ARTERIAL LESIONS ASSOCIATED WITH MEDIAL DISORGANIZATION AND FIBROSIS IN ENDOMYOCARDIAL BIOPSIES FROM HUMAN CARDIAC ALLOGRAFTS

describe distinctive arterial lesions in endomyocardial biopsies from patients with human cardiac allografts, The lesions affected principal ly the media of small arteries and consisted of misorientation of smoo th muscle cells and fibrosis. This remodelling was most prevalent in t he subadventitial zone, but sometimes extended to involve the full thi ckness of the media, In the most extreme cases medial smooth muscle ce lls ran parallel to the long axis of the vessel and were segregated in to small bundles and single cells separated by collagen which merged w ith the adventitial fibrosis. The intima was always normal, Abnormal a rteries were present in 16% of 603 consecutive biopsies from 44 patien ts, and 39% of lesions occurred in 16% of patients, No lesions were fo und in endomyocardial biopsies from 25 non-transplanted patients, nor in mucosal biopsies from both transplanted and non-transplanted patien ts, confirming that the appearances were not due to biopsy artefact, T here was early arterial remodelling in biopsies within two weeks of tr ansplantation and none of the stages resembled vascular rejection, Fif ty per cent of biopsies from some patients contained arterial lesions, suggesting that in susceptible patients they are common.