Fate of Dissected Aortic Arch after Surgical Repair of Acute Type A Aortic Dissection

Objectives: The aim of this study was to evaluate the fate of dissected aortic arch after surgical repair of acute Stanford type A aortic dissection and to delineate dimensions of branched stent-graft prosthesis for endovascular repair of dissected aortic arch according to the true lumen anatomy.

Methods: Between 2001 and 2015, among 274 patients operated for acute type A aortic dissection, 86 (aged 57 ± 13 years, 74% males) had residual dissection in the aortic arch and descending thoracic aorta on pre-discharge computed tomography (CT). Aortic arch geometry was assessed on pre-discharge and follow-up CT including diameters, lengths, dissection extension and entry localization. Median CT follow-up was 46 [10; 125] months.

Results: Altogether 86 patients were included (14 with and 72 without hemiarch replacement). The largest diameter increase was observed in the thoracic descending aorta (+17% [ranging between -14% and +92%] with more than 30% increase in 9 patients. The average aortic arch diameter increase was 6% [-10%; +20%] with true lumen diameter increase of 8% [-12%; +28%]. The aortic arch length increased from 66 [35; 105] mm to 71 [39; 123] mm (+12%) along the greater curvature. In contrast, the descending thoracic aorta length did not change (127 [115; 139] mm versus 129 [117; 149] mm; +0.3%). Diameter of the ascending aortic prosthesis ranged between 21 and 32 mm (mean diameter 27 ± 2 mm), the most common diameter (in 22 patients) was 28 mm. Mean diameter of the true lumen of dissected arch was 27 [10; 44] mm immediately proximal to the origin of the left carotid artery as well as 25 [6; 40] mm immediately proximal to the origin of the left subclavian artery. Diameter of the true lumen of dissected proximal descending aorta ranged between 7 and 35 mm (mean diameter 19 ± 5 mm).

Conclusion: Aortic arch residual dissection after surgical repair of type A dissection leads to aortic arch growth that may result in arch aneurysm requiring treatment. Endovascular repair of dissected aortic arch may be limited by usually small true lumen, requiring new stent design with branches to the supraaortic arteries, which will not disturb the narrow mainstream flow to the descending aorta.

Table 1 Change of aortic diameters

Aortic diameter at	Pre-discharge (mm)	Follow up (mm)	P	Δ (mm)	Δ [%]
Left carotid artery	37.2 ± 5.3	39.8 ± 5.7	0.027	2.0 ± 3.2	5.5 ± 8.3
Left subclavian artery	33.2 ± 5.1	36.8 ± 7.8	0.002	2.8 ± 5.2	6.9 ± 14.0
2 cm distal the origin of the left subclavian artery	34.6 ± 5.2	41.4 ± 9.9	<0.001	5.5 ± 7.0	15.0 ± 18.8
10 cm distal the origin of the left subclavian artery	32.6 ± 4.9	39.6 ± 11.2	<0.001	6.2 ± 7.8	17.1 ± 21.4