Mechanical Thrombectomy

Mechanical thrombectomy (MT) is a procedure performed in the setting of an acute ischaemic stroke. The operator gains access to the cerebral circulation usually via the femoral artery in the groin and gains access to the cerebral circulation. Using specialised kit the operator can remove an occlusive thrombus from the proximal MCA. The clot is aspirated into the device and removed. This allows flow to be recommenced in the obstructed artery. The goal of thrombectomy is to achieve a complete recanalisation (TIMI grade, 3). It may also be used on other large vessel occlusions such as Basilar artery thrombi. Mechanical treatment approaches for acute ischaemic stroke treatment aim for fast and efficient reperfusion with short procedure times and high recanalisation rates, thus extending the treatment window. MT may be used with or instead of IV Alteplase.

Technically there are two different approaches - proximal thrombectomy which is done by using an aspiration catheter to retrieve the thrombus under constant negative pressure. This has been sued in the distal cervical internal carotid artery, the carotid terminus or the basilar artery. Recanalisation rates are approximately 80% with good clinical outcomes [11]. One system used is the Penumbra System (Penumbra, Almeda, USA) which rather than manual aspiration has a dedicated reperfusion catheter connected to a pumping system applying continuous aspiration.

TICI Assessment

The thrombolysis in cerebral infarction (TICI) grading system was described in 2003 by Higashida et al 1 as a tool for determining the response of thrombolytic therapy for ischaemic stroke. In neurointerventional radiology it is commonly used for patients post endovascular revascularisation. Like most therapy response grading systems, it predicts prognosis.


The original description 1 was based on the angiographic appearances of the treated occluded vessel and the distal branches:

  • Grade 0: no perfusion
  • Grade 1: penetration with minimal perfusion
  • Grade 2: partial perfusion
  • Grade 2A: only partial filling (less than two-thirds) of the entire vascular territory is visualized
  • Grade 2B: complete filling of all of the expected vascular territory is visualized but the filling is slower than normal
  • Grade 3: complete perfusion

In 2013 Fugate et al reported marked variability in its definitions and application. A consensus paper from three collaborative groups published in Stroke in 2013 3 recommended a modified scale, and a change of name from Thrombolysis in Cerebral Infarction to modified Treatment in Cerebral Infarction (mTICI), to better reflect the increased use of endovascular therapies.

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