Numerical Simulation Transcatheter Aortic Valve Implantation and Mechanics of Valve Function

As the older population increases, age-related diseases such as aortic stenosis is a common heart condition in which there is a thickening and calcium deposition in the aortic root and aortic valve leaflets. This results in a host of symptoms like angina, embolism, stroke and sudden death. Current default treatment for severe aortic stenosis is surgical aortic valve replacement. Mechanical and bioprosthetic heart valves are common choice for surgical replacement of the diseased valves. However, surgical intervention is extremely risky for a large population of frail patients. Transcatheter Aortic Valve Implantation (TAVI) is being used selectively as a percutaneous alternative to surgical aortic valve replacement. This is a very complex procedure and involves very coordinated team work. This procedure involves steps from valve crimping to implantation and monitoring. Computational simulations of the TAVI help evaluate the valve functioning. In present study, a step-by-step complex numerical simulations of the TAVI procedure including the stent crimping and balloon inflation are presented. The stent frame is assumed as stainless steel and the outer skirt is assumed as polyethylene material. The stent frame is modeled with 3D hexagonal finite elements and the skirt is modeled as thin shell elements with fabric material property. The valve leaflets are modeled as Mooney-Rivlin material. The results of valve crimping and blood flow during ejection phase are presented. The SPH technique is used in modeling the flow through the aortic valve. The stent deformation and the stresses induced due to crimping are presented. The normal and calcified leaflets opening are presented.. The LS-DYNA® multi-physics capabilities of fluid structure interaction is presented..