Echocardiography improves detection of rejection after heterotopic mouse cardiac transplantation.

BACKGROUND

Current assessments of cardiac rejection in murine transplant models rely on subjective estimates of the force of the palpable heart beat that have limited sensitivity and precision.

METHODS

We used 2-dimensional echocardiography to evaluate changes in left ventricular posterior wall thickness (PWT) in a heterotopic cardiac mouse transplant model of rejection. Nine allografts and 6 isografts were imaged daily for 6 days and harvested. Thirteen allografts were imaged daily and harvested at day 3.

RESULTS

Intraobserver variability on PWT was 0.003 +/- 0.09 mm, interobserver variability 0.09 +/- 0.11 mm. Allograft PWT increased after transplantation (0.74 +/- 0.02 mm to 1.28 +/- 0.05 mm at day 5, P <.0001). For isografts, PWT remained constant (0.73 +/- 0.03 mm to 0.85 +/- 0.01 mm) after an initial increase at day 1. Palpation failed to identify rejection at day 3 whereas PWT was already increased (1.15 +/- 0.02 mm in the allografts at day 3 vs 0.85 +/- 0.02 mm in the isografts, P <.0001). There was a relation between histologic score and PWT (P <.0001).

CONCLUSION

Two-dimensional echocardiography allows the noninvasive detection and follow-up of cardiac rejection after transplantation. It eliminates the subjectivity of palpation and provides quantitative and reliable indices of rejection.