Modelling cardiac mitral valve-left ventricular interaction for simulating pathologies and advanced treatment

Abstract

Recent advancements in cardiac computational modelling allow for ready simulation of bileaflet mitral valve (MV) motion in a contracting left ventricle (LV), demonstrating the capability of computational modelling to simulate the MV diseased state and treatment strategies. Furthermore, recent advancements in image-based modelling can be used for pre-procedural planning of mitral prosthetic valve placement and analysis of intraventricular blood flow.

This thesis aims to develop a set of computational models that can simulate normal MV function, MV disorders and treatments to help in the understanding of MV movement and its interaction with blood. In addition, a moving-wall LV computational framework was developed to provide pre-surgical guidance for determining optimal orientation of mitral prostheses.

In this thesis, the structural boundaries of a 2D model of the left heart were represented as a spring-like elastic structure. A 3D LV model was subsequently developed, consisting of ideal geometric-shaped MV leaflets and the LV wall. An experimentally-based hyperelastic material formulation was used to model mechanical behaviour of the MV leaflets. For both 2D and 3D ideal models, the MV chordae tendineae and papillary muscle were incorporated. Finally, for the image-based models based on wide-volume full cycle cardiovascular CT images prior to transcatheter MV implantation (TMVI) were developed and analysed (n = 6 patients). Patient-specific computational fluid dynamics simulations of TMVI at various implant insertion angles were performed (n = 30).

The 2D and 3D ideal models were successful in simulating the normal and prolapsed states of the MV. Additionally, both models were able to simulate blood movement after the MV prosthetic with and without left ventricular outflow tract (LVOT) flow obstruction. In the image-based models, computed pressure gradients following artificial valve placement compared well with clinical measurements and accurately predicted clinical LVOT obstruction. The simulations demonstrated that LVOT obstruction can be mitigated by adjusting the valve insertion angle, with the extent of residual obstruction contingent on the aorto-mitral-annular angle and LV anatomy.