INTRAMYOCARDIAL ELECTROGRAM RECORDINGS FOR DIAGNOSIS AND THERAPY MONITORING OF CARDIAC ALLOGRAFT-REJECTION

The registration of intramyocardial ECG amplitudes (IMEG) is a non-inv asive diagnostic method of monitoring cardiac allograft rejection. In order to detect possible sources of error IMEG signals were recorded i n heterotopic neck hearts in ten beagle dogs. Immunosuppression was ba sed on cyclosporin A. The rejection process was followed by IMEG regis trations as well as by serial myocardial biopsies. Intramyocardial ele ctrogram recordings were made via three unipolar and three bipolar lea ds obtained from screw-in electrodes in both ventricles and the apex o f the allograft. A 10% voltage drop was used as an indicator of reject ion. In four dogs, the first rejection episode was treated with methyl -prednisolone and the therapy's success was monitored by IMEG and repe at biopsy. At autopsy the histology of each electrode circumference wa s correlated with the corresponding IMEG. The average sensitivity of a single lead was not acceptable (unipolar: 28%, bipolar: 47%). When th e voltages of different leads were summed up the sensitivity rose to 4 3% (3 x unipolar), 85% (3 x bipolar) and 100% (all leads). During reje ction therapy the IMEG recovered within 24-48 h. We conclude that in m oderate allograft rejection (grade 2/3a ISHT classification), the reje ction-related changes of intramyocardial ECG voltage amplitude (IMEG) seem to follow a ''focal pattern'' similar to the histology. Therefore the recording of several, preferably bipolar, electrode configuration s appears to enhance adequate diagnostic reliability.