Electrophysiologic substrate for ventricular tachycardia: Correlation of properties in vivo and in vitro

Abstract

Cardiac electrophysiologic studies were performed in 3 control dogs and in 9 dogs with previous (8 to 22 days) anterior myocardial infarction. During programmed stimulation, no control dog had inducible ventricular fibrillation (VF) or tachycardia (VT); 3 dogs with infarcts had inducible VF and 6 had inducible VT. Recordings in vivo were made via a plaque electrode containing 10 bipolar electrodes (3.0 x 1.5 cm) placed on the epicardial surface of the anteroapical left ventricle. Subsequently, epicardial strips (2 mm thick) from beneath the plaque were prepared for studies in vitro. Electrogram durations were significantly greater in dogs with infarcts than in control dogs both in vivo (p < .05) and in vitro (p < .001). Electrogram amplitudes were significantly lower in dogs with VT in vivo (p < .05) and in vitro (p