[Labile arterial hypertension. Hemodynamic study with measurement of renin activity]

Plasma renin activity (PRA) was increased and highly sensitive to stimulation in eight cases of labile hypertension (HT), which were also studied haemodynamically. This increase in PRA would appear to result from neuro-adrenergic hyperactivity. The haemodynamic were characterised by a diversity which may be explained on the basis of differentiated sympathetic hyperactivity: exclusive or predominant beta-adrenergic activity causing a hyperkinetic cardiac state with moderate HT adapted to the increased cardiac output; A simultaneous alpha- and beta-adrenergic activity resulting in cardiac hyperkinesis with a relative or potential increase in peripheral resistance; isolated or predominant alpha-adrenergic hyperactivity causing a potential increase in peripheral resistance revealed or increased by effort, in the presence of a normal cardiac output. In certain cases of labile HT however, despite an increased PRA, haemodynamic findings were normal at rest and with effort, at the time of catheterisation.