The impact of MRI-based inflow for the hemodynamic evaluation of aortic coarctation
L Goubergrits1, R Mevert, P Yevtushenko
1Biofluid Mechanics Laboratory, Charité-Universitätsmedizin Berlin, Thielallee 73, 14195, Berlin, Germany, leonid.goubergrits@charite.de.
Insights
Accurate hemodynamic assessment in aortic coarctation (CoA) is crucial. Using 4D MRI-based velocity profiles in computational fluid dynamics (CFD) improves patient-specific analysis over simplified plug flow models.
Area of Science:
- Cardiovascular Medicine
- Biomedical Engineering
- Medical Imaging
Background:
- Aortic coarctation (CoA) is a congenital heart defect affecting 3-11% of cases, often treatable but linked to reduced life expectancy due to abnormal hemodynamics.
- Effective treatment and long-term outcomes for CoA depend critically on accurate hemodynamic assessment.
Purpose of the Study:
- To investigate the impact of different inlet velocity profiles on computational fluid dynamics (CFD) simulations of aortic coarctation.
- To compare the effects of plug flow versus 4D MRI-based velocity profiles on peak systolic pressure gradient and wall shear stress (WSS).
Main Methods:
- Acquisition of 3D whole-heart (3DWH) and 4D phase-contrast MRI data.
- Reconstruction of thoracic aorta geometries with CoA using ZIB-Amira software.
- Creation of CFD models using FLUENT to simulate pre- and post-treatment scenarios with varying inlet velocity profiles.
Main Results:
- Helical flow at the aorta inlet significantly influences pressure drop and WSS calculations.
- Simplified plug inlet velocity profiles led to significant overestimation of pressure drop (p < 0.05) and underestimation of surface-averaged WSS (p < 0.05).
Conclusions:
- Physiologically accurate 4D MRI-based velocity profiles are essential for precise CFD analysis in CoA.
- Utilizing patient-specific velocity profiles represents a significant advancement towards personalized hemodynamic assessment and treatment planning for aortic coarctation.
Abstract:
Aortic coarctation (CoA) accounting for 3-11% of congenital heart disease can be successfully treated. Long-term results, however, have revealed decreased life expectancy associated with abnormal hemodynamics. Accordingly, an assessment of hemodynamics is the key factor in treatment decisions and successful long-term results. In this study, 3D angiography whole heart (3DWH) and 4D phase-contrast magnetic resonance imaging (MRI) data were acquired. Geometries of the thoracic aorta with CoAs were reconstructed using ZIB-Amira software. X-ray angiograms were used to evaluate the post-treatment geometry. Computational fluid dynamics models in three patients were created to simulate pre- and post-treatment situations using the FLUENT program. The aim of the study was to investigate the impact of the inlet velocity profile (plug vs. MRI-based) with a focus on the peak systole pressure gradient and wall shear stress (WSS). Results show that helical flow at the aorta inlet can significantly affect the assessment of pressure drop and WSS. Simplified plug inlet velocity profiles significantly (p < 0.05) overestimate the pressure drop in pre- and post-treatment geometries and significantly (p < 0.05) underestimate surface-averaged WSS. We conclude that the use of the physiologically correct but time-expensive 4D MRI-based in vivo velocity profile in CFD studies may be an important step towards a patient-specific analysis of CoA hemodynamics.
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