Terminating SVT-mediated recurrent ventricular fibrillation with verapamil.

Verapamil has been established as the drug of choice in the treatment of supraventricular dysrhythmias and is recognized as useful in the treatment of ischemic heart disease and hypertension. However, verapamil has not generally been considered helpful in the treatment of ventricular dysrhythmias. Five cases are reported in which verapamil was used to terminate a cycle of supraventricular tachycardia-mediated recurrent ventricular fibrillation that could not be suppressed by conventional antidysrhythmics such as lidocaine, procainamide, and bretylium, Proposed mechanisms of verapamil's beneficial effect in this usually fatal situation include (1) a reduction in oxygen consumption related to the reduction in heart rate, thereby raising the ventricular fibrillation threshold; (2) direct anti-ischemic effect; and (3) a direct antidysrhythmic effect. These proposed mechanisms are substantiated by clinical studies. On the basis of this observation, it is recommended that in a situation of supraventricular tachycardia-mediated recurrent ventricular fibrillation that cannot be terminated by conventional antidysrhythmics, the administration of verapamil should be considered.