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The effects on left ventricular performance of nifedipine and verapamil in exercise-induced angina pectoris
Insights
Nifedipine and verapamil, both calcium channel blockers, differentially affect heart rate and cardiac output in patients with coronary artery disease. Verapamil increased left heart filling pressure, while nifedipine caused reflex tachycardia during exercise.
Area of Science:
- Cardiology
- Pharmacology
Background:
- Slow channel blocking agents (calcium channel blockers) have known effects on cardiac function.
- The clinical relevance of these differences in patients with impaired left ventricular function due to coronary heart disease is unclear.
Purpose of the Study:
- To compare the hemodynamic effects of equivalent hypotensive doses of nifedipine and verapamil.
- To assess drug effects in patients with severe angina and coronary artery disease.
Main Methods:
- 20 patients with severe angina and coronary artery disease were studied.
- Hemodynamic parameters were measured at rest and during exercise after administration of nifedipine or verapamil.
Main Results:
- Both nifedipine and verapamil reduced systemic blood pressure and vascular resistance.
- Nifedipine increased heart rate and cardiac output, while verapamil increased cardiac output and left heart filling pressure without changing heart rate.
- During exercise, both drugs reduced angina; nifedipine induced reflex tachycardia, unlike verapamil.
Conclusions:
- Nifedipine and verapamil exhibit distinct hemodynamic profiles in patients with coronary artery disease.
- These differences may be relevant for managing patients with impaired left ventricular function.
Abstract:
The differences between slow calcium blocking agents with respect to effects on heart rate, myocardial contractility and atrioventricular conducting time are well described; the relevance of such differences to the treatment of patients with impaired left ventricular function due to coronary heart disease is uncertain. The haemodynamic effects of equivalent hypotensive doses of nifedipine and verapamil were therefore compared in 20 patients with severe angina pectoris associated with angiographically documented coronary artery disease. The plasma concentrations of nifedipine (mean 57 +/- 19; range 27-77 ng/ml) and verapamil (mean 147 +/- 14; range 117-260 ng/ml) at the time of the haemodynamic measurements were of an order usually associated with substantial pharmacodynamic activity. Sitting at rest nifedipine resulted in reduction in systemic arterial pressure (P less than 0.05) and vascular resistance (P less than 0.01); both the heart rate (P less than 0.01) and cardiac output (P less than 0.05) increased without any significant change in the left heart filling pressure. In contrast, verapamil, which similarly reduced systemic blood pressure (P less than 0.05) and vascular resistance (P less than 0.01), increased cardiac output (P less than 0.05) and left heart filling pressure (P less than 0.05) without any change in heart rate. During upright bicycle exercise both drugs attenuated the angina induced in all subjects during the control exercise period. Despite reductions in systemic blood pressure and vascular resistance the cardiac output was unaltered on either drug at the same workload as in the control assessment. The reduction in exercise blood pressure following nifedipine induced a reflex tachycardia; this was not present, despite the similar hypotensive action, after verapamil.(ABSTRACT TRUNCATED AT 250 WORDS)