Flow patterns in ascending aortic aneurysms: Determining the role of hypertension using phase contrast magnetic resonance and computational fluid dynamics

Computers in Biology and Medicine, vol. 172, pp. 108310

Abstract

Thoracic aortic aneurysm (TAA) is a local dilation of the thoracic aorta. Although universally used, aneurysm diameter alone is a poor predictor of major complications such as rupture. There is a need for better biomarkers for risk assessment that also reflect the aberrant flow patterns found in TAAs. Furthermore, hypertension is often present in TAA patients and may play a role in progression of aneurysm. The exact relation between TAAs and hypertension is poorly understood. This study aims to create a numerical model of hypertension in the aorta by using computational fluid dynamics. First, a normotensive state was simulated in which flow and resistance were kept unaltered. Second, a hypertensive state was modeled in which blood inflow was increased by 30%. Third, a hypertensive state was modeled in which the proximal and peripheral resistances and capacitance parameters from the three-element Windkessel boundary condition were adjusted to mimic an increase in resistance of the rest of the cardiovascular system. One patient with degenerative TAA and one healthy control were successfully simulated at hypertensive states and were extensively analyzed. Furthermore, three additional TAA patients and controls were simulated to validate our method. Hemodynamic variables such as wall shear stress, oscillatory shear index, endothelial cell activation potential (ECAP), vorticity and helicity were studied to gain more insight on the effects of hypertension on flow patterns in TAAs. By comparing a TAA patient and a control at normotensive state at peak-systole, helicity and vorticity were found to be lower in the TAA patient throughout the entire domain. No major changes in flow and flow derived quantities were observed for the TAA patient and control when resistance was increased. When flow rate was increased, regions with high ECAP values were found to reduce in TAA patients in the aneurysm region which could reduce the risk of thrombogenesis. Thus, it may be important to assess cardiac output in patients with TAA.

Authors 8

1. Mitch J. F. G. Ramaekers

   Maastricht University Medical Centre · Maastricht University

   Affiliation as printed

   Departments of Cardiology and Radiology and Nuclear Medicine, Maastricht University Medical Center +, Maastricht, The Netherlands; Cardiovascular Research Institute Maastricht (CARIM), Maastricht, The Netherlands

   Cardiovascular Research Institute Maastricht (CARIM), Maastricht, The Netherlands

   Departments of Cardiology and Radiology and Nuclear Medicine, Maastricht University Medical Center +, Maastricht, The Netherlands

2. I.B. van der Vlugt

   Delft University of Technology

   Affiliation as printed

   Department of Chemical Engineering, Faculty of Applied Sciences, Delft University of Technology, Delft, The Netherlands

3. Jos J.M. Westenberg Aachen Department of Radiology, Leiden University Medical Center

   Leiden University Medical Center

   Affiliation as printed

   Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands

4. Romana Perinajová

   J.M. Burgerscentrum · Delft University of Technology

   Affiliation as printed

   Department of Chemical Engineering, Faculty of Applied Sciences, Delft University of Technology, Delft, The Netherlands; J.M. Burgerscentrum Research School for Fluid Mechanics, Delft, The Netherlands

   Department of Chemical Engineering, Faculty of Applied Sciences, Delft University of Technology, Delft, The Netherlands

   J.M. Burgerscentrum Research School for Fluid Mechanics, Delft, The Netherlands

5. Hildo J. Lamb Aachen Department of Radiology, Leiden University Medical Center

   Leiden University Medical Center

   Affiliation as printed

   Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands

6. Joachim Ernst Wildberger

   Maastricht University Medical Centre · Maastricht University

   Affiliation as printed

   Cardiovascular Research Institute Maastricht (CARIM), Maastricht, The Netherlands; Department of Radiology and Nuclear Medicine, Maastricht University Medical Center +, Maastricht, The Netherlands

   Cardiovascular Research Institute Maastricht (CARIM), Maastricht, The Netherlands

   Department of Radiology and Nuclear Medicine, Maastricht University Medical Center +, Maastricht, The Netherlands

7. Saša Kenjereš corresponding

   J.M. Burgerscentrum · Delft University of Technology

   Affiliation as printed

   Department of Chemical Engineering, Faculty of Applied Sciences, Delft University of Technology, Delft, The Netherlands; J.M. Burgerscentrum Research School for Fluid Mechanics, Delft, The Netherlands. Electronic address: s.kenjeres@tudelft.nl

   Department of Chemical Engineering, Faculty of Applied Sciences, Delft University of Technology, Delft, The Netherlands

   J.M. Burgerscentrum Research School for Fluid Mechanics, Delft, The Netherlands

8. Simon M. Schalla

   Maastricht University Medical Centre · Maastricht University

   Affiliation as printed

   Departments of Cardiology and Radiology and Nuclear Medicine, Maastricht University Medical Center +, Maastricht, The Netherlands; Cardiovascular Research Institute Maastricht (CARIM), Maastricht, The Netherlands

   Cardiovascular Research Institute Maastricht (CARIM), Maastricht, The Netherlands

   Departments of Cardiology and Radiology and Nuclear Medicine, Maastricht University Medical Center +, Maastricht, The Netherlands