Aortic Arch Angiography and Common Variations

Aortic Arch Angiography and Common Variations

The left anterior oblique view is the commonly used position for aortic arch angiography, providing excellent visualization of the origins of the major supra-aortic branches. Sometimes, when the left anterior oblique view is insufficient to clearly visualize the openings of these branches, additional angiography in various positions is necessary. The Myla classification system for the Aortic Arch I​ categorizes aortic arches into three types based on the location of the major supra-aortic branch openings. A horizontal line is drawn across the upper and lower borders of the aortic arch, representing the supra-aortic line and the infra-aortic line."
1. Myla Type 1:
The major supra-aortic branch openings are located on the supra-aortic line, accounting for approximately 44.7%.
2. Myla Type 2:
The major supra-aortic branch openings are located between the supra-aortic line and the infra-aortic line, accounting for approximately 31.4%.
3. Myla Type 3:
The major supra-aortic branch openings are located below the infra-aortic line, accounting for approximately 23.9%.With age, the proportion of Myla Type 1 aortic arches decreases, while the proportions of Myla Type 2 and Myla Type 3 aortic arches increase.The incidence of acute angles in the brachiocephalic trunk, left common carotid artery, and left subclavian artery gradually increases.The incidence of mild, moderate, and severe tortuosity of the supra-aortic branches gradually increases.
Common variations are as follows:
1. The brachiocephalic trunk and left common carotid artery share a common trunk, the most common variation, also known as the bovine aortic arch, accounting for approximately 13%.

2. The left common carotid artery originates from the brachiocephalic trunk, accounting for approximately 9%.

3. The left common carotid artery and left subclavian artery share a common trunk, forming the left brachiocephalic trunk (<1%).

4. The left vertebral artery often originates from the aortic arch as a third branch between the left common carotid artery and left subclavian artery (<3%).

5. The left common carotid artery originates from the brachiocephalic trunk, and the left vertebral artery originates from the aortic arch as a second branch (<1%).

6. The left vertebral artery originates directly from the aortic arch as the final branch (<1%). 7. The common brachiocephalic trunk and the left vertebral artery originate directly from the aortic arch as final branches (<1%).

8. The left vertebral artery arises before the left subclavian artery, and the right subclavian artery is the final branch of the aortic arch (<1%).

9. The left vertebral artery originates from both the aortic arch and the left subclavian artery, forming a common trunk (<1%).

10. The aberrant right subclavian artery occurs in approximately 0.4% to 2% of cases.