ENDOTHELIAL DYSFUNCTION EARLY AFTER HEART-TRANSPLANTATION - ASSESSMENT WITH INTRAVASCULAR ULTRASOUND AND DOPPLER

Background. Allograft vasculopathy after heart transplantation is thought to represent a response to endothelial injury in the graft vessels. To assess endothelial function before the onset of anatomic disease, coronary vasomotor responses to adenosine, acetylcholine, and nitroglycerin were evaluated in transplant recipients by intravascular ultrasound imaging and Doppler flow studies. Methods and Results. Nine patients were studied 1 year after heart transplantation. Acetylcholine provoked significant vasoconstriction to 82% of maximal coronary diameter but was associated with an increase in mean coronary blood flow from 63.1 to 204 ml/min. Coronary blood flow increased fivefold in response to adenosine, a normal response. Conclusions. The vasomotor response to acetylcholine at 1 year after heart transplantation is consistent with endothelial dysfunction in the epicardial conduit vessels. Microvascular function as judged by coronary flow reserve appears to be normal.