Wall Stress and Geometry of the Thoracic Aorta in Patients With Aortic Valve Disease.

BACKGROUND: Aortic valve disease increases velocity and changes the way blood enters the aorta. Over time, the biomechanical environment can cause aortic remodelling. We hypothesized that aortic geometry and wall stress would be different in patients with aortic valve disease compared with controls. METHODS: We examined 40 patients with aortic sclerosis (n = 10) or mild (n = 10), moderate (n = 10), and severe (n = 10) aortic stenosis, and also 10 control individuals. The thoracic aorta of each individual was reconstructed into a three-dimensional model from computed tomography. We measured geometric variables and used finite element analysis to compute aortic wall stress. Statistical analyses were performed to test our hypothesis. RESULTS: Aortic wall stress was significantly associated with tortuosity of the descending aorta (r = 0.35, p = 0.01), arch radius (r = 0.49, p < 0.01), ascending aortic diameter (r = 0.59, p < 0.01), and aortic centerline length (r = 0.39, p < 0.01). Wall stress was highest in patients with severe stenosis (p = 0.02), although elevations in wall stress were also noted in those with mild stenosis (p = 0.02), and aortic sclerosis (p = 0.02) compared with controls. Similar trends were observed when we corrected for difference in blood pressure. Total centerline tortuosity was higher in patients with severe aortic stenosis than in controls (p = 0.04), as was descending aorta tortuosity (p = 0.04). CONCLUSIONS: Aortic geometry is associated with aortic wall stress. Patients with aortic valve disease have higher aortic wall stress than controls, and those with severe aortic stenosis have more tortuous aortas. However, increases in geometric measures and wall stress are not stepwise with increasing disease severity.