ENDOTHELIUM-DEPENDENT VASODILATION OF THE SKIN MICROCIRCULATION IN HEART-TRANSPLANT RECIPIENTS

Patients with heart failure demonstrate attenuated endothelium-depende nt vasodilation of the peripheral circulation. while this is suggested to be reversed after heart transplantation. However, data from human subjects are limited and conflict with studies on the peripheral vasom otor tone in cyclosporine-treated animals, suggesting endothelial dysf unction. We recorded forearm skin perfusion responses following graded iontophoresis of 1% acetylcholine (endothelium-dependent) and 1% sodi um nitroprusside (endothelium-independent) by laser Doppler perfusion measurements in 32 heart transplant recipients and 15 age-matched cont rols. III addition, the hyperemic response to 3 min of blood flow occl usion to the forearm was measured on the third finger pulp. With compa rable baseline values, the increases in perfusion to the 4 application s of acetylcholine were significantly attenuated in heart transplant r ecipients compared with controls: 59 +/- 9 vs. 146 +/- 32, 242 +/- 39 vs. 492 +/- 77, 450 +/- 66 vs. 845 +/- 120 and 699 +/- 77 vs. 993 +/- 139% (mean +/- SEM; all p < 0.01). Peak hyperemia (134 +/- 4 vs. 153 /- 12 arbitrary units (AU); p < 0.05), time for the hyperemic perfusio n to return to preocclusive baseline (52.4 vs. 102.9 s; p < 0.01) and hence the area under the perfusion curve (1469 +/- 244 vs. 4581 +/- 92 1 AU s; p < 0.01) were reduced among heart transplant recipients. The area under the perfusion curve correlated significantly, with mean art erial blood pressure (r = - 0.60, p < 0.01) and with the responses to iontophoresis of acelylcholine (r = 0.41 p < 0.01), Two non-invasive t ests of vascular function demonstrate attenuated endothelial-dependent microvascular responses in heart transplant recipients. The relative impact of prior congestive heart failure and postoperative factors, su ch as treatment with cyclosporine. remains to be determined.