Disparate unloading efficacy of the calcium channel blockers, verapamil and nifedipine, on the failing hypertensive left ventricle

Calcium channel blockers reduce arterial smooth muscle tone and lower blood pressure. They may be regarded as left ventricular (LV) unloading agents. LV unloading efficacy of nifedipine (15 patients) and verapamil (14 patients) was tested in hypertensive decompensated patients, during a 1-month treatment period. Nifedipine persistently reduced systemic vascular resistance (SVR), mean arterial pressure, mean pulmonary wedge pressure (PWP), and LV diastolic diameter, and improved cardiac index and velocity of circumferential fiber shortening (Vcf). All of the patients had relief from dyspnea and reduction in heart size. The only side effect was ankle edema in six. Verapamil reduced SVR and mean arterial pressure and was not effective on PWP, LV diastolic diameter, and Vcf. The drug was discontinued in two patients who developed severe dyspnea at rest after 3 to 4 days of continuous oral treatment. Clinical symptoms and signs did not improve in the remaining patients despite persistent pressure reduction. A less potent vasodilating action of verapamil and a prominent depression in cardiac contractility may account for the differential results with the two compounds, in spite of a shared vasodilating antihypertensive effect. These findings indicate 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 influence on afterload and contractility.