Transcarotid artery revascularization of a symptomatic carotid artery with a tortuous intrathoracic component

INTRODUCTION

Transcarotid artery revascularization (TCAR) has emerged as a promising method for revascularizing the internal carotid artery (ICA). TCAR offers greater neurovascular embolic protection than carotid artery stenting (CAS) and is less invasive than carotid endarterectomy (CEA) – the gold standard for surgical treatment of ICA stenosis. Historically, we have not known how TCAR compares with CEA, but our understanding is changing as more data becomes available. One recent study found that TCAR compares favorably to CEA in octogenarians when considering stroke risk and mortality up to one year after surgery.^[1] We found that our patient – an 84-year-old woman with a previous cardiac arrest during aborted right CEA and tortuous common carotid arteries (CCAs) – also benefited from TCAR because it gave direct surgical access to her CCA, a unique feature of this endovascular technique.

CASE REPORT

An 84-year-old female with a complex medical history, including prior coronary stent placement followed by 5-vessel coronary artery bypass surgery, presented with the left arm and leg weakness. Magnetic resonance imaging demonstrated acute infarction in the parietal-occipital region, while computed tomography angiography (CTA) showed >50% calcified stenosis of the bilateral ICAs. She was initially treated with tissue plasminogen activator and placed on dual anti-platelet therapy along with a high-intensity statin. Vascular surgery was consulted for definitive treatment of her right ICA lesion, and it was determined that CEA was the best method for revascularization. Unfortunately, her CEA had to be aborted intraoperatively because she developed pulseless electrical activity (PEA) following heparin administration requiring cardiopulmonary resuscitation. The etiology of her cardiac arrest was unknown but initially attributed to heparin anaphylaxis. She recovered after a brief hospital stay and was discharged on maximum medical therapy.

Five months later, she was referred to our clinic for second opinion of TCAR. Considering her high-risk surgical status and atypical anatomy, further surgical intervention was deferred in favor of continued medical management. Unfortunately, 1 month later, she presented with recurrent transient ischemic attack symptoms due to the right anterofrontal lobe and left hemispheric lesions. On computed tomography (CT), her right carotid artery plaque had high-risk morphology, placing her at risk for ipsilateral stroke without surgery. A CTA of the neck showed tortuous bilateral CCAs [Figure 1], complicating an endovascular approach. Reoperative CEA under general anesthesia was excluded as an option given her intraoperative PEA arrest 7 months prior.

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Figure 1:

An 84-year-old woman who presented with the left arm and leg weakness diagnosed with the right anterofrontal lobe and left hemispheric lesions secondary to internal carotid artery stenosis. Bilateral tortuous common carotid arteries were demonstrated on computed tomography angiography during surgical planning and later with 3D reconstruction, seen above.

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A multidisciplinary team evaluated her for further risk stratification. Echocardiography showed preserved ejection fraction and multiple wall motion abnormalities consistent with her prior myocardial infarction; EKG and nuclear stress testing did not show evidence of new ischemia. Cardiology determined that her prior episode of cardiac arrest was associated with 15 s of asystole followed by junctional and ventricular escape beats, making the patient risk-prohibitive for general anesthesia. An allergist evaluated the patient for heparin anaphylaxis; she did not develop hives, angioedema, flushing, or ventilatory problems during heparin challenge, excluding heparin as a cause of her PEA. Repeat carotid Doppler imaging showed a right ICA peak systolic velocity of 190 cm/s and end diastolic velocity of 40 cm/s, a slight increase from prior with antegrade flow in the right vertebral artery, right ICA/CCA ratio 2.28, left ICA/CCA 2.41 and patent bilateral vertebral arteries. In addition, she had a complete circle of Willis with a dominant left vertebral artery associated with mild atherosclerotic calcification on CT. The patient’s risk factors were evaluated, and per the Vascular Surgery Group Cardiac Risk Index, she scored 6 with her preexisting risk factors (Age >80, CAD, long-term B-blockade use, and a history of coronary artery bypass graft), predicting a 6.6% risk of adverse cardiac outcome during carotid revascularization.^[2] Her Wallaert life expectancy score was medium risk due to her status as an octogenarian, thus denoting an 80% 5-year survival.^[3]

A final surgical approach was deliberated. Transfemoral and transradial CAS were discussed but believed to be non-viable given her tortuous right CCA. We concluded that the patient would be best served with an awake TCAR which would provide greater ability to push through the tortuous carotid, allow for better control of the sheath and provide neurovascular embolic protection. In addition, this approach allowed for neurologic monitoring with limited cardiac-risk under locoregional anesthesia.

