4D- Flow- MRI After Aortic Valve Surgery

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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