Bovine arch – a marker for thoracic aortic aneurysm

1151, oral, cat. 52

BOVINE ARCH – A MARKER FOR THORACIC AORTIC ANEURYSM

M. Hornick, R. Moomiaie, H. Mojibian, M. Tranquilli, J.A. Elefteriades

Yale University School of Medicine, New Haven, CT, USA
Background: “Bovine aortic arch” is a congenital variant of the great vessels of the aorta in which the left common carotid artery and innominate artery share a common origin. Though bovine arch is commonly regarded as a normal variant, very little direct data is available, and suspicion exists that bovine arch may predispose to thoracic aortic aneurysm (TAA).

Methods: With a cardiac imaging specialist, we retrospectively reviewed thoracic CT and/or MRI scans of 175 patients with known TAAs and 240 patients without TAAs to determine the incidence of bovine arch in each group. We reviewed chart records to compare TAA growth rates and clinical outcomes of patients with and without bovine arch.

Results: 20.7% of patients with TAA had concomitant bovine arch variant, compared to 6.7 % of patients without TAA (p<0.0001). Aortic dissection occurred in 38.9% of bovine arch patients, with 30.6% experiencing type B dissection. Rate of aneurysm expansion was 0.42 cm/year in the bovine group, compared to 0.16 cm/year in the non-bovine arch group. Radiology reports cited bovine arch in 6 of the 36 bovine arch patients (16.7%).

Conclusions: 1) Bovine aortic arch is significantly more common in patients with TAA than in the general population. 2) Radiology reports often overlook bovine arch. 3) Aortas in bovine arch patients grow faster than general TAAs. 4) Bovine arch patients tend to dissect, especially in the descending aorta. 5) These observations argue strongly that bovine arch should not be considered a normal variant of arch anatomy.