A novel approach to high-grade carotid stenosis with concomitant extracranial carotid aneurysms using transcarotid artery revascularization

Abstract

We present the novel application of transcarotid artery revascularization (TCAR) in two high-risk patients with high-grade internal artery stenosis and concomitant atherosclerotic extracranial carotid artery aneurysms (ECAAs). ECAAs account for <1% of arterial aneurysms and are usually clinically silent at presentation. Historically, the treatment of ECAAs has been via open reconstruction or stent grafting. TCAR is an effective alternative for carotid revascularization in high-risk patients with high-grade carotid stenosis, but has not been widely used for aneurysmal management. We report two cases to describe our management of concomitant carotid stenoses and ECCA with TCAR.

Extracranial carotid artery aneurysms (ECAAs) are rare, accounting for <1% of all arterial aneurysms.¹ Complications have included rupture, thrombosis, and distal embolization.^1,2 The ECAA treatment options include nonoperative management and open, endovascular, and hybrid techniques. Transcarotid artery revascularization (TCAR), a hybrid procedure used to treat carotid artery stenosis (CAS), uses the ENROUTE transcarotid neuroprotection and stent system (Silk Road Medical, Inc, Sunnyvale, Calif). This novel system passively reverses arterial flow from the common carotid artery (CCA) to the femoral vein, providing neuroprotection and obviating the need for manipulation of the aortic arch.³ We present the application of TCAR for two high-risk patients with high-grade internal carotid artery (ICA) stenosis and concomitant atherosclerotic ECAA. Both patients had provided written informed consent for the report of their case.

Case report

Patient 1

A 64-year-old man was evaluated for critical (80%-99%) asymptomatic right ICA (RICA) stenosis. His medical history included hyperlipidemia, chronic atrial fibrillation, and cardiac pacemaker placement. Carotid Duplex ultrasound examination revealed critical (80%-99%) stenosis of the RICA, a pseudoaneurysm arising from the RICA measuring 1.44 cm × 0.41 cm (Fig 1, A and B), and moderate (50%-69%) stenosis of the left ICA. Computed tomography angiography (CTA) of the head and neck revealed tandem RICA stenoses, with 60% proximal stenosis, followed by 80% stenosis distally, just above the level of the C2 vertebra. Direct communication between the vessel lumen and aneurysm through the intima suggested the presence of an atherosclerotic pseudoaneurysm. The RICA pseudoaneurysm was seen ∼1.2 cm distal to the origin and measured 0.8 cm × 0.5 cm (Fig 1, C and D). No significant stenosis of the arch vessels was found. These anatomic findings showed that the patient was at high risk for coil embolization and, therefore, was offered pseudoaneurysm exclusion with a covered stent graft using TCAR.

Fig 1.

Patient 1. A, Color Doppler ultrasound scan of the right internal carotid artery (RICA) with associated pseudoaneurysm. B, B-mode ultrasound scan of the right internal carotid artery with associated pseudoaneurysm. C, Coronal view of computed tomography angiogram (CTA) demonstrating tandem right internal carotid stenoses and extracranial carotid artery aneurysm (ECAA) of the proximal RICA. D, Three-dimensional reconstruction model demonstrating tandem right internal carotid stenoses and ECAA of the proximal RICA. E, Preoperative right carotid angiogram demonstrating tandem right internal carotid stenoses and ECAA of the proximal RICA. F, Completion right carotid angiogram demonstrating a patent right common carotid to internal carotid artery stent with excluded ECAA.

Patient 2

A 78-year-old man had presented with symptoms of right central retinal artery occlusion. His medical history included chronic obstructive pulmonary disease, congestive heart failure with a left ventricular ejection fraction of 20%, recent myocardial infarction with drug-eluting stent placement, and temporary wearable cardioverter-defibrillator secondary to left bundle branch block. Carotid Duplex ultrasound scanning revealed critical (80%-99%) stenosis in the RICA with <50% stenosis of the left ICA. CTA confirmed the critical stenosis of the RICA. Turbulent flow dynamics within the pseudoaneurysm demonstrated poor contrast opacification of the pseudoaneurysm on CTA. Thus, no ECAA was appreciated on preoperative CT imaging. The patient was deemed a poor surgical candidate in light of his multiple comorbidities and, therefore, was offered TCAR.

