Mechanical Embolectomy Research Articles

029 Does anesthesia influence clinical outcomes in mechanical embolectomy? Real world data from the Merci registry

Background/Purpose: The Merci Retriever was cleared by the Food and Drug Administration in 2004 for use in removing thrombus in acute stroke patients. The original results from Merci were encouraging,...

Comparison of Mechanical Embolectomy and Intraarterial Thrombolysis in Acute Ischemic Stroke within the MCA: MERCI and Multi MERCI compared to PROACT II

Intraarterial thrombolysis and mechanical embolectomy have been studied for endovascular treatment of stroke. The MERCI and Multi MERCI trials of mechanical embolectomy with or without adjuvant intraarterial thrombolysis demonstrated effective recanalization, but with a higher mortality compared with control patients in the PROACT II trial of intraarterial thrombolysis. Differences in trial design may account for this mortality difference. We identified patients in the MERCI and Multi MERCI trials who would have been eligible for PROACT II. Rates of good outcome (mRS < or =2) and mortality at 90 days were compared, adjusting for differences in baseline NIHSS score and age. Sixty-eight patients enrolled in MERCI and 81 enrolled in Multi MERCI were eligible for PROACT II. In both unadjusted and adjusted analyses, PROACT II-eligible embolectomy patients showed a trend toward better clinical outcomes compared to the PROACT II control arm (adjusted, MERCI 35.4% [p = ns], Multi MERCI 42.8% [p = 0.048], PROACT II control, 25.4%). In both unadjusted and adjusted analyses, mortality rates did not significantly differ between embolectomy patients and PROACT II control patients (adjusted analysis, MERCI 29.1%, Multi MERCI 18.0%, PROACT II control, 27.1%). Compared with the PROACT II treatment group, embolectomy groups showed similar rates of good outcome and mortality. Differences in mortality and proportion of good outcome between the MERCI/Multi MERCI trials and the PROACT II trial are explained by differences in study design and baseline characteristics of patients. Mechanical embolectomy and IA thrombolysis may each be reasonable strategies for acute stroke; a randomized trial is necessary to confirm these results.

Basilar Artery Occlusion Following C1 Lateral Mass Fracture Managed by Mechanical and Pharmacological Thrombolysis

Vertebral artery injury following cervical spine trauma can be associated with stroke. We present a case of a C1 fracture resulting in vertebral artery dissection and neurological decline as a result of basilar artery occlusion treated with chemical and mechanical thrombolysis resulting in basilar artery patency and clinical improvement. The patient is a 43-year-old female who was involved in a motor vehicle collision where she sustained multiple cervical spine injuries including a comminuted fracture of the left lateral mass of C1 resulting in vertebral artery dissection which eventually led to a basilar artery embolus and occlusion. A total of 15 mg of intraarterial tissue plasminogen activator was infused throughout the clot, followed by mechanical clot embolectomy using an FDA-approved device. Her neurological exam improved post-procedurally and she was discharged with a left hemiparesis to a rehabilitation facility 3 weeks after admission. At 15 month follow up, she is neurologically intact with the exception of some subtle difficulty with fine motor movement in the right upper extremity and mild dysmetria on the right. With this case, we report a rare and potentially devastating complication of C1 fracture. To our knowledge there are only two previously reported cases where a C1 fracture has been associated with basilar artery occlusion resulting in death and locked-in syndrome respectively. In this case, chemical thrombolysis and mechanical thrombectomy resulted in recanalization of the basilar artery with excellent long-term neurological outcome.

Percutaneous Clot Removal Devices in Acute Ischemic Stroke

We conducted a systematic review and meta-analysis of mechanical thrombectomy in the treatment of ischemic stroke and assessed factors for technical and clinical success and survival. We searched the literature using MEDLINE and EMBASE for January 1, 2000, through March 1, 2006. Studies were limited to those in human beings; there were no language or study design restrictions. Validity assessment was performed using the Newcastle-Ottawa Scale. The pooled cohort was compared with a historical cohort matched for sex, age, and National Institutes of Health Stroke Survey score. The search yielded 114 publications. Two authors determined inclusibility (interrater agreement, kappa = 0.94). Mean preprocedure National Institutes of Health Stroke Survey score was 20.4. The middle cerebral artery (36%) and the posterior circulation (38%) were the most frequently occluded areas. The clot was accessible in 85% of the patients. Hemorrhage occurred in 22% of the patients. Of 81 patients with concurrent thrombolysis, 18.5% had hemorrhage compared with 27.3% of 66 patients without thrombolysis (P = .21). Of the 126 patients with accessible clots, 36% had a good modified Rankin score (<or=2) and 29% died; in patients with inaccessible clots, 24% had a good modified Rankin score and 38% died. Factors associated with clinical success were younger age (P = .001) and lower National Institutes of Health Stroke Survey score at admission to the hospital (P = .001). Compared with a matched cohort, patients who received mechanical intervention were 14.8 times more likely to have a good modified Rankin score (95% confidence interval, 4.4-50.0; P < .001). Percutaneous mechanical embolectomy in the treatment of acute ischemic stroke is feasible and seems to provide an option for some patients seen after the interval for administration of intravenous tissue plasminogen activator therapy has elapsed.

