MICROVASCULAR VASODILATORY FUNCTION AT 3 MONTHS AND ONE-YEAR AFTER CARDIAC TRANSPLANTATION

Coronary occlusive disease (COD) is the major complication after the f irst year in cardiac transplant patients and may be initiated by perio perative factors. Coronary angiography is usually used but is an insen sitive monitoring method. Coronary flow measurements allow investigati on of the responses of the coronary microvasculature. The authors inve stigated the hypothesis that coronary flow responses (CFR) to papaveri ne (a nonendothelial-dependent vasodilator) and acetylcholine (an endo thelial dependent vasodilator) are impaired early after cardiac transp lantation. Ten patients were studied at three months (3/12) and one ye ar (12/12) after transplantation. No patients had COD on angiography. A Doppler flow probe was inserted into the proximal left anterior desc ending coronary artery in all patients. Incremental doses of intracoro nary papaverine (Pap), and glyceryl trinitrate followed by acetylcholi ne (Ach), were given until maximum hyperemia was achieved. CFR for eac h drug was defined as the ratio of resting to peak coronary blood velo city. CFRPap was lower at 3/12 as compared with 12/12: 3.1 SD 1.1 vers us 3.9 SD 1.3 (P = 0.05, Student's t test). CFRAch was impaired at 3/1 2 as compared with 12/12: 1.9 SD 0.6 versus 2.6 SD 0.5 (P = 0.01). End othelial- and nonendothelial-dependent microvascular vasodilation are impaired early after cardiac transplantation but subsequently improve. Perioperative coronary damage may play a crucial role in the pathogen esis of COD.