Coronary microvascular endothelial dysfunction in transplanted children

Aims To assess the response of the coronary microcirculation to acetylcholi ne (endothelium-dependent vasodilator) and of adenosine (endothelium-indepe ndent vasodilator) in children after heart transplantation and to verify wh ether endothelial dysfunction is time-dependent. Methods and Results Ne studied the endothelial function of 26 asymptomatic children previously submitted to heart transplantation, with normal transpl anted hearts and epicardial coronary arteries. Ten untransplanted children served as controls. The response of coronary blood dow velocity to intracor onary infusion of acetylcholine (1.8 mug.min(-1)) and adenosine (270 mug.mi n(-1)) was assessed using a Doppler wire positioned in an epicardial corona ry branch. In the study group, coronary blood flow velocity increased sligh tly during acetylcholine infusion (geak/baseline ratio=1.17 +/- 0.22). The ratio was inversely correlated with the length of follow-up (r=-0.50; P=0.0 078). The peak/baseline ratio in control children was 1.76 +/- 0.73 (P<0.00 02 vs study group). After adenosine infusion, the coronary blood flow veloc ity peak/baseline ratio was 3.75 +/- 1.54 in transplanted children and 3.72 +/- 1.34 in controls (P=ns). Conclusions Endothelial dysfunction in paediatric transplanted patients bec omes more evident in patients with longer follow-up. This finding could gro ve useful in the prevention of accelerated arteriosclerosis. (C) 2001 The E uropean Society of Cardiology.