Biomechanical Study On The Influence Of The Geometry Of Sinotubular Junction Taper On Aortic Valve Closure Function

Arterial switch operation is an ideal surgical procedure for the complete transposition of the great arteries.The geometrical structure of the new aortic root is considered as important factors of postoperative induced aortic insufficiency.However,the sinotubular junction taper on the effect of aortic valve closure function haven't been deep researched.The purpose of this research is that the biomechanical mechanism of the different sinotubular junction taper on the effect of aortic valve closure function be investigated from numerical simulation and experiment.To provided the reference and basis for arterial switch operation and helped clinicians determine the geometry of the new aortic root.According to the related research about the geometric relationship of the aortic root,this research established an idealized geometric model of aortic root in different sinotubular junction taper.On the basis of the geometric model,the finite element model and the experiment of pulsatile flow model were established.The sinotubular junction taper angle for 0 degrees of the finite element model as the reference model A,the finite element model B,C,D,E,F,G were established with the sinotubular junction taper angle for 1 degrees,3 degrees,5 degrees,7 degrees,9 degrees,11 degrees.The leaflet contact pressures were obtained by finite element analysis.And the different sinotubular junction taper on the effect of the aortic valve closure function were analyzed.In the experiment of pulsatile flow,the model A,B,C,D were established with the sinotubular junction taper angle for 0 degrees,1 degrees,3 degrees,5 degrees by 3D print.According to ISO5840 standard,the experiment of pulsatile flow was performed under the condition of cardiac output of 2-7L/min with artificial bioprosthetic heart valve.The parameters such as the mean transvalvular pressure gradients,the regurgitation fraction and effective valve orifice area were compared and analyzed.The sinotubular junction taper on the effect of the performance of artificial bioprosthetic heart valve were evaluated by the parameters.The results of this research showed: first,on the structural finite element analysis,compared with the reference model A,the leaflet contact pressure of the model B,C,D,E,F,and G increased by 10.5%,28.2%,91.6%,97.6%,259.5%,119.9%,respectively.Second,the following results were obtained from the experiment of pulsatile flow.(1)The mean transvalvular pressure gradients agreed well with the national standard,and all smaller than 10 mmHg.On the same output condition,the maximum mean transvalvular pressure gradients of the different models were about 25%.(2)With the increase of cardiac output,the results showed a lower the regurgitation fraction of model B and a higher the regurgitation fraction of model C.On the same output condition,the maximum change of the regurgitation fraction of different models was about 54%.In the case of smaller stroke volume,the model B has the maximum the effective valve orifice area.In the case of larger stroke volume,the model C has the maximum the effective valve orifice area.These following conclusions can be drawn.First,with the increase of sinotubular junction taper,the leaflet contact pressure increased in the structural finite element numerical simulation.The influence of the different sinotubular junction taper on the leaflet contact pressure was different.The larger leaflet contact pressure may be the cause of aortic regurgitation.In the aspect of the experiment of pulsatile flow,(1)the smaller sinotubular junction taper showed beneficial to decrease the regurgitation fraction.(2)The different sinotubular junction taper had a different influence on the mean transvalvular pressure gradients of the artificial bioprosthesis valve.(3)The different sinotubular junction taper had influence on the effective valve orifice area of the artificial bioprosthesis valve.Therefore,clinical surgery should consider that in the case of smaller stroke volume,the smaller sinotubular junction taper was beneficial to increase the effective valve orifice area.In the case of larger stroke volume,the larger sinotubular junction taper was beneficial to increase the effective valve orifice area.