Treatment

Neither patient had a history of previous neck surgery or evidence of systemic or local infection. With the use of an endoluminal treatment modality, a histopathologic examination, the reference standard test for confirming the diagnosis of pseudoaneurysms, was not obtained. Both patients were considered to have pseudoaneurysms because of the findings of an ECAA associated with atherosclerotic plaque related to intimal disruption directly feeding into the pseudoaneurysm on CTA and ultrasound examination. Both patients received a loading dose of aspirin and clopidogrel preoperatively. With the patient under general anesthesia, a 3-cm vertical incision was made between the sternal and clavicular heads of the sternocleidomastoid muscle to expose the right CCA. Two purse-string sutures were placed using 5-0 Prolene suture (Ethicon, Inc, Cornelia, Ga) over the CCA. The patients were heparinized to an activated clotting time of >250 seconds. Next, ultrasound-guided access of the left common femoral vein was obtained, and a 6F venous sheath was placed. Once the activated clotting time had reached 250 seconds, the CCA was accessed with a micropuncture needle, and a 4F micropuncture sheath was placed over the wire. A carotid angiogram was performed to mark the carotid bifurcation (Fig 1, E). In the second patient, the carotid angiogram revealed a large aneurysm defined by a filling turbulence of the right distal CCA and a very tight RICA stenosis (Fig 2, A). A stiff J-tip wire was advanced under fluoroscopic guidance without crossing the carotid bifurcation. The sheath was upsized to an 8F sheath and secured to the patient's soft tissues. The femoral sheath was exchanged for the flow reversal device, which was connected and tested for low and high flow. After initiating flow reversal, the lesion was crossed with a Balance Middle Weight guidewire (Abbott Cardiovascular, Santa Clara, Calif). The lesion was predilated with a 5/30 mm balloon in the first patient. No predilatation was performed in the second patient. Next, Viabahn stent grafts (WL Gore, Flagstaff, Ariz) were deployed under active high flow reversal, successfully excluding the pseudoaneurysm (Viabahn stents, 8/50 mm for patient 1; 7/50 mm for patient 2). After deployment, the stent graft was postdilated in both patients. The completion angiogram confirmed patency of the RICA, complete exclusion of the aneurysm, and no contrast filling of the external carotid artery (Figs 1, F and 2, B). In both patients, the CCA puncture site was closed with the previously placed purse-string sutures. Hemostasis was achieved, and the incision was closed in standard fashion. Both patients were neurologically intact on awakening. Their postoperative courses were uneventful, and both were discharged the next day on dual antiplatelet therapy using aspirin and clopidogrel. Both patients remained asymptomatic at the 6-month follow-up examination with a patent RICA stent and successfully excluded pseudoaneurysm seen on the carotid Duplex ultrasound scans.

Fig 2.

Patient 2. A, Preoperative right carotid angiogram demonstrating critical stenosis of the RICA with string sign and distal right common carotid artery (CCA) aneurysm. B, Completion right carotid angiogram demonstrating patent right common carotid to internal carotid artery (ICA) stent with excluded extracranial carotid artery aneurysm (ECAA).

Discussion

At present, the management of ECAAs varies widely. Because of its rarity, no formal evidence-based recommendations are available for ECAA treatment.⁴ Nonoperative ECAA management alone has had an unacceptably high stroke rate.⁵ Open repair can effectively manage ECAAs; however, it increases the risk of cranial nerve injury.⁴ Recently, endovascular repair has become an accepted alternative.⁶

In the study by Li et al,⁷ 224 patients had undergone endovascular stenting of ECAAs. Aneurysmal thrombus was found in 18.4% of the patients.⁷ Because the major mortality risk of ECAAs is stroke, an endovascular approach with neuroprotection has made TCAR an appealing option for treating high-grade ICA stenosis with ECAAs. Temporary cerebral blood flow reversal via direct CCA access prevents the occurrence of distal embolization during lesion crossing and stent deployment. The ROADSTER (Safety and Efficacy Study for Reverse Flow Used During Carotid Artery Stenting Procedure) trial demonstrated an overall stroke rate of 1.4%, the lowest ever reported for any prospective, multicenter clinical trial using carotid artery stenting.⁸ Rizwan et al⁹ demonstrated the treatment of an isolated ECAA with TCAR in two patients. Their rationale was based on the neuroprotective advantages of flow reversal when crossing the aneurysm, which is usually associated with significant intramural thrombus, and the expected disadvantages of placing a distal embolic protection device.

Concomitant CAS and ECAA management has not been well described in reported studies. Coiling has been described as an option for the management of ECAAs with or without stenting. In our patients, we considered stent grafting as a safer option to minimize instrumentation and distal embolization in a highly stenotic ICA. Therefore, we used TCAR technology and off-label use Viabahn stents to treat the CAS and concomitant ECAA. For the first patient, the decision was based on the presence of preoperative tandem high-grade stenoses with concomitant ECAA, significantly increasing the potential for embolization during lesion manipulation. For the second patient, patient-related factors had initially driven our decision to TCAR as the aneurysm could not be clearly identified by the preoperative imaging studies. On intraoperative identification of the ECAA, we determined that TCAR could successfully address both pathologic entities in one setting. We were able to perform TCAR safely and effectively to treat both the RICA stenosis and the ECAA.

Conclusion

TCAR is a safe option and should be a part of the armamentarium for the surgical management of ECAAs, especially in high-risk patients with concomitant ICA stenosis.

From the Society for Clinical Vascular Surgery