AUTONOMIC NERVOUS ACTIVITY IN ELDERLY DIPPER AND NON-DIPPER PATIENTS WITH ESSENTIAL-HYPERTENSION

The pathogenetic mechanisms of the blunted nocturnal fall in blood pre ssure, frequently observed in elderly patients with essential hyperten sion, are unclear. The aim of this study was to evaluate the autonomic nervous system in elderly dipper and non-dipper hypertensive subjects . The study group consisted of twelve non-dipper and twelve dipper hyp ertensive patients (mean age 77.7 and 73.8 years, respectively). Non-d ippers were defined as subjects whose nocturnal fall in systolic blood pressure (SEP), evaluated by means of Ambulatory Blood Pressure Monit oring, was less than 10% of diurnal SEP. All the patients underwent th e following cardiovascular tests to explore autonomic function: Tilt T able? Valsalva Maneuver, Deep Breathing, Cough. The tests were perform ed under standard conditions, and heart rate and blood pressure were c ontinuously recorded. Valsalva ratio (VR), Expiration/Inspiration Rati o (E/IR) and Cough Test Ratio (CTR) were calculated. Mann Whitney's an d chi(2) tests were used for comparison between groups. Relationships were assessed by univariate and multivariate analyses. Non-dipper hype rtensive subjects showed significantly lower scores in VR (11.1+/-0.08 vs 1.28+/-0.14), E/IR (1.11+/-0.07 vs 1.21+/-0.10), and CTR (1.07+/-0 .02 vs 1.15+/-0.07). During the tilt test, a significant decrease in S EP and a late increase in heart rate were observed in non-dippers. The day-night difference in SEP was significantly related to VR, CTR and maximal SEP drop during tilting. The findings confirm that non-dippers show an impairment in autonomic nervous drive, which is characterized mainly by decreased parasympathetic activity. These observations may explain the increase in cardiovascular risk in non-dippers, (C) 1997, Editrice Kurtis.