Further Insight into Mechanisms of Ventricular Tachycardia from the Clinical Electrophysiology Laboratory

Sustained, monomorphic ventricular tachycardia (VT) in patients with prior myocardial infarction is usually caused by reentry (Wellens, et al., 1976; Josephson, et al., 1985; de Bakker, et al., 1988; Downar, et al., 1988), and several different lines of evidence from experimental and clinical studies have implicated a zone of slow conduction as being a critical component of the reentrant circuit (El-Sherif, et al., 1983; Gessman, et al., 1983; Gallagher, et al., 1985; Frank, et al., 1987; Stevenson, et al., 1987; Kay, et al., 1988; Morady, et al., 1988). In a study published in this issue of the Joumal of Cardiovascular Electrophysiology, Fitzgerald et al. (1991) present evidence that a single area of slow conduction may participate in the reentrant circuits of two or three different VTs. This elegant study provides new insight into mechanisms of VT and also serves as an excellent example of the value of carefully recording and analyzing intracardiac electrograms in the clinical electrophysiology laboratory.