The aim of this observational pilot study is to determine whether intolerance of carotid occlusion during carotid artery stenting can be predicted with preprocedural transcranial Doppler evaluation.

Carotid artery stenting procedures are increasingly performed with devices that involve endovascular clamping of the common carotid artery, thus exposing the ipsilateral hemisphere to hypoperfusion. Approximately 5% of patients do not tolerate the clamp and are in increased risk of periprocedural cerebrovascular complication such as transient ischemic attack or stroke. To date, there is no method available that could be used to predict the risk of occlusion intolerance. The aim of this study is to determine whether preprocedural evaluation with transcranial Doppler ultrasonography can be effective in prediction of occlusion intolerance.

Inclusion Criteria:

• Either >50% symptomatic carotid artery stenosis (transient ischemic attack or ischemic stroke within 6 months before procedure) or >70% asymptomatic carotid artery stenosis eligible for carotid artery stenting with proximal flow arrest protection
• Signed informed consent

Exclusion Criteria:

• Disagreement to be included in the study
• Inadequate acoustic window for transcranial Doppler ultrasound monitoring
• Carotid occlusion
• Significant extracranial artery stenosis (>50%) other than target artery
• Inability to hold breath for sufficient time (approximately 30s)

Adult patients with carotid artery stenosis indicated for carotid artery stenting with the use of proximal flow arrest protection device.