Overview of Cardiac Allograft Pathology

Cardiac allograft pathology is quite similar the transplant pathology of other solid organ allografts. It is important to anticipate the histopathological changes based on the time after transplantation. Changes most commonly observed during the first two months after transplantation include preservation or ischemia/reperfusion, acute rejection, previous biopsy sites, and occasionally, opportunistic infections. Ischemia/reperfusion injury is most common in the first endomyocardial biopsy, which is usually obtained between one and two weeks after transplantation. Therapy-requiring acute rejection is also most common and most severe within the first 4 -6 weeks after transplantation. Thereafter, serious rejection is relatively uncommon. Since endomyocardial biopsies are routinely obtained at weekly or biweekly intervals during the first few post-operative weeks, pathology related to previous biopsy sites is also common during this early time period. Compared to kidney, liver and intestinal allografts, opportunistic infections such as viral infections by the Herpes family(HSV, CMV, EBV and HSV) rarely involve the heart allograft.

Histopathological findings in endomyocardial biopsies obtained late after transplantation are more limited than those seen early after transplantation. Although mild focal or diffuse rejection is relatively common, more serious, therapy-requiring moderate or severe rejection are distinctly uncommon. In contrast, Quilty lesions, or endomyocardial infiltrates(EI) are seen in a significant number of EMB obtained after long term survival. Other relatively common late changes observed include patchy or diffuse endocardial, interstitial or perivascular fibrosis.

Selected References

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2. Billingham ME. Cardiac Transplantation. In: Sale GE, ed. The Pathology of Organ Transplantation. Boston: Butterworths, 1990:133-152.
3. Billingham ME, Cary NRB, Hammond ME, et al. A working formulation for the standardization of nomenclature in the diagnosis of heart and lung rejection. Heart rejection study group. J Heart Transplant 1990;9(6):587-593.
4. Billingham ME. - Pathology and etiology of chronic rejection of the heart. Clin Transplant 1994;8(3 Pt 2):289-292.
5. Tazelaar HD, Edwards WD. Pathology of cardiac transplantation: recipient hearts (chronic heart failure) and donor hearts (acute and chronic rejection). [Review]. Mayo Clin Proc 1992;67(7):685-696.
6. Winters GL, Costanzo-Nordin MR. Pathological findings in 2300 consecutive endomyocardial biopsies. Mod Pathol 1991;4(4):441-448.
7. Kemnitz J, Cohnert T, Schafters H, et al. A classification of cardiac allograft rejection. Am J Surg Pathol 1987;11(7):503-515.
8. Pardo-Mindan FJ, Lozano MD, Contreras-Mejuto F, et al. Pathology of heart transplant through endomyocardial biopsy. Semin Diagn Pathol 1992;9(3):238-248.

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