Morphometric changes of the right ventricle in the first two weeks after clinical heart transplantation: analysis of myocardial biopsies from patients with complicated versus uncomplicated course.

OBJECTIVE The early phase following heart transplantation (HTx) is characterized by the development of right ventricular myocardial fibrosis (MF) and cardiomyocyte hypertrophy (CH). The question is if there are differences in development of MF and CH between patients with complicated versus patients with uncomplicated postoperative course. METHODS Endomyocardial biopsies were taken from 58 donor hearts before implantation and one and two weeks after HTx. According to the clinical course in the first year after HTx and the rejection grading (ISHLT), four groups were classified: (a) uneventful course, (b) transplant failure, (c) infections, and (d) rejection episodes > or = 1R. The volume densities of various tissue components and cardiomyocyte diameters were measured by stereological and morphometrical methods. RESULTS From implantation to the first two weeks, most groups showed a significant increase of endomysial and perimysial connective tissues. There was a significant CH recognizable, especially in the rejection group. However, nucleus surface, a hypertrophy parameter, showed no significant change during follow-up. There were no statistically significant differences in volume densities of interstitial space, capillaries, nuclei and cardiomyocytes between the collectives and points in time. Sarcomere length as marker of contraction status of cardiomyocytes remained at the same level and showed no significant differences. Demographic data showed no significant differences and will be presented. CONCLUSIONS Patients with complicated and uncomplicated courses show different degrees of histopathological changes after HTx. The extent of hypertrophy differs especially between the collectives. Measurement of endomysial connective tissue points to later postoperative course in the recipient. These findings may reflect a pattern of remodeling specific to the transplanted heart.