Some therapeutic applications of vasodilating agents

Abstract

Dr. Gold: This conference on the therapeutic application of vasodilator agents has been the scene of much spirited discussion between the pharmacologists and the clinicians. It revolved almost exclusively around the use of these agents in peripheral vascular disorders like Raynaud's disease, thromboangiitis obliterans and other forms of vascular conditions involving restricted blood flow to the skin and muscles of the limbs. The agents considered included not only some of the older and better known materials with a more or less indiscriminate vasodilator action on blood vessels without relation to their nerve supply such as nitroglycerin, alcohol, papaverine, histamine, but also some of the autonomic blocking agents like priscoline, which because of their rather highly selective pattern of action present intriguing possibilities for therapy. Various shades of opinion regarding the value of these materials found expression, some of the clinical experts favoring their use strongly, others taking a more lukewarm position, others expressing doubt concerning their value. There was general agreement that the vasodilators are of no particular value in obliterative arterial disease unless there is superimposed spasm. The belief was fairly generally expressed that they are useful in such conditions as Raynaud's phenomenon or Raynaud's disease in which abnormal constriction of vessels in the skin is the chief problem. Attempts on the part of experts in the treatment of peripheral vascular diseases to make out a case for vasodilator agents against vasospastic conditions in the skeletal muscles encountered obstacles. The pharmacologists maintained that there is a biological reciprocal relationship between the state of the blood vessels in the skin and that in the skeletal muscles, vasodilatation in the skin being associated with vasoconstriction in the skeletal muscles. They questioned not only the theoretical basis for the use of vasodilator agents in intermittent claudication but also the clinical evidence on their utility in these conditions. Apparently excellent results are obtained these days with systematic regimens of treatment including vasodilator agents, so that the loss of limbs has been reduced to a minimum; but what part the dilating agents play in this remained without a decisive answer, one questioning whether the results might not be due to alcohol that these patients receive, another suggesting that cessation of smoking may be the essential component in the method of treatment. There was considerable discussion of the value of artificial fever in thromboangiitis obliterans and intra-arterial vasodilator agents for the acute situation of an arterial occlusion. Recent experiments on the use of nitroglycerin in vasospastic states were discussed. The conference closed with the interesting observations that graded exercise in the form of walking at specified speeds acts as an effective vasodilating measure in intermittent claudication and may well be more important in the long-range management of peripheral vascular problems than the medications in current use.