Complication avoidance
Careful selection of patients for stroke intervention
with adherence to recent evidence based guidelines is the first step in avoiding pitfalls. Imaging modalities such as CT/MRI perfusion remain a mainstay for determining the salvageability of penumbra, but significant
attention is paid to control of hypertension to prevent both reperfusion
injury and hemorrhage in patients who undergo stroke intervention. Blood
pressure control is an integral component in avoiding post
recanalization injury or SICH even in normotensive patients as delayed
hypertension can occur \cite{Coutts_2003}. The use and titration of antihypertensive medications
such as Nicardipine before, during, and after recanalization reduce
potential for both reperfusion injury and reperfusion hemorrhage.
Nicardipine is a preferred medication as it does not increase cerebral
blood flow nor promote vasodilation features of other, less favored
antihypertensives.
Vasospasm, Arterial Perforation and Dissection
Vasospasm
Vasospasm, arterial perforation, dissection are well known complications in the context of acute ischemic stroke intervention.
Vasospasm, which is a sudden constriction of a blood vessel, has rare clinical significance in the setting of acute ischemic stroke intervention.
The majority of vasospasm seen in stroke intervention is produced by mechanical stimulation of a vessel by contact with a catheter. Vasospasm, depending on severity, may have deleterious effects either locally at the site, or distal to the site if not addressed appropriately. In inexperienced hands, it is not uncommon to see vasospasm within the cervical internal carotid artery and beyond as the interventionalist hastily attempts to climb larger bore catheter in preparation for thrombectomy. Although preexisting atherosclerosis and underlying unhealthy vasculature may predispose vessels to vasospasm, these complications can occur in healthier vessels even with the gentlest of manipulations.
Complication Avoidance
It is imperative for the interventionist to demonstrate the utmost care and finesse when performing a stroke intervention. Appropriate pre-procedure planning should be undertaken so that anticipation of the vessel diameters and calibers might change the selection of guide catheter or wire. A preoperative review of the patient's CT angiography perhaps might dissuade use of an 8 or 9 French system as the guiding catheter. In the event that vasospasm does occur, simple maneuvers may alleviate the local irritation. Pulling the catheter back more proximally, in essence, allowing the affected vessel to "cool down" seems to be one effective approach. However, as time is of the essence in stroke intervention, when this event occurs, local intraarterial verpamil can be of great utility in relaxing the vessel and allowing the procedure to go on without further delay. The (ARE YOU THINKING OF ADDING ANYTHING HERE? THIS LOOKS COMPLETE ALREADY)
Dissection
Dissection can involve any vessel, either extracranial or intracranial vessels. Any aggressive manipulation of a catheter or wire can cause damage to the intima of the vessel and create a dissection flap. It is incumbent upon the interventionalist to select guide catheters with which they are comfortable and softer wires to minimize the potential for dissection. Disssections increase the risk of occlusive or thromboembolic complications and may lead to severe neurological deficits if not dealt with appropriately. Common sites for dissection are most notably seen in the cervical carotid artery and the petrocavernous segments of the ICA. Dissection can appear as an intimal flap on DSA and double lumen in CTA. Although sometimes asymptomatic, the effects of dissection are thromboembolic in nature and may put the patient at further risk of stroke.
Complication avoidance
Even in the most skilled hands, dissection can occur when climbing a catheter over a wire in an already diseased vessel. The decision to treat a dissection is based on severity i.e. flow limiting dissections. Balloon angioplasty or stenting of the vessel may be needed to treat a flow limiting dissection. If the flap is treated by stenting, dual antiplatelet therapy is required and may increase risk of bleeding.
Perforation
Vessel perforation, which is caused by wire penetration through a vessel lumen can have catastrophic effects even in the most straightforward of thrombectomy cases. Albeit rare, this complication if dealt with in a timely fashion does not preclude ultimately a good outcome for the patient suffering from an acute stroke. Mokin et. al concluded that Intraprocedural perforations during stent retriever thrombectomy were rare, but when they occurred were associated with high mortality. In this multicenter retrospective study, perforations were most commonly found to occurr at distal occlusion sites and were often characterized by difficulty traversing the occlusion with a microcatheter or microwire, or while withdrawing the stent retriever \cite{Mokin_2016}. If the patient has a history of intracranial atheroclerotic disease (ICAD), it may predispose them to sustaining vessel injury and perforation especially if a microwire is used to cross a lesion or if a stent retriever is deployed in
Complication Avoidance
Aside from experience and skill which are still not immune to complication, in the rare event vessel perforation occurs, immediate verification must first be made. Initial measures include reducing blood pressure (BP) and reversal of anticoagulation if deemed necessary will lessen the severity of the bleed. Several techniques have been described in the literature for handling the acute vessel perforation one of which is employment of temporary balloon inflation proximal to the perforation. This technique allows for temporary occlusion of the vessel and therefore a chance for platelet aggregation preventing further extravasation. To avoid prolonged ischemia decrease bloody supply to already at risk tissue, we recommend the use of balloon occlusion for five to ten minutes at a time.
Conclusion
As thrombectomy has gained more traction and indications have opened up for treatment of acute ischemic stroke, there will invariably be an increase in complications. Complications are often unavoidable, however, anticipation and preparation for complications can allow for better outcomes. Stroke intervention should be performed by experts at high volume centers if possible. This ensures that patients receive treatment from teams that have seen and done an adequate number of stroke cases. Outcomes for stroke intervention, as is the case in many other procedures, can depend upon the skill of the neurointerventionist which comes from his or her experience. Recognition of potential risk factors can help prevent complications but in the rare cases complications do occur, understanding the reasons for which they occur and knowing how to handle them can make all the difference. There are no significant evidenced based guideline for the management of complications which occur in acute stroke intervention. The complications are well known and documented in the literature but most management is based heavily on anectdotal evidence. The field of stroke intervention continues to grow and evolve, and as newer technologies emerge, complication avoidance alongside complication management are necessary for optimal outcomes for patients.