Key result
Increasing LVAD support level reduced aortic valve open duration (0.23s to 0.14s) and increased von Mises stress in most leaflet areas from 0-0.4 MPa to 0.4-0.8 MPa, reaching >0.8 MPa when closed.
Why the study?
Does the level of LVAD support affect the biomechanical stress and strain on the aortic valve?
Does the level of LVAD support affect the biomechanical stress and strain on the aortic valve?
Computational modeling suggests that maintaining an aortic valve open duration of >0.2 seconds during LVAD support minimizes leaflet stress and may improve biomechanical outcomes.
Higher LVAD support may increase aortic valve stress; leaves open optimal settings to preserve leaflet durability.
BACKGROUND Although aortic valve disease caused by left ventricular assist device (LVAD) support has attracted more and more attention, the precise biomechanical effects of LVAD support level on the aortic valve are still unclear. MATERIAL AND METHODS A structural finite element models study was conducted using an ideal aortic valve geometric model. Four different study conditions were designed, according to the reduction of the open duration of the aortic valve. The isotropic hyperelastic constitutive equation was chosen to reflect the mechanical property of the leaflets. The distribution of the stress, strain, and transient dynamics of the leaflet were calculated. RESULTS Along with the increase of LVAD support level, the open duration of the aortic valve was also reduced by the increase of LVAD support (low support level case 0.23 seconds versus middle support level case 0.2 seconds versus high support level case 0.14 seconds). Moreover, along with the increase of support mode of LVAD, the von Mises stress in most leaflet areas was increased from the low stress level (0-0.4 MPa) to the middle region (0.4-0.8 MPa). Once the leaflets were continuously closed, the high stress level (larger than 0.8 MPa) was observed. In contrast, the support level of LVAD only had slight effects on the distribution of von Mises strain. According to the aforementioned results, maintaining the open duration of aortic valve longer than 0.2 seconds could achieve better performance of biomechanical states of leaflets. CONCLUSIONS This study could provide useful information on the determination of optimal LVAD support strategy.
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Zhang et al. (2018) studied Aortic valve disease caused by left ventricular assist device (LVAD) support. Left ventricular assist device (LVAD) support level vs. Different support levels (low, middle, high, continuously closed) was evaluated on Biomechanical states of leaflets (von Mises stress, strain, and open duration). Increasing LVAD support level reduced aortic valve open duration (0.23s to 0.14s) and increased von Mises stress in most leaflet areas from 0-0.4 MPa to 0.4-0.8 MPa, reaching >0.8 MPa when closed.
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