login
  Password reminder
NeuroNews
Contact the editor Visit NeuroNews Twitter feed Visit NeuroNews Facebook page
 

The current role of temporary endovascular bypass in acute stroke


Thursday, 17 May 2012 10:18

By Maxim Mokin, Elad I Levy and Tareq Kass-Hout


Over the last decade, we have witnessed rapid advancement of endovascular techniques for acute ischaemic stroke treatment. Accumulating evidence from studies testing both intravenous and intra-arterial revascularisation approaches clearly demonstrates that improved outcomes are directly associated with our ability to achieve early successful recanalisation of the occluded vessels. Our initial experience with mechanical thrombectomy using the Merci retriever device and the Penumbra aspiration system showed higher recanalisation rates, when comparing the results to historical controls from the Prolyse in Acute Cerebral Thromboembolism (PROACT) II trial of intra-arterial pharmacological thrombolysis. Still, both thrombectomy approaches have been criticised for higher rates of complications (namely, intracranial haemorrhage) and high mortality rates as well as technical complexity; moreover, neither device was able to demonstrate 100% recanalisation rates in major trials.


The use of intracranial stents for acute stroke revascularisation was originally attempted as “the last resort” approach when stroke interventionists faced challenging cases refractory to pharmacological and mechanical intra-arterial manipulations.

Several centres began to use first balloon-mounted stents and later self-expandable stents and soon realised that stenting allowed robust restoration of blood flow. Instead of a rescue therapy, stenting was now considered a first-line treatment.


Closed-cell stents allow partial expansion and recapture (re-sheathing), creating a concept called “temporary endovascular bypass”. In this technique, a stent is temporarily deployed, achieving instant recanalisation. The theory behind this approach is that the radial force generated during stent expansion disrupts the thrombus and plasters it against the vessel wall, allowing robust restoration of blood flow to the ischaemic brain. Restored blood flow potentiates the endogenous thrombolytic system, which can be further enhanced by pharmacological agents, such as recombinant tissue plasminogen activator (rtPA) or glycoprotein IIb/IIIa inhibitors, administered locally via a microcatheter injection. Once sufficient blood flow is established, which can assessed with serial angiographic injection runs, the stent is recaptured. The fundamental difference of the “temporary endovascular bypass” approach from Penumbra aspiration thrombectomy or Merci mechanical thrombectomy is the ability to establish instant recanalisation. Therefore, during the time it takes for the endogenous thrombolytic system to lyse the clot, the affected brain territory receives full blood supply.

The obvious advantage of recapturing and removing the stent, rather than permanently deploying it, is avoiding the need for dual antiplatelet therapy, which is mandatory for patients in whom an intracranial stent is implanted. Patients with large strokes are at high risk for reperfusion haemorrhage, and the dual antiplatelet therapy would certainly elevate such risk. This issue can become of even more concern in patients with atrial fibrillation (which is a frequent cause of large vessel occlusion), given the requirement for long-term anticoagulation agents. Also, patients with permanently placed intracranial stents are at risk for in-stent restenosis.


The obvious concern for the temporary endovascular bypass concept is that complete thrombus dissolution might not be achieved when relying on the endogenous thrombolytic system alone. The use of additional pharmacological agents would carry risk for intracranial haemorrhage. Although clot disruption and augmented blood flow as a result of temporary stent placement are powerful facilitators of the process of thrombus lysis, larger thrombus load and time-dependent thrombus organisation in patients with stroke presenting after several hours of symptom onset would make the temporary endovascular bypass approach alone prone to recurrent thrombosis.


These limitations have been successfully overcome by combining the concept of temporary endovascular bypass with thrombus extraction using stent-retrieval technology. The stent-retriever is used not only to establish immediate blood flow but also as a capture device and is retracted into a guide catheter with the thrombus trapped within the stent walls. Efficacy, safety, and superiority of this approach in comparison to earlier-generation mechanical thrombectomy with the Merci device were recently demonstrated in the Solitaire FR With the Intention For Thrombectomy (SWIFT) trial. The trial was stopped nearly one year before the anticipated finish date because of clear evidence of superiority of the Solitaire device.


