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A Pulsatile Simulator for the in Vitro Analysis of the Mitral Valve with Tri-Axial Papillary Muscle Displacement

Purpose We developed a new pulsatile hydrodynamic simulator for the in vitro testing of mitral valve (MV) samples. The required specifications included a 3D positioning system for the papillary muscles (PMs) that is accurate and simple to manage; measurement of the force exerted by the chordae tendineae on the PMs; and the possibility to visually inspect the MV for kinematic analysis. Methods An atrial/ventricular chamber system was developed. The ventricular chamber housed a triaxial actuator system that was aligned to a morphometric Cartesian frame, allowing for PM positioning even while tests are running. Each PM holder had an embedded load cell for force measurement. The atrial chamber was designed so as to permit MV visual inspection, maintaining a non-disturbed flow at the sample inlet. The setup was subjected to trials with fresh porcine MVs. Flow and pressure difference across the MVs and PM forces were measured in different MV configurations, with different PM spatial dislocations. High speed video recordings were acquired. Results The positioning accuracy was assessed. Tests with MVs showed good usability, even by the non-engineering personnel. The effects of PM displacement on valve function (valve competence and PM forces) was consistent with previously published data, thus confirming the general soundness of the design principles. Conclusions The developed simulator is a promising instrument for performing MV in vitro tests in a precise, well-repeatable manner. The ability to completely adjust the PM position while a test is running boosts the simulator's potential for detailed investigations of the pathological and surgically treated MV.