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DOI: 10.1055/s-0032-1332392
Histology of Melody heart valves and surgically implanted RVOT-conduits
Objectives: We examined and compared interventionally and surgically implanted valved conduits in the pulmonary position after surgical explantation by means of histology and immunohistochemistry.
Methods: 7 Melody valves were histologically analysed (implantation time 21 months to 4.5 years). Indication for explantation had been stenosis in 6 and valve insufficiency in 1 patient. 2 patients had suffered from endocarditis. 10 homografts, 3 Contegra conduits, and 11 Hancock conduits served as controls (implantation time 6 months to 19 years). All explants were worked up using a uniform protocol with fixation in formalin and embedding in methylmethacrylate. Serial sections were obtained by sectioning with a diamond cutter and grinding, thus saving the metal/tissue interface for histological evaluation.
Results: All Melody valve leaflets were thin and seemed intact. There were slightly more inflammatory reactions locally related to Melody valves as compared to other pulmonary conduits, especially in one of the patients after endocarditis. Reason for stenosis in both groups appeared to be pseudointima proliferation with an identical pattern of fibromuscular cells and extracellular matrix components. No significant thrombotic deposits were seen. Endothelialisation could be demonstrated in all specimen with antibodies against von-Willebrand factor and CD-31, respectively.
Conclusions: This is the first series of explanted Melody valves that is analysed histologically and compared to surgically implanted valved conduits in the pulmonary position. The quality of tissue reactions appeared very similar in both groups, whereas there were more pronounced inflammatory reactions locally related to Melody valves.