The Effect Of Arterial Blood Flowing On The Activity Of Homograft Heart Valves In The Process Of Cryopreservation

The history of artificial heart valve now was nearly half a century. The application of themechanical valve greatly enhance and improve the security of the valve replacement surgery, butwe still can’t overcome its inherent shortcomings. While homograft heart valves have excellenthemodynamic characteristics and good biocompatibility, it is easy to calcification and long-termdurability is poor. In recent years, cryopreservation and clinical application of homograft heartvalves has been gradually carried out at home and abroad, but due to a variety of differenttechniques, the actual preservation and clinical applications are also different.ObjectiveTo study the protective effect about arterial blood flowing to homograft heart valves in theprocess of preparation and cryopreservation, and further to explore its possible mechanisms.MethodsTwelve healthy and adult Chinese white rabbits were acted as receptors. Thirty-sixChinese white rabbits（1～1.5 month-old） were acted as the donors, and we surgery to removetheir aortic valves. Then divided those aortic valves into three groups randomly, marked as A, Band C. We preserved group A, as the control group, in liquid nitrogen after gradient cooling;group B and group C, as the experimental groups, were transplanted to carotid artery on bothsides of the receptors. After 48 hours and 72 hours, respectively, removed the aortic valves ofGroup B and group C, and preserved them in liquid nitrogen after gradient cooling. After sixweeks, observed the structural changes of those valves’tissue by optical microscope and detectedthe water content, cell survival rate and calcium content about the valves’tissue.ResultsThere were no difference in ventricular surface of three groups（A, B, C,） observed byoptical microscope, but the shrinkage degree of fiber layer in the group B and C were less than ingroup A. The water content of the aortic valves tissue in group B and C were higher than ingroup A （F=10.49，P=0.001）, but it was no significant difference between group B and group C（P=0.63）. The survival cell rate of the aortic valves’tissue in group B and C were higher than in group A （F=12.85, P <0.001）, but it was no significant difference between group B and group C（P=0.16）. The calcium content of the aortic valves’tissue in group B and C were less than ingroup A （F=121.22, P<0.001）, but it was no significant difference between group B and group C（P=0.21）.ConclusionThe arterial blood flowing could reduce the difference of shrinkage degree between theventricular surface and the fiber layer in homograft heart valves. It also could improve homograftheart valves’cells live rate and water content, and reduce homograft heart valves’calcificationextent in the process of cryopreservation. It has better prospects for homograft heart valves’durability. Arterial blood could reduce homograft heart valves’tissue damage. It is probablyrelated to mechanical force and various components of arterial blood flowing (such as Na⁺, K⁺,Ga²⁺etc).