Endovascular approaches to acute stroke, part 2: a comprehensive review of studies and trials

Fabrication of Shape Memory Polymer Endovascular Thrombectomy Device for Treating Ischemic Stroke

Stroke is the second result for death and ischemic stroke constitutes most of all stroke cases. Ischemic stroke takes place when blood clot or embolus blocks cerebral vessel and interrupts blood flow, which often leads to brain damage, permanent disability, or death. There is a 4.5-h (golden hour) treatment window to restore blood flow prior to permanent neurological impairment results. Current stroke treatments consist mechanical system or thrombolytic drug therapy to disrupt or dissolve thrombus. Promising method for stroke treatment is mechanical retrieving of thrombi employing device deployed endovascularly. Advent of smart materials has led to research fabrication of several minimally invasive endovascular devices that take advantage of new materials capabilities. One of these capabilities is shape memory, is capability of material to store temporary form, then activate to primary shape as subjected to stimuli. Shape memory polymers (SMPs) are employed as good materials for thrombectomy device fabrication. Therefore, current review presents thrombectomy device development and fabrication with SMPs. Design, performance, limitations, and in vitro or in vivo clinical results of SMP-based thrombectomy devices are identified. Review also sheds light on SMP's future outlook and recommendations for thrombectomy device application, opening a new era for advanced materials in materials science.

Controversies in Imaging of Patients with Acute Ischemic Stroke: AJR Expert Panel Narrative Review

The development of reperfusion therapies has profoundly impacted stroke care, initially with the advent of IV thrombolytic (IVT) treatment and, more recently, with the development and refinement of endovascular treatment (EVT). Progress in neuroimaging has supported the paradigm shift of stroke care, and advanced neuroimaging now has a fundamental role in triaging patients for both IVT and EVT. As the standard of care for acute ischemic stroke (AIS) evolves, controversies remain in certain clinical scenarios. This article explores the use of multimodality imaging for treatment selection of AIS in the context of recent guidelines, highlighting controversial topics and providing guidance for clinical practice. Results of major randomized trials supporting EVT are reviewed. Advantages and disadvantages of CT, CTA, MRI, and MRA in stroke diagnosis are summarized, with attention to level 1 evidence supporting the role of vascular imaging and perfusion imaging. Patient selection is compared between approaches based on time thresholds and physiologic approaches based on infarct core measurement using imaging. Moreover, various imaging approaches to core measurement are described. As ongoing studies push treatment boundaries, advanced imaging is expected to help identify a widening range of patients who may benefit from therapy.

Endovascular management for tandem occlusions of anterior cerebral circulation

Objectives:

To compare the endovascular approaches and techniques used to treat tandem occlusions of anterior cerebral circulation.

Methods:

A literature review was carried out using PubMed to review the studies that described endovascular therapies for patients with tandem cerebral occlusions.

Results:

A total of 106 patients (median age: 64 years; range: 18-90 years) were identified. The median National Institutes of Health Stroke scale score at the time of admission for 104 patients was 16.5 (standard deviation [SD] ±5.7). The mean times and ranges from symptom onset to recanalization were 396.85 minutes (range: 120-1,574 minutes) and from groin puncture to recanalization were 80.3 minutes (range: 14-180 minutes). The mean outcome modified Rankin scale (mRS) score was 2.31 (SD ±2.2), and 61.3% of patients had an outcome mRS score ≤2. Moreover, 80% of patients with a groin puncture-to-recanalization time of ≤60 minutes had a mRS score ≤2 compared to 51.5% of patients with longer times (p=0.02). Despite that only 11.3% of patients underwent a retrograde approach, 81.8% of them had an outcome mRS score ≤2 compared to 60.8% of patients with an anterograde approach (p=0.023).

Conclusion:

A groin puncture-to-recanalization time of <60 minutes and a retrograde approach were shown to be favorable prognostic factors in terms of mRS score. The use of intravenous tissue plasminogen activator was associated with higher Thrombolysis In Cerebral Infarction scores, but not superior prognosis based on mRS.

Mechanical behavior of rf-treated thrombus in mechanical thrombectomy

Intra-arterial mechanical thrombectomy (IAMT) treatments for ischemic stroke have higher recanalization rate, longer treatment time window and lower risk of symptomatic intracerebral hemorrhage (sICH). However, distal embolization may occur because of loose fragments produced during maceration and engagement. The naturally coagulated thrombus is fragile and has poor binding with thrombectomy device. Improvement of thrombus-device binding can reduce fragments breaking loose during wire pull and enhance protein crosslinking in the thrombus that can increase fragmentation resistance. The effects of in-situ applied radio frequency (rf) treatment on thrombus-wire binding and interfacial fracture have been examined in this study using wire pull tests that are mechanically analogous to the embolus retrieval method in thrombectomy. Wire inserted into a thrombus was pull tested after rf-treatment. Pull test results showed that rf-treatment improves binding and reduces thrombus slippage from over 90% to less than 10%. Fracture pull test results also showed that fracture energy density of thrombus-device interface increased 40X after rf-treatment. The dramatic increase in resistance against fracture suggests that the use of in-situ rf-treatment is a promising treatment addition to reduce distal embolization and improve clinical outcomes in mechanical thrombectomy.

[Technical standards for the interventional treatment of acute ischemic stroke]

Acute ischemic stroke is the leading cause of acquired disability and its treatment is still a major challenge. For more than a decade, various mechanical devices have been developed for the recanalization of proximal artery occlusions in acute ischemic stroke but most of them have been approved for clinical use, only on the basis of uncontrolled case series. Intravenous thrombolysis with recombinant tissue-specific plasminogen activator administered (iv rtPA) within 4.5 h of symptom onset is so far the only approved medicinal treatment in the acute phase of cerebral infarction. With the introduction of stent retrievers, mechanical thrombectomy has demonstrated substantial rates of partial or complete arterial recanalization and improved outcomes compared with iv rtPA and best medical treatment alone in multiple randomized clinical trials in select patients with acute ischemic stroke and proximal artery occlusions. This review discusses the evolution of endovascular stroke therapy followed by a discussion of the current technical standards of mechanical thrombectomy that have to be considered during endovascular stroke therapy and the updated treatment recommendations of the ESO Karolinska stroke update.

A numerical framework to investigate hemodynamics during endovascular mechanical recanalization in acute stroke

Ischemic stroke, caused by embolism of cerebral vessels, inflicts high morbidity and mortality. Endovascular aspiration of the blood clot is an interventional technique for the recanalization of the occluded arteries. However, the hemodynamics in the Circle of Willis (CoW) are not completely understood, which results in medical misjudgment and complications during surgeries. In this study we establish a multiscale description of cerebral hemodynamics during aspiration thrombectomy. First, the CoW is modeled as a 1D pipe network on the basis of computed tomography angiography (CTA) scans. Afterwards, a vascular occlusion is placed in the middle cerebral artery and the relevant section of the CoW is transferred to a 3D computational fluid dynamic (CFD) domain. A suction catheter in different positions is included in the CFD simulations. The boundary conditions of the 3D domain are taken from the 1D domain to ensure system coupling. A Eulerian-Eulerian multiphase simulation describes the process of thrombus aspiration. The physiological blood flow in the 1D and 3D domains is validated with literature data. Further on, it is proved that domain reduction and pressure coupling at the boundaries are an appropriate method to reduce computational costs. Future work will apply the developed framework to various clinical questions.

