Use of the New Solitaire (TM) AB Device for Mechanical Thrombectomy when Merci Clot Retriever Has Failed to Remove the Clot. A Case Report

Stentrievers : An engineering review

The advent of endovascular therapy for acute large vessel occlusion has revolutionized stroke treatment. Timely access to endovascular therapy, and the ability to restore intracranial flow in a safe, efficient, and efficacious manner has been critical to the success of the thrombectomy procedure. The stentriever has been a mainstay of endovascular stroke therapy, and current guidelines recommend the usage of stentrievers in the treatment of large vessel occlusion stroke. Despite the success of existing stentrievers, there continues to be significant development in the field, with newer stentrievers attempting to improve on each of the three key aspects of the thrombectomy procedure. Here, we elucidate the technical requirements that a stentriever must fulfill. We then review the basic variables of stent design, including the raw material and its form, fabrication method, geometric configuration, and further additions. Lastly, a selection of stentrievers from successive generations are reviewed using these engineering parameters, and clinical data is presented. Further avenues of stentriever development and testing are also presented.

Endovascular Intervention in Acute Ischemic Stroke: History and Evolution

Stroke is a leading cause of serious long-term disability in the US. Endovascular therapy (EVT), in the form of mechanical thrombectomy, is now a standard of care for patients with acute ischemic stroke with a large vessel occlusion. This article reviews the evolution of EVT in the management of acute ischemic stroke and how it has led to the concept of tissue window over the widely publicized time window.

Factors influencing the outcome of cardiogenic cerebral embolism: a literature review

OBJECTIVE

The onset of cardiogenic cerebral embolism is sudden, dangerous, and often has high morbidity and mortality. Improving understanding of factors contributing to outcomes of cardiogenic cerebral embolism will improve prognostic and therapeutic capabilities.

METHODS

Through PubMed and Google Scholar, this paper examined and analyzed the factors implicated in the outcome of patients with cardiogenic cerebral embolism using the key terms 'cardiogenic cerebral embolism', 'atrial fibrillation', 'stroke related diseases', 'collateral circulation', 'emboli profile', 'epigenetic' up to 28 February 2021. Full texts of the retrieved articles were accessed. In general, in these literatures, National Institute Health of Stroke Scale (NIHSS) score ≥ 17, modified Rankin Scale (mRS) score ≥ 2, stroke recurrence, death caused by stroke are regarded as the criteria of poor prognosis. As long as one of these conditions occurs, it is judged as poor prognosis.

RESULTS

Factors influencing patient outcomes including patient outcome include severity of neurological impairment, types and severity of combined heart diseases, establishment of cerebral collateral circulation, treatments, components of emboli causing cardiogenic cerebral embolism, existence and control of other system complications, distribution and expression of inflammatory immune cells and molecules in the course of cardiogenic cerebral embolism, and epigenetic changes related to disease prognosis.

CONCLUSION

Regarding to prevention and treatment of cardiogenic cerebral embolism, the related factors, such as clinical setting, emboli pathological profile, and epigenetic changes should be emphasized so that outcomes and recurrence of cardiogenic cerebral embolism can be improvised.

Acute ischemic stroke endovascular therapy

Endovascular therapy (EVT) has become the standard treatment for large-vessel occlusion (LVO) acute ischemic stroke (AIS). EVT is now indicated in patients up to 24h from their last known well, provided that the patient meets specific clinical and imaging criteria. Improvements in thrombectomy devices, techniques, and operator experience have allowed successful EVT of ICA terminus, M1-MCA occlusions as well as proximal M2-MCA, basilar artery occlusions, and revascularization of tandem lesions. Mechanical thrombectomy failures still occur due to several factors, however, highlighting the need for further device and technical improvements. An ongoing debate exists regarding the need for pre-EVT thrombolytic agents, thrombectomy techniques, distal occlusions, anesthesia methods, the role of advanced neuroimaging, the treatment of patients with larger infarct core, and those presenting with milder stroke symptoms. Many of these questions are the subject of current or upcoming clinical trials. This review aims to provide an outline and discussion about the established recommendations and emerging topics regarding EVT for LVO AIS.

