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Baroreflex sensitivity and the blood pressure response to beta-blockade
X Chen1, M O Hassan, J V Jones
1Department of Cardiovascular Medicine, University of Oxford, Canada.
Journal of Human Hypertension
|April 16, 1999
Summary
Beta-blockade treatment in hypertensive patients improved baroreflex sensitivity (BRS) and reduced blood pressure (BP). Higher BRS correlated with lower BP, but exercise responses varied, impacting BP variability.
Area of Science:
- Cardiovascular medicine
- Pharmacology
- Hypertension research
Background:
- Baroreflex sensitivity (BRS) is crucial for blood pressure (BP) regulation.
- Beta-blockers are commonly used to manage hypertension.
- The relationship between beta-blockade, BRS, and BP variability requires further elucidation.
Purpose of the Study:
- To investigate the association between changes in BRS and reductions in ambulatory BP or its variability in hypertensive patients on beta-blocker monotherapy.
- To assess the impact of chronic beta-blockade on BRS and its correlation with BP parameters during rest and exercise.
Main Methods:
- 35 hypertensive patients received beta-blocker monotherapy (atenolol, metoprolol, pindolol, or propranolol) for a mean of 5 months.
- Intra-arterial BP was measured at rest and during exercise.
- BRS was assessed using the phenylephrine injection technique; 24-h ambulatory BP monitoring evaluated BP and its variability.
Main Results:
- Beta-blockade increased BRS in 24 patients and decreased it in 11, with overall BRS significantly rising (P<0.01).
- Waking ambulatory mean arterial pressure (MAP) decreased significantly (P<0.0001), but BP variability remained unchanged.
- Higher post-treatment BRS correlated with decreased waking MAP (r = -0.55, P<0.001) but not BP variability (r = -0.08).
- Beta-blockade attenuated exercise pressor response; increased BRS correlated with greater systolic BP rise during exercise (r = 0.63, P<0.001).
Conclusions:
- Chronic beta-blockade improves BRS and reduces ambulatory BP in hypertensive patients, with higher BRS linked to greater BP reduction.
- The potential benefit of beta-blockade on BP variability at rest may be counteracted by increased pressor responses during exercise.
- Individual variations in BRS response to beta-blockers highlight the complexity of their cardiovascular effects and potential implications for conditions like dilated cardiomyopathy.