4D flow cardiovascular magnetic resonance for monitoring of aortic valve repair in bicuspid aortic valve disease

Lenz A, Petersen J, Riedel C, Weinrich JM, Kooijman H, Schoennagel BP, Adam G, von Kodolitsch Y, Reichenspurner H, Girdauskas E, Bannas P.

J Cardiovasc Magn Reson. 2020 Apr 30;22(1):29. doi: 10.1186/s12968-020-00608-0.

PMID: 32354361 Free PMC Article

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Abstract

Background: Aortic valve repair has become a treatment option for adults with symptomatic bicuspid (BAV) or unicuspid (UAV) aortic valve insufficiency. Our aim was to demonstrate the feasibility of 4D flow cardiovascular magnetic resonance (CMR) to assess the impact of aortic valve repair on changes in blood flow dynamics in patients with symptomatic BAV or UAV.

Methods: Twenty patients with adult congenital heart disease (median 35 years, range 18-64; 16 male) and symptomatic aortic valve regurgitation (15 BAV, 5 UAV) were prospectively studied. All patients underwent 4D flow CMR before and after aortic valve repair. Aortic valve regurgitant fraction and systolic peak velocity were estimated. The degree of helical and vortical flow was evaluated according to a 3-point scale. Relative flow displacement and wall shear stress (WSS) were quantified at predefined levels in the thoracic aorta.

Results: All patients underwent successful aortic valve repair with a significant reduction of aortic valve regurgitation (16.7 ± 9.8% to 6.4 ± 4.4%, p < 0.001) and systolic peak velocity (2.3 ± 0.9 to 1.9 ± 0.4 m/s, p = 0.014). Both helical flow (1.6 ± 0.6 vs. 0.9 ± 0.5, p < 0.001) and vortical flow (1.2 ± 0.8 vs. 0.5 ± 0.6, p = 0.002) as well as both flow displacement (0.3 ± 0.1 vs. 0.25 ± 0.1, p = 0.031) and WSS (0.8 ± 0.2 N/m2 vs. 0.5 ± 0.2 N/m2, p < 0.001) in the ascending aorta were significantly reduced after aortic valve repair.

Conclusions: 4D flow CMR allows assessment of the impact of aortic valve repair on changes in blood flow dynamics in patients with bicuspid aortic valve disease.

 

Fig. 1 Intraoperative situs of aortic valve repair in bicuspid aortic valve (BAV) disease. The surgical repair consists of reduction of the aortic valve anulus using suture annuloplasty and correction of the prolapse of the fused cup. The aim is the recreation of the optimal aortic root geometry. This includes reduction of the basal ring diameter to less than 25 mm and restoration of effective cusp height (coaptation length) above 8 mm. a and b Correction of cusp prolapse by means of plication sutures (arrows). c Surgery results in a symmetric configuration of the bicuspid aortic valve (arrow heads) with a commissural angle of 180°, resembling a Sievers type 0 valve. In this patient, additional replacement of the aortic root with Dacron prosthesis for aneurysm has been performed

Fig. 2 4D flow CMR-based characterization of flow dynamics in a 24-year-old man with bicuspid aortic valve before and after aortic valve repair. a Velocity-coded 4D flow CMR reveals an accelerated eccentric asymmetric flow jet (indicated by yellow and red streamlines) and a pronounced helical flow pattern (arrows) in the ascending aorta before surgery. The flow jet impacts and travels along the right aortic wall. b Extracted analysis plane (solid line) at the aortic valve level shows eccentric regurgitation of insufficient bicuspid valve (15.3%) (c) Extracted analysis plane (dashed line) at the level of the mid-ascending aorta shows the marked eccentric flow pattern (relative flow displacement: 0.43), resulting in increased global WSS (1.2 N/m2). d After surgery, velocity-coded 4D flow CMR shows reduced helical flow with a more cohesive central flow pattern more parallel to the vessel wall of the ascending aorta. e Extracted analysis plane at the aortic valve level after surgery shows decreased regurgitation (5.6%) (f) Extracted analysis plane at the level of the mid-ascending aorta demonstrates more centralized flow (relative flow displacement: 0.27), resulting in decreased global WSS (0.75 N/m2) after aortic valve repair

Fig. 3 4D flow CMR-based characterization of flow dynamics in a 30-year-old woman with unicuspid aortic valve before and after aortic valve repair. a Velocity-coded 4D flow CMR reveals an accelerated and highly eccentric asymmetric flow jet (indicated by yellow and red streamlines) and a pronounced helical (arrows) and vortical flow pattern (arrowhead) in the ascending aorta before surgery. The flow jet impacts and travels along the right-anterior aortic wall. b Extracted analysis plane (solid line) at the aortic valve level shows regurgitation of insufficient bicuspid valve (20%) (c) Extracted analysis plane (dashed line) at the level of the mid-ascending aorta shows the marked eccentric flow pattern (relative flow displacement: 0.37), resulting in increased global WSS (0.9 N/m2). d After surgery, velocity-coded 4D flow CMR shows reduced helical and vortical flow with a more cohesive central flow pattern more parallel to the vessel wall of the ascending aorta. e Extracted analysis plane at the aortic valve level shows decreased regurgitation (5.8%) after surgery (f) Extracted analysis plane at the level of the mid-ascending aorta demonstrates a more centralized flow (relative flow displacement: 0.24), resulting in decreased global WSS (0.37 N/m2) after aortic valve repair

Fig. 4 Flow displacement in the ascending aorta before and after aortic valve repair in patients with adult congenital heart disease. Flow displacement was significantly reduced after surgery (0.3 ± 0.1 vs. 0.25 ± 0.1) at the level of the mid-ascending aorta (midAAo). There was no significant reduction in flow displacement at the level of the sinotubular junction (STJ) and the proximal aortic arch (proxAA). Red lines indicate patients with unicuspid aortic valves and diamonds indicate patients with additional aortic root remodeling

Fig. 5 Circumferential and segmental wall shear stress (WSS) in the thoracic aorta before and after aortic valve repair in patients with congenital heart disease. a Graphs of quantitative analyses of circumferential peak systolic WSS show a significant reduction at the level of the mid-ascending aorta (midAAo), proximal aortic arch (proxAA), and distal aortic arch (distAA). Red lines indicate patients with unicuspid aortic valves and diamonds indicate patients with additional aortic root remodeling. b Spider charts of segmental peak systolic WSS at eight standardized local anatomic positions of the vessel wall (A, anterior; LA, left anterior; L, left; LP, left posterior; P, posterior; RP, right posterior; R, right; RA, right anterior) before (red spiders) and after (blue spiders) surgery. Highest segmental WSS was observed in the anterior, right-anterior, and right segments in the mid-ascending aorta as well as in the anterior and left-anterior segments of the proximal aortic arch. Asterisks indicate segments with significantly reduced WSS after aortic valve surgery. Of note, changes in peak systolic segmental WSS values are co-located with the changes in localized outflow jets and the position of elevated velocity before and after surgery

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