Solitaire Stentectomy Using a Stent-Retriever Technique in a Porcine Model

PURPOSE

Mechanical thrombectomy using the Solitaire device has become a standard treatment of ischemic stroke due to large vessel occlusions. Inadvertent detachment is a feared complication, which is associated with poor clinical outcome. The aim of this experimental study was to assess in a porcine model the feasibility and effectiveness of rescuing detached Solitaire devices using different stent retrievers.

METHODS

Solitaire FR devices (4 × 15/20 mm and 6 × 20/30 mm) were placed in the axillary artery of pigs. By means of 3 different stent retrievers (Trevo ProVue; EmboTrap II revascularization device; 3D revascularization device) a total of 24 rescue maneuvers (8 per retriever) were performed by deploying the retrievers within the deployed Solitaire devices and trapping parts of the Solitaire within the microcatheter. Rescue rates, rescue time and complications were assessed.

RESULTS

Overall stentectomy of the Solitaire devices was successful in all cases (100%). Time of rescue was comparable using the applied stent retrievers (Trevo ProVue; EmboTrap II revascularization device; 3D revascularization device). Complications, such as entrapment of the Solitaire-retriever complex at the intermediate catheter, Solitaire migration, vasospasm, perforation, or dissection were not observed.

CONCLUSION

Stentectomy of inadvertently detached Solitaire devices using different stent retrievers is a feasible and effective method. Rescue rates and times with the Trevo ProVue, EmboTrap II and 3D revascularization device were comparable.

Endovascular Stroke Therapy

Ischemic stroke is a leading cause of death and disability throughout the world and is both preventable and treatable. This review focuses on the treatment of the most severe form of ischemic stroke, namely large-vessel ischemic stroke, using endovascular techniques. Such therapies were proven effective in 2015. These therapies are among the most beneficial surgical therapies ever subjected to randomized clinical trials. Recent research has explored treating patients up to 24 h following the onset of stroke using advanced imaging techniques to select patients with brain tissue still at risk. These new findings suggest there exists a tissue clock rather than a time clock when selecting patients for therapy. Stroke systems throughout the world are now embracing endovascular stroke therapy. Improving regional stroke systems of care and expanding eligibility for patients are a major focus of current research.

Use of a complete autologous blood recovery system (the Sorin Xtra® Autotransfusion System) during mechanical thrombectomy of extensive cerebral venous sinus thrombosis

Background The endovascular therapy for cerebral venous sinus thrombosis (CVST) is currently accepted as a second-line treatment for patients who have failed or those in whom systemic anticoagulation is contraindicated or in a subgroup of patients presenting with rapid neurologic deterioration. A number of different mechanical and pharmacologic endovascular strategies have been reported, either as separate or combined approaches. These new catheters and aspiration systems have a high power and vacuum capacity, which carries a risk of anemization of the patient and hypovolemic shock, being necessitating the transfusion of the patient. Material and methods Because of the problems that donor blood transfusion can bring, we describe the use of a Sorin Xtra® Autotransfusion System (ATS). This complete autologous blood recovery system was designed for use in procedures where medium- to high-volume blood loss occurs, such as major surgeries. We have adapted it to recover all the blood aspirated during the mechanical thrombectomy procedures of the dural cerebral venous sinuses, since they are procedures that can cause a significant loss of blood. One advantage to this is the patient receives his or her own blood instead of donor blood, so there is no risk of contracting outside diseases or transfusion reactions. Conclusions This technical note describes a novel and previously unpublished technical approach to CVST that can be immediately applied to clinical practice. It also raises awareness among the interventional neuroradiologist and anesthesiologist communities about novel, potentially lifesaving endovascular treatments in patients with extensive CVST.

Unwanted detachment of the Solitaire device during mechanical thrombectomy in acute ischemic stroke

Background

The use of retrievable stents for endovascular clot retrieval has dramatically improved successful revascularization and clinical outcome in selected patients with acute stroke.

Objective

To describe the rate and clinical consequences of unwanted spontaneous detachment of these devices during mechanical thrombectomy.

