Comparisons of simulation results between passive and active fluid structure interaction models for left ventricle in hypertrophic obstructive cardiomyopathy

Abstract

Background: Patient-specific active fluid-structure interactions (FSI) model is a useful approach to non-invasively investigate the hemodynamics in the heart. However, it takes a lot of effort to obtain the proper external force boundary conditions for active models, which heavily restrained the time-sensitive clinical applications of active computational models.

Methods: The simulation results of 12 passive FSI models based on 6 patients' pre-operative and post-operative CT images were compared with corresponding active models to investigate the differences in hemodynamics and cardiac mechanics between these models.

Results: In comparing the passive and active models, it was found that there was no significant difference in pressure difference and shear stress on mitral valve leaflet (MVL) at the pre-SAM time point, but a significant difference was found in wall stress on the inner boundary of left ventricle (endocardium). It was also found that pressure difference on the coapted MVL and the shear stress on MVL were significantly decreased after successful surgery in both active and passive models.

Conclusion: Our results suggested that the passive models may provide good approximated hemodynamic results at 5% RR interval, which is crucial for analyzing the initiation of systolic anterior motion (SAM). Comparing to active models, the passive models decrease the complexity of the modeling construction and the difficulty of convergence significantly. These findings suggest that, with proper boundary conditions and sufficient clinical data, the passive computational model may be a good substitution model for the active model to perform hemodynamic analysis of the initiation of SAM.

Keywords: Active computational model; Fluid–structure interactions; Left ventricle; Mitral valve; Passive computational model; Systolic anterior motion.

Fig. 1

Comparisons of numerical simulation results at pre-SAM time point (5% RR interval time point) obtained from active and passive models. Active models, a distribution of wall stress on cutting surface; b 3D-velocity vector flow map; c distribution of pressure difference on coapted MVL; d distribution of shear stress on MVL; e–h were the corresponding results obtained from passive models. AML anterior mitral leaflet, PML posterior mitral leaflet

Fig. 2

Comparisons of active and passive models in wall stress of each slice obtained from pre-operative/post-operative models for different patients. active.Post post-operative active model, passive.Post post-operative passive model, active.Pre pre-operative active model, passive.Pre pre-operative passive model. Stress-P1Max = maximum value of wall stress (stress-P₁) values

Fig. 3

Comparisons of the difference of maximum/mean pressure values on coapted mitral valve leaflets (MVL) before (pre-op) and after surgery (post-op). The red lines indicate the patient received an unsatisfactory outcome, and the black lines indicate that the patients receiving successful surgery. a Results obtained from active models; b results obtained from passive models

Fig. 4

Comparisons of the mean value of maximum/mean fluid shear stress on coapted mitral valve leaflets (MVL) before and after surgery. The black lines indicate the patients with successful surgery, and the red lines indicate the patient with failed surgery. a Results obtained from active models; b results obtained from passive models