Use of signal averaging to identify low level late potentials in hearts prone to developing tachyarrhythmias.

Our studies have shown that infarcted dogs which exhibit inducible sustained ventricular tachycardia had late potentials and could be distinguished from those with no arrhythmias by the following QRS characteristics. A QRS duration greater than 63 msec and a duration of late activity below 30 microvolts greater than 18 msec. In addition, delayed and fractionated epicardial activation in the infarcted region correlates with late potentials on the body surface. Finally, induced ventricular fibrillation in this animal model appears to have mixed causes and is a non-specific end point.