Effects of lower body negative pressure in hypertensive patients with left ventricular hypertrophy.

We studied the response of forearm vascular resistance to lower body negative pressure (LBNP) at -10 and -40 mmHg in seven established hypertensives with left ventricular hypertrophy (LVH) and seven age-matched normotensive controls. To evaluate the specific role of ventricular baroreceptors, we also investigated the effects of propranolol on the reflex response. Under control conditions, graded LBNP induced a progressive decrease in central venous pressure (CVP) and increased forearm vascular resistance. Changes in CVP and forearm vascular resistance were inversely correlated both in controls (r = -0.944) and in hypertensives (r = -0.960), P less than 0.001 for both. No difference was found between the regression slopes obtained for the two groups (normotensives, -30; hypertensives, -40; NS). After propranolol there was a significant reduction in the increase in forearm vascular resistance induced by -40 mmHg LBNP in normotensives but not in hypertensives. Consequently, the slope of the regression delta CVP/delta forearm vascular resistance was reduced in normotensives (-21) but not in hypertensives. In contrast, propranolol did not attenuate the vasoconstrictor response to other stimuli. Left ventricular hypertrophy therefore seems to be associated with changes in the role of the different cardiopulmonary receptor areas during mediation of the haemodynamic response to stimulated orthostatic stress.