Comparison of verapamil and practolol in paroxysmal supraventricular tachycardia.

40 patients with paroxysmal supraventricular tachycardia were allocated to two different treatment groups according to their year of birth. Those patients born on odd years were given 5 mg of practolol intravenously, those born on even years receiving 5 mg of verapamil, and if the tachycardia continued, the same injection was repeated after 5 minutes. If practolol treatment failed, the patient was given 5 mg of verapamil half an hour later, and vice versa. Verapamil restored sinus rhythm in 19 patients out of 20. Practolol proved effective in 8 out of 20. In patients who were switched over to the other treatment verapamil was effective in 9 out of 11 and practolol in 1 patient. Side effects were few. Marked hypotension occurred in 2 patients, in 1 patient after 5 mg of verapamil, and after 5 mg of practolol in the other. It is concluded that verapamil is a very effective agent in the treatment of paroxysmal supraventricular tachycardia. Selection of patients is emphasized to increase the safety of its use.