Systemic arterial compliance and diastolic runoff in essential hypertension.

Systemic arterial compliance was estimated in 31 men, including 15 patients with sustained essential hypertension and 16 normal subjects of the same age. Values were derived from analysis of the monoexponential blood pressure-time curve during diastole, according to a simple viscoelastic model. In normal subjects, baseline arterial compliance was 2.56 +/- 0.18 ml/mm Hg. A significant decrease (1.88 +/- 0.13 ml/mm Hg; P less than 0.001) was observed in hypertensives. Administration of vasoactive substances (angiotensin and sodium nitroprusside) showed that, for the same blood pressure levels, normal subjects and hypertensives had similar values for compliance. However, the correlation between the basal values of diastolic pressure and compliance was significant in normal subjects (r = --0.76) but not in hypertensives (r = --0.33); these results suggested differences between acute and long-term conditions in patients and controls. Calculated diastolic runoff was similar in both groups, approximating 58 and 55% of the stroke volume respectively. This study provides evidence that, in sustained essential hypertension, (1) the reduced arterial compliance cannot be related exclusively to the level of blood pressure, but also requires some abnormality of the volume of large arteries, and (2) the reservoir role of the large arteries is maintained.