Considerations about Occlusion of the Intracranial Distal Internal Carotid Artery

Occlusion of the intracranial distal internal carotid artery (ICA) is one of the most critical conditions among the cases of acute stroke in the anterior circulation. The introduction of selective endovascular treatment first using thrombolytic agents replaced later by the mechanical thrombectomy using various devices has improved the prognosis in a certain number of these patients. Among the factors influencing the prognosis of these patients, one is the collateral circulation which in these cases is mainly characterized by leptomeningeal anastomoses. The collateral can, however, be impaired, by distal embolization and by anomalies of the Circle of Willis: the aim of this study is to describe these aspects.

Functional outcomes and recanalization rates of stent retrievers in acute ischaemic stroke: A systematic review and meta-analysis

BACKGROUND AND PURPOSE

Intra-arterial therapy for acute ischaemic stroke has evolved rapidly in the last few years. Stent retrievers have now replaced 'first-generation' devices, which have been the principle devices tested in stroke trials.Our aims were to determine the rates of successful recanalization and functional independence in acute stroke patients treated with stent retrievers. We also sought to assess the safety outcomes of stent retrievers by assessing the rates of mortality and intra-cranial haemorrhage.

MATERIALS AND METHODS

We conducted a systematic review and meta-analysis of studies which utilized stent retrievers as sole treatment or as part of a multi-modal approach in acute ischaemic stroke.

RESULTS

We identified 20 eligible studies: 17 on Solitaire (ev3/Covidien, Irvine, California, USA) (n = 762) and three on Trevo (Stryker, Kalamazoo, Michigan, USA) (n = 210). The mean age of participants was 66.8 (range 62.1-73.0) years and the M:F ratio was 1.1:1. The average stroke severity score (National Institutes of Health Stroke Scale (NIHSS)) at presentation was 17.2. The weighted mean symptom onset to arterial puncture and procedural duration were 265.4 minutes and 54.8 minutes, respectively.Successful recanalization was achieved in 84.5% of patients with a weighted mean of 2.0 stent retriever passes. Independent functional outcome was achieved in 51.2% and the mortality rate was 16.8%.

CONCLUSION

Stent retrievers have the potential to achieve a high rate of recanalization and functional independence whilst being relatively safe. They should be assessed in well-designed randomized controlled trials to determine their efficacy and assess whether they compare favourably with 'standard treatment' in stroke.

Advances in stroke therapy

Stroke is a leading cause of death, long-term disability, and socioeconomic costs, highlighting the urgent need for more effective treatments. Intravenous administration of tissue plasminogen activator (t-PA) is the only FDA-approved therapy to re-establish cerebral blood flow. However, because of increased risk of hemorrhage beyond 3 h post stroke, few stroke patients (1-2%) benefit from t-PA; t-PA, which has neurotoxic effects, can also aggravate the extent of reperfusion injury by increasing blood-brain barrier permeability. An alternative strategy is needed to extend the window of intervention, minimize damage from reperfusion injury, and promote brain repair leading to neurological recovery. Reactive oxygen species (ROS), generated soon after ischemia and during reperfusion and thereafter, are considered the main mediators of ischemic injury. Antioxidant enzymes such as catalase, superoxide dismutase, etc. can neutralize ROS-mediated injury but their effective delivery to the brain remains a challenge. In this article, we review various therapeutic approaches including surgical interventions, and discuss the potential of nanoparticle-mediated delivery of antioxidants for stroke therapy.

Recurrent Cardioembolic Stroke Treated Successfully with Repeated Mechanical Thrombectomy within the Acute Index Stroke Period

Background

The safety of repeated mechanical thrombectomy within the acute stroke period has not yet been clearly demonstrated. We describe herein a patient who was successfully treated with repeated mechanical thrombectomy within the acute index stroke period.

Case Report

A 50-year-old woman with atrial fibrillation presented with left-sided weakness caused by occlusion of the right middle cerebral artery (MCA). Emergent mechanical thrombectomy with the Solitaire device achieved complete recanalization. The left MCA occlusion redeveloped at 6 days after the first treatment, at which time her international normalized ratio (INR) was 2.3. Endovascular thrombectomy was reattempted rapidly and complete recanalization was achieved again. Her neurologic symptoms resolved after the thrombectomy.

Conclusions

This case demonstrates that repeated mechanical thrombectomy can be safely and successfully performed even in a patient with a high INR and a recurrent stroke during the acute period after the index stroke.

The Dotter method revisited: early experience with a novel method of rapid internal carotid artery revascularization in the setting of acute ischemic stroke

BACKGROUND

Tandem occlusive disease in the setting of acute ischemic stroke involving cervical and cerebral arteries has been associated with poor neurological outcome and poses significant challenges to neurointerventionists. Previously described endovascular methods typically involve carotid revascularization with stent placement prior to or following intracranial thrombectomy. Stent-based approaches, however, require the use of antiplatelet therapy which may increase the risk of hemorrhagic transformation. We describe a novel modified Dotter technique which may be used for carotid revascularization in lieu of stenting. This technique can eliminate the need for antiplatelet therapy, reduce procedure times, and possibly reduce hemorrhagic conversion rates.

METHODS

Seven patients presenting between April 2013 and January 2014 were treated with this technique. All patients had carotid stenosis of 65-100% and tandem middle cerebral artery occlusions. National Institutes of Health (NIH) Stroke Scale scores as well as clinical and procedural times were recorded. Pre- and post-Dotter stenosis was measured using the NASCET criteria. Follow-up imaging and clinical data were reviewed.

RESULTS

The mean age was 64 years and mean initial NIH Stroke Scale score was 11.7. Mean groin to recanalization time was 26 min. Thrombolysis In Cerebral Infarction grade 2b-3 was achieved in all patients. The mean stenosis was 88% preoperatively and 61% postoperatively. There were no intracranial hemorrhages. The modified Rankin Scale score was 0 in six patients (86%) and 6 in one patient (14%).

CONCLUSIONS

The Dotter stroke technique is a feasible and safe alternative to carotid stenting in the setting of acute ischemic stroke and may reduce the risk of hemorrhagic conversion. No re-occlusion occurred during follow-up in patients with post-Dotter stenosis ≤65%.

Cerebral arterial calcification is an imaging prognostic marker for revascularization treatment of acute middle cerebral arterial occlusion

BACKGROUND AND PURPOSE

To study the significance of intracranial artery calcification as a prognostic marker for acute ischemic stroke patients undergoing revascularization treatment after middle cerebral artery (MCA) trunk occlusion.

