Regulation of Distal Blood Perfusion: Local Control of the Peripheral Circulation in Functional and Critical Ischemia,and in Patients with Abdominal Aortic Aneurysm

Abstract

The blood flow rate in the tissues of the extremities is autoregu lated so perfusion is constant despite changes in systemic arterial pressure; modulations of arteriolar tone are constantly modifying microvascular blood flow according to metabolic needs, and a local sympathetic venoarteriolar axon reflex is operative as an edema protecting mechanism. In the arteriove nous anastomoses of the pulps there is neither autoregulation nor venoarteri olar reflex. In patients with intermittent claudication, these phenomena are not disturbed, but in patients with critical limb ischemia, the blood flow rate is extremely low, and the vascular bed is paralysed with the absence of autoregulation and of venoarteriolar reflex. In patients with nonspecific infrarenal aortic aneurysm, the peripheral blood flow rate is four times high er than in normal controls, but autoregulation and venoarteriolar reflex are present; the responses of the pulp shunt vessels are like those of normal sub jects. These findings imply a peripheral functional component affecting arte rioles but not arteriovenous anastomoses.