Unsteady flow through a new mechanical heart valve prosthesis analysed by digital particle image velocimetry

Digital particle image velocimetry was used to study the pulsatile flow through a new mechanical heart valve prosthesis. The design of the new prosthesis with three leaflets in symmetric arrangement is similar to the human aortic heart valve. A fully transparent 1: 1 model of the valve was used for laser-based flow visualization and velocity measurements to optimize the valve design. Planar velocity field measurements of the time-dependent flow field and high-speed recordings of the occluder motion were carried out in physiological pulsatile flow. The new valve shows a well-defined core flow with small wakes behind the leaflets. The specific three-leaflet design yields a desired wash-out effect of the stagnant regions in the aortic sinuses during valve opening and closure. The leaflets begin to close in an early stage of the end of the flow cycle which is promoted by induced backflow near-the walls and the sinuses. This leads to a relatively smooth valve closure and a reduced impact velocity.