Perioperative and Long-term Outcomes of Carotid Endarterectomy for Japanese Asymptomatic Cervical Carotid Artery Stenosis: A Single Institution Study

Prediction of cross-clamp-induced cerebral ischemia during carotid endarterectomy using arterial blood flow assessment

BACKGROUND

Cross-clamping during carotid endarterectomy (CEA) is associated with the risk of cerebral ischemia. Various studies have evaluated different criteria for detecting cerebral ischemia, but difficulties arise when ischemic changes appear after the carotid artery is cross-clamped and incised. Here, we explored a parameter that can predict cerebral ischemia prior to cross-clamping during CEA using a blood-flow meter.

METHODS

The carotid arterial blood flow was measured directly (direct ABF) in the common carotid artery prior to cross-clamping. The anatomical information in preoperative magnetic resonance imaging, cerebral blood flow in xenon-enhanced computed tomography, and carotid peak systolic flow velocity by carotid echo from the skin surface were also evaluated. A decrease in the short-latency somatosensory evoked potentials (SSEP) during cross-clamping to insert a shunt was assessed, and a decrease in amplitude of ≥50% was considered an indicator for cerebral ischemia. Surgery was performed under general anesthesia, and a shunt was inserted in all cases.

RESULTS

Of 156 CEA patients between April 2013 and March 2020, 30 had decreased SSEP during cross-clamping. The baseline characteristics and intra- and postoperative findings were not significantly different between patients with and without a decrease in SSEP. Among the evaluated parameters, only the direct-ABF ratio (ABF-internal carotid artery/ABF-common carotid artery) differed significantly between the two groups (p=0.011). The direct-ABF ratio ≤0.58 was predictive of cerebral ischemia during CEA.

CONCLUSIONS

Direct-ABF measurement with an ultrasonic blood-flow meter can be useful for predicting cerebral ischemia prior to carotid artery cross-clamping during CEA.

Evidence-Based Carotid Interventions for Stroke Prevention: State-of-the-art Review

Carotid artery stenosis is responsible for between 10-20% of all ischaemic strokes. Interventions, such as carotid endarterectomy and carotid stenting, effectively reduce the risk of stroke in selected individuals. This review describes the history of carotid interventions, and summarises reliable evidence on the safety and efficacy of these interventions gained from large randomised clinical trials.Early trials comparing carotid endarterectomy to medical therapy alone in symptomatic patients, and asymptomatic patients, demonstrated that endarterectomy halved the risk of stroke and perioperative death in these two unique populations. The absolute risk reduction was smaller in the asymptomatic carotid trials, consistent with their lower absolute stroke risk. More recent trials in symptomatic patients, suggest that carotid stenting has similar long term durability to carotid endarterectomy, but possibly has higher procedural hazards dominated by non-disabling strokes. The Asymptomatic Carotid Surgery Trial-2, along with individual patient data meta-analysis of all asymptomatic trials, will provide reliable evidence for the choice of intervention in asymptomatic patients in whom a decision has been made for carotid revascularisation. Given improvements in effective cardiovascular medical therapy, in particular lipid-lowering medications, there is renewed uncertainty as to whether carotid interventions still provide meaningful net reductions in stroke risk in asymptomatic populations. Four large trials in Europe and the US are currently underway, and are expected to report long-term results in the next decade.It is essential that surgeons, interventionalists, and physicians continue to randomise large numbers of patients from around the world to clarify current uncertainty around the management of asymptomatic carotid stenosis.