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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{at}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.

View larger version (31K): [in this window] [in a new window]   Figure 1. TCD recordings were obtained via transtemporal approach at a depth of 53 mm with an 11.8-mm gate of insonation. Graphic below spectra frames shows presumed clot location in MCA main stem. Frame 1, Minimal flow signal in proximal MCA at time of IV rtPA bolus (13:02). After 30 minutes of continuous IV rtPA infusion: frames 2 and 3, early restoration of flow signals with increasing frequencies and microembolic signals (arrow); frame 4, turbulent stenotic signal with audible chirping components, suggesting clot dissolution; frame 5, hyperemic flow with velocities elevated above age-expected values and relatively low pulsatility (Gosling pulsatility index 0.73), indicating distal vasodilation; frame 6, hyperemic flow with velocities elevated above age-expected values and normal pulsatility (Gosling pulsatility index 0.93), showing proximal MCA reperfusion with distal vasomotor response.

This case demonstrates rapid recanalization of a presumed embolic clot occluding the MCA stem. TCD can detect residual blood flow around the clot, which may play a role in the process of intracranial clot dissolution similar to myocardial infarction.² TCD can noninvasively monitor recanalization and has a potential to identify patients who may not require additional thrombolysis or other clot disruption therapies.

Footnotes

The editor of Images in Cardiovascular Medicine is Hugh A. McAllister, Jr, MD, Chief, Department of Pathology, St Luke’s Episcopal Hospital and Texas Heart Institute, and Clinical Professor of Pathology, University of Texas Medical School and Baylor College of Medicine.

Circulation encourages readers to submit cardiovascular images to Dr Hugh A. McAllister, Jr, St Luke’s Episcopal Hospital and Texas Heart Institute, 6720 Bertner Ave, MC1-267, Houston, TX 77030.

References

1. Grotta JC, Alexandrov AV. TPA-associated reperfusion in acute ischemic stroke demonstrated by SPECT. Stroke. 1998;29:429–432.[Abstract/Free Full Text]
   
2. Anderson JL. Why does thrombolysis fail? Breaking through the reperfusion ceiling. Am J Cardiol. 1997;80:1588–1590.[Medline] [Order article via Infotrieve]
   

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Demchuk, A. M. Articles by Alexandrov, A. V. Search for Related Content PubMed PubMed Citation Articles by Demchuk, A. M. Articles by Alexandrov, A. V. Related Collections Thrombolysis Acute Cerebral Infarction Brain Circulation and Metabolism Doppler ultrasound, Transcranial Doppler etc. Fibrinolysis