Abstract

Mitral Annular Calcification (MAC) is a degenerative heart disease corresponding to a deformation and narrowing of the mitral valve. Up to 42% of people aged over 65 have it, and 60% of people aged over 85. The aim of the present work was to understand the flow downstream of a calcified valve and to investigate how both the severity and the orientation affect the characteristics of the velocity field, vorticity field, viscous energy loss, vortex formation time, viscous shear stress, particle path, and shear accumulation.
For the purpose of this experimental thesis, particle image velocimetry was conducted at physiological flow and pressure conditions in two stages. The first stage is the in vitro experiment with seven different mitral valve configurations: (1) normal, (2) mild, (3) moderate with two orientations, (4) severe with three different orientations. Results show that compared with a normal case the instantaneous velocity, vorticity, and shear stress fields in addition to the energy loss evolution and vortex formation time significantly increase with MAC severities. It also showed, that keeping the same severity but modifying the orientation of the mitral valve also significantly lead to sub-optimal hemodynamic configurations.
Findings of this study indicate that the presence of MAC and orientation in the mitral valve significantly alters the hemodynamics in the left ventricle. This study sheds some light on the crucial rule that the orientation of the mitral valve plays in the severity assessment.
The second stage is experiments with models of patient specific valves with three different configurations (1) normal, (2) moderate MAC and (3) severe MAC. Results show that compared with a normal case the velocity and vorticity fields increased with MAC severities. Interestingly, it also showed, that the moderate case had higher averaged energy loss than that of the severe case. The energy loss of the severe was even less than that of the normal.
In conclusion, this study advances the current state of understanding of flow through calcified mitral valve by investigating how MAC affects the hemodynamics in the LV. Results can be used as the foundation for further investigations in order to better clinically evaluate mitral annular calcification.