Truncus Bicaroticus With Arteria Lusoria: A Rare Combination of Aortic Root Anatomy Complicating Cardiac Catheterization

Branching of the great vessels from the aorta normally progresses with the brachiocephalic trunk as the first takeoff followed by the left common carotid and left subclavian artery in approximately 85% of cases.¹ Variants of great vessel branching patterns include the so-called bovine arch, arteria lusoria or aberrant right subclavian artery (ARSA), aberrant origin of the vertebral arteries, and truncus bicaroticus, or common origin of the carotid arteries (COCA). These aberrancies are quite rare, some with an incidence of < 1%.^1,2

These vascular anomalies become clinically relevant when they pose difficulty for operators in surgical and interventional specialties, necessitating unique approaches, catheters, and techniques to overcome. We present a case of concomitant aortic arch abnormalities during a diagnostic workup for transcatheter aortic valve replacement (TAVR) in a patient with previous coronary artery bypass grafting (CABG).

Case Presentation

A 66-year-old woman with coronary artery disease (CAD) status post-CABG and stage D1 aortic stenosis (AS) presented with exertional dyspnea. She was referred for coronary angiography as part of a workup for TAVR. Echocardiography confirmed severe AS with a peak velocity of 4.1 m/s, mean pressure gradient of 50 mm Hg, and an aortic valve area of 0.7 cm². The patient was scheduled for cardiac catheterization with anticipated left radial artery approach for intubation and opacification of the left internal mammary artery (LIMA). However, this approach was abandoned during the procedure due to discovery of aberrant left radial artery anatomy, and the procedure was completed via femoral access.

Subsequent coronary angiography revealed 3-vessel CAD, patent saphenous vein grafts (SVG) to the right coronary artery (RCA) and a diagonal branch vessel with an occluded SVG to the left circumflex. Difficulty was encountered when engaging the left subclavian artery using a JR 4.0 diagnostic catheter for LIMA angiography. Nonselective angiography of the aortic arch was performed and demonstrated an uncommon anatomical variant (Figure 1, left). The right common carotid artery (CCA) [A] and the left CCA [B] arose from a single trunk, consistent with truncus bicaroticus or COCA [C]. The right subclavian artery [D] originated distal to the left subclavian artery otherwise known as arteria lusoria or ARSA forming an incomplete vascular ring [E]. Selective engagement of the left subclavian artery remained problematic even with the use of specialty arch catheters (Headhunter and LIMA catheters). The procedure concluded without confirming patency of the LIMA graft. A total of 145 mL of Omnipaque (iohexol injection) contrast was used for the procedure, and no adverse events occurred.

Same-day access of the ipsilateral ulnar artery was not pursued because of the risk of hand ischemia. The patient underwent repeat catheterization utilizing left ulnar artery access after adequate recovery time from the initial left radial approach. Selective LIMA angiography was achieved and demonstrated a patent LIMA to LAD graft. A computed tomography (CT) aorta for purposes of TAVR planning was able to reconstruct the aortic arch vasculature (Figure 1, right) confirming the presence of both ARSA and COCA. The patient went on to undergo successful TAVR with subsequent improvement of clinical symptoms.