Implantable cardioverter defibrillator therapy.

Sudden cardiac death (SCD) is a major healthcare problem worldwide. The majority of SCD events occur in patients with clinically recognized heart disease and most episodes result from ventricular tachyarrhythmias. Implantable cardioverter defibrillator (ICD) therapy prevents SCD in specific patient populations. Significant progress in the design and technology has been made since the Food and Drug Administration first approved the ICD in 1985. First-generation ICDs were large, were implanted in the abdomen, required a thoracotomy for placing epicardial defibrillation patches, and were nonprogrammable. Contemporary ICDs have been substantially downsized, are implanted via a transvenous approach, and are multiprogrammable. Device implantation has been simplified to be similar to that of a permanent pacemaker. In addition to treating life-threatening ventricular arrhythmias, ICDs now treat bradyarrhythmias, atrial arrhythmias, and congestive heart failure. The purpose of this article is to describe the evidence supporting the use of ICD therapy and to explain the current devices used in clinical practice.