Transradial Approach to Cerebral Aneurysm Occlusion in a Patient with an Aberrant Right Subclavian Artery: A Case Report

Background

A retroesophageal right subclavian artery, or arteria lusoria, is an anatomical variant in which the right subclavian artery arises distal to the left subclavian artery as a fourth branch of the aorta. It courses towards the right arm behind the trachea and esophagus. This anatomic variant has just a 1% prevalence in the general population, but is present in almost 1 in 4 individuals who have 1 or more chromosomal defects [1,2]. It remains clinically silent in the majority of cases, usually only discovered during angiographic procedures.

In a study in which a transradial approach was used during coronary interventions, among the 0.45% of patients with a lusoria arteria, the procedural success rate was just 60%, versus 97.5% in patients without this anatomical variant [3]. To date, there have been no reports published on the treatment of cerebral aneurysms in patients with this aberrancy of the right subclavian artery.

Case Report

A 60-year-old woman presented to our unit with a subarachnoid hemorrhage: Hunt Hess 4, Fisher 4 (Figure 1). The patient was intubated, then a right radial approach was used to occlude the aneurism using a technique described in previous publications [4,5].

A Simmons type 2 catheter (Merit Medical Systems, Utah, USA) was slid over a 260 mm 0.035”glide-wire (Terumo Interventional Systems, Somerset, NJ) at the aortic valve. A 90° angle was observed between the ascending aorta and right subclavian artery (Figure 2). Three-vessel angiography was performed with the Simmons catheter. Left carotid injection was performed with a completely curved Simmons catheter (Figure 3). Over the glide-wire, we ascended an intermediate 072” Navien catheter (Medtronic, Minneapolis, Minnesota, USA) up to the carotid petrous segment. Then, over a 0.014”guide-wire, we advanced a microcatheter into the aneurysm (Figure 4), where we released 8 coils to successfully occlude it (Figures 5, 6).

Discussion

Usually, an aberrant right subclavian artery is discovered after the decision has been made to use the radial approach for an intervention; consequently, it is important to have a tool on hand that can be used to overcome this aberrancy. In such patients, using the right radial artery approach, instead of the Simmons catheter going straight into the ascending aorta, as usual, it ends up in the descending aorta, where a straight-angle curve to the ascending aorta must be navigated to reach the aortic valve.

This variation in anatomy adds a new curve before catheterization of the supra-aortic vessels (Figure 3). This anatomical variant does not preclude further advancement of a Simmons catheter, since a glide-wire can be employed to facilitate navigation of the curve. Nonetheless, the new curvature increases the difficulty of catheterization and makes holding the micro-catheter inside cerebral vessels more difficult during therapeutic procedures. In this scenario, where the pathology is more distant, a long-sheath system cannot be used, since its rigid component does not reach far enough to help navigate the vessel’s aberrant curvature. Similarly, using classic guide catheters alone is useless, because they are too short to provide the stability needed for the procedure.

Intracranial support catheters have both adequate flexibility to conform to such curves and enough length to reach the carotid artery’s petrous segment and provide stability to the microcatheter. We believe these 2 characteristics are the basis for the therapeutic success we achieved in our patient. The key moment in our procedure was negotiating the intracranial support catheter with the glide-wire at the first loop between the right subclavian and left carotid artery. This step required a very distal wire position as the intracranial support catheter was advanced. Once the tip of the catheter reached the carotid artery’s petrous segment, however, the remainder of the procedure was relatively straight-forward.

This is the first report of cerebral aneurysm embolization in a patient with an aberrant right subclavian artery. Based on our experience, we believe that using an intermediate catheter is key to approaching the carotid vessel and, once there, holding the microcatheter inside the aneurysm so it can be treated.

Conclusions

The discovery of an aberrant right subclavian artery during cerebral angiography performed through a right transradial approach renders the treatment of cerebral aneurysms more difficult. Utilizing an intracranial support catheter can facilitate the embolization of cerebral aneurysms in patients with this anatomical variant.