METHODS

Patients with acute MCA trunk occlusion, who underwent intravenous and/or intra-arterial revascularization treatment, were enrolled. Intracranial artery calcification scores were calculated by counting calcified intracranial arteries among major seven arteries on computed tomographic angiography. Patients were divided into high (HCB; score ≥3) or low calcification burden (LCB; score <3) groups. Demographic, imaging, and outcome data were compared, and whether HCB is a prognostic factor was evaluated. Grave prognosis was defined as modified Rankin Scale 5-6 for this study.

RESULTS

Of 80 enrolled patients, the HCB group comprised 15 patients, who were older, and more commonly had diabetes than patients in the LCB group. Initial National Institutes of Health Stroke Scale (NIHSS) scores did not differ (HCB 13.3±2.7 vs. LCB 14.6±3.8) between groups. The final good reperfusion after revascularization treatment (thrombolysis in cerebral infarction score 2b-3, HCB 66.7% vs. LCB 69.2%) was similarly achieved in both groups. However, the HCB group had significantly higher NIHSS scores at discharge (16.0±12.3 vs. 7.9±8.3), and more frequent grave outcome at 3 months (57.1% vs. 22.0%) than the LCB group. HCB was proven as an independent predictor for grave outcome at 3 months when several confounding factors were adjusted (odds ratio 4.135, 95% confidence interval, 1.045-16.359, P=0.043).

CONCLUSIONS

Intracranial HCB was associated with grave prognosis in patients who have undergone revascularization for acute MCA trunk occlusion.

Predictors of poor outcome despite recanalization: a multiple regression analysis of the NASA registry

BACKGROUND

Mechanical thrombectomy with stent-retrievers results in higher recanalization rates compared with previous devices. Despite successful recanalization rates (Thrombolysis in Cerebral Infarction (TICI) score ≥2b) of 70-83%, good outcomes by 90-day modified Rankin Scale (mRS) score ≤2 are achieved in only 40-55% of patients. We evaluated predictors of poor outcomes (mRS >2) despite successful recanalization (TICI ≥2b) in the North American Solitaire Stent Retriever Acute Stroke (NASA) registry.

METHODS

Logistic regression was used to evaluate baseline characteristics and recanalization outcomes for association with 90-day mRS score of 0-2 (good outcome) vs 3-6 (poor outcome). Univariate tests were carried out for all factors. A multivariable model was developed based on backwards selection from the factors with at least marginal significance (p≤0.10) on univariate analysis with the retention criterion set at p≤0.05. The model was refit to minimize the number of cases excluded because of missing covariate values; the c-statistic was a measure of predictive power.

RESULTS

Of 354 patients, 256 (72.3%) were recanalized successfully. Based on 234 recanalized patients evaluated for 90-day mRS score, 116 (49.6%) had poor outcomes. Univariate analysis identified an increased risk of poor outcome for age ≥80 years, occlusion site of internal carotid artery (ICA)/basilar artery, National Institute of Health Stroke Scale (NIHSS) score ≥18, history of diabetes mellitus, TICI 2b, use of rescue therapy, not using a balloon-guided catheter or intravenous tissue plasminogen activator (IV t-PA), and >30 min to recanalization (p≤0.05). In multivariable analysis, age ≥80 years, occlusion site ICA/basilar, initial NIHSS score ≥18, diabetes, absence of IV t-PA, ≥3 passes, and use of rescue therapy were significant independent predictors of poor 90-day outcome in a model with good predictive power (c-index=0.80).

CONCLUSIONS

Age, occlusion site, high NIHSS, diabetes, no IV t-PA, ≥3 passes, and use of rescue therapy are associated with poor 90-day outcome despite successful recanalization.

MR CLEAN, a multicenter randomized clinical trial of endovascular treatment for acute ischemic stroke in the Netherlands: study protocol for a randomized controlled trial

BACKGROUND

Endovascular or intra-arterial treatment (IAT) increases the likelihood of recanalization in patients with acute ischemic stroke caused by a proximal intracranial arterial occlusion. However, a beneficial effect of IAT on functional recovery in patients with acute ischemic stroke remains unproven. The aim of this study is to assess the effect of IAT on functional outcome in patients with acute ischemic stroke. Additionally, we aim to assess the safety of IAT, and the effect on recanalization of different mechanical treatment modalities.

METHODS/DESIGN

A multicenter randomized clinical trial with blinded outcome assessment. The active comparison is IAT versus no IAT. IAT may consist of intra-arterial thrombolysis with alteplase or urokinase, mechanical treatment or both. Mechanical treatment refers to retraction, aspiration, sonolysis, or use of a retrievable stent (stent-retriever). Patients with a relevant intracranial proximal arterial occlusion of the anterior circulation, who can be treated within 6 hours after stroke onset, are eligible. Treatment effect will be estimated with ordinal logistic regression (shift analysis); 500 patients will be included in the trial for a power of 80% to detect a shift leading to a decrease in dependency in 10% of treated patients. The primary outcome is the score on the modified Rankin scale at 90 days. Secondary outcomes are the National Institutes of Health stroke scale score at 24 hours, vessel patency at 24 hours, infarct size on day 5, and the occurrence of major bleeding during the first 5 days.

DISCUSSION

If IAT leads to a 10% absolute reduction in poor outcome after stroke, careful implementation of the intervention could save approximately 1% of all new stroke cases from death or disability annually.

TRIAL REGISTRATION

NTR1804 (7 May 2009)/ISRCTN10888758 (24 July 2012).

Endovascular stroke therapy

BACKGROUND

Following the development of intravenous thrombolysis as a successful treatment for ischaemic stroke, advances in neurointerventional radiology have facilitated endovascular approaches to treatment. This article reviews the available endovascular therapeutic options and their evidence-base.

SUMMARY

Initial studies demonstrated that endovascular treatment of ischaemic stroke with intra-arterial thrombolysis and/or the use of clot-retrieval, thrombus aspiration and stent-retriever devices produced early recanalisation and reperfusion and improved neurological outcome. More recent randomised trials, however, have failed to show translation of recanalisation into successful clinical outcome with 'time to treatment' proving crucial. In this rapidly evolving field, combined therapy incorporating intravenous and intra-arterial thrombolysis in combination with endovascular clot-retrieval has been developed and further studies are expected to yield better evidence to guide the optimal treatment of acute cerebral ischaemia.

Early Postmarket Experience After US Food and Drug Administration Approval With the Trevo Device for Thrombectomy for Acute Ischemic Stroke

BACKGROUND:

TREVO 2 showed the Trevo stent retriever to be more successful for revascularization than Merci for acute stroke intervention in patients treated within 8 hours of symptom onset. These results led to US Food and Drug Administration approval of Trevo.

OBJECTIVE:

To report the first postmarket experience with Trevo since US Food and Drug Administration approval at a single high-volume comprehensive stroke center in the United States.

METHODS:

A retrospective analysis of prospectively collected data was conducted in patients who underwent intervention for ischemic stroke with the Trevo device. Trevo was used alone or in conjunction with other intra-arterial devices. Two groups of patients were identified: those with symptom onset within (group 1) and those with symptom onset beyond (group 2) 8 hours. Recanalization, outcome, symptomatic intracranial hemorrhage, and in-hospital and 90-day mortality were assessed.

