Intravenous verapamil in the treatment of paroxysmal supraventricular tachycardia in children.

Fifty-four spontaneous episodes of paroxysmal supraventricular tachycardia (PSVT) in 23 patients, varying in age from one day to fourteen years, were treated with intravenous verapamil according to a specific protocol. Stable sinus rhythm was obtained promptly with no side effects in 76% of episodes. There was no response in 9%; an unstable rhythm in 7.5%; and severe side effects (hypotension, sinus bradycardia and cardio-respiratory arrest) in 7.5%. All severe side effects were associated with larger than recommended doses of verapamil. Intravenous verapamil reverted 100% of all episodes of idiopathic PSVT in eight patients; 83% of episodes in five patients with congenital heart disease; and only 57% of episodes in nine patients with Wolff-Parkinson-White syndrome. It was ineffective in one neonate who had had intra-uterine SVT.