Delayed reversal of impaired metabolic vasodilation in patients with end-stage heart failure during long-term circulatory support with a left ventricular assist device.

BACKGROUND: Whether increased cardiac output during chronic circulatory support with a left ventricular assist device (LVAD) is associated with improved metabolic vasodilation in the peripheral circulation of patients with congestive heart failure is unknown.
METHODS: Forearm blood flow, determined by venous occlusion plethysmography, mean arterial pressure, and cardiac output were measured at rest and after 5 minutes of arterial occlusion (a maximal metabolic vasodilatory stimulus) in 14 patients with severe heart failure before LVAD implantation, and in the early (<4 weeks) and late (8 to 12 weeks) postoperative recovery phases after LVAD implantation. Nine normal subjects served as controls. Vascular conductance was calculated as the ratio of forearm blood flow and mean arterial pressure.
RESULTS: Mean arterial pressure and cardiac output increased to normal values in the early and late recovery phases after LVAD implantation. Resting forearm blood flow and vascular conductance were similar to normal subjects in the early and late recovery phases after LVAD implantation. Peak forearm blood flow and vascular conductance were significantly less than control subjects in the early preoperative recovery phase (p < 0.05) but were similar to control subjects in the late postoperative recovery phase after LVAD implantation.
CONCLUSIONS: In spite of early normalization of cardiac output, mean arterial pressure, and resting forearm blood flow during chronic circulatory support with the LVAD, peak forearm blood flow, and peak vascular conductance did not increase to values similar to those observed in normal subjects until the late postoperative recovery period. The delayed effect of the LVAD on metabolic vasodilation may be related to flow-dependent changes in the peripheral vasculature of patients with heart failure.