Velocities, shear stresses and blood damage potential of the leakage jets of the Medtronic Parallel bileaflet valve.

Even nowadays, the essential problem of mechanical heart valve prostheses is the risk of thromboembolic events mainly caused by unnatural hemodynamics, e.g. just a few years ago the Medtronic Parallel (MP) showed unsatisfactory clinical results caused by thrombi.

Leakage flow at mechanical heart valve prostheses: improved washout or increased blood damage?

Background And Aims Of The Study: An essential problem of mechanical heart valve (MHV) prostheses is the risk of thromboembolic events and consequent need of lifetime anticoagulation due to unnatural hemodynamics that results in traumatization of red blood cells and platelets. The precise spatial and tidal localization of blood-damaging events within the flow is poorly understood. The present study addresses the question whether leakage flow at MHV, which is claimed to improve washout in the hinge areas of microthrombi and platelet-activating agents, is responsible for significant blood damage.

Comparison of valvular resistance, stroke work loss, and Gorlin valve area for quantification of aortic stenosis. An in vitro study in a pulsatile aortic flow model.

Background: Valvular resistance and stroke work loss have been proposed as alternative measures of stenotic valvular lesions that may be less flow dependent and, thus, superior over valve area calculations for the quantification of aortic stenosis. The present in vitro study was designed to compare the impacts of valvular resistance, stroke work loss, and Gorlin valve area as hemodynamic indexes of aortic stenosis.

Methods And Results: In a pulsatile aortic flow model, rigid stenotic orifices in varying sizes (0.