Intraoperative measurement of the ascending aortic diameter at the onset of aortic dissection

Background Although prior studies have associated aortic size with dissection risk, none have corrected for dissection-related aortic expansion. This study aimed to establish a measurement approach to determine the ascending aortic diameter before dissection. Methods The samples of dissected ascending aortas were obtained from 36 patients at the time of their operation. In this study, the intimal lumen diameter measured at its maximal stretching state was used as a reliable surrogate for the pre-dissection aortic diameter. Subsequently, the relationship between this surrogate and the aortic diameter measured on post-dissection CT at the corresponding levels was further analyzed. Results Using this method, the pre-dissection ascending aortic diameter was measured as 37.5 ± 6.6 mm, whereas the post-dissection CT measurement at the same level increased to 43.9 ± 7.0 mm. After excluding patients with non-A-non-B aortic dissection, the mean ascending aortic diameter increased by approximately 20% after dissection compared with the pre-dissection value, corresponding to an absolute increase of 7.5 mm in diameter. Conclusions Although aortic diameter remains a robust indicator for prophylactic surgery in the study population, acute aortic dissection is seldom associated with true ascending aortic aneurysms and occurs with normal or near-normal aortic dimensions in most patients. When dissection occurs in the setting of a small aortic diameter, it likely reflects a profound functional vulnerability of the aortic tissue to catastrophic aortic events.