B-adrenergic blocking treatment and 24-hour baroreflex sensitivity in essential hypertensive patients

Abstract

We dynamically evaluated the effects of β-blockade on the sensitivity of arterial baroreflex control of heart rate in 10 mild or moderate essential hypertensive patients in whom blood pressure was recorded intra-arterially for 24 hours in ambulatory conditions. Twenty-four-hour baroreflex sensitivity was assessed by both (1) a time-domain approach based on the calculation of the slope of the regression line between linearly related progressive increases in systolic blood pressure and pulse interval (+PI/+SBP sequences) and decreases in systolic blood pressure and pulse interval (−PI/−SBP sequences) and (2) a frequency-domain approach, ie, the ratio between the spectral powers of pulse interval and systolic blood pressure around 0.1 Hz (α coefficient). Data were obtained before and after 1 month of administration of either acebutolol (n=5) or labetalol (n=5). Before treatment, the 24-hour average slopes of the +PI/+SBP and −PI/−SBP sequences were 4.36+0.32 and 4.05 ±0.27 ms/mm Hg, respectively, while the a coefficient was 7.78±0.7 ms/mm Hg. After β-blockade, these values were increased by 25.3±6.8%, 25.0±8.0%, and 32.1+9.3%, respectively (P.01 for all values). Thus, β-blockers potentiate baroreflex sensitivity in daily life. Time-domain and frequency-domain methods yielded superimposable results in dynamically evaluating 24-hour baroreflex sensitivity and its changes after β-blockade. © 1994 American Heart Association, Inc.