We proceeded with TCAR under regional anesthesia with cervical plexus block. The procedure began with an incision between the heads of the sternocleidomastoid muscle. The common carotid artery (CCA) was dissected and looped with umbilical tape allowing some of the carotid redundancy to be pulled out of the surgical incision. The right CCA was accessed using the Seldinger technique, followed by the insertion of the standard TCAR microcatheter, allowing for angiographic definition of the bifurcation. The catheter and access wire were advanced to the bifurcation and replaced with a stiff Amplatz wire. Next, the “sheath stopper” which prevents the TCAR sheath from advancing more than 2.5 cm into the carotid artery, was removed, allowing the 8.5 French TCAR sheath to be advanced up to 12 cm into the artery. The sheath was advanced under fluoroscopy to ensure the dilator did not pass the carotid bifurcation. This step removed the tortuous component of the carotid [Figure 2]. With the sheath beyond the intra-thoracic tortuous component, we proceeded with the regular TCAR operative steps after establishing flow reversal. The lesion was defined angiographically as 75% stenosis of the proximal ICA. Prestenting angioplasty with a 5 mm balloon was followed by deployment of an 8 mm × 40 mm Enroute stent (Silk Road Medical, Inc., Sunnyvale, CA). We waited for 2 min on continuous flow reversal after stent deployment before completion angiography was performed.

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Figure 2:

An 84-year-old woman who presented with left arm and leg weakness diagnosed with the right anterofrontal lobe and left hemispheric lesions secondary to internal carotid artery stenosis. Bilateral tortuous common carotid arteries were demonstrated on computed tomography angiography during surgical planning. Intraoperative right oblique digital subtraction angiography showing the carotid artery following stent insertion with the sheath advanced to remove tortuosity (a) and the sheath retracted to allow the carotid to return its native conformation (b).

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At the end of the case, cerebral angiography showed appropriate flow in the right anterior and middle cerebral arteries. We observed improved cross-hemispheric filling through the anterior communicating artery. The patient remained alert during the procedure without evidence of perioperative neurologic complications. She has completed 2-year follow-up without evidence of repeat neurologic event and routine duplex surveillance shows no evidence of post-operative in-stent stenosis or access-related complications.

DISCUSSION

The patient’s prior cardiac arrest during her initial CEA made her risk-prohibitive for reoperative CEA. Anatomy was the major obstacle to revascularizing her ICA endovascularly. The intra-thoracic portion of her CCA tortuosity measured 6 cm [Figure 3], which would have made it challenging to maneuver from transfemoral or trans-radial access. This patient also had complex medical factors, including prior multivessel CABG and concern for heparin-associated anaphylaxis, a rarely documented phenomenon.^[4] A multidisciplinary team determined that she was not allergic to heparin, but her prior cardiac arrest made her risk-prohibitive for general anesthesia. For these reasons, and due to the author’s surgical expertise with direct transcervical carotid access, a TCAR with loco-regional anesthesia was chosen to revascularize her ICA.

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Figure 3:

An 84-year-old woman who presented with left arm and leg weakness diagnosed with the right anterofrontal lobe and left hemispheric lesions secondary to internal carotid artery stenosis. Bilateral tortuous common carotid arteries were demonstrated on computed tomography angiography during surgical planning. Subtracted TeraRecon imaging revealed 6 cm intrathoracic common carotid artery tortuosity.

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To successfully complete a TCAR in this case, patient-specific factors had to be considered. The instructions for use (IFU) criteria for the Enroute transcarotid neuroprotection system recommend greater than a 5 cm distance between the CCA access site and the carotid bifurcation.^[5] The patient in our case had 3.9 cm separating her clavicle from her carotid bifurcation, making her a poor candidate. If she had been allergic to heparin, TCAR would have been contraindicated per the Enroute IFU, but notably, our center has completed the procedure using bivalirudin as a heparin alternative. The short, 3.9-cm distance to her bifurcation and the long intrathoracic length of her CCA tortuosity necessitated that we advance the sheath without the “sheath stopper” to the full 6 cm distance intraoperatively. This maneuver allowed us to straighten her CCA and stent her ICA lesion.

We could not identify literature related to tortuous carotid traversal for TCAR with Enroute system-use to date of this procedure. In patients with typical anatomy undergoing TCAR, stabilization of the CCA for micropuncture can be achieved with mechanical traction using an umbilical tape loop. When the sheath is advanced into the CCA, it is best controlled by placing counter-traction on the umbilical tape loop.^[6] Several studies describe techniques for overcoming tortuous vasculature, but these fail to address the main anatomical challenge of crossing a tortuous CCA to revascularize a stenotic ICA.^[7,8]

TCAR is associated with the lowest CAS 30-day stroke rates in high-risk patients.^[6] Recent data showed no significant outcome difference between TCAR and CEA in octogenarians.^[1] In addition, this study showed TCAR to be superior to transfemoral CAS in terms of stroke rate and composite outcomes of myocardial infarction and death. Finally, recent data would suggest that the number of intraprocedural cerebral embolic events, as detected by transcranial doppler, with TCAR rival that of CEA both with and without a shunt and remains significantly less than CAS with distal filter.^[9]

CONCLUSION

TCAR provides many benefits over other methods of revascularization. In this case, TCAR provided us with direct access to the patient’s tortuous CCA. We found that advancing the Enrourte sheath without the “sheath-stopper” into a tortuous CCA provided sufficient straightening for the completion of a TCAR. This is a rare disease presentation but demonstrates the applicability of TCAR to overcome complex anatomy and comorbid conditions.