The impact of aortic arch geometry on flow dynamics using a simplified approach with magnetic resonance velocity...

We sought to determine, in vivo, the impact of aortic arch geometry on flow dynamics, which affects overall cardiovascular energetics and has implications for organ perfusion and Doppler flow calculations.

Twenty-seven patients (13 with left and 14 with right aortic arches) underwent magnetic resonance phase-encoded velocity mapping in the ascending and descending aorta. The cross-sectional area were divided into 4 equal quadrants aligned along the long axis of the aorta for analysis. Significance P < .05.

In the ascending aorta, there was a significantly higher total flow throughout the cardiac cycle in the posterior and leftward quadrant of right aortic arch than left aortic arch (P = .007) that was compensated for by significantly lower flow in anterior and rightward quadrant of right aortic arch than left aortic arch (P = .02). In the right aortic arch, maximum velocity (100 +/- 14 cm/second) occurred in 7/9 patients in the right half while in left aortic arch, maximum velocity (107 +/- 20 cm/second) occurred in 13/15 in the left half. In the descending aorta, whether left aortic arch or right aortic arch, the posterior half appeared to have greater flow than the anterior half.

Right aortic arch geometry impacts flow dynamics in the ascending aorta whereas it is not altered in the descending aorta, where flow is predominantly in the posterior half. The sidedness of the aortic arch determined the location of maximum velocity. Alternatively, this also may suggest that hemodynamics could have played a role in the development of right aortic arch in certain individuals.