Methods

We studied 262 consecutive patients treated with the retrievable stent, Solitaire, for acute ischemic stroke between November 2008 and April 2015. Clinical, procedural, and outcome variables were compared between patients with and without unexpected detachment of this device. Detachment was classified as proximal to the stent proximal marker (type A) or distal to the marker (type B). Poor functional outcome was defined as modified Rankin scale score >2 at 90 days.

Results

Unwanted detachment occurred in 6/262 (2.3%) cases, four of type A and two of type B. Stent recovery was possible in three patients, all of ‘type A’, but in none of ‘type B’. The number of prior passes was higher in patients with undesired detachment (3 (2–5) vs 2 (1–3), p=0.007). Detachment was associated with higher rate of symptomatic intracranial hemorrhage (SICH) (33.3% vs 4.3%, p=0.001), poorer outcome (100% vs 54.8%, p=0.028), and higher mortality rate at 90 days (50% vs 17%, p=0.038).

Conclusions

Unwanted detachment of a Solitaire is an uncommon complication during mechanical thrombectomy in patients with acute ischemic stroke and is associated with the clot retrieval attempts, SICH, poor outcome, and higher mortality.

[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.

Inadvertent Stent Retriever Detachment: A Multicenter Case Series and Review of Device Experience FDA Reports

Mechanical thrombectomy using retrievable stents or stent retriever devices has become the mainstay of intra-arterial therapy for acute ischemic stroke. The recent publication of a series of positive trials supporting intra-arterial therapy as standard of care for the treatment of large vessel occlusion will likely further increase stent retriever use. Rarely, premature stent detachment during thrombectomy may be encountered. In our multicenter case series, we found a rate of detachment of less than 1% (n = 7/1,067), and all were first-generation Solitaire FR devices. A review of the US Food and Drug Administration database of device experience yielded 90 individual adverse reports of detachment. There were 82, 1 and 7 detachments of Solitaire FR (first generation), Solitaire FR2 (second generation) and Trevo devices, respectively. We conclude with a brief overview of the technical and procedural considerations which may be helpful in avoiding this rare complication.

Mechanical thrombectomy with 'ADAPT' technique by transcervical access in acute ischemic stroke

Background

The mechanical thrombectomy (MT) for endovascular clot retrieval has dramatically improved successful revascularization and clinical outcome in selected acute stroke patients. MT is typically performed via a transfemoral approach, but catheterization of the occluded vessel can be problematic in cases of extensive vessel tortuosity. We describe a case of MT with the ‘ADAPT’ technique by direct carotid access due to an inability to catheterize the ICA by a transfemoral approach for acute cerebral ischemia in the setting of left MCA occlusion. Excellent angiographic and good clinical results were obtained without any complications.

Case report

An 80-year-old woman was admitted with a stroke by occlusion of the left MCA, with an NIHSS: 11, and an ASPECT: 7 in the CT. Under sedation a transfemoral angiography was performed, but after multiple attempts, it was impossible to make a stable catheterization of the left CCA. A transcervical approach was pursued. With ultrasound guidance the CCA was catheterized. Using the ‘ADAPT’ technique, we performed a successful MT. Post-procedure angiography (at 14 minutes) demonstrated recanalization of the entire left MCA (TICI: 3), without complications. The carotid access point was closed with a percutaneous closure. Control TC at 24 h showed a slight hypodensity in the left lenticular nucleus, and loss of gray-white matter differentiation in the adjacent cortex. Neurologically, the patient presented with progressive improvement. At discharge, she had an NIHSS: 0, mRS: 0 and Barthel: 100.

Conclusions

MT by direct carotid access is an effective alternative technique in those cases where it is not accessible by a transfemoral approach.

Recanalization and Reperfusion Therapies of Acute Ischemic Stroke: What have We Learned, What are the Major Research Questions, and Where are We Headed?

