Key result
Aortoseptal angle steepening generated substantial hemodynamic stress abnormalities, including a >45% increase in temporal shear magnitude and >66% decrease in wall shear stress divergence.
Why the study?
Discrete subaortic stenosis is more prevalent in LVOT anatomies with a steep aortoseptal angle, suggesting hemodynamics may play an etiologic role.
Does aortoseptal angle steepening impact left ventricular hemodynamic stress in a 3D model?
Does aortoseptal angle steepening impact left ventricular hemodynamic stress in a 3D model?
Effect estimate: >45% increase in TSM; >66% decrease in WSS divergence
Steepening of the aortoseptal angle creates substantial hemodynamic stress abnormalities in the left ventricular outflow tract, potentially contributing to the formation of discrete subaortic stenosis.
Steep AoSA perturbs LVOT flow and elevates wall shear stress in models; leaves open hemodynamic contribution to DSS, requiring clinical validation.
PURPOSE: Discrete subaortic stenosis (DSS) is an obstructive cardiac disease caused by a membranous lesion in the left ventricular (LV) outflow tract (LVOT). Although its etiology is unknown, the higher prevalence of DSS in LVOT anatomies featuring a steep aortoseptal angle (AoSA) suggests a potential role for hemodynamics. Therefore, the objective of this study was to quantify the impact of AoSA steepening on the LV three-dimensional (3D) hemodynamic stress environment. METHODS: A 3D LV model reconstructed from cardiac cine-magnetic resonance imaging was connected to four LVOT geometrical variations spanning the clinical AoSA range (115°-160°). LV hemodynamic stresses were characterized in terms of cycle-averaged pressure, temporal shear magnitude (TSM), and oscillatory shear index. The wall shear stress (WSS) topological skeleton was further analyzed by computing the scaled divergence of the WSS vector field. RESULTS: AoSA steepening caused an increasingly perturbed subaortic flow marked by LVOT flow skewness and complex 3D secondary flow patterns. These disturbances generated WSS overloads (>45% increase in TSM vs. 160° model) on the inferior LVOT wall, and increased WSS contraction (>66% decrease in WSS divergence vs. 160° model) in regions prone to DSS membrane formation. CONCLUSIONS: AoSA steepening generated substantial hemodynamic stress abnormalities in LVOT regions prone to DSS formation. Further studies are needed to assess the possible impact of such mechanical abnormalities on the tissue and cellular responses.
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Shar et al. (2022) studied Discrete subaortic stenosis. Aortoseptal angle steepening vs. 160° model was evaluated on LV hemodynamic stresses (temporal shear magnitude and wall shear stress divergence) (>45% increase in TSM; >66% decrease in WSS divergence). Aortoseptal angle steepening generated substantial hemodynamic stress abnormalities, including a >45% increase in temporal shear magnitude and >66% decrease in wall shear stress divergence.
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