Abstract 20706: Mitral Valve (MV) Leaflet Coaptation Area Does Not Influence Leaflet Stress in Finite Element Simulation
Objectives: Providing redundant leaflet tissue to increase the coaptation area after repair for regurgitation has been proposed to decrease pressure load-induced mechanical stress on the MV leaflets and ensure durable repair. We hypothesized that redundant noncoapted leaflet material, not increased leaflet coaptation area, reduces stress.
Methods: To assess whether increased leaflet coaptation length alone modifies stress distribution, normal human MV geometric models (n=3) were constructed using real-time 3D echocardiography. Leaflet coaptation length was set to 5%, 50%, or 100% of normal. The computational models were loaded with a mid-systolic transvalvular pressure gradient of 80 mmHg using finite element analysis (FEA). Subsequently, to test whether additional leaflet tissue distributed uniformly in the noncoapted leaflets would decrease predicted stresses, the FEA surface meshes were expanded by 2% in the noncoapted leaflet region - while keeping annular dimensions unchanged - and reloaded. All data are presented as mean ± standard deviation.
Results: Changes in leaflet coaptation length did not alter the von Mises stress distribution in either the coapted or noncoapted leaflet regions (see figure, A-C): peak leaflet stress was 0.36±0.17 MPa at 100% (actual), 0.35±0.14 MPa at 50%, and 0.34±0.14 MPa at 10% coaptation lengths (F=0.011 and P=0.99 by ANOVA). Increasing the noncoapted leaflet area by 2% decreased the peak valvular stresses (see figure, D) by 24±11% (P =.02 by paired t-test).
Conclusions: Redundant MV leaflet tissue reduces pressure load-induced mechanical stress on the noncoapted leaflets; the extent of coaptation does not independently influence leaflet stresses. Operative or interventional strategies for MV repair - including ring annuloplasty and leaflet resection - which increase coaptation length in isolation are not expected to be beneficial with respect to altering the mechanical stresses on the MV.
- © 2010 by American Heart Association, Inc.