Treatment of Acute Vertebrobasilar Occlusion Using Thrombectomy with Stent Retrievers: Initial Experience with 18 Patients

Materials and Methods

This series included a retrospective analysis of all patients who presented at our hospital with acute vertebrobasilar stroke and were treated directly with intra-arterial thrombectomy by using retrievable stents between January 2010 and January 2012.

All patients with stroke who arrive at our hospital undergo an initial imaging protocol that includes urgent nonenhanced CT, CT angiography, and CT perfusion. Patients with an NIHSS score of >6 and evidence of vertebrobasilar occlusion on CT angiography undergo mechanical thrombectomy in the initial 24-hour period after stroke onset. For patients who are referred from other centers, we recommend administration of intravenous thrombolysis during patient transfer and angiography suite preparation. The exclusion criteria for mechanical thrombectomy are the presence of cerebral hemorrhage, evidence of established large cerebellar and brain stem infarction on nonenhanced CT, the absence of vascular occlusion on CT angiography, >24 hours since symptom onset, or any medical conditions that preclude general anesthesia. Before angiography and/or mechanical thrombectomy, all patients (or relatives) must give informed consent.

All thrombectomy procedures in these series were performed with the patient under general anesthesia. During the procedure, no antiplatelet or intravenous anticoagulants were administered (except heparin in the flushing systems). Angiography was performed via femoral approach by using a 9F sheath and a diagnostic catheter, generally a JB 4F (Cordis, Miami Lakes, Florida). An initial angiographic series from both vertebral arteries was performed to confirm occlusion and to evaluate the best access to the occlusion site. Location of the clot was divided into the vertebral artery, the proximal basilar artery (from the confluence of the vertebral arteries to the anterior inferior cerebellar artery), the mid-basilar artery (from the anterior inferior cerebellar artery to the superior cerebellar artery), the distal basilar artery (distal to the superior cerebellar artery), and the posterior cerebral artery.

Once the location of the clot had been identified, the diagnostic catheter was removed and an 8F Merci balloon guide catheter (Concentric Medical, Mountain View, California) was advanced and placed in the cervical segment of the dominant vertebral artery. In cases in which this balloon guide catheter could not be placed in the vertebral artery due to the small caliber of the vessel, a Neuron 6F delivery catheter (Penumbra, Alameda, California) was placed instead. A Rebar-18, Marksman-21 (both ev3, Irvine, California), or Trevo-18 microcatheter (Concentric Medical) with a 0.014-inch microwire (generally a Transend [Boston Scientific, Natick, Massachusetts] or Traxcess [MicroVention, Aliso Viejo, California]) was then advanced distally to the clot. The microwire was then removed, and a stent retriever (either Solitaire AB, Solitaire FR [ev3], or Trevo) was used to engage and snare the clot. Once the clot was captured, the balloon guide catheter was inflated to temporarily arrest forward flow while the clot was being withdrawn. The clot was first pulled into the guide catheter and then completely out of the body while aspirating with a 50-mL syringe. The balloon was then deflated, and the flow was restored. In cases performed with Neuron as the guide catheter, retrieval of the stent and aspiration were performed without vessel occlusion. In the event of major residual stenosis due to an atherosclerotic plaque, a definitive intracranial stent (Pharos Vitesse; Micrus Endovascular, San Jose, California) was deployed. All these patients received a loading dose of 300 mg of clopidogrel (by a nasogastric tube) and 500 mg of intravenous aspirin (lysine acetylsalicylate) before placement of the definitive stent.

After the procedure, patients were admitted to the intensive care unit. A nonenhanced CT was routinely performed in the first 24 hours after the procedure to rule out hemorrhage, and antiplatelet or anticoagulation therapy was then initiated. The choice of therapy depended on the suspected etiology of the stroke. Initial anticoagulation with intravenous heparin and a posterior switch to acenocoumarol was used for inferred cardioembolism, while antiplatelet therapy (aspirin, 200 mg a day, or clopidogrel, 75 mg a day) was preferred when atherothrombotic etiologies were suspected. The control of blood pressure, fever, hyperglycemia, aspiration risk, deep venous thrombosis prophylaxis, and all other essential aspects in acute stroke management was carried out following current stroke guidelines.²³

Clinical data recorded for the study included sex, age, vascular risk factors (high blood pressure, diabetes mellitus, hypercholesterolemia, cigarette smoking, atrial fibrillation, previous stroke, coronary disease), stroke subtype according to the TOAST classification,²⁴ occluded artery, and initial NIHSS and mRS scores. The outcome measures included arterial recanalization according to the Thrombolysis in Cerebral Infarction scale, both postprocedural and discharge NIHSS scores, and discharge mRS and 90-day mRS scores.

Extensive additional technical data from each procedure were also obtained, including the type of guide catheter, the artery used for guide-catheter placement, the occlusion site, the type of retrievable stent used, the number of devices needed for retrieval, the number of passes, the definitive intracranial stent, procedural time, the time from symptom onset to groin puncture, and also the time to revascularization.