REGULATION OF THE BAROREFLEX AND RESTING BLOOD-PRESSURE VARIATIONS INHYPERTENSIVES

The object of this study was to compare the variability of blood press ure measured non-invasively with the Finapres under resting conditions in hypertensive patients with non-hypertensive subjects matched for a ge, and to evaluate the relationship between resting blood pressure, i .e. without any stimulation, and the sensitivity of the baroreflex eva luated by crossed spectral analysis (SA). Thirty-four hypertensives (W HO criteria) untreated for three weeks, with a mean age of 50 +/- 7 ye ars, were compared with 60 control subjects with a mean age of 50 +/- 9 years. The blood pressure and heart rate were measured continuously in the dorsal decubitus and standing positions. The direct and crossed SA was undertaken by a specific programme using the fast Fourier meth od. The average blood pressure of controls differed significantly from that of the hypertensive population (118 +/- 15/65 +/- 10 mmHg vs 157 +/- 20/86 +/- 11 mmHg). The mean heart rate of the hypertensives was faster: 76 +/- 11 vs 67 +/- 10 beats/min (p < 0.001). Under basal cond itions, there was greater absolute variability in the hypertensive sub jects but the relative variability and heart rate were the same as tho se of the controls. Direct SA provided additional data by showing that this variability was due to LF oscillations. Crossed SA showed a chan ge in the sensitivity of the slope of regulation of the baroreflex in hypertensives, 7.35 vs 8.68 ms/mmHg (p < 0.05). These results show tha t, under basal conditions, it is possible to demonstrate an increase i n the absolute variability in blood pressure in hypertensive patients. The crossed SA study measuring the sensitivity of the slope of regula tion of the spontaneous baroreflex is useful in comparing the increase d variability of the resting blood pressure with the quality of the ba roreflex regulation.