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 circulator y support with a left ventricular assist device (LVAD) is associated w ith improved metabolic vasodilation in the peripheral circulation of p atients with congestive heart failure is unknown. Methods: Forearm blo od flow, determined by venous occlusion plethysmography, mean arterial pressure, and cardiac output were measured at rest and after 5 minute s of arterial occlusion (a maximal metabolic vasodilatory stimulus) in 14 patients with severe heart failure before LVAD implantation, and i n the early (<4 weeks) and late (8 to 12 weeks) postoperative recovery phases after LVAD implantation. Nine normal subjects served as contro ls. Vascular conductance was calculated as the ratio of forearm blood flow and mean arterial pressure. Results: Mean arterial pressure and c ardiac output increased to normal values in the early and late recover y phases after LVAD implantation. Resting forearm blood flow and vascu lar conductance were similar to normal subjects in the early and late recovery phases after LVAD implantation. Peak forearm blood flow and v ascular conductance were significantly less than control subjects in t he early preoperative recovery phase (p < 0.05) but were similar to co ntrol subjects in the late postoperative recovery phase after LVAD imp lantation. Conclusions: In spite of early normalization of cardiac out put, mean arterial pressure, and resting forearm blood flow during chr onic circulatory support with the LVAD, peak forearm blood flow, and p eak vascular conductance did not increase to values similar to those o bserved in normal subjects until the late postoperative recovery perio d. The delayed effect of the LVAD on metabolic vasodilation may be rel ated to flow-dependent changes in the peripheral vasculature of patien ts with heart failure.