Abstract
The development of drugs which selectively block the "slow" channels by which calcium enters the cell (calcium antagonists) has provided valuable information about the role of transmembrane calcium exchange in man and has offered new therapeutic approaches. The principal effect on the cardiovascular system is relaxation of vascular smooth muscle but some of these drugs also have electrophysiological effects, especially slowing of conduction in the atrioventricular node; verapamil is the agent of choice in supraventricular tachycardia. Significant myocardial depression does not usually occur with doses used clinically. The calcium antagonists have specific value in variant angina. By causing peripheral vasodilatation they are also effective hypotensive agents and do not cause reflex tachycardia in chronic use. Their value in hypertrophic cardiomyopathy and in the protection of ischaemic myocardium remains to be proven.