Fluid Dynamics of Coarctation of the Aorta and Effect of Bicuspid Aortic Valve

Abstract

Up to 80% of patients with coarctation of the aorta (COA) have a bicuspid aortic valve (BAV). Patients with COA and BAV have elevated risks of aortic complications despite successful surgical repair. The development of such complications involves the interplay between the mechanical forces applied on the artery and the biological processes occurring at the cellular level. The focus of this study is on hemodynamic modifications induced in the aorta in the presence of a COA and a BAV. For this purpose, numerical investigations and magnetic resonance imaging measurements were conducted with different configurations: (1) normal: normal aorta and normal aortic valve; (2) isolated COA: aorta with COA (75% reduction by area) and normal aortic valve; (3) complex COA: aorta with the same severity of COA (75% reduction by area) and BAV. The results show that the coexistence of COA and BAV significantly alters blood flow in the aorta with a significant increase in the maximal velocity, secondary flow, pressure loss, time-averaged wall shear stress and oscillatory shear index downstream of the COA. These findings can contribute to a better understanding of why patients with complex COA have adverse outcome even following a successful surgery.

The Influences of Swirl Flow on Fractional Flow Reserve in Mild/Moderate/Severe Stenotic Coronary Arterial Models

“…6. The FFR variation showed a convex curve at the stenosis throat, identical to results reported previously [17]. The quantitative differences in FFR between the cases of non-swirl flow and swirl flow were relatively large in mild stenosis compared with moderate/severe stenosis.…”

“…Therefore, many groups have focused on the pressure ratio to obtain FFR value. However, few studies have evaluated the influence of swirl flows on pressure-based distributions in post-stenotic regions [16][17][18]. In a previous study of flow phenomena in a stenotic model with swirl flow, the swirl flow from the aortic valve was shown to induce a more marked drop in pressure than aortic stenosis [17].…”

“…However, few studies have evaluated the influence of swirl flows on pressure-based distributions in post-stenotic regions [16][17][18]. In a previous study of flow phenomena in a stenotic model with swirl flow, the swirl flow from the aortic valve was shown to induce a more marked drop in pressure than aortic stenosis [17]. Sung et al [16] reported that the flow is affected by rotation and stenosis at same time, although only 50% stenosis models were considered suitable to elucidate the effects of rotating flow.…”

Incidence, morphology, and progression of bicuspid aortic valve in pediatric and young adult subjects with coexisting congenital heart defects

“…Even though the association of BAV with defects such as coarctation of aorta (CoA) is well recognized, the association with other cardiac lesions has not been well described. [11][12][13][14] The purpose of this study was to identify the incidence of BAV, define the cusp fusion morphology in association with various forms of CHD, and determine the differences in prognosis and progression of BAV disease in patients with CHD compared with patients with isolated BAV. This study ultimately attempts to describe the natural history of BAV in patients with associated CHD and to determine if coexisting CHD predispose to rapid or worse disease progression.…”

Elimination of Transcoarctation Pressure Gradients Has No Impact on Left Ventricular Function or Aortic Shear Stress After Intervention in Patients With Mild Coarctation

“…Although whole human blood tends to exhibit non-Newtonian behavior at shear rates under 100 s −1 near the vessel walls, the shear rates in large arteries are generally observed to be greater than 100 s −1 and hence it is reasonable to assume a Newtonian fluid in the simulation. The arterial wall was treated as a rigid wall as Jin et al (2003) (53) and Keshavarz-Motamed et al (2013) (54) showed that rigid wall assumption for the aorta is realistic; and as patients with COA are usually hypertensive and characterized by reduced compliance and elevated stiffness index in both proximal and distal aorta (7,31,32,33). …”