Hemodynamic evaluation for mitral valve replacement
X He, S Feng, H Wang, S WangAbstract
Background
Mitral valve replacement (MVR) alters left ventricular hemodynamics, potentially leading to thrombosis, hemolysis, and ventricular remodeling. While prior studies have assessed prosthetic valve flows, a direct in vitro comparison of vortex evolution and blood transport efficiency among native, bioprosthetic, and mechanical valves remains limited.
Purpose
This study aimed to quantitatively evaluate the impact of different mitral valve types on LV vortex structures and blood transport, focusing on residence time and apical washout.
Methods
We constructed a left heart simulator using a 3D-printed silicone LV and native porcine mitral apparatus. Three valve conditions were tested: native, bioprosthetic and bileaflet mechanical (Figure 1). Time-resolved tomographic particle image velocimetry (Tomo-PIV) was applied to capture three-dimensional velocity fields, and then the Q-criterion was adopted to identify the intraventricular vortex patterns. Lagrangian particle tracking was performed to compute blood residence time (τ, in cardiac cycles) and the apical-transit ratio (percentage of particles passing through the apical region of the LV) (Figure 1).
Results
Prosthetic valves fundamentally altered diastolic vortex morphology and transport dynamics (Figure 2). The native valve formed a saddle-shaped diastolic vortex ring with optimal apical convection, resulting in the shortest residence time (46.0 ± 1.1% residual blood after 3 cycles) and highest apical-transit ratio (74.8 ± 2.2%). The bioprosthetic valve produced a near-circular vortex ring with intermediate transport efficiency (52.7 ± 1.6% residual blood; 72.7 ± 1.5% apical transit). The mechanical valve generated fragmented crescent-shaped vortices confined to the basal LV, resulting in the longest residence time (64.7 ± 7.0% residual blood) and the lowest apical-transit ratio (50.7 ± 11.2%). These findings indicate that mechanical valves are associated with significantly prolonged blood stasis and reduced apical washout.
Conclusions
This study demonstrates that native mitral valve hemodynamics optimize apical washout and minimize intraventricular stasis through organized vortex convection. Both bioprosthetic and mechanical valves disrupt this physiological flow, with mechanical valves exhibiting the most pronounced deficits in transport efficiency. These results highlight the importance of vortex-driven apical washout in LV hemodynamics and suggest that future valve designs should aim to restore physiological vortex-driven apical washout.Figure 1.Experimental Process and MethodsFigure 2.Results Presentation