Pulsatile flow past St. Jude Medical bileaflet valve. An in vitro study.

An in vitro hemodynamic study of the St. Jude Medical bileaflet aortic prosthesis was performed in a mock circulatory system simulating physiological pulsatile flow. The study included measurements of pressure drop across the valves, percent regurgitation, velocity, and turbulence in a model human aorta. The measurements indicated that pressure drop (mean systolic pressure drop of 6.2 mm Hg), percent regurgitation (10.15%), and turbulent normal stresses immediately downstream from the valve (825 dynes/cm2) were better than those with other prosthetic valves and bioprostheses. The flow development in the aorta was not significantly affected by the orientation of the bileaflet valve in the root of the aorta. However, velocity measurements immediately downstream from the valves showed flow reversal and separation in the vicinity of the hinge points of the leaflets where thrombus formation has been previously reported.