RESULTS:

Fifty-two patients were identified, 27 in group 1 and 25 in group 2. Thrombolysis in Cerebral Infarction grade 2 to 3 revascularization was achieved in 93% of group 1 and 84% of group 2 patients. In-hospital mortality and symptomatic intracranial hemorrhage rates were 3.8% and 12% for groups 1 and 2, respectively. Ninety-day mortality was 15% and 24% for groups 1 and 2, respectively. In groups 1 and 2, 48% and 42% of patients, respectively, had good outcomes (modified Rankin Scale score, 0–2), and 50% in both groups of patients achieved Thrombolysis in Cerebral Infarction grade 3 revascularization. Group 2 had longer revascularization times and required adjuvant devices more frequently.

CONCLUSION:

Our postmarket experience shows that in highly selected patients Trevo is safe and effective, even beyond 8 hours, despite longer procedure times and the need for adjuvant devices.

Outcomes in severe middle cerebral artery ischemic stroke

BACKGROUND

Severe middle cerebral artery stroke (MCA) is associated with a high rate of morbidity and mortality. We assessed the hypothesis that patient-specific variables may be associated with outcomes. We also sought to describe under-recognized patient-centered outcomes.

METHODS

A consecutive, multi-institution, retrospective cohort of adult patients (≤70 years) was established from 2009 to 2011. We included patients with NIHSS score ≥15 and infarct volume ≥60 mL measured within 48 h of symptom onset. Malignant edema was defined as the development of midline brain shift of ≥5 mm in the first 5 days. Exclusion criterion was enrollment in any experimental trial. A univariate and multivariate logistic regression analysis was performed to model and predict the factors related to outcomes.

RESULTS

46 patients (29 female, 17 male; mean age 57.3 ± 1.5 years) met study criteria. The mortality rate was 28% (n = 13). In a multivariate analysis, only concurrent anterior cerebral artery (ACA) involvement was associated with mortality (OR 9.78, 95% CI 1.15, 82.8, p = 0.04). In the malignant edema subgroup (n = 23, 58%), 4 died (17%), 7 underwent decompressive craniectomy (30%), 7 underwent tracheostomy (30%), and 15 underwent gastrostomy (65%).

CONCLUSIONS

Adverse outcomes after severe stroke are common. Concurrent ACA involvement predicts mortality in severe MCA stroke. It is useful to understand the incidence of life-sustaining procedures, such as tracheostomy and gastrostomy, as well as factors that contribute to their necessity.

Endovascular treatment of acute ischemic stroke

Early recanalization of the occluded artery leads to better clinical outcomes in patients with acute ischemic stroke (AIS) through protection of the time-sensitive penumbra. Intravenous administration of pharmacologic thrombolytic agents has been a standard treatment for AIS. To get better rates of recanalization, enhance the time window, and diminish the possibility of intracranial hemorrhage, endovascular thrombectomy was launched, with first authorization of the Merci clot retriever, a corkscrew-like apparatus, followed by approval of the Penumbra thromboaspiration system. Both devices lead to a high rate of recanalization. On the other hand, time to recanalization was on an average of 45 minutes, with most of the patients attaining only partial recanalization. More lately, retrievable stents have shown promise in decreasing the time to recanalization, and attaining a superior rate of complete clot resolution. The retrievable stent can be released within the clot to engage it within the struts of the stent, and afterwards it is taken back by pulling it under flow arrest. Neurointerventional techniques have a persistently ever-increasing and stimulating role in the management of AIS, as indicated by the advent of several important techniques. Stent retrievers have the capability to be ascertained as the most important approach to endovascular stroke treatment.

Outcome prediction in acute stroke patients considered for endovascular treatment: a novel tool

Functional outcome following emergent intra-arterial thrombectomy is variable and likely reflects the heterogeneous characteristics of acute stroke patients. The aims of our study were (1) to study which pre-treatment variables correlate with functional outcome and (2) to devise a tool which would reliably predict outcome. Prospective data of patients treated with intra-arterial mechanical thrombectomy in our institution between 2010 and 2012 were collected. A preliminary univariate analysis of baseline variables was performed and data outliers were identified by constructing scatter and box plots. Systematic bivariate analysis was then carried out using a linear regression model and the individual contributing weights of the variables to outcome calculated. The B and constant values from the regression were used to construct a predictive formula. Fifty-seven patients, 35 males (61.4%) and 22 females (38.6%) with a mean age of 62.3 years (range 26-87) were included in the cohort. Statistical correlations of baseline variables and functional outcome showed that age, National Institutes of Health Stroke Scale at presentation and CT leptomeningeal collaterals were strongly correlated (p<0.01), and were later included in the linear regression model. A tool was devised from the regression formula combining weighted inputs of the three variables. Regression statistics and residual analysis were then performed to assess the accuracy and reliability of the proposed tool. The proposed tool is easy to use and reliably predicts functional outcome prior to endovascular therapy. It may help clinical decision-making in the acute setting and offers 'tailor-made' outcome expectations.

Endovascular treatment of tandem vascular occlusions in acute ischemic stroke

BACKGROUND AND PURPOSE

Tandem vascular occlusions are an important cause of acute ischemic stroke (AIS) and present unique treatment challenges. We report our experience of managing a subset of AIS patients with extracranial vascular stenting/angioplasty and intracranial revascularization.

METHODS

Consecutive patients who presented at three centers with AIS from tandem vascular occlusions confirmed by brain and neck CT imaging were included in the study. We retrospectively analyzed the patient demographics, National Institute of Health Stroke Scale (NIHSS) score and modified Rankin Scale (mRS) score at the time of admission, treatment strategy, angiographic results using the Thrombolysis In Cerebral Infarction (TICI) score, and clinical and imaging follow-up.

RESULTS

Twenty-eight patients were included. The mean NIHSS score at admission was 18. Extracranial carotid occlusions with a concomitant middle cerebral artery occlusion were seen in 89.3% of patients (n=25) and vertebral artery combined with basilar artery lesions in 10.7% (n=3). An antegrade approach (ie, treatment of the extracranial lesion first) was used in 24 patients (85.7%). Proximal occlusion recanalization was achieved usually with a stent (n=27; 96.4%). Pursuant to intracranial revascularization techniques, ≥ TICI 2A recanalization was seen in 96.4% of patients. An mRS score of ≤ 2 at 90 days was achieved in 56.5% of patients.

CONCLUSIONS

Our study shows preliminary data from three centers on recanalization of tandem occlusions in patients presenting with AIS. There was a preference to revascularize the proximal occlusion using a stent followed by distal recanalization with mechanical thrombectomy, intra-arterial thrombolysis or a combination of these. This approach has low periprocedural complications and can achieve an excellent angiographic and clinical outcome.

Machine learning for outcome prediction of acute ischemic stroke post intra-arterial therapy

Introduction

Stroke is a major cause of death and disability. Accurately predicting stroke outcome from a set of predictive variables may identify high-risk patients and guide treatment approaches, leading to decreased morbidity. Logistic regression models allow for the identification and validation of predictive variables. However, advanced machine learning algorithms offer an alternative, in particular, for large-scale multi-institutional data, with the advantage of easily incorporating newly available data to improve prediction performance. Our aim was to design and compare different machine learning methods, capable of predicting the outcome of endovascular intervention in acute anterior circulation ischaemic stroke.