Thrombolytic Toxicity: Blood Brain Barrier Disruption in Human Ischemic Stroke

Background: In experimental models of cerebral ischemia, thrombolytic drugs have been demonstrated to have a number of neurovascular toxic effects including blood brain barrier disruption. Early barrier opening caused by focal cerebral ischemia in human stroke can be assessed by the presence of gadolinium enhancement of cerebrospinal fluid, termed ‘Hyperintense Acute Injury Marker’ (HARM). Methods: In a retrospective analysis, the frequency of HARM was studied in 140 patients, 38 receiving intra-arterial thrombolytics, 18 undergoing mechanical embolectomy, 24 receiving intravenous tissue plasminogen activator and 60 patients receiving no acute intervention. Results: HARM was found in 66% of patients undergoing intra-arterial thrombolysis and 50% of patients receiving intravenous tissue plasminogen activator, compared to 28% of patients undergoing mechanical embolectomy and 30% of patients receiving no acute therapy (p = 0.002). Both thrombolytic therapy (p = 0.001) and age (p = 0.001) were independent predictors of HARM. HARM was an independent predictor of hemorrhagic transformation (p = 0.007). Conclusions: This is the first study in humans providing supportive evidence of the neurovascular toxic effects of thrombolytics and suggests that HARM may be used as a biomarker of blood brain barrier disruption in future research of acute stroke therapies.

Mechanical endovascular recanalization therapies

The review compares recent trials using mechanical endovascular therapies with and without adjuvants to treat acute stroke. The Multi Mechanical Embolus Removal in Cerebral Ischemia trial showed that good revascularization success could be obtained using the Merci retrievers within 8 h of symptom onset. In patients with persistent vascular occlusions despite intravenous tissue plasminogen activator, mechanical embolectomy appeared to be safe. The Interventional Management of Stroke II study achieved similar final revascularization success using low-dose tissue plasminogen activator within 3 h of symptom onset followed by intra-arterial tissue plasminogen activator or EKOS ultrasound plus intra-arterial tissue plasminogen activator. In these trials, patients with recanalization had better outcomes than those without revascularization. Effects of trial design, such as time to treatment, patient age, and use of adjuvant therapies, may affect outcomes. Recent trials of mechanical endovascular therapies have shown recanalization in the majority of target vessels and better outcomes in those patients in whom recanalization was achieved than in those without recanalization. Differences in trial design and lack of head to head comparisons to date make it difficult to determine whether one treatment approach is better than another.

Comparative in vitro study of five mechanical embolectomy systems: effectiveness of clot removal and risk of distal embolization

We report an in vitro study comparing the effectiveness of clot removal and clot fragmentation of five embolectomy systems. A flow model was embolized with fresh and old thrombi, occluding an inner diameter of 2-5 mm simulating internal carotid artery (ICA), basilar artery (BA) and middle cerebral artery (MCA) branch occlusion. Embolectomy was performed using five retrieval systems: CATCH (Balt), Merci retriever (Concentric), InTime and Attracter (Boston Scientific), and the Phenox Clot Retriever (Phenox). Clot removal and evidence and type of thrombus fragmentation and distal embolization were recorded. There were no observable differences attributable to thrombus age. The Merci, CATCH and Phenox Clot Retriever were equally able to mobilize and remove thrombi with the exception of one particularly firm clot. There were marked differences in terms of thrombus fragmentation and distal embolization. All devices produced micro- and macrofragments during penetration and retrieval. The Phenox Clot Retriever was able to filter fragments. The InTime and Attracter devices failed to retrieve thrombi in this model and achieved partial removal at best with a tendency towards thrombus displacement and fragmentation. Within limits, the experimental setup was appropriate for generating occlusions of diameter 2-5 mm of various lengths, simulating ICA, BA and MCA thromboembolism. In this model, thrombus mobilization appeared to be less dependent upon the individual design of the retrieval system than on thrombus fragmentation. The ability to prevent distal embolization is, however, strongly dependent on the ability of a thrombectomy device to capture fragments that are generated during removal of the device.

