence now support the superiority of implantable cardioverter defibrillator (ICD) therapy over antiarrhythmic therapy for both primary and secondary prevention of SCD in advanced ischemic heart disease. Optimization of ICD therapy in advanced ischemic cardiomyopathy includes preventing right ventricular pacing as well as the use of highly effective anti-tachycardia pacing to reduce the number of shocks. While expensive, ICD therapy has been shown to compare favorably to the accepted standard of hemodialysis in cost effectiveness analyses. 

Implantable Cardioverter Defibrillators for Secondary Prevention of Sudden Cardiac Death... 

Following resuscitation from ventricular fibrillation (VF) or pulseless VT, ICD implantation is a proven strategy for the prevention of recurrent SCD. Three prospective, randomized, controlled trials, the Antiarrhythmics Versus Implantable Defibrillators (AVID) study, the Canadian Implantable Defibrillator Study (CIDS), and the Cardiac Arrest Study Hamburg (CASH), support this strategy [27-29]. 

Bloomfield DM, Steinman RC, Namerow PB, et al. Microvolt T-wave alternans distinguishes between patients likely and patients not likely to benefit from implanted cardiac defibrillator therapy a solution to the multicenter automatic defibrillator implantation trial (MADIT) II conundrum. Circulation. Oct 5 2004 110(14) 1885-1889. 

Kuck KH, Cappato R, Siebels J, et al. Randomized comparison of antiarrhythmic drug therapy with implantable defibrillators in patients resuscitated from cardiac arrest the Cardiac Arrest Study Hamburg (CASH). Circulation. Aug 15 2000 102(7) 748-754. 

However, the long-term effects of cardiac resynchronization therapy (CRT) on morbidity and mortality were not known. Two clinical trials have established the morbidity and mortality effects of CRT. The COMPANION trial was a three armed trial, testing optimal medical therapy (OPT) against OPT plus CRT by a pacemaker or a OPT plus CRT by an implantable cardioverter-defibrillator (CRT-D) [118]. In this study, patients were enrolled prior to... 

Young JB, Abraham WT, Smith AL, et al. Combined cardiac resynchronization and implantable cardioversion defibrillation in advanced chronic heart failure the MIRACLE ICD Trial, [see comment]. JAMA 2003 289 2685-94. 

Bristow MR, Saxon LA, Boehmer J, et al. Cardiac-resynchronization therapy with or without an implantable defibrillator in advanced chronic heart failure, [see comment]. N. Engl. J. Med. 2004 350 2140-50. 

Myoblast therapy raises the possibility of arrhythmogenic effects. Consequently, many clinical studies require the placement of cardiac defibrillators in patients receiving myoblasts. 

Deflbrillation is one of the few interventions that has been shown to improve outcome from cardiac arrest. The cardiac arrhythmias commonly associated with sudden collapse are (1) asystole and (2) rapid and ineffective depolarization due to ventricular flbrillation (VF), pulseless ventricular tachycardia (VT), or supraventricular tachycardia with 1 1 ventricular response (as can occur with pre-excitation syndromes). The best strategy is to treat collapsed patients who have a broad-complex tachycardia at once by external Direct Current (DC) defibrillation. 

As left ventricular dysfunction is a major predictor of sudden arrhythmic death, cardiac death and total mortality, it can be stated that in general sudden cardiac death prevention is achievable with the combination of an implantable cardioverter defibrillator (ICD) and medical therapy. 

Drug therapy and the use of cardioverter defibrillators will not improve the prognosis of patients in this stage. Cardiac transplantation will be the only option. With the patient s informed consent, even inactivation of an ICD can be considered as a possible option in this stage of the disease. The critical issue is fiuid retention control. To achieve this objective, the administration of intravenous positive inotropic agents cannot be weaned off. As a strategy for palliation, vasodilators are sometimes used even though they may worsen mortality. 

The cornerstone of therapy for ventricular fibrillation is electrical deflbrillation. In the acute setting, defibrination is first-line therapy. Intravenous bretylium can occasionally contribute to conversion, but this is infrequent. In the management of out-of-hospital cardiac arrest, high-dose epinephrine (5 mg intravenously) improves the rate of successful resuscitation in patients with asystole, but not in those with ventricular fibrillation, when compared with the standard dose of 1 mg. Vasopressin (40 U intravenously) may more effective than 1 mg intravenous epinephrine in out-of-hospital patients with ventricular fibrillation that is resistant to electrical defibrillation. The OPTIC smdy (see Connolly et al., 2006) showed that amiodarone plus jS-blocker is superior than sotalol or jS-blocker alone for reducing ICD shocks in patients with reduced left ventricular function and history of sustained VT, VF, or cardiac arrest. 

Adrenaline is used in cardiac resuscitation to convert asystole prior to defibrillation. It is also used in acute hypotensive emergencies and low cardiac output states, especially in severe sepsis or following extracorporeal circulation in cardiac surgery. In anaphylactic shock the combination of powerful a (vasoconstriction) and 32 (bronchodilatation) effects may be life-saving (Appendix AAGBI protocol). Adrenaline is also used to relieve bronchoconstriction in bronchial asthma and status asthmaticus. Dose... 

Sotalol is approved for the treatment of life-threatening ventricular arrhythmias and the maintenance of sinus rhythm in patients with atrial fibrillation. It is also approved for treatment of supraventricular and ventricular arrhythmias in the pediatric age group. Sotalol decreases the threshold for cardiac defibrillation. 

Fig. 13 Schematic illustration of the implantation of an automatic cardiac defibrillator. (By permission of World Medicine-. J,H, Tarme, 1981, 16(25), 64.)...

Silver, copper and other oxosalts have been extensively studied as cathodes in laboratory cells commercial power sources, principally for pacemakers, using silver chromate were manufactured until the 1980s, and silver vanadate or silver vanadium oxide (Ag2V4On), first reported by workers at Wilson Greatbatch Ltd, is currently used as cathode in implantable cardiac defibrillator batteries. 

Cells for implantable cardiac defibrillators require a capacity of 1 Ah and the capability of supplying current pulses of 4-5 W for periods of... 

A serious deleterious outcome associated to date primarily with myoblasts (and with thawed BM in chemotherapy patients) (50) is the incidence of cardiac electrical instability for a presumed transient period after cell delivery. These early reports of electrical instability in patients after the receipt of autologous skeletal myoblasts have led to doubts about the safety of these cells as a treatment in the injured heart. Patients who received myoblasts in the earliest clinical studies (33,38) were extremely ill patients with an expected high potential for negative electrical events. In fact, many of the patients who were included in the early trials met the Multicenter Automatic Defibrillator Implantation Trial MADIT-II criteria, which were presented after those trials began, and suggested that all patients who met those criteria be treated with AlCDs. As a result, in more recent clinical studies, many investigators have only enrolled patients who receive AlCDs... 

Abbreviations ICD, internal cardiac defibrillator, MI myocardial infarction SCO, sudden cardiac death. ... 

Takeuchi, E.S. 1995. Reliability systems for implantable cardiac defibrillator batteries. J. Power. Sources. 54 115-119. 

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