Two placebo-controlled trials have shown that early administration of intravenous recombinant tissue plasminogen activator (rt-PA) after ischemic stroke improves outcomes up to 4.5 h after symptoms onset; however, six other trials contradict these results. We also know from analysis of the pooled data that benefits from treatment decrease as time from stroke onset to start of treatment increases. In addition to time, another important factor is patient selection through multimodal imaging, combining data from artery status, and salvageable tissue measures. Nonetheless, at the present time randomized controlled trials (RCTs) cannot demonstrate any beneficial outcomes for neuroimaging mismatch selection after 4.5 h from symptoms onset. By focusing on cases of large arterial occlusion, we know that recanalization is crucial, so endovascular treatment is an approach of interest. The use of intra-arterial thrombolysis was tested in two small RCTs that demonstrated clear benefits in terms of higher recanalization and also in clinical outcomes. But a new paradigm of stroke treatment may have begun with mechanical thrombectomy. In this field, Merci devices have been overtaken by fully deployed closed-cell self-expanding stents (stent-retrievers or “stent-trievers”). However, despite the high rate of recanalization achieved with stent-retrievers compared with other recanalization treatments, the use of these devices cannot clearly demonstrate better outcomes. Thus, futile recanalization occurs when successful recanalization fails to improve functional outcome. Recently, three RCTs, namely synthesis, IMS-III, and MR-rescue, have not been demonstrated any clear benefit for endovascular treatment. Most likely, these trials were not adequately designed to prove the superiority of endovascular treatment because they did not use optimal target populations, vascular status was not evaluated in all patients, relatively high rates of patients did not have enough mismatch, time from baseline neuroimaging to recanalization were too long or the devices used are now obsolete relative to stent-retrievers. Several RCTs currently underway are trying to determine whether bridging therapy is more effective than intravenous treatment and if mechanical thrombectomy is more effective than best medical treatment in patients ineligible for intravenous thrombolysis.

Development of the Trevo ProVue Retriever for intracranial clot removal in acute ischemic stroke

It is estimated that 15 million people worldwide have a stroke each year. Of the estimated 795,000 strokes that occur in the United States annually, the majority are ischemic strokes resulting from an obstruction within a vessel supplying blood to the brain. The treatment goal for these patients is to restore blood flow as quickly as possible. Increasingly, endovascular treatments that interact directly with the clot are being pursued as options. Receiving U.S. Food and Drug Administration clearance in 2012, the Trevo® Retriever is a stent-like structure to be deployed at the site of an occlusion to allow the occluding thrombus to integrate into the device for subsequent removal and restoration of blood flow. The subsequent generation of the device, the ProVue Retriever, is fully radiopaque and designed to provide physicians with maximal information about the interaction of the device with the clot, providing enhanced feedback during the procedure. In this brief historical review, the development pathway, clinical experience, and future directions of the Trevo devices are summarized.

Acute combined revascularization in acute ischemic stroke with intracranial arterial occlusion: self-expanding solitaire stent during intravenous thrombolysis

PURPOSE

To investigate the safety and efficacy of the self-expanding Solitaire stent used during intravenous thrombolysis (IVT) for intracranial arterial occlusion (IAO) in acute ischemic stroke (AIS).

MATERIALS AND METHODS

Consecutive nonselected patients with AIS with IAO documented on computed tomographic angiography or magnetic resonance angiography and treated with IVT were included in this prospective study. Stent intervention was initiated and performed during administration of IVT without waiting for any clinical or radiologic signs of potential recanalization. Stroke severity was assessed by National Institutes of Health Stroke Scale (NIHSS), and 90-day clinical outcome was assessed by modified Rankin scale (mRS), with a good outcome defined as an mRS score of 0-2. Recanalization was rated by thrombolysis in cerebral infarction (TICI) scale.

RESULTS

Fifty patients (mean age, 66.8 y ± 14.6) had a baseline median NIHSS score of 18.0. Overall recanalization was achieved in 94% of patients, and complete recanalization (ie, TICI 3 flow) was achieved in 72% of patients. The mean time from stroke onset to maximal recanalization was 244.2 minutes ± 87.9, with a median of 232.5 minutes. The average number of device passes was 1.5, with a mean procedure time to maximal recanalization of 49.5 minutes ± 13.0. Symptomatic intracerebral hemorrhage occurred in 6% of patients. The median mRS score at 90 days was 1, and 60% of patients had a good outcome (ie, mRS score 0-2). The overall 3-month mortality rate was 14%.

CONCLUSIONS

Combined revascularization with the Solitaire stent during IVT appears to be safe and effective in the treatment of acute IAO.

