Pacemakers, defibrillators, and direct current cardioversion.
Technology for pacemakers and automatic implantable defibrillators continues to evolve.  Emphasis is placed not only on preventing cardiac death, but also on improving symptoms and quality of life.  The basic antibradycardia function of pacemakers is complemented by highly sophisticated rate-responsive capabilities.  The search for the perfect physiologic sensor has not ended; potential limitations of the systems currently available are considered in this review.  Reports on outcome with pacing in different populations are also discussed.  There have been two important advances in automatic implantable defibrillators.  One is the introduction of the third generation defibrillator in clinical investigation.  A tiered therapy (including antitachycardia pacing, cardioversion, and defibrillation) can now be programmed in the same device, with the protection of back-up antibradycardia pacing.  The other remarkable innovation is the expanding use of nonthoracotomy techniques for implantable cardioverter-defibrillator placement.  This approach permits the avoidance of a subcutaneous patch electrode in some cases, the system being entirely transvenous.  Finally, recent insights on external cardioversion for atrial arrhythmias are briefly reviewed.
Sgarbossa
E B
EB
Cleveland Clinic Foundation, Ohio.
Black
I W
IW
Maloney
J D
JD
D000328:Adult; D001145:Arrhythmias, Cardiac / Q000517:prevention & control / Q000628:therapy; D002304:Cardiac Pacing, Artificial; D002648:Child; D017147:Defibrillators, Implantable; D004554:Electric Countershock / Q000009:adverse effects / Q000379:methods*; D004566:Electrodes; D006801:Humans; D010138:Pacemaker, Artificial; D011788:Quality of Life