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