Revascularization-outcome paradox: not only time and collaterals status, but also complete recanalization contribute to good neurological outcome

The rate of successful recanalization in endovascular trials has not always mirrored the rate of good clinical outcomes, creating a revascularization-outcome paradox. In early experience with the new generation of stent-based thrombectomy devices, 45-77% of patients have achieved good 90-day outcomes despite treatment up to eight-hours after symptom onset. These rates of good functional outcome are clearly higher than those previously reported with other endovascular strategies. We propose that among the factors influencing this difference is the far higher complete recanalization rate and the high ratio of Thrombolysis in Myocardial Infarction 3/Thrombolysis in Myocardial Infarction 2 recanalization obtained with stent retrievers in comparison with previous generation mechanical thrombectomy devices. Recently, we achieved Thrombolysis in Myocardial Infarction 3 in 94% of patients and Thrombolysis in Myocardial Infarction 2 in 6% in a series of patients with acute middle cerebral artery occlusions who were managed with stent-thrombectomy within eight-hours of symptom onset. Good outcomes were achieved in 77%. Extent of recanalization appears to interact with time and collateral supply in determining clinical outcomes.

A single center experience of stenting in symptomatic intracranial atherosclerosis

Atherosclerotic intracranial arterial stenosis is an important cause of stroke that is increasingly being treated with percutaneous transluminal angioplasty and stenting (PTAS) to prevent recurrent stroke. However, PTAS has been compared with medical management in a randomized trial (SAMMPRIS), where aggressive medical management was superior to PTAS with the use of the Wingspan stent system, however in our experience we have had good results and have experienced no complications with this therapy. In a retrospective, single-center study we enrolled seven consecutive patients with a symptomatic angiographically proven atherosclerotic intracranial arterial stenosis of the anterior and posterior circulation. All cases received adjuvant therapy (aspirin and clopidogrel or ticlopidine) before and after deployment of the device. The procedures were performed with the patient under general anesthesia. We use the Wingspan stent system. The occlusion site was middle cerebral artery (MCA) in three patients, proximal internal carotid artery (ICA) in one patient and vertebrobasilar artery in three patients. Primary interventional successful revascularization was achieved in all cases. Four patients had no residual stenosis, and the other three had 20%, 30% and 40% residual stenosis (Table 1). All patients showed a clinical improvement after stent deployment. No peri-interventional events or neurologic complications occurred directly related to the technique. Patency rate was 100% at the last examination in six cases, one case had a pre-occlusive stenosis, requiring angioplasty. No patients died during the follow-up period, and 100% of patients showed good functional outcome at three months (modified Rankin Scale score ≤ 2). Although the SAMMPRIS study showed that aggressive medical management was superior to PTAS, our results suggest that intracranial stenting is safe and effective, probably due to an extraordinary selection of candidates and to an exquisite technique.

Mechanically assisted intra-arterial thrombolysis in acute cerebral infarction

The aim of this study was to assess the clinical efficacy and safety of mechanically assisted thrombolysis in the treatment of acute cerebral infarction. Mechanically assisted intra-arterial urokinase thrombolysis was conducted on 28 patients with acute cerebral infarction with a disease onset time of 90–450 min. The maximum level of urokinase was 1,150,000 units. Thrombus disruption with a microwire, retrieval with a microcatheter and stent-assisted revascularization were performed. The recanalization rate, bleeding complications and modified Rankin scale (mRS) score were observed within 3 months of surgery. Our results showed that mechanically assisted thrombolysis was successfully conducted on 23 patients, with a recanalization rate of 82.1% (23/28), average recanalization time of 65.22 min and mRS score ≤3.5. Five cases of recanalization were invalid, including 2 cases of mortality, 1 case with an mRS score of 4 and 2 cases with an mRS score ≤3. In the recanalization group, the mechanically assisted thrombolysis did not increase the number of bleeding complications. Our study demonstrated that the safety of mechanically assisted thrombolysis for the treatment of acute cerebral infarction is equivalent to that of simple intra-arterial thrombolysis, but that the former has a higher efficiency. Mechanically assisted thrombolysis is able to reduce the urokinase dosage and recanalization time, and increase the recanalization rate.

