REENTRANT VENTRICULAR ARRHYTHMIAS IN THE LATE MYOCARDIAL-INFARCTION PERIOD .17. CORRELATION OF ACTIVATION PATTERNS OF SINUS AND REENTRANT VENTRICULAR-TACHYCARDIA

The relationship between myocardial sites with late activation during sinus rhythm and sites critical for the initiation and sustentation of reentrant ventricular tachycardia was systematically examined in the 4-day-old postinfarction canine heart. The critical sites for prevention of the initiation of reentry and for termination of sustained figure-of-8 reentrant tachycardia by cryothermal techniques were correlated with the last 20 msec isochrone during sinus rhythm. In 12 experiments, 20 critical sites were examiend. The mean distance between sites critical for reentry and the latest isochrone during sinus rhythm was 26.7±13.3 mm. Only five sites (25%) were within a 12 mm distance, which corresponded to the diameter of the cryoprobe. Nine sites (45%) were within a 24 mm distance (twice the diameter of the cryoprobe), while 11 sites (55%) were separated by more than 24 mm. In three experiments the sites of latest activation during sinus rhythm represented areas showing Wenckebach period or 2:1 conduction block. These sites became dissociated and did not participate in the reentrant excitation induced by premature stimulation. Poor correlation was explained by the fact that sites critical for reentry were intimately related to the location and extent of the arcs of functional conduction block while sites of delayed activation during sinus rhythm were not. © 1990.