Heterotopic heart transplantation alters high-energy phosphate metabolism irrespective of cardiac allograft rejection.
This study was undertaken to validate the potential of 31P magnetic resonance spectroscopy (MRS) as a noninvasive alternative for transvenous endomyocardial biopsy in detecting cardiac allograft rejection. Donor hearts from either Lewis rats (L) or Brown-Norway rats (BN) were transplanted into the neck of L rats resulting in a non-rejecting group L-L and a rejecting group L-BN. L-L and L-BN rats were serially studied by means of 31P MRS from postoperatine day 1-8. In addition, rejection was confirmed by histology. A similar, marked decrease in phosphocreative/beta- adenosinetriphosphate (PCr/ATP) ratio from day 1-3 was observed in both L-L and L-BN hearts. This ratio levelled off on postoperative day 3 and remained depressed on subsequent postoperative days in both groups, although histology showed an increase in the severity of rejection in L-BN. However, the PCr signal/noise ratio in L-BN started to decrease after day 4, coinciding with the histologic evidence of severe rejection (score IV), whereas in L-L hearts (score 0) this ratio remained unaltered until day 8. Since high-energy phosphate metabolism is affected by the unloaded status of the heterotopically transplanted heart, irrespective of rejection, the PCr/ATP ratio appears not to be a specific marker for the detection of acute rejection in this model. In contrast, the PCr S/N ratio appears to be a specific and sensitive marker of acute rejection, but only in a late, severe stage.
van Dobbenburgh
J O
JO
Interuniversity Cardiology Institute of The Netherlands, Utrecht, The Netherlands.
Kasbergen
C
C
Slootweg
P J
PJ
Ruigrok
T J
TJ
van Echteld
C J
CJ
D000818:Animals; D006084:Graft Rejection; D016027:Heart Transplantation; D008279:Magnetic Resonance Imaging; D009206:Myocardium / Q000378:metabolism*; D010710:Phosphates / Q000378:metabolism*; D051381:Rats; D011917:Rats, Inbred Lew; D014184:Transplantation, Homologous
D010710:Phosphates