New insights into mitral heart valve prolapse after chordae rupture through fluid-structure interaction computational modeling

Abstract

Mitral valve (MV) dynamics depends on a force balance across the mitral leaflets, the chordae tendineae, the mitral annulus, the papillary muscles and the adjacent ventricular wall. Chordae rupture disrupts the link between the MV and the left ventricle (LV), causing mitral regurgitation (MR), the most common valvular disease. In this study, a fluid-structure interaction (FSI) modeling framework is implemented to investigate the impact of chordae rupture on the left heart (LH) dynamics and severity of MR. A control and seven chordae rupture LH models were developed to simulate a pathological process in which minimal chordae rupture precedes more extensive chordae rupture. Different non-eccentric and eccentric regurgitant jets were identified during systole. Cardiac efficiency was evaluated by the ratio of external stroke work. MV structural results showed that basal/strut chordae were the major load-bearing chordae. An increased number of ruptured chordae resulted in reduced basal/strut tension, but increased marginal/intermediate load. Chordae rupture in a specific scallop did not necessarily involve an increase in the stress of the entire prolapsed leaflet. This work represents a further step towards patient-specific modeling of pathological LH dynamics, and has the potential to improve our understanding of the biomechanical mechanisms and treatment of primary MR.

Figure 1

Flow rate across the AV and MV through the cardiac cycle. PML is divided into P1, P2 and P3 scallops.

Figure 2

Chordae tension at peak systole. APM: anterolateral PM, PPM: posteromedial PM.

Figure 3

Stress distribution in the mitral leaflets at peak systole.

Figure 4

Averaged max. principal stress (MPa) in the mitral leaflets at peak systole.

Figure 5

Velocity streamlines showing regurgitant jet structures at peak systole.

Figure 6

Representative pressure-volume loop for the isolated P2 model.

Figure 7

Computational modeling protocol for investigation of LH dynamics following mitral chordae rupture.

Figure 8

(A) LH model, (B) MV model reconstructed from MSCT images, (C) top view of MV with four sub-regions, (D) PML chordae groups. AML chordae not shown for clarity.

Figure 9

Aortic and LA pressure boundary conditions.