Mitral prosthesis opening and flow dynamics in a model of left ventricle : an in vitro study on a monoleaflet mechanical valve
Résumé
A complete understanding of the flow past a mitral valve prosthesis require a new generation of pulse duplicators and more realistic flow conditions. The objective of this study is to describe the opening kinetics of a monoleaflet Medtronic Hall 27-mm mechanical valve in mitral position and to determine the flow pattern within the left ventricle using particle image velocimetry (PIV) for different instants during the cardiac cycle. At the onset of diastolic phase, the flow goes through the major orifice and then through the minor orifice. The two jets generated induce two counterclockwise vortices within the ventricle, which can lead to a partial closure of the valve during mitral E wave deceleration. During diastasis and mitral A wave, only one vortex persists in the ventricle and pushes the valve disk backward at the end of the diastolic phase. The valve disc never reached its maximum opening. This study underscores that the flow past a monoleaflet valve in mitral position is highly dependent on the complex interaction between the inflow, the vortices development within the left ventricle, and the gravity. Such a complex interaction can only be highlighted using new generation of pulse duplicators.