Design conception and experimental setup for in vitro evaluation of mitral prosthetic valves.

BACKGROUND Since most complications related to the operation of prosthetic heart valves is due to disturbances of flow, its hydrodynamic characterization is a useful aid in the design of new prostheses. Simulations of pulsatile flow in cardiac prostheses began nearly 40 years ago, through the development of different mock human circulatory systems, improving the clinical results interpretation. A new design of a pulse duplicator system was developed at Polytechnic School of USP to study prosthetic heart valves. OBJECTIVE To present the conception of a new mock circulatory system for hydrodynamic simulations of cardiac prosthetic valves and the assembly plan of an experiment whose focus is the test of mitral prosthesis. METHODS Its conception is based on the state-of-art's review of these studies and the experience got with the previous mock circulatory systems, particularly the one used in the Instituto Dante Pazzanese de Cardiologia, São Paulo, SP, Brazil. RESULTS In this design, an electric servomotor controlled by computer emits, through a hydraulic piston, a pulse to the left ventricular chamber model, where the heart valves are accomodated. To characterize, in the future, the dynamic operation of mitral prosthetic valves, an experimental setup was mounted to provide measurements of volumetric flow, instantaneous pressure and velocity fields on these valves. Optical access is conveniently provided on the design, making possible the use, in the future, of a LDA system. CONCLUSIONS In order to improve the analysis of hydrodynamic shear stress and prediction of haemolysis, the experimental results may be used to regulate a numerical model using 'Computational Fluid Dynamics' (CFD).