Dysfunction Patterns of Epoxy-Treated Tissue Heart Valves

Purpose: to perform comparative morphological analysis of causes of dysfunction of epoxy-treated, xenoaortic and xenopericardial, tissues heart valves.Materials and methods. We included in this study 475 patients with mitral valve disease who have undergone heart valve replacement with tissue valve: (“KemCor”, n=211 [group 1]; “PeriCor”, n=126 [group 2]; and “UniLine”, n=138 [group 3]). Degenerative changes in 26 tissue valves (n=9 “KemCor”, n=11 “PeriCor”, and n=6 “UniLine”) explanted from the mitral position during the repeat replacement were evaluated macroscopically for the presence of calcifications, perforations, leaflet tears and ruptures, pannus, and leaflet fusion to the stent frame. Analysis of survival, freedom from dysfunction and reoperation of the studied tissue heart valves was performed for the period from January 1, 1995 to March 01, 2017.Results: Pannus overgrowth on the stent struts with extension onto the leaflets was seen on 53.8% of explanted tissue valves. “KemCor” and “PeriCor” tissue valves demonstrated over 70% rate of adhesion formation at the commissure, and in 93% of these cases there were leaflet ruptures at the commissure. Signs of calcification of different grades had 57.6% of specimens. Over 50% of “PeriCor” and “UniLine” tissue valve specimens had calcification at the stent frame. Calcified pannus was noted in 35% of all studied tissue heart valves. Interestingly, dysfunction in 53.3% of the studied tissue heart valves with detected calcification was not associated with calcific deposits. The 6-year actuarial survival for groups I, II and III was 73.5, 66.1 and 87.6%, respectively (group I vs. group II, p=0.6; group II vs. group III - p<0.05; group I vs. group III - p<0.05). The actuarial freedom from reoperation was 81.9%, 75.0% and 94.2%, respectively (pI-II>0.05; pII-III<0.05; pI-III<0.05). The actuarial freedom from dysfunction was 79.6%, 75.0%, and 94.2%, respectively (pI-II>0.05; pII-III<0.05; pI-III<0.05).Conclusion. The structure of dysfunctions of the studied tissue heart valves was represented by primary tissue failure, calcification and pannus growth. Specific design of the “UniLine” valve allowed to prevent the formation of adhesions between leaflets and the frame in the commissure buttress area, and as a result leaflet rupture from the stent struts. Xenopericardial “UniLine” tissue valves turned out to be superior to xenoaortic “KemCor” and “PeriCor” tissue valves in terms of survival, freedom from reoperations and dysfunction within the 6-year follow-up.

A Note on the Blood Analog for In-Vitro Testing of Heart Valve Bioprostheses

Glycerol solution with the viscosity coefficient similar to that of blood is used in evaluating the performance characteristics of prosthetic heart valves in the laboratory. However, physiological saline solution is used as a test fluid in testing tissue heart valves even though the viscosity coefficient does not match that of human blood. It is commonly believed that glycerol is absorbed by the tissue valves and hence the leaflets become stiff, making the test results invalid. However, in our laboratory a comparison of tissue valves exposed to glycerine solution at various times does not indicate any difference in the leaflet opening characteristics. Hence, it is suggested that glycerine solution be used as a test fluid for the evaluation of tissue valves also.