Showing papers by "Elliott M. Antman published in 1984"

Calcium channel blocking agents in the treatment of cardiovascular disorders

Abstract: Calcium ions play an important role in the cardiovascular system. They are involved in electrophysiologic processes, link excitation to muscular contraction, control energy storage and utilization, and constrict vascular smooth muscle in coronary and systemic arteries. A new group of pharmacologic agents that block the passage of calcium ions across cell membranes has been developed. These agents act during the slow inward current of cellular depolarization. The most extensive clinical experience has been obtained with four of these agents: verapamil, nifedipine, perhexiline, and diltiazem. Verapamil, which has profound electrophysiologic effects on the slow inward current, is emerging as a valuable antiarrhythmic agent. Re-entrant supraventricular arrhythmias, such as paroxysmal supraventricular tachycardia, are particularly amenable to treatment with intravenous verapamil. Preliminary trials of long-term therapy with oral verapamil for control of atrial fibrillation, atrial flutter, and paroxysmal supraventricular tachycardia suggest that this agent is effective for therapy of these arrhythmias.

Efficacy and safety of timolol for prevention of supraventricular tachyarrhythmias after coronary artery bypass surgery.

Abstract: Forty-one patients undergoing coronary artery bypass grafting were randomly assigned to receive prophylactic timolol or placebo, given in a double-blind fashion. beta-Adrenoceptor-blocking therapy was stopped at least one half-life before surgery. Three to 7 hr after surgery (304 +/- 56 min), 0.5 mg of timolol or placebo was given intravenously twice daily in a double-blind manner. When oral medications were resumed postoperatively, 10 mg of timolol twice daily or placebo was continued orally. Continuous electrocardiograms were recorded for 24 hr before and for 7 days after surgery with a standard cassette recorder. No patient received digoxin. Both groups were comparable for frequency of preoperative supraventricular arrhythmias, left ventricular ejection fraction, duration of cardiopulmonary bypass, aortic cross-clamp time, number of bypass grafts, and total duration of monitoring. Analysis of arrhythmias was done by hand counts, and supraventricular arrhythmias were divided into supraventricular tachycardia and atrial fibrillation and/or flutter. Timolol decreased the frequency of supraventricular tachycardia (581 episodes placebo vs 84 timolol; p less than .05) and of atrial fibrillation and/or flutter (291 episodes placebo vs five timolol; p less than .05). Timolol decreased the number of patients with severe (heart rate greater than 200 beats/min, duration greater than 50 beats) episodes of supraventricular tachycardia (four placebo vs 0 timolol; p less than .05) and also decreased the number of episodes of severe (heart rate greater than 200 beats/min, duration greater than 5 min) atrial fibrillation and/or flutter (16 placebo vs one timolol; p less than .005). There were differences in the durations of supraventricular arrhythmias.(ABSTRACT TRUNCATED AT 250 WORDS)