104: TIMI Flow Obtained After Mechanical Embolectomy for Acute Ischemic Stroke and Its Impact on Functional Outcome

104: TIMI Flow Obtained After Mechanical Embolectomy for Acute Ischemic Stroke and Its Impact on Functional Outcome

Successful Recovery from Carotid Terminus Occlusion after Mechanical Embolectomy in a Fully Anticoagulated Patient

We describe a case of the patient with multiple contraindications for thrombolysis who underwent successful mechanical embolectomy for occlusion of the right carotid terminus. Her pre-procedural NIHSS was 16. The patient demonstrated remarkable recovery within an hour of the procedure, and this clinical improvement was sustained at followup. This case illustrates that mechanical embolectomy is a safe and potentially very effective intervention to treat major intracranial vessel occlusions in patients with multiple contraindications for thrombolysis.

Endovascular reperfusion therapy in acute ischaemic stroke

Endovascular reperfusion therapy in acute ischaemic stroke comprises a number of pharmacological and mechanical procedures. Mechanical embolectomy offers the promise of efficacious treatment for patients in whom pharmacological thrombolysis is contraindicated or might be ineffective. The purpose of this review is to outline endovascular reperfusion therapy in acute ischaemic stroke with focus on mechanical embolectomy. Data on endovascular reperfusion therapy were acquired through searches in MEDLINE 1990-2006 by cross referencing relevant key words. Mechanical embolectomy works well on large-volume proximal occlusions for which there was previously no effective treatment. Early safety trials are promising, efficacy in terms of recanalisation is substantial, and both safety and efficacy is expected to improve with further advances in technology. Intravenous thrombolysis with tPA revolutionised acute stroke treatment a decade ago. Endovascular reperfusion therapy now offers the promise of a second revolution, expanding the number of patients eligible and the time window open for specific stroke treatment.

Mechanical thrombectomy with snare in patients with acute ischemic stroke

We evaluated the efficacy and safety of thrombus extraction using a microsnare in patients with acute ischemic stroke (AIS). This was a prospective, observational, cohort study in which consecutive patients with AIS (<6 hours of ischemia for anterior circulation and <24 hours for posterior circulation) who had been previously excluded from intravenous tissue plasminogen activator (tPA) thrombolysis were included and followed-up for 3 months. Mechanical embolectomy with a microsnare of 2-4 mm was undertaken as the first treatment. Low-dose intraarterial thrombolysis or angioplasty was used if needed. TIMI grade and modified Rankin stroke scale (mRSS) score were used to evaluate vessel recanalization and clinical efficacy, respectively. Nine patients (mean age 55 years, range 17-69 years) were included. Their basal mean NIHSS score was 16 (range 12-24). In seven out of the nine patients (77.8%) the clot was removed, giving a TIMI grade of 3 in four patients and TIMI grade 2 in three patients. Occlusion sites were: middle cerebral artery (four), basilar artery (two) and anterior cerebral artery plus middle cerebral artery (one). The mean time for recanalization from the start of the procedure was 50 min (range 50-75 min). At 3 months, the mRSS score was 0 in two patients and 3-4 in three patients (two patients died). According to our results, the microsnare is a safe procedure for mechanical thrombectomy with a good recanalization rate. Further studies are required to determine the role of the microsnare in the treatment of AIS.

Preclinical testing of a new clot-retrieving wire device using polyvinyl alcohol hydrogel vascular models

Cerebral embolism is the principal cause of cerebral infarction. Recently, mechanical embolectomy has been proposed as an effective method. We performed a preclinical evaluation of a new mechanical clot-retrieving wire. This clot-retrieving wire consisted of three nitinol loops at the tip of a microguidewire. These three loops could be collapsed into a 0.018-inch wire compatible microcatheter. Each loop was 8 mm long and 3.5 mm wide. For simulation, polyvinyl alcohol (PVA) vascular anatomical models of the human carotid (eight models) and vertebrobasilar (three models) circulation were constructed. A pulsatile flow circulation system was used. Embolic clots were produced using pig blood plasma. The microcatheter and the microguidewire were advanced beyond the clot. The wire was then exchanged for the retrieving wire. The microcatheter was then pulled slightly back to open the loops. The clot was then caught by withdrawal of the system. Once caught, the clot was retrieved to the guiding catheter tip. We investigated the following points: ease of device deployment, clot capture ability, clot removal against blood flow and removal of the clot out of the introducer system. A total of 104 procedures were performed in 11 PVA models and evaluated. The drop rate was 19%. We succeeded in partial and total recanalization in 51.0% of the procedures (53/104) within 30 minutes. This new clot-retrieving wire could be useful for mechanical clot extraction in stroke.

