Coronary arterial pathology in the transplanted human heart

The coronary arteries of 23 transplanted human hearts have been studied following death or re-transplantation, 8 days to 8 years after surgery, with a view to defining the sequence of changes in the first months. Occlusive arteritis occurs in association with acute rejection. Intimal hyperplasia, usually accompanied by disruption of the internal elastic lamina and proliferation of smooth muscle cells, may be seen within two weeks. Lipids and mucopolysaccharides appear in the thickened intima only after about 2 months. The end-state of the process is atherosclerosis, indistinguishable from that of the non-transplanted heart: for this to occur the patient must survive long enough, and therefore the early coronary occlusive process must not be too vigorous. It is unlikely that there are two different diseases of the transplanted coronaries, "chronic rejection" and "atherosclerosis". The apparent difference between these is due to the absence or presence of lipid, which is a function of time. In the transplanted heart, lipid is not an inciting factor in the arteriopathy. In this, the role of mitogens would appear to be critical.