Blood Pressure in the ??Low-Pressure System?? and Cardiac Performance in Essential Hypertension

Abstract

Determinations of central venous pressure, cardiac haemodynamics and rapid volume expansion using iso-oncotic dextran were made in 49 men with sustained, uncomplicated essential hypertension and compared with those in 27 normotensive subjects of the same age and sex. In the hypertensives, central venous pressure was significantly increased in basal conditions while the cardiac index was normal and total blood volume was reduced. There was a positive and significant correlation of central venous pressure with age, arterial pressure and pulmonary wedge pressure. After rapid volume expansion, the slope of the curve relating cardiac output to central venous pressure was within the normal range, while the slope of the curve relating blood volume to central venous pressure was significantly reduced. The study provided evidence that in hypertensives: central venous pressure as well as arterial pressure is increased, the elevated central venous pressure is not due to an alteration in the cardiac 'pump function' or to hypervolaemia but rather to a decrease in the compliance of the venous bed or the left ventricle or both, and the strong correlation with age of the venous disturbances is similar to that found for the arterial side of the circulation.