Increasing cardiovascular parasympathetic nervous activity could have antihypertensive effects. Low-dose transdermal scopolamine increases vagal-cardiac modulation of sinus node and baroreflex sensitivity in healthy subjects and in cardiac patients.Objective
To study the short-term effects of transdermal scopolamine on blood pressure and cardiovascular autonomic control in patients with mild essential hypertension.Design
A randomized, double-blind, placebo-controlled crossover trial with 12 untreated middle-aged [aged 39 ± 5 years (mean ± SD)] patients with mild essential hypertension.Methods
We recorded the electrocardiogram, auscultatory sphygmomanometric and continuous photoplethysmographic finger arterial pressure, and spirometry signals with patients supine and 70° tilted during controlled (0.25 Hz) breathing. Cardiovascular autonomic regulation was analyzed with power spectrum analysis of R-R interval and arterial pressure variability and a spontaneous sequence method for baroreflex sensitivity. In addition, a deep-breathing test was performed to assess maximal breathing-related sinus arrhythmia.Results
Transdermal scopolamine treatment significantly decreased blood pressure both when patients lay supine and when they were in the 70° tilted position. Scopolamine also slowed heart rate and increased baroreflex sensitivity and R-R interval high-frequency variability for both body positionings. In addition, scopolamine accentuated respiratory sinus arrhythmia during deep breathing and blunted the tilt-induced increase in heart rate. Scopolamine did not affect blood pressure variability.Conclusions
Transdermal scopolamine decreases arterial pressure, increases baroreflex sensitivity and accentuates vagal-cardiac modulation of sinus node in patients with mild hypertension. Our study supports the hypothesis that increasing cardiovascular parasympathetic activity could have antihypertensive effects in essential hypertension. J Hypertens 16:321–329 © 1998 Rapid Science Ltd.