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Left ventricular unloading with calcium antagonists
Insights
Nifedipine effectively unloads the left ventricle in hypertensive patients, improving cardiac function and relieving symptoms. Verapamil showed less efficacy and potential adverse effects, highlighting differences in calcium channel blocker actions.
Area of Science:
- Cardiology
- Pharmacology
- Internal Medicine
Background:
- Calcium channel blockers (CCBs) reduce arterial smooth muscle tone, lowering blood pressure.
- CCBs can function as left ventricular unloading agents, crucial in managing heart failure.
Purpose of the Study:
- To compare the left ventricular unloading efficacy of nifedipine and verapamil in hypertensive, decompensated patients.
- To evaluate the impact of these calcium channel blockers on hemodynamic parameters and clinical symptoms.
Main Methods:
- A one-month treatment study involving 15 patients with nifedipine and 14 with verapamil.
- Assessment of systemic vascular resistance, mean arterial pressure, pulmonary wedge pressure, left ventricular diastolic diameter, cardiac index, and velocity of circumferential fiber shortening.
- Monitoring of clinical symptoms, including dyspnea and heart size, and adverse effects.
Main Results:
- Nifedipine significantly reduced vascular resistance, blood pressure, pulmonary wedge pressure, and left ventricular size, while improving cardiac index and contractility.
- Verapamil reduced vascular resistance and blood pressure but did not improve pulmonary wedge pressure, ventricular size, or contractility; 2 patients discontinued due to severe dyspnea.
- Nifedipine led to symptom relief (dyspnea) and reduced heart size in all patients, with ankle edema as the main side effect in 6 cases.
Conclusions:
- Nifedipine demonstrates superior left ventricular unloading efficacy compared to verapamil in hypertensive heart failure.
- The differing effects may stem from verapamil's less potent vasodilation and greater negative inotropic effects on cardiac contractility.
- Functional changes in the failing hypertensive heart can vary significantly between different calcium channel blockers due to their distinct impacts on afterload and contractility.
Abstract:
Calcium channel blockers reduce the arterial smooth muscle tone and lower blood pressure. They may be regarded as left ventricular unloading agents. Left ventricular unloading efficacy of nifedipine (15 cases) and verapamil (14 cases) was tested in hypertensive decompensated patients, through one-month treatment period. Nifedipine persistently reduced systemic vascular resistance, mean arterial pressure, mean pulmonary wedge pressure and left ventricular diastolic diameter and improved cardiac index and velocity of circumferential fiber shortening. All of the patients had relief from dyspnea and reduction in heart size. The only side effect was ankle edema in 6 cases. Verapamil reduced systemic vascular resistance and mean arterial pressure and was not effective on mean pulmonary wedge pressure, left ventricular diastolic diameter and velocity circumferential fiber shortening. The drug was discontinued in 2 patients who developed severe dyspnea at rest after a 3-4 day continued oral treatment. Clinical symptoms and signs did not improve in the remaining subjects despite persistent pressure reduction. A less potent vasodilating action of verapamil and a prominent depression in cardiac contractility may account for the different results with the two compounds, in spite of a shared vasodilating antihypertensive effect. These findings prove that functional changes in the failing hypertensive heart may differ from one calcium blocker to another as a result of interaction and relative preponderance of influences on afterload and contractility.