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Influence of captopril on the arterial baroreceptor reflex in patients with heart failure

K J Osterziel1, N Röhrig, R Dietz

  • 1Department of Internal Medicine, (Cardiology), Ruprecht-Karls-University, Heidelberg, Federal Republic of Germany.

European Heart Journal
|October 1, 1988
PubMed

Insights

Captopril enhances the baroreceptor reflex in heart failure patients, increasing sensitivity to heart rate slowing. This effect is independent of blood pressure changes and mediated by increased vagal tone.

Area of Science:

  • Cardiovascular Physiology
  • Pharmacology
  • Nephrology

Background:

  • Heart failure (HF) affects cardiovascular regulation, including the baroreceptor reflex.
  • The carotid sinus baroreceptor reflex plays a crucial role in maintaining blood pressure homeostasis.
  • Angiotensin-converting enzyme inhibitors (ACEIs) like captopril are used in HF management.

Purpose of the Study:

  • To investigate the effect of a single captopril dose on carotid sinus baroreceptor reflex sensitivity in male patients with heart failure (NYHA II-III).
  • To determine if captopril alters reflex heart rate slowing or blood pressure responses to baroreceptor stimulation.
  • To elucidate the mechanism underlying captopril's influence on baroreflex sensitivity.

Main Methods:

  • 16 male patients with heart failure (NYHA II-III) received a single 25 mg dose of captopril.
  • Carotid sinus baroreceptors were stimulated using an airtight neck chamber.
  • Two indices of baroreflex sensitivity were calculated: sensitivity to reflex heart rate slowing and blood pressure response to neck suction.

Main Results:

  • Captopril significantly reduced blood pressure (11 ± 1.7 mm Hg) but did not alter heart rate.
  • Sensitivity to reflex heart rate slowing increased significantly after captopril administration (from -2.9 ± 0.7 to -5.0 ± 1.3 ms/mmHg).
  • The increase in heart rate slowing sensitivity was more pronounced in patients with higher initial sensitivity and was independent of hemodynamic changes.

Conclusions:

  • Captopril selectively augments the reflex bradycardia mediated by increased vagal efferent tone in heart failure patients.
  • The observed enhancement of baroreflex sensitivity is dependent on the initial reflex sensitivity and not solely due to hemodynamic effects.
  • Captopril's influence on baroreflexes may contribute to its therapeutic benefits in heart failure management.

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