Clinical experience with verapamil.

Verapamil administered by the intravenous route restored sinus rhythm in 33 out of 40 episodes of supraventricular tachycardia. The drug was also effective in reducing ventricular rate in patients with atrial fibrillation. Intracardiac conduction studies using His bundle electrograms showed prolongation of atrioventricular nodal conduction in eight out of nine cases after 5 mg of verapamil were given. The distal conduction was unaffected. Bradycardia and hypotension occurred in two cases and responded promptly to intravenous administration of atropine. Verapamil is an effective antiarrhythmic agent which is, in general, free from significant side effects.