Abstract 12817: Experimental Analysis of Bicuspid Aortic Valve Hemodynamics: Effect of Mild Aortic Dilatation on Systolic Flow Characteristics

Abstract

Introduction: Aortic diameter is a determinant index in deciding surgical intervention for aortic aneurysm with bicuspid aortic valve (BAV). However, the treatment of a mildly dilated ascending aorta remains controversial. We experimentally investigated influence of mild dilatation of the ascending aorta on BAV-related hemodynamics in 3 BAV morphologies. Methods: An MRI-compatible pulsatile flow circulation system incorporating an aortic valve model and aortic arch model was developed. Tricuspid aortic valve (TAV) and 3 asymmetric BAV models including RL-, RN-, and LN-BAV were constructed by suturing bovine pericardium as cusps to aorta. The aortic arch models with the ascending diameters of 30 mm (non-dilatation) and 40 mm (mildly dilatation) were compared. Streamlines and the circulations (m 2 /s) of peak systolic flow in non- and mildly dilated ascending aorta were assessed using 4D-flow MRI in each BAV morphology (Fig). Results: Streamlines showed eccentric aortic valvular outflow jets impinging on the outer curvature of the ascending aorta, proximal arch, and left-anterior supra-valvular aortic wall in RL-, RN-, and LN-BAV, respectively. Regardless of the non-dilated or mildly dilated aorta, the circulations of peak systolic flow were larger in the BAVs than the TAV model (non-dilated aorta, TAV 0.005; RL- 0.016; RN- 0.026; LN-BAV 0.011 m 2 /s, mildly dilated aorta, TAV 0.009; RL- 0.017; RN- 0.028; LN-BAV 0.025 m 2 /s). Right-handed rotation was observed in RL- and RN-BAV, whereas LN-BAV presented left-handed rotation. In LN-BAV, the circulation markedly increased in the mildly dilated ascending aorta. Conclusions: Asymmetric BAV morphology was associated with highly eccentric aortic valvular outflow jet that directly impinged on the aortic wall, and the large circulation of peak systolic flow. The dilatation of the ascending aorta, even mild dilatation, might induce further increase in the circulation of systolic flow, especially in LN-BAV morphology.