Studies have established the effectiveness and relative safety of endovascular intervention. These trials favor rapid endovascular intervention in acute ischemic stroke with proximal vessel occlusion, small infarct core and moderate to good collateral circulation 1) 2) 3) 4).
Currently available are Solitaire and Trevo. A 7 or 8 Fr sheath is placed in the femoral artery, through which a 6 Fr balloon guide catheter is positioned in the ICA (in case of anterior circulation strokes). Angiography is performed to identify site of occlusion. Using fluoroscopy and road mapping, a microcatheter is advanced over a microwire, across the site of occlusion. The microwire is removed and the stent retriever is advanced through the microcatheter such that it extends proximal and distal to the clot. The stent retriever is unsheathed by retracting the microcatheter as the retriever is maintained stationary. The stent retriever expands to its actual size and this results in restoration of flow in the occluded artery. After five minutes, the balloon on the guide catheter is inflated to arrest blood flow. Maintaining gentle aspiration on the guide catheter, the stent retriever and microcatheter are retracted simultaneously. Once both the microcatheter and retriever are with- in the guide catheter, vigorous aspiration is applied as the two devices are concurrently retracted and removed from the patient. Angiography is performed to confirm reconstitution of circulation. Some surgeons administer a small amount of i.a. tPA as ‘mop up’ after mechanical thrombolysis, to address potential distal debris. Vessel perforation during stent retriever withdrawal has been reported 9).
This device includes a microcatheter that is advanced over a microwire, through the positioned guide catheter. The tip of the microcatheter is positioned adjacent to the proximal aspect of the clot. A separator is advanced through the microcatheter that is advanced back and forth through the clot to disrupt it. The proximal end of the microcatheter is connected to an aspiration pump that is turned on to aspirate the clot fragments. Unlike stent retrievers that a ect recanalization within minutes, Penumbra aspiration device takes longer, with median time of 49 min 12).
Its use is confined to the straight arterial segments because of risk of vessel perforation by the separator action.
In addition to above, other techniques to extract thrombus have also been employed with mixed results including, aspiration with a simple syringe attached to a microcatheter, usage of snares, angioplasty at site of thrombus, stenting etc…