Method

We conducted a retrospective study of a prospectively collected database of acute ischaemic stroke treated by endovascular intervention. Using SPSS®, MATLAB®, and Rapidminer®, classical statistics as well as artificial neural network and support vector algorithms were applied to design a supervised machine capable of classifying these predictors into potential good and poor outcomes. These algorithms were trained, validated and tested using randomly divided data.

Results

We included 107 consecutive acute anterior circulation ischaemic stroke patients treated by endovascular technique. Sixty-six were male and the mean age of 65.3. All the available demographic, procedural and clinical factors were included into the models. The final confusion matrix of the neural network, demonstrated an overall congruency of ∼80% between the target and output classes, with favourable receiving operative characteristics. However, after optimisation, the support vector machine had a relatively better performance, with a root mean squared error of 2.064 (SD: ±0.408).

Discussion

We showed promising accuracy of outcome prediction, using supervised machine learning algorithms, with potential for incorporation of larger multicenter datasets, likely further improving prediction. Finally, we propose that a robust machine learning system can potentially optimise the selection process for endovascular versus medical treatment in the management of acute stroke.

Neurothrombectomy in the treatment of acute ischaemic stroke

Major ischaemic stroke is a leading cause of morbidity and mortality in industrialized countries. For patients with acute stroke, fast and effective vessel recanalization is important for successful treatment. Neurothrombectomy--that is, angiographically performed mechanical thrombus removal from intracranial arteries--results in higher recanalization rates than with pharmaceutical thrombolysis alone, but the value of this treatment in terms of clinical outcome remains to be established. This article summarizes the history of intra-arterial stroke treatment, outlines the recent developments and the different techniques used, and discusses the results of current studies on neurothrombectomy. Owing to the high morphological and clinical variability of stroke, careful patient selection in future randomized controlled trials will be crucial for assessment of the true potential of neurothrombectomy.

Levosimendan limits reperfusion injury in a rat middle cerebral artery occlusion (MCAO) model

Background

Neuroprotective strategies in ischemic stroke are an important challenge in clinical and experimental research as an adjunct to reperfusion therapy that may reduce neurologic injury and improve outcome. The neuroprotective properties of levosimendan in traumatic brain injury in vitro, transient global brain ischemia and focal spinal cord ischemia suggest the potential for similar effects in transient brain ischemia.

Methods

Transient brain ischemia was induced for 60 min by intraluminal occlusion of the middle cerebral artery in 40 male Wistar rats under general anesthesia with s-ketamine and xylazine and with continuous monitoring of their blood pressure and cerebral perfusion. Five minutes before inducing reperfusion, a levosimendan bolus (24 μg kg ^-1) was administered over a 20 minute period. Infarct size, brain swelling, neurological function and the expression of inflammatory markers were quantified 24 hours after reperfusion.

Results

Although levosimendan limited the infarct size and brain swelling by 40% and 53%, respectively, no effect on neurological outcome or mortality could be demonstrated. Upregulation of tumor necrosis factor α and intercellular adhesion molecule 1 was significantly impeded. Cerebral blood flow during reperfusion was significantly reduced as a consequence of sustained autoregulation.

Conclusions

Levosimendan demonstrated significant neuroprotective properties in a rat model of transient brain ischemia by reducing reperfusion injury.

Importance of cerebral artery recanalization in patients with stroke with and without neurological improvement after intravenous thrombolysis

BACKGROUND AND PURPOSE

Recanalization status after intravenous thrombolysis (IVT) in patients with ischemic stroke is a reference point to proceed with a rescue reperfusion intervention, although early neurological improvement (NI) may preclude endovascular procedures. We aimed to evaluate the importance of restoration of blood flow at the arterial occlusion site in subgroups of patients with stroke stratified by early NI after IVT.

METHODS

The following patients were recruited from the Safe Implementation of Treatment in Stroke-International Stroke Thrombolysis Register: (1) with baseline vessel occlusion documented by computed tomographic (CT) or magnetic resonance (MR) angiography and follow-up angioimaging between 22 and 36 hours after IVT available; and (2) with dense cerebral artery sign on admission CT scan and results of follow-up CT reported. Recanalization at 24 hours was defined as absence of vessel occlusion or as resolution of dense cerebral artery sign on follow-up 22- to 36-hour imaging. NI was assessed at 2 hours and 24 hours after IVT and was defined as improvement by 20% from baseline National Institute of Health Stroke scale score. Primary outcome measure was independence, defined as modified Rankin scale score 0 to 2 after 3 months.

RESULTS

Of 28136 cases registered between December 2003 and November 2009, 5324 cases (19%) met the inclusion criteria. Patients with both NI at 2 hours post-treatment and vessel recanalization had the best chances to achieve independence at 3 months (adjusted odds ratio, 15.8; 95% confidence interval, 12.5-20.0), followed by those who had NI despite persistent occlusion (adjusted odds ratio, 4.7; 95% confidence interval, 3.6-6.1); and those without NI despite recanalization (adjusted odds ratio, 2.7; 95% confidence interval, 2.2-3.3).

CONCLUSIONS

Recanalization of an occluded artery in acute stroke is associated with favorable functional outcome both in patients with and without NI after IVT. In future evaluations of mechanical thrombectomy and other additional strategies, recanalization should be considered in patients with persisting occlusion after IVT even after significant NI.

Development of endovascular vibrating polymer actuator probe for mechanical thrombolysis: in vivo study

In this study, we propose a new method for the enhancement of intraarterial thrombolysis by use of an endovascular vibrating polymer actuator probe (VPAP), which is fabricated from an ionic polymer metal composite (IPMC) actuator. The endovascular VPAP was fabricated by combining 0.8 × 0.8 × 10 mm3 IPMC samples, 0.22 mm × 50 cm copper wires, and 40 cm of Teflon tube. The purpose of this study was to evaluate the thrombolysis efficiency of an endovascular VPAP in a dog model. Both renal arteries of the enrolled dogs (n = 5) were used in the current study. A distal portion of the renal artery in a mongrel dog was occluded by a blood clot from autologous venous whole blood. Intraarterial thrombolysis was performed by use of a VPAP without the actuation force (control group), by a VPAP-only (VPAP-only group), or with a combination of recombinant tissue plasminogen activator (rtPA) and a VPAP (VPAP + rtPA group). The thrombolysis efficiency was evaluated by the modified Thrombolysis in Myocardial Infarction (TIMI) grading system based on the consensus between two radiologists. The grading scales were compared according to each intraarterial thrombolysis method. The VPAP + rtPA and VPAP-only groups showed a significantly higher thrombolysis efficiency than did the control group (p < 0.05). The VPAP-only group also showed a significantly higher thrombolysis efficiency than did the control group (p < 0.05). The VPAP+ rtPA group showed a significantly higher thrombolysis efficiency than did the VPAP-only group (p < 0.05). The use of an endovascular VPAP was a feasible and useful method for intraarterial thrombolysis, and it enhanced the thrombolysis efficiency when combined with the thrombolytic agent rtPA.

