Aortic root movement: a potential risk factor for aortic dissection

We propose that the aortic root motion plays an important role in aortic dissection. The aortic root motion was measured in 40 cardiac patients using cine angiograms. A finite element model of the aortic root, arch and supra-aortic vessels, was created to assess the influence of axial displacement, twist and pressure on the wall stress. In patients, the axial displacement of the aortic root during the cardiac cycle ranged from 0 to 14 mm. Patients with previous bypass operation had significantly reduced aortic root movement (10 ± 7% of STJ vs. 17 ± 11% of STJ). In the ascending aorta at 120-mmHg pressure, the longitudinal stress was increased from 0.21 Nmm^-2 to 0.32 Nmm^-2 when axial displacement of 8.9 mm was applied. In the same location, a similar increase in the longitudinal stress was seen when the pressure load was increased to 180 mmHg without the axial displacement. The influence of the twist was negligible. In conclusion, axial movement of the aortic root appears to be just as much of a risk factor as hypertension in aortic dissection.