Intra-arterial thrombolysis.

Intra-arterial (IA) thrombolysis is an emerging treatment strategy for acute ischemic stroke. In IA thrombolysis, the cervicocephalic arterial tree is traversed with an endovascular microcatheter delivery system, the catheter port is positioned immediately within and adjacent to the offending thrombus, and fibrinolytic agents are infused directly into the clot. This delivery technique permits high concentrations of lytic agent to be applied to the clot while minimizing systemic exposure. Early open series suggested that IA thrombolysis achieves higher recanalization rates than i.v. thrombolysis. The first randomized Phase III trial of IA thrombolysis, the Prolyse in Acute Cerebral Thromboembolism II (PROACT II) trial, confirmed this promise, showing that IA therapy begun up to 6 hours after symptom onset was associated with higher recanalization rates and better clinical outcomes, with acceptable hemorrhage rates. MRI studies have provided striking imaging evidence of the potential beneficial effects of IA therapy, showing not only rescue of regions of diffusion-perfusion mismatch but also normalization and salvage of some tissues with pretreatment bioenergetic failure evidenced by early diffusion abnormality. The Emergency Management of Stroke Bridging Trial demonstrated the feasibility of combined i.v. and intra-arterial thrombolysis. Intra-arterial thrombolysis is a promising treatment strategy for acute ischemic stroke. In coming years, IA thrombolysis, alone or in combination with endovascular mechanical reperfusion techniques, is likely to be increasingly refined and validated and to become a widely accepted therapy for acute ischemic stroke.