Ascending Aortic Diameter
Several papers have investigated geometric changes induced by aortic dissection, mostly focusing on measurements of aortic diameter. In a multi-center retrospective study, Rylski et al. characterized the morphologic changes induced by aortic dissection by comparing pre-dissection CTAs with post-dissection CTAs in 63 non-Marfans, non-bicuspid aortic valve patients. They determined that aortic dissection changes aortic geometry, noting significant increases in diameter, ellipticity, volume, and tortuosity after aortic dissection. Interestingly, they determined that post-dissection increases in aortic diameter were most pronounced in the mid-ascending aorta, where average maximum diameter was 32% larger after aortic dissection9. In his study on ascending aortic length, Wu et al. found 10 patients with pre-dissection CT scans and noted an average aortic diameter increase of 0.8 cm13. Therefore, it is not surprising that in our study ATAAD patients had significantly greater ascending aortic diameter compared with controls. We evaluated diameter at the STJ and PAB and found that the diameter of the ascending aorta was greater at the PAB. Additionally, we found that a cutoff of 5.5 cm diameter at either site along the ascending aorta was highly specific for ATAAD and was not present in any of the controls. However, only 18% of cases had a maximum ascending aortic diameter >5.5 cm, which further reinforces the need for more sensitive screening criteria.