Comparison of the Vasodilating Effect of Tolazoline After Intra-Arterial and Intravenous Administration

Abstract

It is generally accepted that systemic administration of vasodilator drugs in patients with peripheral arterial insufficiency may have untoward effects with reduced blood flow in ischaemic extremities.~ The main reason for this is the reduction of the systemic blood pressure, and hence of the local perfusion pressure, caused by the general vasodilation. This untoward effect of general vasodilation may be avoided if the drug is administered intra-arterially. Even this form of administration may, however, cause paradoxical reduction of the peripheral blood flow in some instances because of &dquo;proximal stealing&dquo;.Quantitative blood flow measurements and clinical studies after intra-arterial administration of tolazoline have shown varying results.3-5, ', 11, 12, 14, 16 In a preliminary study' an increase of forefoot blood flow after arterial injection of tolazoline was found. The main reason for this effect was that tolazoline, contrary to other vasodilator agents, caused an increase of the systemic blood pressure, while the collateral pressure gradient and the local peripheral resistance remained virutally unchanged.If the local blood flow increase is mainly caused by the central hemodynamic effects of tolazoline the same blood flow response should be obtained whether tolazoline is administered intra-arterially or intravenously. The aim of the present study was to compare the local blood flow response of tolazoline after administration by these two routes in patients with arterial occlusions in the lower extremities. MATERIALS AND METHODSEleven patients with obliterative atherosclerosis in the lower extremities (9 men, 49 to 82 years, and 2 women, 72 and 75 years old) were included in the study. The majority of the patients had concomitant coronary heart disease, but none of' them had overt cardiac insufficiency or had sustained a myocardial infarction for at least 1:2 year prior to the examination. The diagnosis of' obliterative atherosclerosis was based on a thorough clinical examination, and verified by arteriography.In 8 of the patients the main symptom was intermittent claudication of the lower leg, with a claudication distance varying from 25 to 200 (mean 113 m). Arteriography revealed an isolated femoral artery occlusion in 6 and a distal popliteocrural artery occlusion in 2 patients. In 3 patients the main complaint was resting pains in the foot. All the patients had extensive obliterative changes of the femoropopliteocrural arteries on arteriography.Resting blood flow in the forefoot was measured by venous occlusion plethysmography using an air-filled double-walled rubber plethysmograph.2 2 at UQ Library on June 20, 2015 ang.sagepub.com Downloaded from