Thromboembolic Complications
From beginning to end, neurointerventional procedures of any kind predispose patients to having thromboembolic complications. Albeit somewhat ironic, as the discussion relates to stroke intervention and removal of thrombus causing LVO, the risk of thromboembolic complications remains. There is an inherent risk of embolic material forming on catheters and guidewires introduced into the vasculature. This risk can be reduced by cleanliness, organized back table management of catheters and wires as they are introduced and removed from the body. In addition, arterial dissection and vasospasm caused by the guide catheter prior to microcatheter and microwire manipulation can be associated with thromboemboli. Heparinization of the patient is a strategy used by many to minimize the thromboemboli alongside intrarterial verapamil in select instances of severe vasospasm induced by catheters.
More concerning for the neurointerventionist is the possibility of preexisting clot fragments dislodging and leading to embolization of new territory (ENT) due to manipulation of an endovascular device. Distal embolization is a legitimate concern which can be handled with different approaches. The use of stent retrievers of any kind mandates that a lesion be crossed with a microwire for facilitating the unsheathing of the stent retriever device. The mere act of crossing a lesion is in itself an opportunity to dislodge clot debris downstream. Companies in the neurovascular sector tout varying components of their stent retriever devices including stent length, cell size, radial force, and factors which may allow for better clot engagement. A plethora of devices ranging from stent retrievers to balloon guide catheters (BGC) fill the toolbox of the neurointerventionist and should be used based on his/her comfort and experience level with the understanding that no device is immune from complications. Table 1 demonstrates several of these tools, some of which are FDA approved for use in MT. 
The role of direct aspiration versus stent-retrievers is an ongoing debate in stroke and also the subject of ongoing trials. The ASTER trial showed no statistically significant differences in procedural complications like sICH and embolisation in a new territory between stent-retriever and ADAPT (a direct aspiration first-pass technique).  Overall, each device has its unique benefits, however there is no clear discrepancy with regard to ENT. Newer generation devices attempt to account for clot fragmentation in their design. For example, EmboTrap (Neuravi, Ireland) features an inner stent channel within an outer stent (Fig 1). 
Embolization of New Territories