VENTRICULAR FLOW DYNAMIC PAST BILEAFLET PROSTHETIC HEART-VALVES

To characterise hydrodynamic properties of prosthetic heart valves in mitral position, ultrasonic velocity measurements were performed using a cardiovascular simulator. A Duromedics and a Saint-Jude Medical bil eaflet heart valve were tested. The Saint-Jude valve was oriented firs t in an anatomical position, i.e. the tilt axis parallel to the septal wall, and then in an anti-anatomical position. In the anti-anatomical position, from mid diastole to mid systole, two contrarotative vortic es are generated in the ventricle by the interaction between the flow directed by the leaflets downstream from the lateral orifices and the ventricular wall motions. In the anatomical position, the mitral flow penetrates the ventricle principally through the lateral orifice proxi mal to the septal wall, due to the vortex in the atrial chamber. The m itral inflow then circulates along the septal wall to the apex, and pr oduces a large ventricular vortex during systole. In the anatomical po sition, the Saint-Jude thus provides a better ventricular washout duri ng this phase. The mitral inflow through the Duromedics in the anti-an atomical position produces two contrarotative vortices in the ventricl e, but in the opposite sense than downstream the Saint-Jude valve; the flows that penetrate through the lateral orifices are directed to the ventricular walls and then recirculate to the centre of the ventricle , providing a very fluctuating flow near the apex. Thus, a slight diff erence in valve design produces a significant difference in the ventri cular flow fields.