Deliberate Distal Displacement of a Middle Cerebral Artery Embolus as an Alternative Method to Treat a Thrombolytic-Resistant Clot
To the Editor:
Intra-arterial administration of fibrinolytic agents remains the primary endovascular option for patients with acute middle cerebral artery (MCA) thromboembolic disease.1,2 However, the use of fibrinolytic agents is usually limited to a 3- to 6-hour window, is contraindicated in certain circumstances,3 and has little or no effect against some types of clots (organized or tissue emboli, for example). In addition, fibrinolytic agents are associated with a risk of hemorrhage both at the site of the ischemic lesion and in remote intracranial and extracranial locations. As a result of these constraints, mechanical treatment options have recently been developed, including thromboaspiration techniques and thrombectomy devices.4 We illustrate our experience in a patient with acute MCA ischemia, in whom a proximal MCA clot was purposefully advanced into a distal branch in order to limit the extent of tissue infarction.
Our patient was a 42-year-old HIV-positive man admitted for acute respiratory distress. He was intubated and a chest tube placed for pleural effusion. During the hospital stay, he developed a sudden change in mental status and a left hemiplegia. CT showed a hypodensity in the right MCA territory suggesting acute ischemia. Cerebral digital subtraction angiography (DSA) performed ≈3 hours after onset revealed proximal occlusion of the superior division of the right MCA (M2 segment; Figure, A). A 1.9-French microcatheter (Prowler 14, Cordis) was advanced at the contact of the clot. During attempted clot disruption with a 0.014 guide wire (Transcend Ex, Cordis), slight forward motion of the thrombus was observed. Because the presence of a chest tube would limit the dose of tissue plasminogen activator (tPA) that could be safely administered, it was decided to try pushing the clot as far as possible in the MCA distribution using the guide wire. The clot could easily be advanced into the angular artery (Figure, B). This manipulation was followed by intra-arterial administration of 11 mg of tPA without detectable effect on the clot (Figure, C). The patient was able to move his left arm and legs immediately after he woke up from the procedure. His mental status improved gradually to baseline. Intravenous heparin was continued for 24 hours. The patient was discharged home 14 days after the procedure. His neurological examination at discharge only showed a mild left facial droop; the motor strength was 5/5 bilaterally.
Our case illustrates an unusual endovascular technique for acute stroke treatment, which might be useful in patients with absolute or relative contraindications to fibrinolytic agents, clots resistant to fibrinolysis, or clots not accessible to currently available thrombectomy devices. Our patient showed each of the constraints mentioned above: (1) the presence of a chest tube was a relative contraindication to fibrinolytic therapy, (2) the MCA clot ultimately proved resistant to the given dose of fibrinolytic agents, and (3) the location of the clot (proximal M2 segment) was unfavorable to a thrombectomy device such as the Merci (Concentric), which was not then available anyway. In our patient, mechanical distal advancement of the clot into a distal MCA branch resulted in near complete resolution of the clinical symptoms, despite the absence of effect of the fibrinolytic agents.
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I enjoyed reading this report, and I congratulate the authors for their innovative approach. I would like to clarify 2 points concerning the Merci Retriever: (1) the Merci Retriever is indicated for proximal M2 occlusions, and (2) as of September 2005 and 13 months after FDA clearance, many neurointerventionalists have been trained in using the Merci Retriever, and it is now available in 180 hospitals in the US.