Preliminary Study on Mathematical Modeling for the Shape Design of Expanded Polytetrafluoroethylene Pulmonary Valved Conduit

Abstract

Right ventricular outflow tract (RVOT) reconstruction surgery is one of the surgical strategies for congenital heart failure, and is commonly used for the treatment of severe heart failure with pulmonary valvular problems. An expanded polytetrafluoroethylene (ePTFE) pulmonary valve was invented for RVOT reconstruction, and the authors have tested its hemodynamic and hydrodynamic characteristics for design improvement. The special features of the ePTFE valve are as follows: (a) anatomically identical trileaflet structure, and (b) bulging sinuses in the vicinity of leaflets. In this study, we used three types of pulmonary valves; an ePTFE valve with bulging sinuses, an ePTFE valve in straight conduit, and a natural pulmonary arterial valve extracted from a goat after the animal experiment. Then we measured the hemodynamic characteristics of the various types of ePTFE valves using a mechanical pulmonary circulatory system. Next, using the pressure and flow data derived from the mechanical circulatory system, we calculated the mechanical design parameters of the ePTFE valves based on a numerical modeling method by inverse analyses. The mathematical parameters we used in the model were inertia, damping, and stiffness coefficients, and we compared these values among three types of pulmonary valves. We succeeded to estimate the mechanical parameters for each valve from the hemodynamic data. The results suggest that the ePTFE valve with bulging sinuses may exhibit similar parametric characteristics to those calculated from the natural pulmonary heart valves.