Use of stentrievers in acute stroke: tips, tricks, and current results

Stentrievers are stent-like devices used in the treatment of acute ischemic stroke. They have demonstrated efficacy in restoring the intracranial blood flow with low procedural times. This article is a synopsis of the available devices and different techniques. An extensive review of the literature summarizing all the data that have been published demonstrating their clinical impact and complications is also presented.

A meta-analysis of observational intra-arterial stroke therapy studies using the Merci device, Penumbra system, and retrievable stents

BACKGROUND AND PURPOSE

The time from arterial puncture to successful recanalization is an important milestone toward timely recanalization. With the significant improvement in recanalization rates by using thrombectomy devices, procedural time to recanalization is becoming a determinant factor in choosing among available devices. We aimed to assess the impact of time to recanalization on the outcome of intra-arterial stroke therapies.

MATERIALS AND METHODS

We conducted a meta-analysis of studies reporting procedural times in patients with stroke treated with the MD, PS, and RS.

RESULTS

We identified 16 eligible studies: 4 on the MD (n = 357), 8 on the PS (n = 455), and 4 on RS (n = 113). Merci device studies described total procedural duration, while PS and RS studies described puncture-to-recanalization times. With a random-effects model, mean procedural duration for the MD was 120 minutes (95% CI, 105.7-134.2 minutes). Mean puncture to recanalization time for the PS was 64.6 minutes (95% CI, 44.4-84.8 minutes) and 54.7 minutes for RS (95% CI, 47.3-62.2 minutes). Successful recanalization was achieved in 211 of 357 patients (59.1%) in the MD studies (95% CI, 49.3-77.7), 394 of 455 (86.6%) in the PS studies (95% CI, 84.1-93.8), and 105 of 113 (92.9%) in the RS studies (95% CI, 90.9-99.9). Functional independence (mRS ≤2) was achieved in 31.5% of patients in the MD studies, 36.6% in the PS studies, and 46.9% in the RS studies.

CONCLUSIONS

The use of the PS and RS was associated with comparable procedural time to recanalization. Available data did not allow this parameter to be determined for trials using the MD. Retrievable stents achieved the highest rate of successful recanalization and functional outcome and the lowest mortality.

Endovascular popliteal thrombectomy using the self-expanding, retrievable Solitaire recanalization device

PURPOSE

To present an initial peripheral application of the self-expanding, detachable, fully-retrievable Solitaire FR Recanalization Device for endovascular thrombectomy in the lower leg of a patient with acute peripheral limb ischemia.

CASE REPORT

A 79-year-old woman with a long history of peripheral arterial occlusive disease and a femoropopliteal bypass graft presented with sudden grade IIb ischemia of the left lower leg. Conventional antegrade angiography identified total thrombotic occlusion of the tibioperoneal trunk below the distal femoropopliteal bypass anastomosis; the bypass itself was not occluded. When suction thrombectomy was unsuccessful, a 4×20-mm self-expanding, retrievable Solitaire stent was deployed. The thrombus was retrieved, with immediate recanalization of the tibioperoneal trunk and no sequela. Clinical signs of ischemia resolved, and after 6 months of follow-up, no reocclusion had occurred.

CONCLUSION

Developed as a tool to retrieve clots causing acute ischemic stroke, the Solitaire FR Recanalization Device may also have a place in treating patients with acute below-the-knee thrombotic arterial occlusion in whom suction thrombectomy had failed. The Solitaire stent may be an additional endovascular option that can result in successful treatment of acute limb ischemia and avoid more expensive surgical procedures in selected cases.

Safety and efficacy of mechanical thrombectomy with solitaire stent retrieval for acute ischemic stroke: a systematic review

Purpose

In recent years, mechanical thrombectomy using Solitaire stent retrieval has been tried for treating acute ischemic stroke with a large artery occlusion. We systematically reviewed published articles to appraise the evidence that supports the safety and efficacy of the mechanical thrombectomy in acute strokes with Solitaire stent.

Materials and Methods

Systematic searches using Medline and Scopus were performed for studies evaluating mechanical thrombectomy using a Solitaire stent in acute ischemic stroke. Articles were included if they were published since 2008, contained at least 5 subjects, and provided clinical results.

