Histopathologic comparison of a pulmonary autograft and pulmonary homograft in a patient 17 months after a Ross procedure: an autopsy study.

Abstract

BACKGROUND AND AIM OF THE STUDY: The Ross operation has become very popular during the last decade. However little is known about the cellular behaviour of a normally functioning pulmonary autograft. METHODS: This case report deals with a 14-year-old female who died from a non-valve-related cause 17 months after a Ross-Konno operation using a cryop-reserved viable pulmonary homograft for the right outflow tract. Comparison is made between the homologous and autologous pulmonary valves by macroscopic description, histology and immunohistochemistry. RESULTS: The autograft kept its cellular population-except for the dendritic cells which have disappeared, and developed a jet lesion on the ventricular aspect of one cusp as a likely adaptation to a transvalvular gradient. The homograft was extensively devitalized, its cusps being partially covered with a fibrous sheath of recipient origin; few inflammatory cells, consisting of macrophages and rare T lymphocytes were present. CONCLUSIONS: The most puzzling observation, which needs confirmation, is the selective disappearance of the dendritic cells from the viable autograft. It is disappointing that a viable cryopreserved homograft valve has devitalized in the midterm. This phenomenon seems to result from a clinically silent immune reactions.