HUMORAL REJECTION AFTER HEART-TRANSPLANTATION - RELIABILITY OF INTRAMYOCARDIAL ELECTROGRAM RECORDINGS (IMEG) AND MYOCARDIAL BIOPSY

In recent years, as the importance of humoral-mediated rejection has i ncreasingly become recognized, the fact that endomyocardial biopsies ( EX) evaluated according to the criteria of the International Society f or Heart and Lung Transplantation often produce false-negative results has become a matter of concern. To evaluate the reliability of measur ing intramyocardial ECG amplitude (IMEG) and immunofluorescence evalua tion (FITC-labeled anti-IgG/IgM staining) of endomyocardial biopsies ( IFM), heterotopic neck-heart transplantation (HTX) was performed on ei ght beagles previously sensitized through skin transplantations. After HTX, IMEG, echo, and donor-specific antibodies in serum (IgG, IgM) we re determined daily and myocardial biopsies (IFM, BX) were performed o nce every 2 days. Accelerated (humoral) rejection occurred on the 5th (4th-5th) postoperative day and sensitivity of IMEG, IFM, and EX was 1 00%, 75%, and 12.5%, respectively. In each case rejection was recogniz ed so early that it was possible to initiate therapy with ''restitutio ad integrum''. Our results show that, as opposed to endomyocardial bi opsy (IFM, EX), IMEG diagnosis detected humoral mediated rejection ear ly and with high reliability.