Simulation of Altered Blood Flow in Bicuspid Aortic Valve Disease: <i>A Proof of Concept Study</i>

Abstract

Background: Bicuspid aortic valve (BAV) is a common congenital heart disease which is associated with aortic dilatation. There is controversy in the literature regarding the various measures of the biomechanical properties of the aorta in these patients and their relationship to aortic dilatation. The present study aimed to assess both conventional 2D Cardiac Magnetic Resonance Imaging (CMRI) measurements of aortic biomechanics (compliance and distensibility) and a computational fluid dynamics (CFD) approach in patients with BAV and either normal or dilated ascending aorta. Methods: 2D CMRI was performed in 18 patients (6 controls, 6 BAV with dilated ascending aorta and 6 BAV with normal ascending aorta i.e. <36mm diameter) and ascending aortic compliance and distensibility was calculated. CFD was performed with <i>ANSYS Fluent software </i>using 2D CMRI derived parameters to simulate the hemodynamic relationships between blood and the aortic wall. Results: The groups were similar in terms of demographics (mean age 38±13 years, 56% male, pulse pressure 56±15mmHg). There was a numerically lower but not significant difference in aortic compliance between dilated BAV and the other groups. Aortic distensibility was no different between groups. Using CFD, at the mid-ascending aorta pressure was significantly higher in patients with dilated BAV (147.6 ± 24.1 mmHg) than non-dilated BAV (118.6 ± 16.2 mmHg) and controls (124.5 ± 14.4 mmHg), p=0.04. Conclusions: We demonstrate that is possible to estimate regional aortic pressure from 2D CMRI derived parameters using a CFD approach. These novel parameters may add value to surveillance strategies in aortic disease.