SUMMARY: We present a rare case of a complication of placement of a carotid artery stent represented by partial opening of a carotid Wallstent caused by displacement of its metal ring marker, which thus hindered complete expansion of the stent. An intraluminally locked carotid stent necessitated referral of the patient for urgent carotid endarterectomy. A possible reason of this unusual complication can be a manufacturing defect, which, to our knowledge, was not documented previously in open public data bases or on the Internet. Carotid artery stent (CAS) placement is a well-established method for revascularization of the obstructed lumen in patients with carotid artery disease. Complications may occur during the procedure and generally are presented by neurologic symptoms as a result of microembolism or thrombosis, which can be prevented by the use of a protective filter. Less common complications during CAS placement are hemodynamic conditions such as bradycardia and hypotension, which are easily treatable.1-3 Mechanical complications such as spasm or dissection are seen less and less frequently with personal experience and innovations in equipment. Complications caused by unlucky mechanical accidents during stent implantation such as incomplete opening are unusual and therefore can be a reason for unpredictable outcomes of CAS placement. We present a rare case of a CAS complication with incomplete opening of a carotid Wallstent (Boston Scientific, Natick, Mass) caused by displacement of its metal ring marker, which hindered the complete expansion of the stent and required urgent surgical intervention. Case ReportA 71-year-old woman with a history of transient ischemic attack and right internal carotid artery stenosis of more than 70% in the proximal portion previously diagnosed on CT and MR angiography was referred to our hospital for implantation of a carotid stent. CAS with a carotid Wallstent Monorail 4 with a cerebral protection filter (EPI Filter Wire; Boston Scientific) was planned. The patient had received therapy with antiaggregant medications: aspirin 100 mg/day and clopidogrel 75 mg/day for 1 week before stent implantation. A 6F shuttle introducer was placed into the right common carotid artery by the femoral approach, and preprocedure control angiograms were obtained. A cerebral protection filter was placed distally to the obstructed internal carotid artery, and then self-expandable Wallstent (7 ϫ 50 mm) deployment was performed. During deployment, unexpected slipping of the distal ring of the metal marker over the shaft of the stent was observed. The slipped ring at one fourth of the proximal end of the stent hindered the complete expansion of the stent. The shaft of the stent and the protection filter could not be pulled back because the metal ring locked over the stent (Fig 1). Attempts to rescue the fixed stent and slipped metal ring were unsuccessful, and the patient was rushed to the operating room. During endarterectomy, the stent, stent shaft, and protection filter were removed without any ...