Does the Merci Retriever Work?

Section Editors: Geoffrey A. Donnan MD, FRACP Stephen M. Davis MD, FRACP Technically, it works. And remarkably so. The Merci Retriever is a mechanical embolectomy device designed to reopen occluded vessels by extracting occlusive thrombi from the cerebral vasculature. In the Mechanical Embolus Removal in Cerebral Ischemia (MERCI) trial (parts I and II combined), among 151 patients enrolled in the intention-to-treat group; partial or complete recanalization by use of the device alone was achieved in 46%.1 This rate substantially exceeded that in the prespecified comparator group—patients enrolled in the control arm of the Prolyse in Acute Cerebral Thromboembolism (PROACT-II) trial (18%). The associated probability value of <0.0001 indicates a less than 1 in 10 000 chance that this result occurred by chance. The Merci Retriever indeed works. And it works well where we most need it to work: on proximal occlusions for which there was previously no good therapy. Proximal carotid terminus and M1 middle cerebral artery thrombi respond poorly to IV or intra-arterial fibrinolytic therapy, likely attributable in large part to the sheer volume of the clot burden requiring enzymatic digestion. The average volume of carotid terminus thrombi (0.4 ml) is more than an order of magnitude larger than that of M2 middle cerebral artery division thrombi …

Is mechanical embolectomy a safe and efficacious treatment strategy in patients with acute ischemic stroke?

Is mechanical embolectomy a safe and efficacious treatment strategy in patients with acute ischemic stroke?

Safety and Efficacy of Mechanical Embolectomy in Acute Ischemic Stroke: Results of the MERCI Trial

Safety and Efficacy of Mechanical Embolectomy in Acute Ischemic Stroke: Results of the MERCI Trial

Analysis of Thrombi Retrieved from Cerebral Arteries of Patients with Acute Ischemic Stroke.

To obtain insights into the pathogenesis of ischemic stroke, we analyzed thromboemboli and other occlusive material retrieved acutely from the cerebral arteries of patients. The experimental design was an observational study in 25 consecutive patients with acute ischemic stroke treated by endovascular mechanical thromboembolectomy. Patients with acute occlusion of a proximal cerebral artery, a disabling neurologic deficit, and either initiation of therapy within 8 hours of onset or initiation of therapy beyond 8 hours if imaging demonstrated substantial residual penumbral tissue at risk were treated at a tertiary Comprehensive Stroke Center (the UCLA Stroke Center). Thrombus was removed by an endovascular mechanical embolectomy device (Merci® Retriever System, Concentric Medical, Mountain View, CA) after placement by angiographic catheter into the occluded intracranial carotid artery, middle cerebral artery or vertebral-basilar artery under fluoroscopic guidance. Our results show that the large majority (20 of 25) of extracted thrombi have similar histologic architecture, a complex of layered, sometimes serpentine, lengths of fibrin:platelet deposits interspersed with linear streaks of nucleated cells. This histology was prevalent with both cardioembolic and atherosclerotic etiologies, indicating the same pathogenetic influences of blood flow and shear in thrombus formation. This histologic pattern among thrombi was present in both the internal carotid artery (ICA) and the middle cerebral artery (MCA). Clots composed uniformly of erythrocytes were uncommon (3 of 25) and were observed only with incomplete extractions, suggesting that sampling was of the proximal thrombus tail where post-occlusion thrombosis had occurred under conditions of stagnant flow. Calcifications or cholesterol were not present. Thrombus size, not histology, predicted the site of arterial occlusion, with no thrombus larger than 3 mm width causing stroke limited to the MCA and no thrombus larger than 5 mm width removed from the ICA. Fungus-containing thrombus was extracted from one patient who had mycotic valvular disease, and an unusual complication occurred in another case, namely, scraping of a small atheroma and attached intima from the MCA, albeit without clinical consequence. We conclude that thromboemboli that cause acute ischemic stroke are of similar, complex structure, regardless of macroscopic dimensions, and are similarly influenced by blood flow, whether the primary etiology is cardioembolic or atherosclerotic. Embolus size is the critical aspect that determines its ultimate destination, those of more than 5 mm width appearing to bypass the cerebral vessels entirely. The mixed fibrin:platelet pattern present in the preponderance of thromboemboli provides foundation for the success of both antiplatelet and anticoagulant treatment strategies in stroke prevention.

