Transcarotid Artery Endovascular Revascularization
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Also referred to as a TCAR, a transcarotid artery endovascular revascularization is an alternative to carotid endarterectomy for the management of carotid stenosis in patients who are determined to be poor open repair candidates based on high surgical risk or lesion location (distal lesions). Transcarotid artery revascularization (TCAR) is an alternative to trans-femoral stenting and is meant to decrease the risk for micro-embolic strokes through flow reversal through the carotid during stent placement (see below).
Goal: Restoring laminar blood flow through a stenotic carotid artery narrowed by atherosclerotic or neointimal hyperplastic disease.
Overview
Surgical procedure:
The common carotid artery (CCA) is exposed via a small incision superior to the clavicle.
A flexible sheath is inserted into the CCA proximal to the lesion being stented and the distal end (outside the vessel) is connected to a flow reversal system (FRS).
At the same time the femoral vein is also being accessed either percutaneously or via surgical exposure, and a 2nd flexible sheath is inserted. The extraluminal end of the femoral sheath is attached to the other end of the flow reversal system (FRS).
Once connected blood flow from the high pressure CCA to the low pressure femoral vein through the FRS. After flow reversal wires are threaded past the lesion, if indicated pre-dilation of the vessel with balloon angioplasty occurs at this time, followed by deployment of the intralumenal stent. The FRS acts as a filter removing any plaques or disrupted intralumenal, decreasing the risk of micro-embolic strokes.
After successful placement, flow reversal is turned off and blood flow resumes in its normal direction. Sheaths removed and arteriotomy closed.
Video with overview of steps: TCAR | TransCarotid Artery Revascularization Procedure Narrated Animation | Silk Road Medical | https://www.youtube.com/watch?v=MI2s4rv0dJA
Indications:
Stent placement is preferred to carotid endarterectomy if the patient have ANY of a number of comorbid medical disease or anatomical factors (see below) that would complicate the hemodynamic management intraoperatively putting the patient at elevated risk for CV complications (hemodynamic instability / vasoplegia, MI, stroke, arrhythmia, etc) or surgical/airway access.
Medical:
- Age > 75
- Congestive Heart Failure
- LVEF < 35%
- >2 diseased coronaries w/ 70% stenosis
- Unstable angina or abnormal stress test
- MI within 6 weeks
- Need for additional open heart surgery
- Need for major surgery (including vascular)
- Uncontrolled diabetes
- Severe pulmonary disease
Anatomic:
- Prior head/neck surgery or irradiation
- Spinal immobility
- Restenosis post carotid endarterectomy (CEA)
- Surgically inaccessible lesion
- Laryngeal palsy; Laryngectomy
- Permanent contralateral cranial nerve injury
- Contralateral occlusion
- Severe tandem lesions
- Bilateral stenosis requiring treatment
Preoperative management
Patient evaluation:
Assess for the listed conditions/diseases above.
| System | Considerations |
|---|---|
| Airway | Neck mobility, ability to tolerated surgical positioning. Prior neck radiation |
| Neurologic | Baseline neurologic exam, post operatively at risk for micro-embolic strokes. Assess if carotid stenosis is symptomatic (see below) |
| Cardiovascular | Exercise tolerance, assess for listed cardiovascular comorbid diseases above |
| Pulmonary | Exercise tolerance |
| Gastrointestinal | |
| Hematologic | Ensure taking dual anti-platelet therapy per surgical team's directions |
| Renal | Current volume status, relative hypovolemia may adversely affect ability to induce HTN during flow reversal |
| Endocrine | Check BG |
| Other |
- Symptomatic Carotid Stenosis: Stroke or TIA referable to the appropriate carotid artery distribution within the previous six months AND carotid stenosis > 50%.
- Asymptomatic Carotid Stenosis: Atherosclerotic narrowing of the extracranial ICA (>80%) without recent stroke or TIA (Of note, vertigo and syncope are not typical manifestations)
Labs and studies
All carotid surgeries are considered high-risk & pre-surgical testing should follow AHA/ACA guidelines for high-risk noncardiac surgery.
- CBC, electrolytes, creatinine, PT/INR/aPTT
- T&C; consider requesting to have 2 units of pRBC on hold
- 12 lead EKG
- Consider Stress Test (exercise or pharmacology) if:
- Poor or unknown functional status
- Calculated risk for major adverse cardiovascular events (MACE) is >1% on the VQI or NSQIP calculator
- TTE if concerned for CHF, pulmonary HTN, or valvular disease (may impair ability to safely induce needed hypertension intraoperatively)
- Per surgical team's preference either CT angiogram v Carotid ultrasound to define anatomy
Operating room setup
TCAR can be preformed under GA or MAC with regional anesthesia. If planning to use MAC, have supplies for full conversion to GA emergently.
