Trans-Carotid Artery Revascularization

3. Preoperative Assessment
This should focus on an evaluation of comorbid disease, and as described above, which could negatively impact effective blood pressure management and result in an elevated risk of cardiovascular complications. All carotid surgery falls into the high-risk category. Pre-surgical testing should follow AHA/ACA guidelines for high-risk noncardiac surgery.

• 12 lead EKG, standard
• Labs (including CBC, electrolytes, creatinine, coags)
• CT angiogram vs. carotid ultrasound to define anatomy (surgeon’s pervue)
• Consider exercise or pharmacologic stress test if functional status poor or unknown and patient is at elevated risk (>1%) of MACE based on VQI or NSQIP calculator
• Consider TTE if concerned for heart failure, pulmonary hypertension, or valvular disease as these may impair the ability to effectively induce hypertension required during flow reversal

The urgency of the procedure, based on whether the patient is symptomatic or not, should also factor into the decision to obtain additional testing. As is often the case, one needs to weigh the benefits of additional diagnostic information against the cost of delaying the procedure.

4. Preoperative Preparations

• Patient should be on dual anti-platelet therapy (Aspirin / Plavix) + statin for a minimum of 7 days prior to the procedure. This should be continued throughout the perioperative period. If patient has missed a dose, including on the day of surgery, discuss with surgeon and likely re-dose (or even re-load) in preop prior to surgery. 
• Continue any previous prescribed beta blockers
• Carefully consider continuing vs. discontinuing other anti-hypertensives; consider stopping ACEi / ARBs as refractory post-induction hypotension can compromise cerebral perfusion and make induced hypertension during flow reversal difficult

5. Access/Fluids

• Generally 2 good PIVs are adequate, but one should be confident in the integrity of those lines as vasopressors / vasodilators will be required during critical portions of the procedure
• If central access is needed, recommend contralateral IJ / subclavian vs. femoral access
• No restrictions / requirement for fluids per say. It is worth carefully assessing volume status as many of these patients are on diuretics or undergoing hemodialysis for concomitant renal and cardiovascular disease. Relative hypovolemia may adversely affect the ability to achieve induced hypertension required during flow reversal.
• Patients should be type & crossed for at least 2 units of PRBCs ; can consider more depending on the preoperative Hgb.

6. Monitors

• Standard ASA monitors plus…
• Pre-induction arterial line for strict blood pressure monitoring
• Cerebral oximetry to monitor adequacy of collateral circulation via the Circle of Willis during flow reversal
• ACT monitoring during heparinization (target 280-340 seconds)
• Attempt to run all radio-opaque monitoring cables (with the exception of the cerebral oximeter) off the right flank and bundle w/ tourniquet/blue clamp combo. Run the cerebral oximeter cables, a.line, and PIVs around the periphery of the head of bed and bundle. This keeps our lines out of the fluoroscopy path.

7. Anesthetic Technique
This procedure can be performed under either MAC or general anesthesia. Determination of anesthetic technique is based largely on neck anatomy (obese patients may require more stimulating/deeper neck dissection) and the patient’s ability to tolerate lying still for the duration of the procedure. Additional consideration should be given to the extent of comorbidities. This means that, the sicker the patient, the more consideration given to performing the procedure under MAC. For MAC cases, consider dexmedetomidine + low-dose remifentanil infusions. For less sick patients (cardiovascularly and neurologically robust), more consideration should be given to GETA.

Superficial Cervical Plexus Block

Occasionally considered for TCAR done under MAC or as an adjunct to GA to improve pain control and limit the dose of general anesthesia. Due to the location of the incision above the clavicle (in contrast to the larger, more cranially-oriented CEA incision), one really only needs to perform the lower portion of the injections. Recommend performing this as a field block by landmarks since it is faster and equally as effective as ultrasound-guided.

1. Control syringe, ~25g needle
2. 10mL of 0.5% Ropiv or 0.25% Bupiv (consider adding mepivacaine if case done under MAC)
3. Locate posterior border of sternocleidomastoid (SCM)
4. Mark mid-point between mastoid process and clavicle
5. Enter posterior to SCM, 0.5-1 cm deep, aspirate
6. Inject 4 mL, fan cephalad (3 mL), fan caudad (3 mL)

8. Key procedure related points

• Confirm with patient in preop that they took Dual Antiplatelet Therapy (DAPT) the morning of surgery. If inpatient, check MAR to confirm. If not taken, discuss with surgeon.
• Arrange lines out of surgical field / fluoro trajectory (see above). Insure nothing under the head except donut head padding. Consider checking with fluoro prior to surgical exposure.
• Blood pressure maintained at baseline or slightly above during surgical exposure.
• Premedicate w/ glycopyrrolate, unless medically contraindicated (HR > 90 at baseline, severe CAD at risk for cardiac ischemia) to prevent bradycardia / asystole during ballooning at or near carotid baroreceptors
• During flow reversal, maintain SBP > 160 (adjust based on baseline BP, usually 15-20% above baseline) to aid in perfusion via Circle of Willis (CoW). Monitor rSO2 (cerebral oximeter) and flow through TCAR circuit closely during this period – both are measures of adequate CoW perfusion.
• Consider decreasing or stopping vasopressors after stent deployment (during 3-min washout period) as once this step is complete, BP goals immediately shift to SBP 110 - 140 to prevent cerebral hyperperfusion; may need boluses of esmolol or nicardipine / clevidipine to achieve this rapidly
• Post-stenting hypotension is common due to persistent carotid baroreceptor stimulation and often requires vasopressor support to insure adequate cerebral perfusion until hemodynamics stabilize.
• Routine admission to the ICU for 24 hours for close neurologic and hemodynamic monitoring.

​9. 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

10. Positioning / ergonomic considerations

• supine, ipsilateral neck and either groin are prepped
• neck extended with shoulder roll and head rotated away from surgical side to improve exposure
• lines bundled at edges of bed, nothing under the patient’s head ; consider checking w/ fluoroscopy prior to exposure to confirm not in XR path
• drape will be adjacent to patient’s face as it is not feasible to create a large space due to surgical access considerations
• the above conditions result in difficult airway access during MAC if conversion to GETA is required

11. Duration of case
Surgical time : 60-90 min
Total OR time : 120-180 min