Acute vertebrobasilar occlusion: current treatment strategies

Acute vertebrobasilar occlusion (VBO) remains a disease with a high mortality. Local intraarterial fibrinolysis (LIF) can reduce the mortality rate from about 90 to 60%. The combined therapy of i.v. Abciximab and i.a. rt-PA with additional PTA/stenting may improve neurological outcome and significantly reduce mortality, despite an increase of overall bleeding complications. Additional PTA/stenting is an important treatment factor in cases of atherothrombotic occlusion. In embolic occlusions, mechanical catheter devices, such as basket or snare devices or rheolytic systems, are promising therapies for the near future. This article describes diagnostic criteria and treatment factors in acute VBO. Different treatment strategies, such as i.v. and i.a. fibrinolysis, adjunctive application of GP IIb/IIIa inhibitors, PTA/stenting and mechanical embolectomy are addressed in detail.

Multimodal Therapy for the Treatment of Severe Ischemic Stroke Combining GPIIb/IIIa Antagonists and Angioplasty After Failure of Thrombolysis

Intraarterial and intravenous thrombolysis are often ineffective for the treatment of acute ischemic stroke and are associated with a significant risk of intracranial hemorrhage (ICH). Multimodal rescue therapy combining mechanical disruption and platelet GPIIb/IIIa receptor antagonists may improve recanalization. Patients who did not recanalize with thrombolysis were treated with GPIIb/IIIa antagonists, angioplasty, or an embolectomy device. Treatment was individualized based on vascular anatomy, stroke mechanism, patient status, and symptom duration. Twelve patients were treated within 3.8+/-2.2 hours. The mean National Institutes of Health Stroke Scale (NIHSS) score was 19.4+/-4.1. Six patients had carotid terminus occlusion, whereas 5 had middle cerebral artery and 1 had basilar artery occlusion. The average doses of intraarterial tPA and reteplase were 17.1+/-8.6 mg and 2+/-0.6 units, respectively. All patients received either an intravenous or intraarterial abciximab bolus (mean 11.8+/-5.8 mg) and heparin (mean 3278+/-1716U). Eleven were treated with angioplasty and 4 had mechanical embolectomy or stenting. Complete (8) or partial (3) recanalization was achieved in 11 cases. There was only one (8.3%) symptomatic hemorrhage. Patients had a favorable outcome at discharge (mean NIHSS 8.9+/-8.7) and 6 (50%) had an NIHSS < or =4 at discharge. Multimodal rescue therapy was effective at recanalizing occluded cerebral vessels that failed thrombolysis without an excess risk of ICH.

Mechanical Embolus Removal. A New Day Dawning

Mechanical Embolus Removal. A New Day Dawning

Safety and Efficacy of Mechanical Embolectomy in Acute Ischemic Stroke

The only Food and Drug Administration (FDA)-approved treatment for acute ischemic stroke is tissue plasminogen activator (tPA) given intravenously within 3 hours of symptom onset. An alternative strategy for opening intracranial vessels during stroke is mechanical embolectomy, especially for patients ineligible for intravenous tPA. We investigated the safety and efficacy of a novel embolectomy device (Merci Retriever) to open occluded intracranial large vessels within 8 hours of the onset of stroke symptoms in a prospective, nonrandomized, multicenter trial. All patients were ineligible for intravenous tPA. Primary outcomes were recanalization and safety, and secondary outcomes were neurological outcome at 90 days in recanalized versus nonrecanalized patients. Recanalization was achieved in 46% (69/151) of patients on intention to treat analysis, and in 48% (68/141) of patients in whom the device was deployed. This rate is significantly higher than that expected using an historical control of 18% (P<0.0001). Clinically significant procedural complications occurred in 10 of 141 (7.1%) patients. Symptomatic intracranial hemorrhages was observed in 11 of 141 (7.8%) patients. Good neurological outcomes (modified Rankin score < or =2) were more frequent at 90 days in patients with successful recanalization compared with patients with unsuccessful recanalization (46% versus 10%; relative risk [RR], 4.4; 95% CI, 2.1 to 9.3; P<0.0001), and mortality was less (32% versus 54%; RR, 0.59; 95% CI, 0.39 to 0.89; P=0.01). A novel endovascular embolectomy device can significantly restore vascular patency during acute ischemic stroke within 8 hours of stroke symptom onset and provides an alternative intervention for patients who are otherwise ineligible for thrombolytics.