Abstract
The severity of aortic stenosis (AS) has traditionally been graded by measuring hemodynamic parameters of transvalvular pressure gradient, ejection jet velocity, or estimating valve orifice area. Recent research has highlighted limitations of these criteria at effectively grading AS in presence of left ventricle (LV) dysfunction. We hypothesized that simulations coupling the aorta and LV could provide meaningful insight into myocardial biomechanical derangements that accompany AS. A realistic finite element model of the human heart with a coupled lumped-parameter circulatory system was used to simulate AS. Finite element analysis was performed with Abaqus FEA. An anisotropic hyperelastic model was assigned to LV passive properties, and a time-varying elastance function governed the LV active response. Global LV myofiber peak systolic stress (mean ± standard deviation) was 9.31 ± 10.33 kPa at baseline, 13.13 ± 10.29 kPa for moderate AS, and 16.18 ± 10.59 kPa for severe AS. Mean LV myofiber peak systolic strains were −22.40 ± 8.73%, −22.24 ± 8.91%, and −21.97 ± 9.18%, respectively. Stress was significantly elevated compared to baseline for moderate (p < 0.01) and severe AS (p < 0.001), and when compared to each other (p < 0.01). Ventricular regions that experienced the greatest systolic stress were (severe AS vs. baseline) basal inferior (39.87 vs. 30.02 kPa; p < 0.01), mid-anteroseptal (32.29 vs. 24.79 kPa; p < 0.001), and apex (27.99 vs. 23.52 kPa; p < 0.001). This data serves as a reference for future studies that will incorporate patient-specific ventricular geometries and material parameters, aiming to correlate LV biomechanics to AS severity.
Highlights
Aortic stenosis (AS) is the most prevalent valvular heart disease in the developed world (Lindman et al, 2013; Go et al, 2014; Miura et al, 2015)
The mean defined: systemic arterial resistance 1.4e+02 MPa∗s/mm3, systemic venous resistance 9.7e-1 MPa∗s/mm3, tricuspid valve resistance 2.5e-1 MPa∗s/mm3, pulmonary valve resistance 9.7eglobal left ventricle (LV) myofiber stress was significantly different between moderate aortic stenosis (AS) and baseline (p < 0.01) as well as between severe AS and baseline (p < 0.001)
The results indicated that end-systolic wall stress was significantly greater in symptomatic patients at 9.6 kPa than in the asymptomatic patients at 7.6 kPa
Summary
Aortic stenosis (AS) is the most prevalent valvular heart disease in the developed world (Lindman et al, 2013; Go et al, 2014; Miura et al, 2015). Discordant outcomes have been reported on the role of aortic valve replacement for these groups of patients, highlighting the need to better diagnose and select appropriate patients for treatment (Hachicha et al, 2007; Pibarot and Dumesnil, 2012; Pibarot and Clavel, 2015; Tribouilloy et al, 2015; Chadha et al, 2019)
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