The efficacy of IV thrombolysis in patients with moderate-to-severe strokes due to proximal arterial occlusions is restricted by several factors, including the relatively short therapeutic window, poor recanalization rates as the clot burden increases, restrictive eligibility criteria, and the risk of intracerebral hemorrhage. Endovascular techniques improve the rates of recanalization in this patient population, and appear to increase the likelihood of a good functional outcome. Intravenous thrombolysis

FIGURE 4.6 The NeuroFlo device with its dual balloon catheter uniquely designed for partial occlusion of the aorta above and below the origin of the renal arteries.

with rt-PA should be initiated in all eligible patients presenting within 3 hours of stroke onset, and considered as a "bridge" to IAT for appropriate patients with verified proximal vessel occlusions. Mechanical thrombolysis has become a powerful adjunct to IA infusion of chemical thrombolytics, and should be considered as primary therapy in patients who have contraindications to chemical thrombolysis or who present late (up to 8 hours in the anterior circulation). The time window for IAT in the posterior circulation has not been well established, and at this point a judicious decision should be made on a case-by-case basis. The emerging neuroi-maging techniques that identify territory at risk, such as CT and MRI perfusion, are under active investigation to establish triage criteria for patient selection in IAT. These methods may eventually define a subgroup of patients who will benefit from late IV or IA thrombolysis.

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