In our opinion, the concept of temporary endovascular bypass is fundamental to the success of the stentriever approach to acute stroke treatment. Establishing early blood flow is key in preserving brain from irreversible ischaemic damage. Undoubtedly, endovascular therapies for rapid recanalisation of occluded vessels have already demonstrated improved clinical efficacy and safety and will continue to rapidly evolve, leading to improved outcomes in patients with acute stroke.


Maxim Mokin and Tareq Kass-Hout are Stroke fellows, Department of Neurology, School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, New York, USA. Mokin reports no financial relationships. Kass-Hout has received an educational research grant from Genentech.


Elad I Levy is professor of Neurosurgery and Radiology, School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, New York, USA. He receives research grant support (principal investigator: Stent-Assisted Recanalization in acute Ischemic Stroke, SARIS), other research support (devices), and honoraria from Boston Scientific* and research support from Codman & Shurtlef and ev3/Covidien Vascular Therapies; has ownership interests in Intratech Medical and Mynx/Access Closure; serves as a consultant on the board of Scientific Advisors to Codman & Shurtlef; serves as a consultant per project and/or per hour for Codman & Shurtleff, ev3/Covidien Vascular Therapies, and TheraSyn Sensors; and receives fees for carotid stent training from Abbott Vascular and ev3/Covidien Vascular Therapies. He receives no consulting salary arrangements. All consulting is per project and/or per hour. (*Boston Scientific’s neurovascular business has been acquired by Stryker)




Add New Comment

Related Items


Most popular


Revive SE thrombectomy device approved in China, South Korea and Taiwan
Monday, 08 Sep 2014
The Revive SE Device from Codman Neuro is designed to ease navigation through small and tortuous blood vessels and arteries in the cerebral vasculature. The new device enables rapid restoration of ... Revive SE thrombectomy device approved in China, South Korea and Taiwan

Monday, 08 Sep 2014
The Neuravi Thromboembolic Initiative brings together Neuravi engineers with clinicians and researchers in an effort to deepen the understanding of the mechanical properties of clot and occlusion ... Neuravi introduces collaborative clot research initiative at ESMINT

Aggressive resection should be considered for paediatric epilepsy
Thursday, 28 Aug 2014
Physicians from the University of California, San Francisco, USA, report that resection is safe and effective in children with pharmacoresistant focal epilepsy. Aggressive resection should be considered for paediatric epilepsy

Features


Neuro-oncologic treatment for glioblastoma
Monday, 21 Jul 2014
Malignant gliomas are the most common type of primary malignant brain tumour, accounting for 80% of patients and an annual incidence of 5.26 per 100,000 population, or 17,000 new cases diagnosed per ... Neuro-oncologic treatment for glioblastoma

Early brain stimulation may help stroke survivors recover language function
Monday, 21 Jul 2014
Dieter Heiss, who presented on early brain stimulation for stroke patients at the 8th World Congress on Controversies in Neurology (CONy), 8–11 May, Berlin, Germany, writes for NeuroNews on how this ... Early brain stimulation may help stroke survivors recover language function

Profiles


Vladimír Beneš Jr
Tuesday, 30 Sep 2014
Vladimír Beneš Jr is professor and chair at the First Medical School, Charles University, P... Vladimír Beneš Jr

Mauricio Castillo
Monday, 14 Jul 2014
Mauricio Castillo is a professor of Radiology and chief, Division of Neuroradiology, University of N... Mauricio Castillo

Cardiac Rhythm News Vascular News Cardiovascular News Interventional News Spinal News NeuroNews
BIBA Medical BIBA MedTech Insights CX Symposium ilegx
 
Password Reminder

BIBA Medical, 526 Fulham Road, Fulham, London, SW6 5NR.
TEL: +44 (0)20 7736 8788 FAX: +44 (0)20 7736 8283 EMAIL: 
info@bibamedical.com
© BIBA Medical Ltd is a company registered in England and Wales with company number 2944429.
VAT registration number 730 6811 50.
Site Map | Terms and Conditions