Electrophysiologic evaluation of intravenous verapamil in man.

The acute electrophysiological effects of intravenous verapamil (0.15 mg/kg body weight) were studied in 21 subjects with estimated normal impulse formation and conduction. Significant effects were sinus cycle shortening, depression of intranodal conduction and prolongation of AV node refractory periods. Sinus node recovery time, sinoatrial conduction time, atrial refractory periods, infranodal conduction, His--Purkinje system, and bundle branch refractory periods were unchanged. The clinical implications of these properties are discussed.