Dipyridamole-induced coronary vasodilation in human transplanted heart: preliminary report.

Coronary sinus blood flow and resistance were studied before and after intravenous dipyridamole in 4 patients with transplanted heart and normal coronary arteriogram treated by cyclosporine-prednisolone. Results were compared to those of a normal group of 7 subjects. Left ventricular endomyocardial biopsies were performed in the heart transplanted group. Mean right atrial pressure, cardiac index and left ventricular function were normal in the transplanted heart group. Mean aortic pressure and systemic vascular resistances were significantly higher in the transplanted group than in normals (p less than 0.01), but coronary resistance were similar. Dipyridamole-induced vasodilation resulted in an increased coronary sinus blood flow and a decreased coronary resistance in both groups, but these effects were reduced in 1 patient with a transplanted heart that evidenced an important perivascular fibrosis after a subacute rejection. In conclusion, this preliminary report of coronary blood flow in patients with transplanted heart indicates that the ability of coronary sinus blood flow to increase after dipyridamole is normal in the transplanted heart without allograft rejection. A major limitation in coronary vasodilation was observed in 1 patient with rejection antecedents and perivascular fibrosis, which could play a role in left ventricular function deterioration in some patients after heart transplantation.