Left Ventricular Unloading with Calcium Antagonists
Calcium. channel blockers reduce the arterial smooth muscle tone and lower blood pressure. They may be regarded as left ventricular (LV) unloading agents.
LV unloading efficacy of nifedipine (15 cases) and verapamil (14 cases) was tested in hypertensive decompensated patients, through a one-month treatment period.
Nifedipine persistently reduced systemic vascular resistance (SVR), mean arterial pressure (MAP), mean pulmonary wedge pressure (PWP) and LV diastolic diameter (DD) and improved cardiac index and Vcf. 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 SVR and MAP was not effective on PWP, LV, DD and Vcf. 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.
KeywordsMean Arterial Pressure Systemic Vascular Resistance Wall Stress Peripheral Vascular Resistance Diastolic Diameter
Unable to display preview. Download preview PDF.
- 1.M. Guazzi, F. Fabbiocchi, C. Cipolla, P. Montorsi, and P. Sganzerla, Disparate unloading effects of verapamil and nifedipine on the decompensated hypertensive left ventricle, Am.Heart J., in press.Google Scholar
- 2.K. T. Weber, J. Janicki, and L. L. Hefner, Left ventricular force-length relations of isovolumic and ejecting contractions, Am.J.Physiol., 231: 337 (1976).Google Scholar
- 5.A. Zanchetti, Perspectives in antihypertensive treatment, In: “Calcium Antagonism in Cardiovascular Therapy: Experience with Verapamil,” A. Zanchetti and D.M. Krikler, eds., Excerpta Medica, Amsterdam, p. 292 (1981).Google Scholar