Abstract

The dynamic behaviour of a novel chorded mitral prosthesis is studied using an immersed boundary model. To investigate the mechanical behaviour of the mitral design under physiological flow conditions without having to model the left ventricle, we make use of in vivo magnetic resonance images of the left ventricle. The relative motion of the mitral annulus and motion of the ventricle determined from these MRI images is then used as a prescribed boundary condition for the chorded mitral valve in a dynamic cycle. This model allows us to investigate the influences of the flow vortex generated by the ventricle motion on the valve dynamics, as well as the effect of the motion of the chordae attachment points. Results are compared with two other cases: (i) a ventricle model with no prescribed motion of the chordae attachment points, (ii) a tube model in which the ventricle is replaced by a tube, although the motion of the chordae is incorporated. It is found that the vortex flow helps to reduce the cross valve pressure gradient; however, it can significantly increase the chordae and the valve stretch in the commissural region and make the flow field strongly asymmetric. Surprisingly, we observe that the presence of the flow vortex does not necessarily aid the valve closure.