Appropriate sizing of the frozen elephant trunk: How to predict proximal descending aortic diameter prior to dissection?

Abstract

Objective: The predissection aortic diameter is the best reference for determining the size of the frozen elephant trunk in aortic dissection. We aimed to develop a new prediction method to estimate the predissection diameter of proximal descending aorta. Furthermore, we evaluated the accuracy of the estimated predissection proximal descending aortic diameters calculated using 3 prediction methods.

Methods: A total of 39 patients with acute type A aortic dissection who underwent predissection computed tomography were included in derivation sets. We measured the aortic dimensions at 3 levels of the proximal descending aorta: 5, 10, and 15 cm from zone 2. We developed a new prediction method-postdissection aortic diameter divided by 1.13 (AoD_{New factor})-and estimated the predissection aortic diameter using the new and previously proposed methods by Rylski (AoD_Rylski) and Yamauchi (Equation_Yamauchi). Furthermore, we validated the new prediction method using a validation dataset with 24 patients.

Results: The rate of bias ≤2 mm was significantly greater with Equation_Yamauchi and AoD_{New factor} than with AoD_Rylski in the derivation group at each level of the proximal descending aorta (P < .001). In the validation group, the rate of bias ≤2 mm was significantly greater with Equation_Yamauchi and AoD_{New factor} than with AoD_Rylski at 10 cm and 15 cm from zone 2 (10 cm: P = .014, 15 cm: P < .001).

Conclusions: These results suggest that the new prediction method can be used as a simple and accurate estimation method for the predissection aortic diameter at the proximal descending aorta.