The 2010 British Association of Stroke Physicians Survey of interventional treatments for stroke in the United Kingdom

INTRODUCTION

The UK National Stroke Strategy (Department of Health 2007) states that patients should have access to a stroke service with neurointerventional capacity. This survey was conducted by the Clinical Standards Committee of the British Association of Stroke Physicians to get a snapshot of the availability of interventional treatments for stroke in the United Kingdom.

METHODS

Questionnaires covering availability of endovascular treatments for stroke, e.g. intra-arterial thrombolysis and mechanical thrombectomy, were emailed to all British Association of Stroke Physicians members in October 2010. Where more than one response was received from the same hospital, the data were only entered once. If there was a discrepancy between different respondents for the same hospital, details were cross-checked with the respondents to ensure accuracy.

RESULTS

Responses were received from 58 hospitals in England, Scotland, Wales, and Northern Ireland. Intra-arterial thrombolysis and/or mechanical thrombectomy were available in 23 hospitals. Of these, three had not performed any procedures in 2010. Twenty centres had conducted a mean (range) of eight (2-20) procedures during the 10-month period. Thirty-five hospitals were not offering endovascular treatments. Sixteen of these were not referring patients to centres which could provide interventional treatments. Hospitals offering endovascular treatments had a mean (range) of 5.2 (2-12) stroke physicians, 2.3 (0-4) interventional neuroradiologists, and 3.6 (0-9) noninterventional neuroradiologists. Only two hospitals providing interventions had four or more interventional neuroradiologists.

CONCLUSIONS

Only a small number of hospitals in the United Kingdom provide interventional treatments for stroke. Almost 50% of hospitals not providing interventions had no processes in place for referral to providers.

Patient selection for intra-arterial cerebral revascularization in acute ischemic stroke

In acute ischemic stroke, rapid revascularization of the cerebral 'penumbra volume' is the key to better patient outcome. The largest and most proximal cerebral thrombotic artery occlusions can in most cases only be opened by intra-arterial intervention. The use of intra-arterial revascularization is rapidly expanding throughout Europe and North America, despite the risk for serious complications and the fact that the benefit of this treatment has not yet been proven in large, randomized clinical trials. Oslo University Hospital has performed approximately 60 intra-arterial procedures annually in acute ischemic stroke during the last few years. In this paper, we discuss important clinical and ethical aspects learned from our own experience. The future of intra-arterial cerebral revascularization will depend on an accurate preintervention patient selection.

Trevo versus Merci retrievers for thrombectomy revascularisation of large vessel occlusions in acute ischaemic stroke (TREVO 2): a randomised trial

BACKGROUND

Present mechanical devices are unable to achieve recanalisation in up to 20-40% of large vessel occlusion strokes. We compared efficacy and safety of the Trevo Retriever, a new stent-like device, with its US Food and Drug Administration-cleared predecessor, the Merci Retriever.

METHODS

In this open-label randomised controlled trial, we recruited patients at 26 sites in the USA and one in Spain. We included adults aged 18-85 years with angiographically confirmed large vessel occlusion strokes and US National Institutes of Health Stroke Scale (NIHSS) scores of 8-29 within 8 h of symptom onset. We randomly assigned patients (1:1) with sequentially numbered sealed envelopes to thrombectomy with Trevo or Merci devices. Randomisation was stratified by age (≤68 years vs 69-85 years) and NIHSS scores (≤18 vs 19-29) with alternating blocks of various sizes. The primary efficacy endpoint, assessed by an unmasked core laboratory, was thrombolysis in cerebral infarction (TICI) scores of 2 or greater reperfusion with the assigned device alone. The primary safety endpoint was a composite of procedure-related adverse events. Analyses were done by intention to treat. This study is registered with ClinicalTrials.gov, number NCT01270867.

FINDINGS

Between Feb 3, 2011, and Dec 1, 2011, we randomly assigned 88 patients to the Trevo Retriever group and 90 patients to Merci Retriever group. 76 (86%) patients in the Trevo group and 54 (60%) in the Merci group met the primary endpoint after the assigned device was used (odds ratio 4·22, 95% CI 1·92-9·69; p(superiority)<0·0001). Incidence of the primary safety endpoint did not differ between groups (13 [15%] patients in the Trevo group vs 21 [23%] in the Merci group; p=0·1826).

INTERPRETATION

Patients who have had large vessel occlusion strokes but are ineligible for (or refractory to) intravenous tissue plasminogen activator should be treated with the Trevo Retriever in preference to the Merci Retriever.

FUNDING

Stryker Neurovascular.

Combined full-dose IV and endovascular thrombolysis in acute ischaemic stroke

BACKGROUND

There is an increasing trend to treating proximal vessel occlusions with intravenous-inter-arterial (IV-IA) thrombolysis. The best dose of IV tissue plasminogen activator (tPA) remains undetermined. We compared the combination of full-dose IV recombinant tissue plasminogen activator (rtPA) and IA thrombolytic therapy to IA therapy.

METHODS

Between 2002 and 2009, we reviewed our computed tomographic angiography database for patients who received full-dose intravenous rtPA and endovascular therapy or endovascular therapy alone for acute ischaemic stroke treatment. Details of demographics, risk factors, endovascular procedure, and symptomatic intracranial haemorrhage were noted. Modified Rankin Scale ≤2 at three-months was used as good outcome. Recanalization was defined as Thrombolysis in Myocardial Ischaemia 2-3 flow on angiography.

RESULTS

Among 157 patients, 104 patients received IV-IA treatment and 53 patients underwent direct IA therapy. There was a higher recanalization rate with IV-IA therapy compared with IA alone (71% vs. 60%, P < 0·21) which was driven by early recanalization after IV rtPA. Mortality and independent outcome were comparable between the two groups. Symptomatic intracranial haemorrhage occurred in 8% of patients (12% in the IA group, 7% in the IV-IA group) but was more frequent as the intensity of intervention increased from device alone to thrombolytic drug alone to device plus thrombolytic drug(s). Recanalization was a strong predictor of reduced mortality risk ratio (RR) 0·48 confidence interval95 0·27-0·84) and favourable outcome (RR 2·14 confidence interval95 1·3-3·5).

CONCLUSIONS

Combined IV-IA therapy with full-dose intravenous rtPA was safe and results in good recanalization rates without excess symptomatic intracranial haemorrhage. Testing of full-dose IV tPA followed by endovascular treatment in the IMS3 trial is justified.

Neuroendovascular treatments/procedures: are they efficacious and have they improved patient outcomes poststroke?

