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Angiotensin-converting enzyme inhibition, autonomic activity, and hemodynamics in patients with heart failure who
R Willenbrock1, C Ozcelik, K J Osterziel
1Franz Volhard Clinic, Rudolf Virchow University Hospitals, Berlin, Germany.
Insights
Acute angiotensin-converting enzyme inhibition (ACEI) prevents decreases in cardiac output during isometric exercise in congestive heart failure (CHF) patients. ACEI may reduce sympathetic activity, improving cardiovascular response.
Area of Science:
- Cardiology
- Pharmacology
- Physiology
Background:
- Congestive heart failure (CHF) patients exhibit altered autonomic responses and hemodynamics during exercise.
- The impact of angiotensin-converting enzyme inhibition (ACEI) on these responses in CHF during isometric exercise is not well understood.
Purpose of the Study:
- To investigate the effects of acute ACEI on autonomic responses and hemodynamics during isometric exercise in patients with CHF.
- To determine if ACEI can mitigate the decrease in cardiac output observed in CHF patients during isometric stress.
Main Methods:
- A placebo-controlled study design was used.
- Patients with CHF underwent isometric exercise with and without acute ACEI (ramipril).
- Hemodynamic parameters (blood pressure, heart rate, cardiac output, stroke volume) and autonomic responses (spectral analysis of blood pressure, norepinephrine levels) were measured.
Main Results:
- Isometric exercise decreased cardiac output and stroke volume in CHF patients without ACEI.
- Acute ACEI prevented the decrease in cardiac output during isometric exercise.
- ACEI increased parasympathetic activity and prevented the rise in norepinephrine levels seen with isometric stress in CHF patients.
Conclusions:
- Acute ACEI effectively prevents the reduction in cardiac output during isometric exercise in CHF patients.
- The beneficial effect of ACEI may be attributed to a reduction in sympathetic nervous system activity.
- ACEI demonstrates potential in improving cardiovascular function during physical stress in CHF.
Abstract:
Effects of angiotensin-converting enzyme inhibition (ACEI) on autonomic responses and hemodynamics in patients with congestive heart failure (CHF) subjected to isometric exercise have not been studied. We tested whether acute ACEI might influence the effects of isometric exercise in patients with CHF. In the first part of the study we showed that isometric exercise increased blood pressure in the control group and in the CHF group, whereas cardiac output increased only in the control group. Stroke volume remained unchanged in the control group, whereas it decreased significantly in CHF group. We next analyzed the effect of acute ACEI (5 mg ramipril) on the decrease in cardiac output during isometric stress in patients with CHF. During isometric exercise mean blood pressure and heart rate increased similarly in both groups. However, cardiac output decreased during placebo by -0.48 +/- 0.12 L/min (p < 0.01) but not during ACEI. Spectral analysis of blood pressure showed an increase (p < 0.01) in the high-frequency parasympathetic component from 7.3% +/- 3.6% to 18.1% +/- 9.5% after ACEI. norepinephrine plasma levels increased after isometric stress in the placebo group, whereas other hormones did not change. ACEI prevented the norepinephrine increase after isometric stress. Thus the decrease in cardiac output during isometric exercise in patients with CHF was prevented by acute ACEI. The effect of ACE inhibition may be related to reduced sympathetic activity.