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Tiapamil and verapamil significantly reduced peripheral vascular resistance in patients with coronary artery disease, increasing cardiac output and stroke volume without evident depressant effects on hemodynamic variables.
Area of Science:
- Cardiology
- Pharmacology
- Hemodynamics
Background:
- Coronary artery disease (CAD) affects hemodynamic function.
- Understanding drug effects on hemodynamics is crucial for patient management.
Purpose of the Study:
- To investigate the hemodynamic effects of tiapamil and verapamil in patients with CAD.
- To assess the dose-related responses and effects under rest and stress conditions.
Main Methods:
- Cardiac catheterization with pulmonary artery floatation catheter and brachial artery cannulation.
- Fick principle for cardiac output calculation.
- Continuous pressure recordings at rest and during submaximal treadmill exercise in 5 groups of 12 CAD patients.
Main Results:
- Both tiapamil and verapamil demonstrated a dose-related reduction in peripheral vascular resistance (up to 39%).
- Mean arterial pressure decreased in patients with sinus rhythm.
- Cardiac output and stroke volume increased at rest and during stress.
- No significant depressant action on hemodynamic variables was observed.
Conclusions:
- Tiapamil and verapamil effectively reduce peripheral vascular resistance and improve cardiac output in CAD patients.
- The observed effects are likely due to interplay between preload and afterload.
- Further investigation is needed for potential depressant effects in patients with reduced ventricular function.
Abstract:
Hemodynamic studies were carried out after cardiac catheterization with a floatation catheter in the pulmonary artery and cannulation of the brachial artery for the calculation of cardiac output by means of the Fick principle. Continuous pressure recordings were carried out at rest and under submaximal treadmill exercise in the supine body position in 5 homogeneous groups of 12 patients, all with disorders due to coronary disease. In a control test, hemodynamic investigations were carried out at rest before medication, under stress and after recovery. Similar tests were performed after intravenous administration of either isotonic saline as placebo, tiapamil (1.1 and 1.6 mg/kg) or verapamil (0.07 and 0.14 mg/kg). It was shown that there was a marked dose-related reduction in peripheral vascular resistance with a maximum effect occurring at 2-5 min after the intravenous administration of tiapamil (1.1 and 1.6 mg/kg) reaching 23 and 39%, respectively, or verapamil (0.07 and 0.14 mg/kg) attaining 28 and 39%, respectively, at rest and, to a similar extent, under stress conditions. In patients with sinus rhythm, the mean arterial pressure was reduced. Cardiac outputs and stroke volumes were increased at rest as well as under stress. There was no evidence of a depressant action of the drug on hemodynamic variables. An interplay of simultaneous changes in preload and afterload seems to be responsible for the effects obtained. The doses used were those commonly employed in the termination of supraventricular tachyarrhythmias. However, a potential depressant effect of tiapamil in patients with markedly reduced ventricular function is not excluded by this study.