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How to select the optimal size of frozen elephant trunk in total arch replacement for type A acute aortic dissection.

BACKGROUND
Total arch replacement (TAR) with a frozen elephant trunk (FET) is a common technique for acute aortic dissection, but there is no consensus on the optimal size of the FET.


METHODS
Forty-four patients who underwent TAR with FET for acute aortic dissection at our hospital since 2014 were included. The aortic diameter obtained from FET was measured on postoperative computed tomography (CT) and the estimated oversizing ratio was calculated. We investigated the relationship between the estimated oversizing ratio and postoperative outcomes. We also measured the maximum true lumen diameter, circumference of the true lumen, and total aortic diameter at the same level as the FET end on preoperative CT and examined the correlation with the aortic diameter obtained from FET.


RESULTS
The average estimated oversizing ratio was 109%. Early postoperative CT showed complete thrombosis of the false lumen in 41 (93.2%) patients. No distal stent graft-induced new entry occurred during follow-up. The correlation coefficients between the three measurements and aortic diameter obtained from FET were 0.64 (maximum true lumen diameter), 0.76 (true lumen diameter calculated from circumference), and 0.72 (total aortic diameter), respectively.


CONCLUSIONS
The aortic diameter obtained from FET on postoperative CT was strongly correlated with the true lumen diameter calculated from the circumference and total aortic diameter on preoperative CT. It is reasonable to select a size of approximately 130% of the true lumen diameter calculated from the circumference or 80% to 85% of the total aortic diameter.