Exercise-Triggered Paroxysmal Ventricular Tachycardia

Abstract

Electrophysiologic study, isoproterenol infusion and serial treadmill exercise tests before and after administration of propranolol, verapamil, lidocaine and procainamide were done in 3 patients with exercise-triggered ventricular tachycardia. In all 3 patients, organic heart diseases were absent. Ventricular tachycardia was reproducibly provoked with exercise and with isoproterenol infusion. Propranolol (tested in 3 patients) and lidocaine (tested in 3 patients) effectively prevented excerise provocation of tachycardia. Verapamil terminated tachycardia in all 3 patients and successfully prevented exercise provocation of tachycardia in only 2 patients. Procainamide was ineffective in 1 patient and was partially effective in 2 patients. In the latter 2 patients, ventricular ectopies, couplets and short salvos remained provocable with exercise. Electrical stimulations with incremental ventricular pacing and ventricular extrastimulus testing failed to induce tachycardia in all 3 patients. Evidently repetitive rhythmic activities related to the catecholamine-sensitive afterdepolarizations are probably responsible for exercise-triggered ventricular tachycardia.