An Evaluation of Vasodilator Drugs in Occlusive Vascular Disease By Measurement

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Abstract
The article reviews the results of the author''s quantitative investigations by plethysmography of the effect of vasodilator drugs on blood flow in lower limbs of patients affected by occlusive arterial disease. The following observations are made. All the usual alpha blocking vasodilators, while very effective when given systemically in increasing pedal blood flow in healthy limbs, fail to produce vasodilation in a high proportion of limbs with main artery occlusions and peripheral ischemia. Indeed, blood flow in the affected feet may even be reduced. A better localised response might be expected from Intra-arterial infusion of the vasodilator, though this method has practical limitations and is only suitable for short term use. However, in many instances extensive disease in the most peripheral vessels may prevent vasodilation occurring even with intra-arterial therapy. In short, the ischaemic foot is rarely helped by vasodilator drugs and their widespread use here is not justified. Turning to the role of vasodilators in treating intermittent claudication, where a much wider potential field of therapeutic application exists, blood flow measurements with a wide variety of vasodilator drugs, and a consideration of the haemo-dynamic factors involved in active muscle blood flow, provide no rational basis whatever for their use. The reasons for this are set out.