Investigation of Aortic Flow Patterns after Aortic Valve Replacement: Establishment of a New Ex Vivo 4D Flow MRI Model

Objectives: Prediction of aortic hemodynamics after aortic valve replacement (AVR) could help optimize treatment planning and improve outcomes. This study aims to demonstrate an approach to predict postoperative maximum velocity, maximum pressure gradient, secondary flow degree (SFD), and normalized flow displacement (NFD) in patients receiving biological AVR.Methods: Virtual AVR was performed for 10 patients, who received actual AVR with a biological prosthesis. The virtual AVRs used only preoperative anatomical and 4D flow MRI data. Subsequently, computational fluid dynamics (CFD) simulations were performed and the abovementioned hemodynamic parameters compared between postoperative 4D flow MRI data and CFD results.Results: For maximum velocities and pressure gradients, postoperative 4D flow MRI data and CFD results were strongly correlated (R2 = 0.75 and R2 = 0.81) with low root mean square error (0.21 m/s and 3.8 mmHg). SFD and NFD were moderately and weakly correlated at R2 = 0.44 and R2 = 0.20, respectively. Flow visualization through streamlines indicates good qualitative agreement between 4D flow MRI data and CFD results in most cases.Conclusion: The approach presented here seems suitable to estimate postoperative maximum velocity and pressure gradient in patients receiving biological AVR, using only preoperative MRI data. The workflow can be performed in a reasonable time frame and offers a method to estimate postoperative valve prosthesis performance and to identify patients at risk of patient-prosthesis mismatch preoperatively. Novel parameters, such as SFD and NFD, appear to be more sensitive, and estimation seems harder. Further workflow optimization and validation of results seems warranted.

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Blood Flow Patterns In The Ascending Aorta after TAVI And Surgical Aortic Valve Replacement: A Study Using 4D Flow MRI

25th European Students' Conference ◽

10.14293/p2199-8442.1.sopmed.p0low9.v1 ◽

2014 ◽

Author(s):

Ralf Felix Trauzeddel ◽

Ulrike Löbe ◽

Alex Barker ◽

Carmen Gelsinger ◽

Christian Butter ◽

...

Keyword(s):

Blood Flow ◽

Aortic Valve ◽

Aortic Valve Replacement ◽

Valve Replacement ◽

Ascending Aorta ◽

4D Flow Mri ◽

Surgical Aortic Valve Replacement ◽

4D Flow ◽

Flow Mri ◽

Blood Flow Patterns

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Blood Flow Patterns In The Ascending Aorta after TAVI And Surgical Aortic Valve Replacement: A Study Using 4D Flow MRI

10.14293/p2199-8442.1.sop-med.p0low9.v1 ◽

2014 ◽

Author(s):

Ralf Felix Trauzeddel ◽

Ulrike Löbe ◽

Alex Barker ◽

Carmen Gelsinger ◽

Christian Butter ◽

...

Keyword(s):

Blood Flow ◽

Aortic Valve ◽

Flow Patterns ◽

Ascending Aorta ◽

Shear Stresses ◽

Healthy Controls ◽

4D Flow Mri ◽

4D Flow ◽

Flow Mri ◽

Blood Flow Patterns

Background Transcatheter aortic valve implantation (TAVI) is a new method for treating patients with severe aortic stenosis with high risk for or rejected from conventional heart surgery. Its impact on blood flow patterns and parameters in the ascending aorta are unknown. Using 4-dimensional phase contrast MRI (4D Flow MRI) we examined the hemodynamics in the ascending aorta after TAVI and compared them to stented bioprostheses and healthy controls. Methods We used 4D Flow MRI (spatial resolution 1.8x1.8x2.5mm3; temporal resolution 13-22 phases/heart cycle) of the ascending aorta in 14 patients with TAVI (mean age 76 years, 8 males, all Edwards Sapien), 12 patients with different stented bioprostheses (mean age 77 years, 8 males) and 9 healthy controls (mean age 55 years, 8 males) controls using a 1.5T MR system. We examined the distribution of the maximum systolic wall shear stresses as well as the maximum blood flow velocities in the mid-ascending aorta. Results Patients with TAVI and stented bioprosthesis revealed an asymetric distribution of the wall shear stresses with significantly elevated values at the anterior and right-anterior curvature and significantly lower values at the posterior curvature compared to the healthy controls. Concerning the maximum velocities both TAVI and stented bioprostheses revealed an asymetric distribution along the right-anterior curvature where TAVI showed a more anterior distribution compared to the healty controls which showed a central distribution. Conclusion The blood flow patterns in patients with TAVI and stented bioprostheses differs significantly from the ones in healthy controls. However, TAVI and stented bioprosthesis showed small but significant regional differences.

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Hemodynamic Profiles Before and After Surgery in Bicuspid Aortic Valve Disease—A Systematic Review of the Literature

Frontiers in Cardiovascular Medicine ◽

10.3389/fcvm.2021.629227 ◽

2021 ◽

Vol 8 ◽

Author(s):

Daniel G. W. Cave ◽

Hannah Panayiotou ◽

Malenka M. Bissell

Keyword(s):

Systematic Review ◽

Aortic Valve ◽

Bicuspid Aortic Valve ◽

Aortic Valve Disease ◽

Flow Patterns ◽

Valve Disease ◽

Aortic Dilatation ◽

4D Flow Mri ◽

4D Flow ◽

Flow Mri

Bicuspid aortic valve (BAV) disease presents a unique management challenge both pre- and post-operatively. 4D flow MRI offers multiple tools for the assessment of the thoracic aorta in aortic valve disease. In particular, its assessment of flow patterns and wall shear stress have led to new understandings around the mechanisms of aneurysm development in BAV disease. Novel parameters have now been developed that have the potential to predict pathological aortic dilatation and may help to risk stratify BAV patients in future. This systematic review analyses the current 4D flow MRI literature after aortic valve and/or ascending aortic replacement in bicuspid aortic valve disease. 4D flow MRI has also identified distinct challenges posed by this cohort at the time of valve replacement compared to standard management of tri-leaflet disorders, and may help tailor the type and timing of replacement. Eccentric pathological flow patterns seen after bioprosthetic valve implantation, but not with mechanical prostheses, might be an important future consideration in intervention planning. 4D flow MRI also has promising potential in supporting the development of artificial valve prostheses and aortic conduits with more physiological flow patterns.

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