Technologic advances in implantable cardioverter defibrillators

Multiple technologic advances in the implantable cardioverter defibrillator (ICD) have resulted in smaller size, easier implantation, and improved det ection, therapy, and stored diagnostic information. Advanced dual-chamber I CDs are currently available that allow dual-chamber rate-responsive pacing with mode switching, enhanced detection algorithms, antitachycardia pacing, low-energy cardioversion, high-energy shocks, and extensive diagnostics. B ased on improvements in lead systems and improved energy waveforms, almost all devices are being implanted with nonthoracotomy leads in the pectoralis area. The results of recent clinical trials have expanded indications for the ICD for primary and secondary prevention of sudden cardiac death. With advances in capacitor and battery technology coupled with improved lead sys tems and waveform resulting in lower defibrillation thresholds, it is likel y that lower-output, smaller devices will be developed. In the future, ICDs may have expanded indications and may incorporate physiologic sensors to a ccess hemodynamic significance of arrhythmias and algorithms for prediction and prevention of cardiac arrhythmias.