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Acute hemodynamic effects of propranolol, glycerylnitrate, and exercise in coronary patients with left ventricular
Insights
Adding glyceryl nitrate to beta-blockers in heart failure patients with left ventricular dysfunction may reduce hazards. This combination helps patients exercise with beta-blocker benefits but lower ventricular filling pressure.
Area of Science:
- Cardiology
- Pharmacology
- Exercise Physiology
Background:
- Beta-blockers are used for heart failure, but can have adverse effects.
- Glyceryl nitrate may counteract some beta-blocker side effects.
- Hemodynamic effects of the combination in exercising patients with left ventricular dysfunction are not well understood.
Purpose of the Study:
- To examine the hemodynamics of combining beta-blockers and glyceryl nitrate in exercising coronary patients with left ventricular dysfunction.
- To assess the safety and efficacy of this drug combination.
Main Methods:
- Forty patients with left ventricular dysfunction underwent right-heart catheterization.
- Three successive exercise stress tests were performed.
- Hemodynamic parameters were measured at rest and during exercise with and without drug interventions.
Main Results:
- Propranolol (a beta-blocker) reduced heart rate, cardiac output, blood pressure, and left ventricular work during exercise.
- Glyceryl nitrate reduced pulmonary capillary wedge pressure during exercise but did not increase heart rate or reduce cardiac output.
- The drug combination showed hemodynamics similar to propranolol alone, but with lower pulmonary capillary wedge pressure.
Conclusions:
- The combination of beta-blockers and glyceryl nitrate in exercising patients with left ventricular dysfunction resulted in beneficial hemodynamics.
- This combination may reduce the potential risks associated with beta-blocker therapy in these patients.
- Glyceryl nitrate addition allows exercise with beta-blocker benefits while lowering ventricular filling pressure.
Abstract:
Some adverse effects of beta-blockers in heart failure are counteracted by glycerylnitrate. However, the hemodynamics in this condition after giving both drugs are not well known. We examined the drug combination in exercising coronary patients with left ventricular dysfunction. Elevated left ventricular end-diastolic pressure was a measure of dysfunction. A right-heart catheterization with three successive exercise stress tests was done in 40 patients. At repeated exercise without drugs a "warming up" phenomenon was observed, consisting of small but statistically significant reductions in pulmonary capillary wedge pressure, and heart rate. At exercise propranolol reduced heart rate, cardiac output, systemic blood pressure, left ventricular work, and increased arteriovenous oxygen difference. Glycerylnitrate reduced pulmonary capillary wedge pressure at exercise, but, contrary to the findings at rest, it did not increase heart rate or reduce cardiac output. The drug combination resulted in hemodynamics that were similar to those after propranolol alone, except for a lower pulmonary capillary wedge pressure. The drug combination allowed the patients to exercise with the benefits of the beta-blocker, but at a lower ventricular filling pressure. Thus, the potential hazard of giving beta-blockers to patients with left ventricular dysfunction may be reduced by adding glycerylnitrate.