THE MODE OF ONSET OF VENTRICULAR-TACHYCARDIA

Aims The purpose of our study was to investigate the electrical trigge r modes of monomorphic ventricular tachycardia. by analysing stored in tracardiac electrograms, and to identify haemodynamic or electrocardio graphic predictors in patients with cardioverter-defribrillators. Meth ods We recorded 286 episodes of monomorphic ventricular tachycardia in 38 patients with at least three events. The electrical triggers were characterized by the morphology number, complexity, and coupling inter val of premature depolarizations preceding the ventricular tachycardia . We also evaluated clinical and electrocardiographic data. Results We found two basic electrical trigger modes. Two hundred and sixteen eve nts (75%) were observed to have no RR-interval variations before onset . while 70 episodes (25%) had a short-long-short sequence. These episo des invariably featured increased QT disperson. In 31 of 38 patients ( 82%), the ventricular tachycardias were always initiated by the same m ode of onset. In eight patients, the monomorphic ventricular tachycard ias were always triggered by short-long-short sequences. In seven pati ents, more than one onset mechanism was observed. Conclusions Two basi c modes of onset were responsible for monomorphic ventricular tachycar dia: one without RR-interval variations immediately prior to onset and another characterized by short-long-short sequences and increased QT dispersion. The mechanisms were largely patient-specific and not relat ed to cardiac diagnosis or left ventricular function.