Biochemical Analysis Of Stentless Quadrileaflet Bovine Pericardial Mitral Valve With Nonlinear Finite Element Model

Objective:To improve the design for stentless quadrileaflet pericardial mitralvalve, and take a nonlinear finite element model to identify the staticstress distribution of the lately designed type stentless bovine valve atopen and closed position during cardiac cycle.MethodsAccording to the bionical rule, the first generation modified CSstentless quadrileaflet pedeardial mitral valve (MCSV) was fabricated byfour bovine pericardial leaflets, which both anterior leaflet and posteriorleaflet were symmetry, and the valve orifice was oval like. The latelydesigned MCSV's orifice had the same vertical diameter and horizontaldiameter as the first generation one, and its length : width ratio was about3:2. Both types of valves were divided into two groups, each group hadthree valves. The stentless valves were fixed on special designed rigidstents. We took the stentless heart valve and blood stream as a couplesystem to make kinetics analysis and established a reasonable dynamicmodel and effective computational method for imitating opening andclosing phase of the lately designed MCSV, A finite element code wasdeveloped to solve this computational problem using the 8-nodeuper-parameter nonlinear shells and the Newton-Raphson method. This model incorporated the geometry, tissue thickness ,and elastic modulusof the bovine pericardium, the load was the mean transvalvular pressuregradient of the lately designed MCSV at open and dosed position, andthe stress was determined with ANSYS analysis software.Results1.When mitral valve was at open position, the stress of the latelydesigned MCSV was very low. The first principle normal stress in themost areas of the lately designed MCSV were 0.080 to 0.789Mpa.Thelargest principle stress of the four leaflets was 0.903Mpa and occurred inthe border of the leaflets.The second principle normal stress in the mostarea of the lately designed MCSV was 0.005 to 0.167Mpa,The largestsecond stress was 0.946Mpa and occurred in the border of the leaflets.2.When mitral valve were at closed position, the first principlenormal stress in the most areas of the lately designed MCSV was 1.200 to2.410Mpa,the largest principle normal stress of anterior leaflet andposterior leaflet was 3.060Mpa and occurred in the base of the leaflets.The largest principle normal stress of lateral leaflets was 1.809Mpa andoccurred in the free border of the leaflets. The second principle normalstress in the most areas of the lately designed MCSV were 0.051 to0.514Mpa,The largest second principle normal stress wasl.650Mpa andoccurred in the base of the leaflets.3.The average principle normal stress and the distribution of the lately designed MCSV was close to the first generation MCSV. Bothaverage principle normal stress were a little more than that of theprototype anterior leaflet and lower than that of the posterior leaflet, butthere's a high level band in the valvular ring suture area.Conclusions1. The calculated formation of the leaflets at the open and closephases and dynamic model of the lately designed MCSV which wascalculated by finite element analysis had extreme similarity to its actualmovements which was observed in the pulse duplicate flow meterexperiment. The computational method of finite element was convincible.2. The average stress distribution on the leaflets of the latelydesigned MCSV were even. and the lately designed type stentlessbovine valve could improve the endurance of the stentless pericardialmitral valve.