HISTOPATHOLOGIC COMPARISON OF A PULMONARY AUTOGRAFT AND PULMONARY HOMOGRAFT IN A PATIENT 17 MONTHS AFTER A ROSS PROCEDURE - AN AUTOPSY STUDY

Background and aim of the study: The Ross operation has become very po pular during the last decade, However little is known about the cellul ar behaviour of a normally functioning pulmonary autograft. Methods: T his case report deals with a 14-year-old female who died from a non-va lve-related cause 17 months after a Ross-Konno operation using a cryop reserved viable pulmonary homograft for the right outflow tract. Compa rison is made between the homologous and autologous pulmonary valves b y 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 ventri cular aspect of one cusp as a likely adaptation to a transvalvular gra dient. The homograft was extensively devitalized, its cusps being part ially covered with a fibrous sheath of recipient origin; few inflammat ory cells, consisting of macrophages and rare T lymphocytes were prese nt. Conclusions: The most puzzling observation, which needs confirmati on, is the selective disappearance of the dendritic cells from the via ble autograft. It is disappointing that a viable cryopreserved homogra ft valve has devitalized in the midterm. This phenomenon seems to resu lt from a clinically silent immune reactions.