Transcatheter aortic valve replacement alters ascending aortic blood flow and wall shear stress patterns: A 4D flow MRI comparison with age-matched, elderly controls

• Published in: European radiology Vol. 29; no. 3; pp. 1444 - 1451
• Main Authors: Farag, E. S., Vendrik, J., van Ooij, P., Poortvliet, Q. L., van Kesteren, F., Wollersheim, L. W., Kaya, A., Driessen, A. H. G., Piek, J. J., Koch, K. T., Baan, J., Planken, R. N., Kluin, J., Nederveen, A. J., de Mol, B. A. J. M.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-03-2019; Springer Nature B.V
• Subjects: Age; Aged; Aged, 80 and over; Aneurysms; Aorta; Aorta - diagnostic imaging; Aorta - physiopathology; Aortic valve; Aortic Valve - diagnostic imaging; Aortic Valve - surgery; Aortic Valve Stenosis - diagnosis; Aortic Valve Stenosis - physiopathology; Aortic Valve Stenosis - surgery; Blood flow; Blood Flow Velocity - physiology; Control methods; Coronary vessels; Diagnostic Radiology; Displacement; Eccentricity; Female; Flow characteristics; Flow velocity; Gender; Geriatrics; Heart Valve Prosthesis; Humans; Imaging; Internal Medicine; Interventional Radiology; Magnetic Resonance; Magnetic resonance imaging; Magnetic Resonance Imaging - methods; Male; Medicine; Medicine & Public Health; Neuroradiology; Older people; Patients; Radiology; Risk assessment; Shear stress; Stress, Mechanical; Surgery; Thorax; Transcatheter Aortic Valve Replacement - methods; Ultrasound; Wall shear stresses; Thoracic aorta; Cardiac surgical procedures; Magnetic resonance imaging; Aortic valve; Transcatheter aortic valve replacement
• ISSN: 0938-7994; 1432-1084
• DOI: 10.1007/s00330-018-5672-z

Background
With the implementation of transcatheter aortic valve replacement (TAVR) in lower-risk patients, evaluation of blood flow characteristics and the effect of TAVR on aortic dilatation becomes of considerable interest. We employed 4D flow MRI in the ascending aorta of patients after TAVR to assess wall shear stress (WSS) and compare blood flow patterns with surgical aortic valve replacement (SAVR) and age- and gender-matched controls.
Methods
Fourteen post-TAVR patients and ten age- and gender-matched controls underwent kt-PCA accelerated 4D flow MRI of the thoracic aorta at 3.0 Tesla. Velocity and wall shear stress was compared between the two groups. In addition, aortic flow eccentricity and displacement was assessed and compared between TAVR patients, controls and 14 SAVR patients recruited as part of an earlier study.
Results
Compared to controls, abnormally elevated WSS was present in 30±10% of the ascending aortic wall in TAVR patients. Increased WSS was present along the posterior mid-ascending aorta and the anterior distal-ascending aorta in all TAVR patients. TAVR results in eccentric and displaced flow in the mid- and distal-ascending aorta, whereas blood flow displacement in SAVR patients occurs only in the distal-ascending aorta.
Conclusion
This study shows that TAVR results in increased blood flow velocity and WSS in the ascending aorta compared to age- and gender-matched elderly controls. This finding warrants longitudinal assessment of aortic dilatation after TAVR in the era of potential TAVR in lower-risk patients. Additionally, TAVR results in altered blood flow eccentricity and displacement in the mid- and distal-ascending aorta, whereas SAVR only results in altered blood flow eccentricity and displacement in the distal-ascending aorta.
Key Points
• TAVR results in increased blood flow velocity and WSS in the ascending aorta.
• Longitudinal assessment of aortic dilatation after TAVR is warranted in the era of potential TAVR in lower-risk patients.
• Both TAVR and SAVR result in altered blood flow patterns in the ascending aorta when compared to age-matched controls.