The Evaluation of the Intramyocardial Coronary Microvasculature Subsequent to Heart Transplantation Using Microscopic and Immunohistochemical Methods

Introduction: This paper presents some histologic and immunohistochemical aspects of the intramyocardial microvascular network performed subsequently to cardiac transplantation in Romanian patients.
Material and method: We investigated a group of 30 heart transplant patients, aged between 12 and 58 at the time of transplantation, with an average age of 39 years, 23 male and 7 female patients. We studied in these patients the affection of the intramyocardial microvascular network subsequently to cardiac transplantation, using histologic and immunohistochemical standard methods. We followed the occurrence of foam cell arteritis at the level of large epicardial coronary arteries, as a direct sign of chronic rejection, lesions detected post-mortem at necropsy.
Results: In our study the most frequently detected microvascular lesions were the endothelial cell alterations, vascular wall thickening and severe perivascular fibrosis. Ischemia and reperfusion lesions with slight microvascular impairment were present in all patients in the first post-transplant biopsies (first 3–6 weeks). Acute cellular rejection developed in 6 patients in the middle and late period, in these cases we detected vasculitis lesions at the level of endomyocardial biopsies. Chronic rejection has affected three patients, who presented lesions at the level of large epicardial coronary arteries, as well as at the level of the small intramyocardial ones, such as wall thickening or perivascular fibrosis.
Conclusion: Subsequent to heart transplantation, small intramyocardial vessels are affected by immunological (rejection) or non-immunological factors (ischemia and fibrosis). Histologic and immunohistochemical study methods applied at the level of endomyocardial biopsies or post-mortem are useful for accurate assessment of small intramyocardial vessels and their involvement in the viability of the allograft.