Interventional neuroradiologists are offering endovascular clot retrieval for ischemic stroke patients who do not qualify or improve with intravenous thrombolytics.
Kai U. Frerichs, MD, Director of Interventional Neuroradiology and Director of Endovascular Neurosurgery at Brigham and Women’s Hospital, is one of few specialists in New England to offer a recently FDA-approved catheterization device for the retrieval of clots in ischemic stroke patients.
High Success Rates
Participating in the multi-center national MERCI (Mechanical Embolus Removal in Cerebral Ischemia) Trial, including more than 140 patients who did not qualify for intravenous thrombolytics (t-PA), Dr. Frerichs has seen up to a 60 percent success rate in clot retrieval and recanalization in patients treated with the Merci® Retrieval System.
Dr. Frerichs employs the Merci Retrieval System as the first line of therapy if intravenous t-PA has failed or cannot be given. The most common reason that t-PA cannot be administered is late presentation beyond three hours after the onset of stroke symptoms. The System can be used up to eight hours after the event.
The Merci Retrieval System consists of:
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Balloon guide catheter – The balloon guide catheter is inserted through a small incision in the femoral artery, and, under x-ray guidance, is maneuvered to the carotid artery;
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Microcatheter – A guidewire and the microcatheter are deployed through the balloon guide catheter and placed just beyond the clot;
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Retriever device – The retriever device ensnares the clot.
Once the clot is captured, the balloon guide catheter is inflated to temporarily reverse forward flow while the clot is being withdrawn. The clot is pulled into the balloon guide catheter and extracted from the patient. The balloon is deflated, and blood flow is restored.
Patient Profile: Clot Retrieval Following Unsuccessful t-PA
A 77-year-old female, who collapsed at home and was unable to move her left side, was transported by Emergency Medical Service to the Emergency Department at Brigham and Women’s Hospital in Boston. She arrived within three hours of the onset of stroke symptoms. She had a history of atrial fibrillation and was found to be subtherapeutic on Coumadin®.
Evaluation
Emergency evaluation revealed a National Institutes of Health (NIH) stroke scale of 17, and computed tomography scan* showed a dense right middle cerebral artery (R MCA) consistent with R MCA occlusion. Complete left hemiplegia and hemineglect indicated that lack of perfusion affected the entire right hemisphere of the brain. *Magnetic resonance imaging was not used due to a pacemaker.
Treatment
Intravenous thrombolytics (t-PA) were given but did not improve symptoms. The patient was transitioned to the Brigham and Women’s Hospital neurointerventional suite – two dedicated procedure rooms within the OR complex – for emergent endovascular treatment.
A diagnostic angiogram (Figure 1) confirmed complete occlusion of the R MCA main trunk and showed minimal collateral flow provided by pial vessels from the anterior cerebral artery. The diagnostic catheter was replaced with the Merci balloon guide catheter, and the System’s microcatheter and retriever devices were navigated through the balloon guide catheter and the occluded segment. The retriever device was deployed distal to the clot and withdrawn. During retrieval of the clot, the balloon - located in the internal carotid artery - was inflated for flow reversal to prevent partial loss of the clot in the bloodstream. Successful retrieval of the clot was achieved in a single pass of the Merci retriever device, and complete
recanalization of the R MCA was confirmed with angiography (Figure 2) approximately five hours following the onset of symptoms.
Post-procedure
The patient awoke from the procedure with significant improvement. Twenty-four hours following the procedure, she was found to be neurologically intact. She was discharged one week later – after comorbidities were appropriately addressed, including adjustment of the Coumadin dose. Post-operative CT scan showed no infarcts.
Specialized Care for Stroke Patients
The team of specialists at the Stroke and Cerebrovascular Center – part of the Institute for the Neurosciences at Brigham and Women’s Hospital – applies innovative, multimodality treatment designed to address each patient’s needs and improve the outcome of patients with stroke and cerebrovascular disease, including acute stroke, aneurysms, carotid occlusive disease, and vascular malformations (AVMs and cavernous and venous malformations).
Neurosurgeons, neurointerventionalists, vascular surgeons, and emergency medicine physicians in the Center work together to deliver rapid, accurate, and advanced assessment and treatment for patients, including:
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Innovative medical and endovascular therapies – Intravenous or intra-arterial thrombolysis with t-PA and mechanical thrombolysis and clot retrieval;
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Neurosurgical techniques – Intra-cranial bypass, craniectomy and hemispheric decompression, carotid endarterectomy, skull base approaches, AVM resection,stereotactic radiosurgery, and endovascular surgery (angioplasty and stenting);
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Neuro-interventional procedures – Revascularization, angioplasty, stenting, aneurysm coiling, and microcatheter injection.
Indications for Referral
The Merci® Retrieval System is generally suitable for ischemic stroke patients who:
Information and Referrals
For more information about the Stroke and Cerebrovascular Center at Brigham and Women’s Hospital, please contact a Referral Coordinator at (617) 732-9894.
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