Effects of wall motion and compliance on flow patterns in the ascending aorta.

Helical flows have been observed in the ascending aorta in vivo, and geometric curvature has been suggested to be a major contributing factor. We employed magnetic resonance imaging (MRI) and velocity mapping to develop a computational model to examine the effects of curvature and also wall compliance and movement upon flow patterns. In the computational model, MRI-derived geometry and velocities were imposed as boundary conditions, which included both radial expansion-contraction and translational motion of the wall. The computed results were in agreement with the MR data only when full wall motion was included in the model, suggesting that the flow patterns observed in the ascending aorta arise not only from geometric curvature of the arch but also from the motion of the aorta resulting from its attachment to the beating heart.