Have appropriate vasoactive medication available quickly titrate blood pressure intraoperatively
- Push Medications: consider Epi, NE, Phenylephrine, Nitroglycerin, Esmolol, Nicardipine
- Prepared Drips: Norepinephrine (or preferred short acting vasopressor) spiked & in line, consider having for vasodilatory drip of choice in room
Additional Medications: Heparin & Protamine
Run lines & monitors outside of fluoroscopy path to optimize surgical field
Patient preparation and premedication
- Verify that patient is taking Dual Antiplatelet Therapy (DAPT; Aspirin / Plavix) & a statin for the last 7 days including the morning of surgery. If dose not taken, discuss giving preOP with surgical team
- Continue home beta-blockers
- Verify medication that impact BP control or cause refractory hypotension compromising cerebral blood flow on induction or during flow reversal (ARB/ACEi) have not been taken
Regional and neuraxial techniques
Superficial Cervical Plexus Block
- With block procedure can be preformed with MAC
- Benefit in GA cases by decreasing opioid requirement, allows for more rapid neurologic assessment postoperatively
Intraoperative management
Monitoring and access
- Standard ASA monitors, 5 lead EKG
- Pre-induction arterial line
- PIV x 2 (note vasoactive medications will be in PIVs, make sure lines are stable/running well)
- Cerebral oximetry to monitor adequacy of collateral circulation via the Circle of Willis during flow reversal; ideally placed and calibrate while patient is awake.
- Intraoperative ACT monitoring during heparinization (target 250-350; verify goal with surgical team)
Induction and airway management
- If planning on MAC with natural airway & superficial cervical plexus block, consider sedation with remifentanil infusion.
GA: Slow controlled induction, goal to maintain BP at baseline to prevent decreased cerebral perfusion
Positioning
- Supine, neck extended, shoulder roll, head turned away from surgical site
Maintenance and surgical considerations
TIVA/Balanced anesthetic/inhalational anesthetic are reasonable
Have clear communication with the surgical team about what stage of the surgery they are in, critical for BP management/patient safety during a TCAR.
- Surgical Exposure: maintain BP at baseline or slightly higher
- Carotid Balloon Inflation: Can cause Bradycardia/asystole due to proximity near carotid baroreceptors. Give preventative glycopyrrolate (unless patient has contraindications to having a further elevated HR; baseline HR > 90 or severe CAD)
- Flow Reversal: Maintain SBP >160 or 20% above baseline SBP to aid perfusion via Circle of Willis. Closely monitor cerebral oximeter (rSO2) during this time.
- Stent Deployment: Risk for acute cerebral hyperperfusion. Stop vasopressors, have closed loop communication about BP goal with surgical team and give push vasoactive medications as needed to meet goals (commonly SBP 110-140). Not uncommon to require boluses of nitroglycerin/esmolol/nicardipine to achieve this rapidly
- During Closing, post-stent Hypotension is common due to persistent carotid baroreceptor stimulation and may require vasopressor support to insure adequate cerebral perfusion until hemodynamics stabilize.
Emergence
- Avoid bucking due to neck incision & carotid artery puncture.
- Consider remifentanil, dexmedetomidine, or appropriate opioid titration prior to emergence
Postoperative management
Disposition
- PACU -> IMC for close neurologic and hemodynamic monitoring
Pain management
- Opioids
- Regional anesthesia
Potential complications
- Embolic stroke : during exposure or due to insufficient flow reversal
- Stroke due to hypoperfusion / insufficient collateral flow via Circle of Willis; watershed infarct
- Bleeding due to catheter dislodgement: higher risk during MAC as opposed to GA
- Reperfusion injury: ipsilateral ACA/MCA distribution now seeing higher pressure and flow since no longer obstructed by stenotic segment of carotid artery. Stroke like syndrome which can manifest as encephalopathy or unilateral sensory / motor deficits, seizure, or rarely, intracranial hemorrhage
Procedure variants
| Variant 1 | Variant 2 | |
|---|---|---|
| Unique considerations | ||
| Position | Supine | |
| Surgical time | ||
| EBL | ||
| Postoperative disposition | ||
| Pain management | ||
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References
1.) Columbo JA, Martinez-Camblor P, O’Malley AJ, et al. Association of Adoption of Transcarotid Artery Revascularization With Center-Level Perioperative Outcomes. JAMA Netw Open. 2021;4(2):e2037885. doi:10.1001/jamanetworkopen.2020.37885
2.) Ankam A, Kinthala S, Madabhushi P. Anesthetic Considerations for Transcarotid Artery Revascularization: Experience and Review of Forty Cases From a Single Medical Center. Cureus. 2020 Dec 24;12(12):e12250. doi: 10.7759/cureus.12250. PMID: 33505816; PMCID: PMC7822093.
3.) Silk Road Medical. TCAR surveillance project. Accessed January 1, 2020. https://silkroadmed.com/tcar-surveillance-project/