Effects of carvedilol therapy on autonomic function and baroreflex sensitivity in individuals with newly-diagnosed essential hypertension

Objective: To investigate the effects of carvedilol therapy on autonomic ca rdiovascular regulation and baroreflex sensitivity, by short-term spectral analysis of heart rate (R-R) and systolic blood pressure (S-S) variability. Patients and Methods: The trial was conducted in 12 adults (seven men and f ive women, mean age 37 +/- 7 years) with newly diagnosed hypertension. Pati ents were classified as having mild or moderate hypertension (stages I to I I). R-R, S-S and respiratory signals were recorded during rest and after sy mpathetic activation by head-up tilt, before and after receiving a 15-day c ourse of carvedilol (25mg once daily). Cross-spectral analysis of R-R and S -S signals was used to determine the baroreflex sensitivity index (alpha in dex). Results: At rest after carvedilol therapy, the R-R and S-S LF (low frequenc y) normalised units (nu) significantly decreased (p = 0.0002 and p = 0.003, respectively), while the HF (high frequency) component reciprocally increa sed. The R-R LF/HF ratio decreased significantly (1.28 +/- 1.58 vs 0.41 +/- 0.29, p = 0.008). The alpha index also increased significantly (12.04 +/- 6.25 vs 16.05 +/- 7.45, p = 0.002). During tilt, carvedilol therapy reduced the R-R and S-S LF (p = 0.0003 and 0.002, respectively), but preserved the LF increase normally induced by passive orthostatism, and significantly in creased the alpha index (6.18 +/- 1.97 vs 8.89 +/- 3.29, p = 0.014). Conclusion: Our findings suggested that carvedilol attenuates cardiovascula r sympathetic responsiveness and improves baroreflex sensitivity.