Impact of Anesthesia on the Dimension of the Ascending Aorta

Dilatation of the ascending aorta often progresses silently in an asymptomatic patient, until an acute complication occurs (such as a dissection or rupture), which is directly related to the diameter of the aortic. To prevent these extremely harmful situations, aortic replacement surgery, as indicated by significant dilatation of the ascending aorta, could be the option of choice (1). The decision to perform elective surgery depends on the measurement of the thoracic aorta diameter, which would rely on the largest aortic dimension. Trans-thoracic echocardiography (TTE) is widely used to assess the aortic root (2), and results from computed tomography (CT) scans are used to evaluate the ascending aorta beyond the sinotubular junction (3, 4). Both these tests facilitate follow-up evaluation of patients with thoracic aortic aneurysm. Usually, patients are referred for surgery based on the findings of one or both of these examinations. Furthermore, when a patient is referred for surgery, intra-operative trans-esophageal echocardiography (TEE) is often performed after induction of the anesthesia in order to evaluate the aortic dimension and valve function. In some cases, the diameter of the aorta is considered borderline for replacement, in which case the TEE measurement could reverse the decision-making, especially when the indication for surgery is due to valve pathology, with the aorta being a secondary consideration. From the investigators experience, intra-operative TEE aortic measurements after the anesthesia are not entirely accurate, and could under-estimate the diameter of the aorta. Relying on intra-operative TEE measurements could result in under-treatment of the dilated aorta, especially when its replacement is secondary to other cardiac pathologies (e.g. AVR, CABG) that require surgery. Influence of intra-operative anesthesia on TEE measurements of the aorta are not described in the current literature. If the investigators hypothesis is correct, adjustments will need to be made regarding the surgical management of patients with borderline aortic dimensions.