Cerebral Perfusion Optimization With Transcranial Doppler Monitoring During Transcarotid Artery Revascularization
Samuel B Booth, Shashank Sharma, Zsolt Garami, Charudatta Bavare, Maham Rahimi
Houston Methodist, Houston, TX
INTRODUCTION: Contralateral carotid occlusion (CCO) is a clinically significant finding in patients presenting for carotid revascularization. While the optimal revascularization strategy in such patients remains a contentious topic, transcarotid artery revascularization (TCAR) has shown safe and effective results. In addition, intraoperative transcranial doppler (TCD) provides real-time monitoring of cerebral hemodynamics allowing immediate recognition and intervention if ischemia is detected.
A 72-year-old man was transferred to the treating hospital’s ICU with evidence of right hemispheric stroke and a NIHSS of 6. Upon presentation to the ICU, the patient had already been administered tPA. Past medical history was significant for CAD treated with two stents, COPD, symptomatic PAD, HLD, HTN, and a 55-pack year smoking history. In addition, the patient had received radiation therapy for basal cell carcinoma of the nose 8 months prior to this presentation.
METHODS: Further diagnostic imaging confirmed the right hemispheric stroke and a large penumbra. Imaging also revealed reconstitution of flow in the right ICA at the proximal cavernous segment, despite a severely (70-99%) stenosed left ICA/carotid bulb. Vascular surgery was consulted and TCAR was performed 3 days later. The decision to intervene in this patient was decided based on the patient’s high risk of future cerebrovascular events with impaired collateral cerebral perfusion and a recent CVA. Given the patient’s extensive comorbidities and history of previous head and neck irradiation, TCAR was chosen over carotid endarterectomy (CEA).
RESULTS: Under general anesthesia with TCD neuromonitoring, the patient’s left common carotid artery (CCA) and right femoral vein were accessed to perform TCAR with flow reversal. Intraoperative angiogram was performed revealing the bifurcation and severe left ICA stenosis. TCAR sheaths in the carotid artery and femoral vein were connected using the provided TCAR tubing and passive flow reversal was begun. The CCA was then clamped, and high-flow reversal was initiated (Figure 1a). At this point, TCD detected zero flow in the left middle cerebral artery prompting unclamping and initiation of low-flow reversal on the TCAR device. The CCA was then re-clamped and TCD monitoring revealed >50% anterograde flow (Figure 1b). The lesion was then successfully crossed and an ENROUTE Transcarotid Stent (Silk Road Medical) was deployed. Completion angiogram revealed no residual stenosis. The remainder of the operation was without complication. Following extubation in the OR, the patient moved all 4 extremities equally. The patient recovered without any further neurologic sequelae, ultimately being discharged two days later. 
CONCLUSIONS: This case emphasizes the importance of intensive neuromonitoring during TCAR and the optimization of flow reversal to suit a patient’s cerebrovascular demand. The real-time detection of absent ipsilateral flow with TCD allowed for an immediate switch from high to low-flow reversal, mitigating intraoperative ischemia. As the application of TCAR expands, vigilance to intraoperative monitoring and relevant adjustments in procedural technique will help serve as a barrier to complications.
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