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(Circulation. 1999;100:2282.)
© 1999 American Heart Association, Inc.

Images in Cardiovascular Medicine

Evolution of Rapid Middle Cerebral Artery Recanalization During Intravenous Thrombolysis for Acute Ischemic Stroke

Andrew M. Demchuk, MD, FRCPC; Theodore H. Wein, MD, FRCPC; Robert A. Felberg, MD; Ioannis Christou, MD; Andrei V. Alexandrov, MD, RVT

From the Center for Noninvasive Brain Perfusion Studies and the Stroke Treatment Team, University of Texas–Houston Medical School. Dr Demchuk is now at the Seaman Family MR Research Centre, Department of Clinical Neurosciences, University of Calgary, Calgary, Alberta, Canada; Dr Wein is now at the UMH Neurology Clinic, University of Michigan, Ann Arbor.

Correspondence to Dr Andrew M. Demchuk, Seaman Family MR Research Centre, 1403 29th St NW, Calgary, Alberta, Canada T2N 2T9. E-mail ademchuk@dcns.ucalgary.ca

Intravenous recombinant tissue plasminogen activator (rtPA) is thought to benefit patients with acute ischemic stroke by producing early reperfusion.¹ Transcranial Doppler (TCD) is a noninvasive method that can monitor the recanalization process in real time when occlusion occurs in the proximal intracranial vessels.

We present our findings during rtPA infusion in a 56-year-old man with acute ischemic stroke to illustrate the time course of changes that occur in a middle cerebral artery (MCA) stem occlusion treated by intravenous thrombolysis. We used a 2-MHz portable unit (Multigon 500 mol/L) with a pulse-wave transducer mounted on a head frame (Marc 500, Spencer Technologies) to insonate the MCA at a constant angle through the temporal bone. At the initiation of rtPA treatment, only minimal antegrade flow was visualized (Figure, frame 1), indicating MCA main-stem near-occlusion. The MCA flow signals started to improve 30 minutes later (frames 2 and 3). Microembolic signals were heard as chirping sounds with unidirectional appearance on screen (white arrow, frame 2), consistent with the beginning of clot breakdown and washout. A brief period of a stenotic signal was seen (frame 4), representing early partial recanalization. This was rapidly followed by the appearance of a hyperemic low-resistance flow (frames 5 and 6), indicating complete reperfusion of the MCA stem. Thus, a complete recanalization was achieved within 36 minutes of initiation of rtPA infusion. Once the residual blood flow signals around the clot started to improve, only a few additional minutes were necessary to achieve complete recanalization.

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