The role of Tissue Doppler imaging in the noninvasive detection of chronic rejection after heterotopic cardiac transplantation in rats.
BACKGROUND
Chronic rejection is a risk factor for the development of cardiac allograft vasculopathy (CAV) in heart transplant recipients. A useful animal model to study the role of immunosuppressive strategies in the prevention of chronic rejection involves heterotopic abdominal cardiac transplantation in rats. The detection of rejection and concurrent CAV traditionally involves subjective serial palpation of the graft from a scale of 0 to 4, with 4 indicating vigorous beats. Recent advances in murine echocardiography, in particular Tissue Doppler imaging (TDI), may allow for objective in vivo monitoring of chronic rejection in this transplant model.


OBJECTIVE
The objective of this study was to compare the diagnostic accuracy of murine echocardiography as compared to the abdominal palpation heart score for the noninvasive detection of chronic cardiac graft rejection.


METHODS
In an animal model of heterotopic cardiac transplantation, 18 male Fischer and Lewis rats were used as donors and recipients, respectively. Abdominal palpation and murine transthoracic echocardiography were performed to assess in vivo function of the transplanted heart. Left ventricular (LV) structure and function and TDI indices, including endocardial velocity (Vendo) and strain rate (SR), were evaluated in the ectopic heart. Graft tissues were processed for histological examination and graded for chronic rejection.


RESULTS
Abdominal palpation scores were obtained in all 18 rats; score 1 (n = 5); score 2 (n = 4); score 3 (n = 6); and score 4 (n = 3). The mean LV ejection fraction was significantly (P <0.01) lower in score 3 and 4 grafts as compared to score 1 grafts. There was no correlation between the abdominal palpation score and LV systolic function. There was a significant relationship between decreasing Vendo or SR values and increasing grades of rejection (r = 0.65, P <0.05 and r = 0.75, P < 0.05, respectively).


CONCLUSIONS
TDI of the transplanted heart in rats is feasible, reproducible, and more sensitive than palpation for the detection of chronic rejection.
Jassal
Davinder S
DS
Cardiology Division, Department of Cardiac Sciences, St. Boniface General Hospital, Manitoba, Canada. djassal@sbgh.mb.ca
Othman
Rgia A
RA
Ahmadie
Roien
R
Fang
Tielan
T
Zieroth
Shelley
S
Fischer
Gabor
G
Moghadasian
Mohammed H
MH
D000818:Animals; D015150:Echocardiography, Doppler / Q000379:methods; D006084:Graft Rejection / Q000000981:diagnostic imaging*; D016027:Heart Transplantation / Q000000981:diagnostic imaging* / Q000276:immunology; D008297:Male; D051381:Rats; D011916:Rats, Inbred F344; D011917:Rats, Inbred Lew; D016042:Transplantation, Heterotopic