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Baroreflex sensitivity changes with calcium antagonist therapy in elderly subjects with isolated systolic
M A James1, H Rakicka, R B Panerai
1University Department of Medicine for the Elderly, Glenfield General Hospital, Leicester, UK.
Insights
Calcium-channel blockers improve blood pressure and cardiovascular reflexes in elderly patients with isolated systolic hypertension. This therapy enhances baroreflex sensitivity and autonomic responses, aiding cardiovascular homeostasis.
Area of Science:
- Cardiology
- Gerontology
- Pharmacology
Background:
- Isolated systolic hypertension is common in the elderly.
- Cardiovascular homeostasis can be compromised in this population.
- Calcium-channel blockers are a potential therapeutic option.
Purpose of the Study:
- To investigate the effects of modified-release nifedipine on cardiovascular homeostasis in elderly individuals with isolated systolic hypertension.
- To assess changes in blood pressure, heart rate, blood pressure variability, and baroreflex sensitivity.
Main Methods:
- Randomized, double-blind, placebo-controlled crossover study.
- 14 elderly subjects with isolated systolic hypertension.
- 6 weeks of modified-release nifedipine or placebo therapy.
- Measurements included clinic and 24-h BP, heart rate, BP variability, baroreflex sensitivity, and autonomic reflex tests (tilt, cold face stimulus).
Main Results:
- Nifedipine significantly reduced clinic and 24-h systolic and diastolic blood pressure.
- Baroreflex sensitivity significantly increased with nifedipine treatment.
- Autonomic responses during tilt testing showed improved heart rate increase and reduced BP fall.
- Heart rate and BP variability remained unchanged.
Conclusions:
- Modified-release nifedipine effectively improves blood pressure control in elderly patients with isolated systolic hypertension.
- Calcium-channel blocker therapy can enhance baroreflex sensitivity and improve cardiovascular autonomic function.
- These findings suggest significant benefits for cardiovascular homeostasis in this patient group.
Abstract:
In order to study the effects of calcium-blocking therapy on cardiovascular homeostasis in elderly subjects with isolated systolic hypertension, we performed a randomised double-blind placebo-controlled crossover study of 6 weeks therapy with modified-release nifedipine or placebo. Changes with calcium-blocker treatment in clinic and 24-h blood pressure (BP), heart rate, BP variability, baroreflex sensitivity (BRS) by three methods (Valsalva manoeuvre, phenylephrine and sodium nitroprusside injection), and in baroreflex- and non-baroreflex-mediated reflexes (tilt and cold face stimulus) were studied in 14 elderly subjects (mean age [+/- SEM] 70 +/- 1 years) with sustained isolated systolic hypertension (clinic BP 179 +/- 3/85 +/- 1 mm Hg). Clinic systolic BP, but not diastolic BP, was reduced with treatment (by 14 +/- 6 mm Hg, P = 0.03, diastolic BP 4 +/- 3 mm Hg, P = 0.16). Twenty-four hour BP was also reduced by nifedipine treatment (by 18 +/- 3/9 +/- 2 mm Hg, both P < 0.001). Clinic and 24-h heart rate, and daytime BP variability, were unchanged with treatment. BRS was significantly increased during nifedipine therapy by all three measurement methods (all P < 0.05). With 60 degrees tilt during active treatment, subjects exhibited a greater heart rate increase (P < 0.01), and a reduced fall in systolic (P < 0.05) and diastolic BP (P < 0.05). Thus despite the arteriosclerosis and reductions in large artery compliance described in elderly patients with isolated systolic hypertension, clinically important improvements in clinic and ambulatory BP and some aspects of cardiovascular homeostasis can be achieved with calcium-channel blocking therapy.