Reversal of a calcium-mediated vasoconstrictor component in patients with congestive heart failure.

Overview

The influx of calcium into vascular smooth muscle cells is a major determinant of vasoconstriction, yet this concept has not been explored in congestive heart failure (CHF). We therefore used an "isolated" forearm model to assess the direct effects of the inhibition of calcium influx into vascular smooth muscle in 11 patients who had CHF, with use of the soluble dihydropyridine, nicardipine. Nicardipine produced a dose-dependent increase of forearm blood flow and a reduction of resistance, without producing a systemic hemodynamic effect. Patients with the lowest baseline forearm blood flow levels had the greatest percentage increases in forearm blood flow (r = -0.729, p less than 0.01), and a favorable metabolic effect was documented by a reduction in oxygen extraction across the forearm. This study demonstrated the importance of vascular smooth muscle intracellular calcium as a determinant of vasoconstriction in patients who have CHF.