POSTURAL VASOCONSTRICTOR RESPONSE IN HUMAN HEART-FAILURE

In order to study whether posturally induced vasoconstriction is impai red in subjects with heart failure, laser Doppler fluximetry was used to measure blood flow in the cutaneous microvascular bed of the foot a t rest and during passive lowering of the extremity below heart level, in subjects with idiopathic dilated cardiomyopathy and in healthy con trols. Two sites were studied: the toe pulp where arteriovenous anasto moses are numerous and the dorsum of the foot where such anastomoses a re absent. Despite demonstrating a marked reduction in cutaneous blood flow at rest at each site [dorsum 3.0 AU (1.8-4.5) [median (range)] i n heart failure patients vs. 4.5 AU (1.8-31.6) in controls; toe 8.7 AU (3.1-33.5) in heart failure vs. 44.7 AU (5.2-280.0) in controls, p < 0.01], the results suggest that in non-oedematous subjects with severe left ventricular dysfunction there is no major disturbance of the pos tural vasoconstrictor response, either at a site rich in highly innerv ated anastomoses [43.6% (14.5-89.4) vs. 43.7% (15.6-91.1)] or in a sit e with few such anastomoses [79.7% (39.6-92.3) vs. 69.6% (10.1-94.9)].