Micromechanics of the Aortic Valve:Durability Testing

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EXCEED THE SPACE PROVIDED. With the emergence of Catheter-lmplantable (Cl) valves, the bioprosthetic heart valve field has come full circle. In the 70's and early 80's, the valve industry was young and na'i've. Hundreds of surgeons and engineers toyed with dozens of different valve designs. Many of these early designs failed, most were rejected, and with the passage of time and clinical experience, the industry settled with stentless and stent- mounted porcine xenograft and bovine pericardial valves. This limited choice of bioprostheses, however, turned out to be a great benefit for heart valve recipients. For the past 15 years, patients have enjoyed outstanding performance and safety with current generation bioprosthetic valves - a very different scenario from the nascent period of prosthetic valves in which flawed designs lead to early valve failure and patient death. With the emergence of Cl valves, we have returned to the days when immature and potentially flawed devices are tested on patients during clinical trials. This need not happen. Much can be learned from the lessons of the past and applied to the refinement of Catheter-lmplantable valves. We propose to develop functionally accurate fluid-structure interaction (FSI) finite element analysis (FEA) models of pericardial tissue-based Cl valves and prospectively test a series of design iterations. Specifically, we will (i) simulate the fabrication process of a generic Cl valve using our existing FEA technology, duplicating the internal pre-stress of its components, (ii) characterize the fluid dynamics environment within a hydrodynamic valve tester using digital particle image velocimetry (DPIV) so that we can (iii) validate the FSI model of a simplified Cl valve against real functional data. This will enable us to then (iv) simulate a series of design, manufacture and deployment variations in a modeling environment that is realistic and representative of a real Catheter-lmplantable valve. Computational modelling approaches have had limited use in most biomedical devices because failure mechanisms are not well known. Computer modeling, however, can have great benefit in the application of known failure mechanisms to completely new valve designs. The new wave of Cl valves is in dire need of design review and analysis, and hence fertile ground for computational modeling studies. The lessons learned with conventional bioprosthetic valves can be applied to Cl valves, their design and performance improved, and complications in clinical trials thus reduced. PERFORMANCE SITE ========================================Section End===========================================