Stroke management
All patients with an acute ischemic stroke who are admitted to our institution within a time window of 4.5 hours after onset of clinical symptoms are treated either via intravenous rtPA administration, a combination of intravenous rtPA administration and endovascular treatment, or endovascular treatment only. Endovascular treatment comprises intra-arterial rtPA administration and / or mechanical recanalization. If patients are admitted later than 4.5 hours after onset of symptoms, or the onset of symptoms is unknown, only endovascular treatment is considered.
The indication for neurointerventional stroke treatment is always assessed by both, an experienced neuroradiologist and an experienced neurologist. Decision making is based on clinical criteria, the results of initial computed tomography (CT) studies, and the absence or presence of contraindications for any of the above mentioned procedures. Initial CT studies in patients suffering from acute ischemic stroke comprise unenhanced cranial CT, CT angiography, and perfusion CT. Clear criteria in favour of an endovascular approach are: 1) occlusion of large arteries: the internal carotid artery (ICA), M1 and M2 segments of the middle cerebral artery (MCA), A1 and A2 segments of the anterior cerebral artery (ACA), basilar artery (BA), P1 and P2 segments of the posterior cerebral artery (PCA). 2) Any contraindication for an intravenous rtPA therapy. Endovascular treatment is not initiated if CT perfusion studies indicate that there is no relevant penumbra, i.e. the parenchyma at risk has already been irreversibly damaged. If there is an indication for endovascular treatment, patients have been admitted within 4.5 hours after onset of symptoms, and there is no contraindication for intravenous rtPA therapy, intravenous rtPA therapy will be combined with endovascular therapy. If the area of infarction comprises more than one third of the MCA territory, the onset of symptoms is later than 4.5 hours or unknown, or there are contraindications for intravenous rtPA therapy, endovascular treatment is considered without additional intravenous rtPA therapy.
If intravenous rtPA therapy is to be combined with endovascular therapy, application of rtPA is initiated right at the end of the CT examination, but discontinued when endovascular access is achieved. Thus, patients undergoing mechanical recanalization usually receive a thrombolytic bridging therapy with a reduced dose of intravenously applied recombinant tissue plasminogen activator (rtPA), if contraindications are absent.
Neurointerventional stroke treatment in our institution is performed under general anaesthesia and by an experienced interventional neuroradiologist.
Basic steps of the intervention are as follows: the interventional neuroradiologist places a long sheath or balloon catheter in the carotid artery via a femoral assess. Then, the thrombus is passed with a microcatheter through which a stent-retriever is placed and expanded within the thrombus. The stent-retriever is then slowly withdrawn after an incubation period of 3-5 minutes. During retrieval, constant aspiration through the sheath or inflated balloon catheter is provided by an aspiration pump (Penumbra, Alameda, CA, USA).
If necessary to gain access to the site of occlusion, carotid artery stenting (CAS) is performed with a self expanding stent (Carotid Wallstent®, Boston Scientific, Natick, MA, USA) under administration of a glycoprotein IIb/IIIa inhibitor (Tirofiban).
Typical neurointerventional tools are as follows: a long 7F or 8F sheath (Cook Medical, Bloomington, IN, USA) or a 9F ballon catheter (Stryker, Kalamazoo,MI, USA) for access to the internal carotid artery. Preferred microcatheters are Trevo™ 18 (Stryker) or Rebar™ 18 (Covidien, Mansfield, MA, USA), and 27’’ microcatheters, preferred microwire is the Synchro-2® soft 14 (Stryker). Selection of the thrombectomy device is based on a case to case decision, taking into account the diameters and geometry of the affected vessels. Trevo® Pro (Stryker) and Solitaire™ FR Revascularisation Device (Covidien) are used in the majority of cases. Other devices less frequently used include the Penumbra Separator™ 3D (Penumbra) and the pREset (Phenox, Bochum, Germany).
During angiography, the applied contrast agent (Iopamidol, Solutrast®, 300 mg/mol, Bracco Imaging GmbH, Konstanz, Germany) is commonly diluted in an 8:2 ratio with a saline solution.
A postinterventional CT scan is performed after the end of the procedure. All patients are then submitted to either a stroke unit or an intensive care unit for at least 24 hours. Usually patients receive standard ASA therapy (100 mg) plus low dose heparinization during clinical treatment. If CAS has been performed, clopidogrel (75 mg) is added for three months. Antiplatelet or anticoagulant therapy is always discussed between neurointerventionalists and neurologists in charge.