Performance of Novel Polymer Heart Valve in Ovine Mitral Model

Objective: Evaluate the performance, hemocompatibility and histopathological consequences of a novel polymer mitral valve implant compared to Carpentier-Edwards bovine pericardial valve in an ovine model. This polymer valve (silicone polyurethan urea) was previously compared to bovine pericardial valve in the aortic position and found to be equivalent.Methods: Four sheep underwent thoracotomy open heart surgery on cardiopulmonary bypass in which both anterior and posterior mitral leaflets were excised and a patented polymer heart valve was implanted. The control group had implant of a bovine pericardial valve. Post-operative transthoracic echocardiograms were performed to evaluate valve function on post-op days 7-14, 30, 60 and pre-termination at 90 days. Blood samples for hematologic and chemistry measurements were obtained on the same schedule. Gross and histological examination of the valves was done after excision on POD 90. Histological exam of the heart, brain, kidneys and liver were done to identify potential embolic injury. Enoxaparin was given from POD 4 to POD 42.Results: Serial echocardiographic measurements showed comparable values between pre-operative and post-operative studies. There were no significant changes in blood test results in either group. The polymer valve leaflets were free of pannus, calcium-mineralization, shrinkage, endothelium or reduction in pliability. There was appropriate endothelialization and fibrosis at each tissue/frame interface. The bovine pericardial valve results were similar with the exception of fibrous pannus extending onto leaflet surface.Conclusions: The novel polymer mitral valve has a functional and safety profile that is similar to a bovine pericardial valve. However, the polymer valve has no cellular or thrombotic debris on its leaflets. It appears to be safe for human implants.