Computational modeling of blood flow in the aorta-insights into eccentric dilatation of the ascending aorta after surgery for coarctation

Objective: To assess whether combining a computational modeling technique with data from patient magnetic resonance imaging studies can detect different fluid dynamics and vascular biomechanical properties of the ascending and horizontal aorta in patients with angulated "gothic'' arch geometry compared with those with normal "Romanesque'' arch geometry after aortic coarctation repair. Methods: Advanced computational fluid dynamics techniques (coupled Navier-Stokes and elastodynamics equations) were used to predict the fluid-wall interactions in large arteries. We modeled the fluid dynamics and shear stress in the ascending and horizontal aorta in cases of "gothic'' arch and normal "Romanesque'' aortic arch geometry. A total of 30 patients after aortic coarctation repair prospectively underwent 3-dimensional magnetic resonance imaging angiography of the thoracic aorta. Measurements of the ascending and horizontal aorta were assessed using multiplanar reformatting images. Results: Our computational model demonstrated that wall shear stress is greater in those with an angulated "gothic'' aortic arch than in those with a "Romanesque'' arch. In particular, wall shear stress affected the anterior and posterior segments of the ascending aorta and the inferior and superior segments of the horizontal aorta (vs the left and right segments). In vivo, a "gothic'' arch was associated with dilatation of the ascending and horizontal aorta, which was eccentric rather than concentric (P <. 05). Conclusions: Our results have shown that wall shear stress is eccentric and significantly increased in the ascending and horizontal aorta in patients with a "gothic'' aortic arch after repair of coarctation. This suggests that patients with an angulated "gothic'' aortic arch might warrant increased surveillance for aortic complications.