Toward Endografting of the Ascending Aorta: Insight into Dynamics Using Dynamic Cine-CTA

PURPOSE: To evaluate pulsatility and movement along the ascending thoracic aorta using dynamic electrocardiographically-gated 64-slice cine computed tomographic angiography (CTA). METHODS: Diameter and area change and center of mass (COM) movement of the ascending thoracic aorta was determined per cardiac cycle in 15 patients at surgically relevant anatomical levels: (A) 5 mm distal to the coronary arteries, (B) 5 mm proximal to the innominate artery, and (C) halfway up the ascending aorta. Additionally, COM movement was determined 1 cm (level P) and 2 cm (level Q) distal from the origins of the innominate, left carotid, and left subclavian arteries. Eight gated datasets covering the cardiac cycle were used to reconstruct images at each level perpendicular to the aortic lumen. The distance between important anatomical landmarks was determined. RESULTS: All levels showed significant cardiac cycle-induced diameter and area changes (p<0.001), with the largest pulsatility 5 mm distal to the coronary arteries. Mean maximum diameter changes were (A) 17.4%+/-4.8% (range 7.5%-27.5%), (B) 13.9%+/-3.5% (range 10.6%-25.0%), and (C) 12.9%+/-3.4% (8.3%-19.6%). Mean area changes were (A) 12.7%+/-5.5% (range 4.3%-21.8%), (B) 7.5%+/-2.0% (range 4.1%-11.0%), and (C) 5.6%+/-2.2% (range 1.9%-11.4%). Mean maximum COM movements were (A) 6.1+/-2.0 mm (range 2.7-9.0), (B) 2.3+/-1.1 mm (range 1.1-5.6), and (C) 3.6+/-1.5 mm (range 1.4-6.5). Mean COM movements of the innominate, left carotid, and left subclavian arteries, respectively, were (P) 1.9+/-0.7 mm (range 0.9-3.7), 2.4+/-0.6 mm (range 1.4-3.3), and 1.9+/-0.6 mm (range 0.8-2.8), and (Q) 1.8+/-0.7 mm (range 0.8-3.5), 1.8+/-0.6 mm (range 0.8-2.7), 1.9+/-0.6 mm (range 1.1-3.4). CONCLUSION: The dynamics of the ascending thoracic aorta and the arch vessels are impressive, showing a wide range of 3-dimensional motions. Future ascending arch branched and fenestrated thoracic endograft designs must consider this active local environment, as it may have implications for durability, sealing, and ultimate clinical success.