Experiment Study On Bio-Mechanical Properties Of Aortic Valves And Aortic Walls Under Different Physics State

The article is based on comprehensive reading on the techniques of cell extraction and the techniques of cryopreservation in liquid nitrogen .The biomechanical features of porcine aortic valves and aortic walls after cell extraction were studied and we also studied hominine aortic valves and aortic walls after preserved in liquid nitrogen from 3 months to 8 years, so as to lead the experiment research of cell framework and hominine valve replacement surgery in applications. In our cell extraction experiment research we use porcine hearts, because the biomechanical features of porcine aortic valve and aortic wall bear great similarity with that of human body's. Get their fresh aortic valves and aortic walls and then extract the cell, comparing with the fresh group, study the biomechanical features.In our liquid nitrogen preserved experiment, according to the preserved time we divided the hominine aortic valves and aortic walls into many groups, to find out whether the preserved time has effects on biomechanical properties of cryopreserved aortic allografts, to guide clinic applications. The specimens were tested under one-dimensional axial extension, and stress-strain curves of them were got; to the experiment of porcine aortic valves and aortic walls' cell extraction, we did stress relaxation; After stress relaxation, the stress relaxation curves were generalized; Finally the ultimate lagrangian stress were measured.By statistical analysis on the experiment results, we can got the following conclusion:There are no obvious differences in tensile strength, stress-strain curve parameters and stress relaxation curves of porcine aortic walls before and after cell extraction. For porcine aortic valves, there are some obvious difference in tensile strength and slope of lined parts of stress-strain curves before and after cell extraction. From the point of clinic applications view, we can't use porcine aortic valves after cell extraction as cell framework.The procedure-controlled temperature device and being preserved in liquid nitrogen have no obvious effects on biomechanical properties of allografts. From the parameters' statistical result of stress-strain curves, we can see that the biomechanical properties of aortic valves and aortic walls which stored in liquid nitrogen in 3 years tend to steady. however stored for above 4 years are obviously different, then not suit to clinic appliance. Tensile strength of latitude and longitude are different, it necessary to pay attention to the anisotropy of aortic walls in the surgery.