Stroke is the second most common cause of death in women and African Americans, the fourth leading cause of death in Caucasians, and the fifth leading cause of death in men in the United States (). In addition, stroke costs the nation greater than $57 billion dollars annually through its direct and indirect costs. For example, in the year 2009 alone, the estimated expenditure on the cost of stroke for hospitalization, rehabilitation, and institutionalization was $68.9 billion. Fortunately, there are many treatment strategies available to individuals who had a stroke if they meet certain clinical and time criteria as well as being geographically located in a region where these treatments are available, such as nationally certified stroke centers. Specifically, intravenous and intra-arterial recombinant tissue plasminogen activator (rtPA) and mechanical thrombolysis are used for acute ischemic stroke, whereas treatments for acute hemorrhagic stroke resulting from subarachnoid hemorrhage secondary to ruptured cerebral aneurysm include both endovascular coiling as well as surgical clipping. However, patient outcomes from some of these treatments are controversial. First, it appears that, although revascularization post mechanical thrombectomy has high success rates, patient clinical and neurological outcomes as evidenced by low modified Rankin Scale scores are not as favorable when compared with intravenous or intra-arterial thombolysis. However, endovascular coiling for ruptured cerebral aneurysms resulting in subarachnoid hemorrhage appears to be superior to aneurysm clipping in both clinical and neurological outcomes. Future studies need to focus on making subject pools more homogeneous as well as using standardized outcome measures to facilitate external validation of their results.

The natural history of acute ischemic stroke due to intracranial large-vessel occlusion: what do we know?

Acute ischemic stroke (AIS) is an important public health issue with major impact on not only patients and families but also on the society as well. Among patients who suffer from AIS, those who have the event due to large-vessel occlusion are thought to have the worse outcome. Because most of the effort in endovascular treatment of AIS is aimed toward this type of stroke, it is important to understand its natural history. The goal of this manuscript was to briefly discuss the natural history of AIS due to large-vessel occlusion based on recent literature.

Neuroimaging in acute stroke: choosing the right patient for neurointervention

Although the non-contrast computed tomography head continues as the sole mandatory imaging technique before intravenous thrombolysis, the increased availability of advanced infarct/penumbral imaging techniques and confidence in their use have led many to adopt them into routine practice--most particularly before intra-arterial interventions. Computed tomography versus magnetic resonance-based routes to imaging the cerebral vasculature, cell death, and parenchymal perfusion have differing advantages in terms of speed, availability, exposures to contrast and radiation, sensitivity, and resolution. Continued refinement and future developments, such as the ability to quantitate perfusion, promise to lead to tailored treatment protocols that respect the individual variations in anatomy, physiology, and pathology. This should lead both to an extension of treatment to patients currently excluded by rigid time windows and the avoidance of futile therapies and their associated morbidities.

Endovascular stroke therapy: a single-center retrospective review

OBJECT

Endovascular treatment of acute ischemic stroke delivers direct therapy at the site of an occluded cerebral artery and can be employed beyond the 3-4.5-hour window limit set for intravenous recombinant tissue plasminogen activator. In this paper, the authors report their experience with various endovascular therapies in acute ischemic stroke.

METHODS

The authors conducted a retrospective review of their clinical database for acute ischemic stroke in large-vessel cerebral territories that underwent endovascular treatment between May 2005 and February 2009. Endovascular treatment was defined as pharmacological and/or mechanical intervention, angioplasty, stenting, or a combination of these methods. Admission National Institutes of Health Stroke Scale and the modified Rankin Scale scores were recorded. Thrombolysis in Myocardial Infarction (TIMI) scores of 0, 1, 2A, 2B, and 3 were used to define recanalization.

RESULTS

Forty procedures were performed in 39 patients, with 1 patient having sequential bilateral strokes. Nine patients were lost to follow-up after discharge. Strokes in the carotid artery circulation occurred in 82.5% of cases, and those in the vertebral-basilar territory occurred in 17.5%. The Merci device was used in 22 (55%) of 40 procedures, and the Penumbra device in 9 (22.5%) of 40. Angioplasty was performed in 15 (37.5%) of 40 procedures, and intraarterial recombinant tissue plasminogen activator was administered in 23 (57.5%) of 40 procedures. In 23 (57.5%) of 40 cases, multiple recanalization methods were used. The recanalization rate for all methods was 60%. The recanalization rate from TIMI Score 0/1 occlusions was 71.4% (20 of 28). An estimated modified Rankin Scale score of ≤ 2 was obtained in 11 (36.7%) of 30 cases. The overall mortality rate was 26.7% (8 of 30). Intracerebral hemorrhage at 24 hours postprocedure was noted in 17 (42.5%) of 40 cases, 3 (7.5%) of which were symptomatic.

CONCLUSIONS

The authors' institution performs endovascular stroke treatment with a safety and efficacy profile comparable to those of other major endovascular stroke therapy studies. Recanalization was associated with an improved clinical outcome. Protocols to maximize efficient triage of patients and better documentation of stroke treatments can assist in further studies.

Endovascular treatment strategies for acute ischemic stroke

The limitations of intravenous thrombolysis therapy have paved the way for the development of novel endovascular technologies for use in the setting of acute stroke. These technologies range from direct intraarterial thrombolysis to various thrombus disruption or retrieval devices to angioplasty and stenting. The tools in the armamentarium of the neuroendovascular interventionalist enable fast, effective revascularization to be offered to a wider population of patients that may otherwise have few therapeutic options available to them. In this paper, we review the current state-of-the-art in neuroendovascular intervention for acute ischemic stroke. Particular emphasis is placed on delineating the indications and outcomes for use of these various technologies.

Endovascular therapy of 623 patients with anterior circulation stroke

BACKGROUND AND PURPOSE

Endovascular therapy of acute ischemic stroke has been shown to be beneficial for selected patients. The purpose of this study is to determine predictors of outcome in a large cohort of patients treated with intra-arterial thrombolysis, mechanical revascularization techniques, or both.

METHODS

We prospectively acquired data for 623 patients with acute cerebral infarcts in the carotid artery territory who received endovascular treatment at a single center. Logistic regression analysis was performed to determine predictors of outcome.

RESULTS

Median National Institutes of Health Stroke Scale (NIHSS) at admission was 15. Partial or complete recanalization was achieved in 70.3% of patients; it was independently associated with hypercholesterolemia (P=0.02), absence of coronary artery disease (P=0.023), and more proximal occlusion site (P<0.0001). After 3 months, 80.5% of patients had survived, and 48.9% of patients reached favorable outcome (modified Rankin scale score 0-2). Good collaterals (P<0.0001), recanalization (P=0.023), hypercholesterolemia (P=0.03), lower NIHSS at admission (P=0.001), and younger age (P<0.0001) were independent predictors for survival. More peripheral occlusion site (P<0.0001), recanalization (P<0.0001), hypercholesterolemia (P=0.002), good collaterals (P=0.002), lower NIHSS (P<0.0001), younger age (P<0.0001), absence of diabetes (P=0.002), and no previous antithrombotic therapy (P=0.036) predicted favorable outcome. Time to treatment was only a predictor of outcome, when collaterals were excluded from the model. Symptomatic intracerebral hemorrhage occurred in 5.5% and was independently predicted by poor collaterals (P=0.004).

