Transcervical extracorporeal reverse flow neuroprotection for reducing the risk of stroke during carotid artery stenting

5.1 Death from myocardial infarction 48 hours after the procedure was reported in 1 patient in a prospective case series of 212 patients treated by transcervical carotid artery stenting with flow reversal. Death was reported in 2 patients in a case series of 141 patients treated by transcervical carotid artery stenting with flow reversal. One patient died from respiratory failure within 30 days of the procedure and another patient died from myocardial infarction 15 days after the procedure after readmission with pneumonia and diabetic ketoacidosis.

5.2 Transient intolerance to flow reversal was reported in 1 patient treated by transcervical carotid artery stenting in a comparative study of 81 patients treated by transcervical carotid artery stenting (n=36) or carotid endarterectomy (n=45). Clamping of the common carotid artery was maintained only during the key steps of the procedure. Intolerance to flow reversal was reported in 1% (3/219) of procedures in the case series of 212 patients; this was treated by declamping the common carotid artery and rapidly completing the procedure.

5.3 Major dissection of the common carotid artery was reported in 1 patient treated by transcervical carotid artery stenting in the comparative study of 81 patients. This was treated by a bypass from the common carotid artery to the distal internal carotid artery. Arterial dissection was reported in 6% (8/141) of patients in the case series of 141 patients. For 5 dissections, no treatment was needed; they were at the site of the arterial sheath or between the sheath and the carotid bifurcation. For the 3 dissections that needed treatment, 1 procedure was converted to carotid endarterectomy at the original procedure, 1 needed the placement of a second stent during the original procedure and 1 was repaired surgically during the original procedure. One of the patients with a dissection had a minor ipsilateral stroke 8 hours after the procedure. This was judged to be unrelated to the dissection because the second stent had adequately managed the intimal flap.

5.4 Severe spasm of the distal carotid artery was reported in 1 patient treated by transcervical carotid artery stenting in the comparative study of 81 patients. Severe distal internal carotid spasm was reported in 2% (4/212) of patients in the case series of 212 patients; this was treated with intra-arterial nitroglycerin in 1 patient and it resolved spontaneously after guide wire withdrawal in 3 patients. Severe distal internal carotid spasm was reported in 2 patients in a case series of 62 patients treated by transcervical carotid artery stenting with flow reversal; this was treated with intra‑arterial nitroglycerin. Distal internal carotid artery spasm was reported in 13% (6/48) of patients in a case series of 48 patients treated by carotid artery stenting with flow reversal. This was treated with intra-arterial nitroglycerin.

5.5 Bradycardia and hypotension related to balloon inflation was reported in 6% (2/36) of patients treated by transcervical carotid artery stenting in the comparative study of 81 patients. This was successfully treated with atropine. Bradycardia was reported in 13% (4/31) of patients in the transcervical carotid artery stenting with flow reversal group and in none of the patients in the transfemoral carotid artery stenting group with distal filter neuroprotection (n=24) in a comparative study of 55 patients.

5.6 Extensive cerebral haematoma was reported in 1 patient in the case series of 62 patients; this was identified on a CT scan after the patient returned with hemiplegia and aphasia after an episode of intense headache 48 hours after hospital discharge. It was treated by surgical drainage.

5.7 Transient laryngeal nerve palsy was reported in 1% (2/212) of patients in the case series of 212 patients; this was secondary to impregnation of the nerve with local anaesthesia. Cranial nerve injury affecting the 10th nerve was reported in 1 patient in the case series of 141 patients; this caused hoarseness, which fully resolved at 6 months.

5.8 Cervical haematoma was reported in 6% (2/31) of patients treated by transcervical carotid artery stenting in the comparative study of 55 patients; one of the 2 patients was treated by surgical drainage and had no neurological sequelae. Cervical haematoma was reported in 1 patient in the case series of 212 patients; this was treated by surgical drainage.

5.9 In addition to safety outcomes reported in the literature, specialist advisers are asked about anecdotal adverse events (events which they have heard about) and about theoretical adverse events (events which they think might possibly occur, even if they have never done so). For this procedure, specialist advisers did not list any anecdotal adverse events. They considered that the following were theoretical adverse events: false aneurysm at the site of puncture, potential risk to the brain of reversing the flow in the internal carotid artery for the duration of the procedure and potential risk of re-establishing antegrade flow (reperfusion injury).