Transcarotid Artery Revascularization for Symptomatic Retropharyngeal Internal Carotid Artery Stenosis

Introduction

Transcarotid artery revascularization (TCAR) has emerged as a safe alternative to transfemoral carotid artery stenting (TF-CAS) for patients with severe carotid artery stenosis. ¹ The safety and efficacy of transcarotid stenting with dynamic flow reversal have been supported by preliminary prospective studies.^2,3 Indications for TCAR include a range of anatomic and physiologic risk factors, making it a valuable option for specific patient populations. For example, patients with high internal carotid artery (ICA) lesions, age >75, severe heart disease, or recent myocardial infarction, along with other indications.^4,5 Comprehensive guidelines on TCAR, however, are still evolving due to its novelty and ongoing research.

Anatomic variants pose significant challenges to the management and intervention of carotid artery stenosis. Retropharyngeal ICA, for example, represents a rare yet well-documented anatomical variant. Anatomic definitions of retropharyngeal ICAs vary. Studies defining a retropharyngeal ICA as any placement medial to the uncovertebral joint found the variant present in 2.6% of patients. ⁶ Other studies defined the variant as any ICA placed ICA beyond a marginally retropharyngeal position, as determined by neuroradiologists. ⁷ With this definition, the prevalence of a retropharyngeal ICA was 15.5% of patients. Numerous complications associated with this anatomic variant have been reported, including hemorrhage during otolaryngological procedures, accidental puncture during glossopharyngeal block, and injury during intubation.^8,9 In addition to life-threatening bleeding during procedures in the oral cavity or oropharynx, retropharyngeal ICA’s anatomical depth poses risks when exposing the vessel during vascular procedures.

The preferred surgical approach to retropharyngeal ICA has not been detailed in the available literature. This case report highlights an instance where TCAR was deployed as an effective treatment for a patient with a retropharyngeal ICA and severe, symptomatic carotid artery stenosis. The patient’s vascular anomaly necessitated careful consideration and innovative approaches, making it a pertinent topic in TCAR utilization.

Permission was obtained from the patient to publish this case report.

Case Report

A 70-year-old African American female with a past medical history of hypertension, type II diabetes mellitus, recent transient ischemic attack on clopidogrel, and no smoking history presented to the vascular surgery clinic complaining of two recent episodes of lip numbness and right upper extremity numbness and tingling. The patient was right-handed. The patient was asymptomatic during her initial visit.

A carotid duplex exam performed during her initial visit showed a peak systolic velocity (PSV) of 440 cm/s in the left distal ICA. PSVs in the left common carotid artery and proximal ICA were 61 cm/s and 44 cm/s, respectively. Of note, the ultrasound could not adequately visualize distal to the lesion, which was 4-5 cm deep to the skin. The patient was sent for CT angiography (CTA) of the cerebral arteries and instructed to follow up the next day.

The patient provided new information about her history at her visit the next day. In addition to numbness and tingling, she experienced two prolonged episodes of slurred speech over the past month. Physical examination during this visit was unremarkable. She was oriented to self, place, and time, had normal strength and coordination bilaterally, and had no gross sensory deficits. No gross upper or lower extremity vascular abnormalities were appreciated.

CTA of the carotids demonstrated a lesion of the left distal ICA with more than 90% stenosis. Images also showed a retropharyngeal location of the ICA, nearly along the midline. The distal end of the lesion was located at the level of the 2nd cervical vertebra, with proximal extension above C2. (Image 1) ICA lesions cephalad to C2 are not an absolute contraindication to carotid endarterectomy, a lesion located this high can be difficult and require dangerous maneuvers. ¹⁰ The patient was diagnosed with a transient ischemic attack and sent to the hospital for immediate admission, systemic heparinization, and possible intervention.

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Image 1.

CTA of the carotid arteries after initial visit. Circle indicates the left ICA within the retropharyngeal space. Marked stenosis of the left ICA is demonstrated.

Interventional options for this patient included medical management, CEA, transfemoral carotid artery stenting (TF-CAS), and TCAR. Given the patient’s symptoms and imaging findings, a multidisciplinary team discussed the interventional options. The depth of the lesion relative to the skin made CEA a very high-risk procedure. Her age and extent of stenosis increased the risk of perioperative CVA with TF-CAS. Therefore, it was determined that TCAR was the best option considering the patient’s complex anatomy and severity of disease. The patient agreed to undergo TCAR after counseling on the risks and benefits of the procedure.

Treatment

The patient was treated with Plavix and Aspirin before the procedure. Local anesthesia was performed in the operating room before the procedure. A transverse incision was made between the sternal and clavicular heads of the sternocleidomastoid muscle below the omohyoid after the CCA was identified. Ultrasound was used to identify the least diseased portion of the CCA for dissection. The CCA was then isolated, and a vessel loop was placed around the proximal 1/3 under direct vision. The contralateral common femoral vein (CFV) was accessed using standard access and the venous return sheath was advanced into the CFV.

TCAR was then performed in the standard fashion. Primary stenting was performed with a 9 mm x 40mm ENROUTE® Transcarotid Stent. Due to distal kinking after primary stent placement, an additional 7 mm × 20  mm ENROUTE® Transcarotid Stent was placed. Confirmation of precise stent placement and vessel patency were confirmed via angiography. (Images 2–4).

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Image 2.

Intraoperative carotid angiogram before TCAR and stent placement. Arrow indicates severe stenosis of the left ICA.

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Image 3.

Intraoperative carotid angiogram after the primary stent placement. Arrow indicates distal kinking after stent placement.

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Image 4.

Intraoperative carotid angiogram after TCAR and stent placement. Angiogram demonstrates vessel patency.

Anterograde flow was restored after the successful completion of the procedure. The patient was neurologically intact throughout and following the procedure. The patient was prescribed aspirin and Plavix and instructed to continue her statin regimen.

The patient denied any recurrent symptoms during follow-ups with vascular surgery. She denied any issues swallowing at the three-month follow-up. Carotid duplex exam at three-month follow-up showed a PSV of 42 cm/s in the left distal ICA.

Discussion

In this case report, we detailed the successful utilization of TCAR in a patient with severe symptomatic carotid artery stenosis and a rare anatomical variant, a retropharyngeal ICA. This unique vascular anomaly posed considerable challenges to traditional treatment methods.

The success of this case suggests the need to consider high-risk anatomic variants such as retropharyngeal ICA when deciding between interventions for carotid artery stenosis. We argue retropharyngeal ICA, along with other similarly challenging anatomic variants, should be considered as indications for TCAR.

This report also underscores the necessity for further investigation into the selection criteria for TCAR. As evidence for the safety and effectiveness of TCAR grows, extensive research is required to delineate the parameters that warrant its use. This will not only enhance our understanding of TCAR but also contribute to refining the scope of this innovative technique in carotid artery disease management. The commitment to future research is instrumental in solidifying TCAR’s role in addressing complex carotid artery pathology while prioritizing patient safety and outcomes.

Conclusion

This case demonstrates the successful use of TCAR in managing severe carotid artery stenosis complicated by a rare retropharyngeal ICA variant. It highlights the need to consider anatomical variants when determining treatment strategies for carotid artery disease. This patient’s favorable outcome suggests that TCAR should be considered for such high-risk anatomical variants. Further research is needed to refine the criteria for TCA, but the case highlights TCAR’s evolving role as a valuable intervention in addressing complex carotid artery pathology.