In the present study, the performance of the liquid nitrogen frozen and thinned bovine pericardium was studied and compared with the porcine pericardium. The microstructure and mechanical properties of the bovine pericardium were observed and tested by hematoxylin-eosin (HE) staining and tensile test respectively. In all conditions, porcine pericardium was selected as a control group. The results showed that there was little difference in the performance of bovine pericardium after being frozen by liquid nitrogen. The secant modulus and ultimate strength of the thinned bovine pericardium were similar to those of porcine pericardium, however, the elastic modulus was a little higher than porcine pericardium. The study suggested that the performance of the thinned bovine pericardium was similar to those of porcine pericardium. It was easy for the thinned bovine pericardium to obtain a relatively ideal thickness and expected performance, therefore, the thinned bovine pericardium can be used as the materials of transcatheter aortic valve leaflets.
Animals ; Aortic Valve ; Bioprosthesis ; Cattle ; Elastic Modulus ; Freezing ; Heart Valve Prosthesis ; Nitrogen ; Pericardium ; physiology ; Swine

Objective To investigate the mechanical behavior of bovine pericardium with different orientations after compression and evaluate its effects on the duration of transcatheter aortic valve. Methods According to the fiber directions, the pericardial strips were divided into 12 groups of transverse, longitudinal and oblique pericardial strips, and each group included 3 strips of pericardium. One strip maintained the original state, and the other two strips were under 12.5 N and 25 N compression, respectively for 1 h. The mechanical properties of compressed samples were tested and analyzed subsequently in uniaxial tension test. Results The samples with different orientations showed obvious anisotropy before and after compression. The secant modulus, elastic modulus and ultimate tensile strength of the longitudinal pericardium were generally greater than those of the oblique pericardium, while the oblique pericardium was larger than the transverse pericardium. For longitudinal and oblique bovine pericardium under 25 N compression, the average tensile strength ratio was 0.92 and 0.87, respectively, and the ratio of tensile strength before and after compression had a significant difference (P＜0.05). The average tensile strength ratio of transverse bovine pericardium after 25 N compression was 0.97, and there was no significant difference in the ratio of tensile strength before and after compression (P＞0.05). Conclusions The compressive damage of the pericardia with different fiber orientations was very small under low stresses at transitory time. For design and production of transcatheter aortic valves, the orientations of the pericardium and the changes of strength after compression should be taken into consideration.