NONINVASIVE DETERMINATION OF HUMAN AORTIC COMPLIANCE

We determined the compliance of the aortic ''Windkessel'' using a non- invasive, method. The occlusion of the lower extremities (5 min, 180 m m Hg) elicited reactive hyperemia. An abrupt change in pressure in the occluding cuffs from 180 to 60 mm Hg increased femoral blood flow (me asured by pulsed Doppler) and decreased blood pressure (measured by Pe naz continuous method). During abrupt decrease in blood pressure, the compliance was calculated as a ratio of the blood volume flowing out o f the aorta via the femoral arteries to the decrease of blood pressure . The measurements were made repeatedly in eight healthy men, and in p atients with essential hypertension (ten patients with essential hyper tension, IInd degree - WHO without traitment and six patients with ess ential hypertension, IInd degree - WHO treated with slow released vera pamil). Compliance in the first group was 1.18 +/- 0.25 ml.mm Hg-1, in the second 0.96 +/- 0.21 ml.mm Hg-1, and in the third group 0.90 +/- 0.11 ml.mm Hg-1. We found a negative correlation between compliance an d arterial blood pressure. However the relative large scatter requires repeated measurements.