A review of the confirmation algorithm and related timing cycles of St. Jude ICDs.

The confirmation algorithm of implantable cardioverter-defibrillators (ICDs) functioning in the uncommitted mode verifies the presence of a continuing tachyarrhythmia during or following charging of the capacitor. Confirmation is usually applied in relation to the first shock. The details of the normal reconfirmation process of St. Jude ICDs and its role in delayed shock delivery or other abnormalities have received relatively little attention. This review describes the confirmation process of St. Jude ICDs and provides an illustrative clinical example of delayed shock as a result of a pacing or sensing lead fracture. The fundamental timing cycles of St. Jude ICDs are also reviewed to facilitate understanding of the problems related to the confirmation process.