Ventricular activation patterns of spontaneous and induced ventricular rhythms in canine one-day-old myocardial infarction. Evidence for focal and reentrant mechanisms.

摘要: We studied isochronal maps of ventricular activation during spontaneous multiform rhythms (rates 120-190/min) and pacing-induced tachyarrhythmias (rate 230-450/min) in dogs 1 day after myocardial infarction. Recordings were obtained from the entire epicardial surface selected endocardial intramural sites utilizing a computerized multiplexing technique. Spontaneous had focal origin surviving subendocardial Purkinje network underlying infarction showed frequent shift pacemaker site. On other hand, fast consistently induced same by bursts rapid pacing or programmed premature stimulation tendency to degenerate into fibrillation. Pacing-induced due reentrant that developed mainly surviving, electrophysiologically abnormal, layer overlying The last stimulated heat initiated reentry resulted continuous arc functional conduction block two slowly circulating fronts around both ends block. rejoined on distal side before breaking through reactivate an area proximal This splitting initial single separate arcs. Reentrant subsequently continued as synchronous circuits which conducted clockwise counterclockwise directions, respectively. Reentry spontaneously terminated when leading edge encountered refractory tissue failed advance. presence was hallmark stable activation. development three more asynchronous pattern "prefibrillatory." seen develop pleomorphic tachycardias torsades de pointes type degenerated Ventricular fibrillation maintained continuously changing multiple circuits. transition probably related nonhomogeneous shortening refractoriness different parts myocardium.