concurrently deployed by withdrawal of the microcatheter, straddling the thrombus. After placing the device within the thrombus for 3 – 5 minutes, the device is then pulled back in its expanded state along with continuous aspiration from a 50ml syringe via the guide catheter. Up to five passes using this technique may be performed if initially unsuccessful. 11 An improved final recanalisation success rate using Thrombolysis in Cerebral infarction( TICI) score of 2b – 3 is often achieved using this combined stentriever – aspiration mechanical thrombectomy. 12
Use of anaesthesia during the procedure The use of general versus local anaesthesia or conscious sedation currently varies.. General anaesthesia reduces subject distress and movement, and it can make the technical aspects easier; by contrast, conscious sedation allows continuous neurological monitoring for complications, and it avoids any potential hazard of general anaesthetic agents. Two studies presented at the 3rd European Stroke Organisation Conference( ESOC) in 2017( GOLIATH and ANSTROKE) both suggested that general anaesthesia and conscious sedation are equally safe. 7 Thus, either approach currently seems reasonable and the decision can be made on the level of local anaesthetic expertise available and the clinical stability of the patient, which may point to direction of either of these approaches.
Figure 2 Basic stentriever technique. A, B) AP and lateral views of pre-procedural catheter angiogram showing MCA occlusion in a patient with straight cervical ICA; C) Microcatheter advanced across the thrombus; D) Stentriever positioned across the thrombus; E, F) AP and lateral post-procedure catheter angiogram showing complete revascularisation.
Basic stentriever technique Figure 2 shows the basic method for this technique.
A 6F or 8F guide catheter is introduced to the arch of aorta under fluoroscopic guidance and then placed into the target vessel ICA or VBA. 10 A micro catheter is then negotiated across the thrombus by tracking over a guidewire. The stentriever device is then passed through the microcatheter so that it is positioned across the thrombus. Next, the device is unsheathed and
Procedure limitations and potential complications Despite their superiority in improving clinical outcomes in patients with acute ischaemic strokes, stent retrievers are not without complications. Although the stent retriever devices are generally safe, 13 complications of endovascular procedures can result from direct device-related vascular injury, vascular access and the use of radiological contrast media. The most common complications include the vessel perforation, 14 – 16 which occurred in 1.6 % patients in the 5 % positive endovascular trials( range 0.9 %– 4.9 %); symptomatic intracranial haemorrhage( 3.6 %– 9.3 %); subarachnoid haemorrhage( 0.6 %– 4.9 %); arterial dissection( 0.6 %– 3.9 %); emboli to new territories( 1.0 %– 8.6 % in randomised controlled trials); vasospasm; and vascular access site complications( including dissection, pseudoaneurysm, retroperitoneal haematoma and infection). Another side effect of using stents in the treatment of acute ischaemic stroke is acute in-stent thrombosis in cases where the stent is permanently left in place following successful recanalisation. In that case, a halfsystemic loading dose of a factor IIb / IIIa inhibitor, such as eptifibatide or abciximab, may be delivered intra-arterially via the guide catheter. 17 Techniques requiring a larger 8F system have slightly increased risk of arterial injury especially in elderly patients with atherosclerotic vessels. 18
The overall procedural complication rate from recent randomised controlled trials is in the range of 15 %, but it must be emphasised that many do not adversely affect clinical outcome. Stent retriever detachment 19 – 21 is an uncommon complication( about 2 %– 3 % with first-generation
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