CONCLUSIONS

Several independent predictors for outcome and complications were identified. Unlike in intravenous thrombolysis trials, time to treatment was a predictor of outcome only when collaterals were excluded from the model, indicating the important role of collaterals for the time window.

Safety and feasibility of NeuroFlo use in eight- to 24-hour ischemic stroke patients

BACKGROUND

Acute treatment of ischemic stroke patients presenting more than eight-hours after symptom onset remains limited and largely unproven. Partial aortic occlusion using the NeuroFlo catheter can augment cerebral perfusion in animals. We investigated the safety and feasibility of employing this novel catheter to treat ischemic stroke patients eight-hours to 24 h following symptom onset.

METHODS

A multicenter, single-arm trial enrolled ischemic stroke patients at nine international academic medical centers. Eligibility included age 18-85 years old, National Institutes of Health stroke scale (NIHSS) score between four and 20, within eight-hours to 24 h after symptom onset, and perfusion-diffusion mismatch confirmed by magnetic resonance imaging. The primary outcome was all adverse events occurring from baseline to 30 days posttreatment. Secondary outcomes included stroke severity on neurological indices through 90 days. This study is registered with ClinicalTrials.gov, number NCT00436592.

RESULTS

A total of 26 patients were enrolled. Of these, 25 received treatment (one excluded due to aortic morphology); five (20%) died. Favorable neurological outcome at 90 days (modified Rankin score 0-2 vs. 3-6) was associated with lower baseline NIHSS (P  <  0·001) and with longer duration from symptom discovery to treatment. There were no symptomatic intracranial hemorrhages or parenchymal hematomas. Asymptomatic intracranial hemorrhage was visible on computed tomography in 32% and only on microbleed in another 20%.

CONCLUSIONS

Partial aortic occlusion using the NeuroFlo catheter, a novel collateral therapeutic strategy, appears safe and feasible in stroke patients eight-hours to 24 h after symptom onset.

The impact of thromboemboli histology on the performance of a mechanical thrombectomy device

BACKGROUND AND PURPOSE

Recently we published a novel method of thrombus preparation for use in a swine model for evaluation of thrombectomy designs. The clot (fibrin rich clot) is characterized by its similarity in histologic characteristics to the thromboemboli recovered from stroke patients. The purpose of this latest study was to evaluate if the performance of a mechanical thrombectomy device was affected by the histologic characteristics of thromboembolus. Erythrocyte rich clot, which was created using exogenous thrombin, and the novel experimental clot with abundance of fibrin/cellular component were used for comparison. The Merci clot retriever was used for the evaluation and the angiographic outcomes were analyzed.

MATERIALS AND METHODS

Two histologically different types of experimental clot, a conventionally used thrombin-induced clot (erythrocyte-rich clot) and a novel experimental clot that is similar in histologic characteristics to the thromboemboli recovered from patients with stroke (fibrin-rich clot), were prepared. Eight extracranial arteries in swine were occluded with erythrocyte-rich clot (group A), and 8 were occluded with fibrin-rich clot (group B), and MT by using the Merci clot retriever device was performed. Angiographic results in each group were evaluated.

RESULTS

A total of 48 attempts at MT were made. The average number of attempts to achieve TIMI grade II or III recanalization was 2.75 times in group A and 4.5 times in group B (P < .001), respectively. The mean time to achieve recanalization was 15.5 minutes in group A and 81.5 minutes in group B (P < .01). Every vessel in group A showed recanalization (100%), whereas only 3 of 8 samples (37.5%) achieved recanalization in group B.

CONCLUSIONS

In this model, arteries occluded by fibrin-rich clot demonstrated a significantly lower recanalization rate, lower final TIMI score, and a longer mean recanalization time than did arteries occluded by erythrocyte-rich clot. The angiographic outcome of MT by using the Merci clot retriever system was influenced by the histologic characteristics of the occluding thromboembolus.

Ischemic stroke--novel therapeutic strategies

OBJECTIVES

Treatment of acute, ischemic stroke has changed markedly during the last two decades. We review existing data for optimizing modern stroke care.

RESULTS

Implementation of stroke units, giving systematic treatment and observation to stroke patients, has lead to a significant reduction in death and dependency. Introduction of intravenous rt-PA (IVT) within 3 h for selected stroke patients and recent extension of the time window to 4.5 h improved the outcome even further. Still, one must consider that IVT has several limitations, such as a narrow time window and several contraindications, and the effect is modest, particularly in strokes with a large vessel occlusion. Recanalization of the occluded vessel is a major predictor for good outcome and should be set as a goal. Intra-arterial rt-PA (IAT) and the concept of bridging therapy (IVT prior to IAT or thrombectomy with a mechanical device) may improve recanalization rates and outcome. Randomized controlled trials (RCT) are available for IAT, but not for thrombectomy with devices, and we mostly have retrospective non-controlled data. The Merci- and Penumbra system are the most studied devices, for which recent studies report acceptable safety and efficacy.

CONCLUSIONS

Sufficiently powered RCTs to evaluate the effect of thrombectomy with mechanical devices are warranted, but as the natural course of a large vessel stroke carries a devastating prognosis, a proactive recanalization approach is justified based on today's knowledge.

Anoxic-ischemic encephalopathy and strokes causing impaired consciousness

Coma due to global or focal ischemia or hemorrhage is reviewed. Impaired consciousness due to anoxic-ischemic encephalopathy after cardiac arrest is common but prognostically problematic. Recent guidelines need to be refined for those patients who have received therapeutic hypothermia. Strokes, both ischemic and hemorrhagic, can affect the level of consciousness by damaging specific brain structures involved in alertness because of widespread cerebral injury or secondary cerebral or systemic complications.

Comparison of the Incidence of parenchymal hematoma and poor outcome in patients with carotid terminus occlusion treated with intra-arterial urokinase alone or with combined IV rtPA and intra-arterial urokinase

BACKGROUND AND PURPOSE

Patients with acute CTO generally have a poor prognosis, despite IV or IA thrombolytic treatment. The goal of this study was to analyze the results of patients with CTO who had IA urokinase treatment with or without initial IV rtPA based on a bridging protocol.

MATERIALS AND METHODS

Sixteen consecutive patients with acute ischemic stroke due to CTO who had combined IV and IA or a single IA thrombolytic treatment were enrolled. The baseline characteristics and prognosis were described. The patients who did and did not develop a PH shortly after treatment were compared.

RESULTS

The mean age was 66.4 years, and the median initial NIHSS score was 17. The median dose of IA urokinase was 320,000 U, and recanalization (TICI grade II-III) was achieved in 12 patients (75%). However, 5 patients died and 10 patients had poor prognosis with mRS 5-6 at discharge. Six patients (37.5%) with a PH had a higher NIHSS score 1 day after treatment (26.7 versus 13.6, P = .002), and they had more frequent mortality (66.7% versus 10.0%, P = .018) and worse prognosis (mRS 5-6; 100% versus 40%, P = .016) at discharge than patients without PH.

CONCLUSIONS

Patients with CTO who received IA urokinase treatment based on a bridging protocol had a poor prognosis. The development of PH might affect this outcome.