814-1 Variations of Segmental Endothelium Dependent and Endothelium Independent Vasomotor Tone in the Long Term Follow Up After Cardiac Transplantation (Qualitative Changes in Endothelial Function)

To assess segmental vasoconstrictor and dilator responses in patients after cardiac transplantation (CT) without obvious angiographic disease we infused the endothelium dependent vasodilator acetylcholine (ACH) and the endothelium independent vasodilator SIN-1 sequentially into the left coronary artery. ACH infusions always preceded SIN-1 infusions. Responses of 156 nonstenotic coronary segments (LAD and CX) were investigated in 26 patients (P). Group 1: l0 P 11.3±3 months after CT. Group 2: 16 P 52±11 months after CT. Five different responses to ACH followed by SIN-1 were observed: A) dilation followed by no change (fully preserved endothelium dependent function). B) dilation followed by further dilation. C) no change followed by dilation. D) constriction followed by dilation (defective endogenous NO-release and intact vascular smooth muscle function). EI constriction followed by constriction (defective endogenous NO-release and defective vascular smooth muscle function).ResultsDifferent segmental reaction types in both groups.proximal LADdistal LADGroup 1:20% A, 20% B. 30% C. 30% D50% C. 50% DGroup 2:19% C. 69% 0.12% E12% C. 81% D.7% EConclusion(1) In only 20% of patients 1 year after CT the endothelium dependent vasodilation is completely preserved. In 40% of the patients 1 year after CT the endothelium shows segmental heterogeneity in response to ACH [absence of endothelium dependent vasodilation (type A and B) in the distal segment]. (2) In the long term course after CT more than 80% of P have defective endothelial function in proximal and distal segments [absence of endothelium dependent vasodilation (type A and B) in the proximal and distal segment]. Moreover approximately 10% have defective vascular smooth muscle function. Functional assessment of endothelial integrity in P after CT shows time dependent qualitative differences between proXimal and distal coronary segment