Results

Thirteen articles (262 cases) were included in this review. The mean time of the procedures ranged from 37 to 95.6 minutes in 10 studies. The success of recanalization was achieved in 89.7% and the recanalization rate varied from 66.7% to 100% in all 13 studies. The overall rates of the symptomatic hemorrhagic complications and mortality were 6.8% and 11.1%, respectively. A favorable outcome of mRS 2 or under was 47.3%. Procedure-induced complications developed in 3.4%.

Conclusion

The present review suggested that mechanical thrombectomy using a Solitaire stent in acute ischemic stroke was effective in recanalizing the occluded artery. The rate of procedural complications was small.

Intra-arterial therapy for acute ischemic stroke

Intra-arterial therapy (IAT) for acute ischemic stroke refers to endovascular catheter-based approaches to achieve recanalization using mechanical clot disruption, locally injected thrombolytic agents or both. IAT may be used in addition to intravenous tissue plasminogen activator (tPA) or in patients who do not qualify for tPA, usually because they are outside the approved 3-h timeframe window or have contraindications, such as elevated international normalized ratio or partial thromboplastin time. Recanalization rates correlate with clinical improvement, and with the newest catheters it is possible to achieve recanalization in roughly 80% of patients treated. However, while the catheters are approved by the Food and Drug Administration, there are still no randomized trial data demonstrating the role of current IAT therapy vs either tPA or standard management. IAT is reserved for patients with large artery occlusions in the basilar, distal carotid, or proximal middle cerebral arteries. Imaging the penumbra using magnetic resonance imaging or computed tomographic perfusion is currently the most frequently used way to identify patients who might benefit. However, the imaging and clinical criteria for identifying which patients benefit, and perhaps more importantly those who will do poorly despite IAT, remain unclear.

Early single center experience with the solitaire thrombectomy device for the treatment of acute ischemic stroke

We report the immediate technical and clinical outcome of a new self-expanding fully retrievable stent in the treatment of acute ischemic stroke. Eleven consecutive patients with acute intracerebral artery occlusions were treated with a self-expandable fully retrievable intracranial stent (Solitaire AB). Four patients had an occlusion of the basilar artery, five had a middle cerebral artery occlusion and two had terminal carotid artery occlusions. Recanalization results were assessed by follow-up angiography immediately after the procedure. Neurologic status was evaluated before and after treatment (90-day follow-up) according to the National Institutes of Health Stroke Scale (NIHSS) and modified Rankin scales (mRS).Successful revascularization (TICI 2a/b and 3) was achieved in 11 of 11 (100%) patients, a TICI 3 state was accomplished in two (18%) patients, and partial recanalization or slow distal branch filling with filling of more than two-thirds of the vessel territory (TICI 2a/2b) was achieved in nine (82%) patients. The stent was removed in all patients. The mean time from stroke symptom onset to recanalization was 339 minutes (+/- 114.3 minutes). NIHSS on admission was 16.09 (+/- 4.7). Almost two-thirds of the patients (61.2%) improved by >6 points on the NIHSS at discharge, and 30% showed a mRS of <2 at 90 days. Mortality was 9%. One patient with a BA occlusion had a massive brain stem infarction and died two days after the procedure. There were no intracranial hemorrhages.The use of the Solitaire in ischemic stroke patients shows encouraging results. However, further prospective large randomized trials are mandatory to confirm these early results.

Impact of retrievable stents on acute ischemic stroke treatment

BACKGROUND AND PURPOSE

Retrievable stents combine the high recanalization rate of stents and the capability of removing the thrombus offered by mechanical thrombectomy devices. We hypothesized that retrievable stents shorten time to recanalization in the multimodal approach for endovascular stroke treatment.

MATERIALS AND METHODS

Forty consecutive patients with acute ischemic stroke and undergoing endovascular therapy were included. Treatment included thromboaspiration, thrombus disruption, thrombolysis, PTA, and stent placement. In 17 patients, a retrievable stent was used (group A) in addition to multimodal therapy. The remaining 23 patients constituted group B. Baseline characteristics, occlusion sites, urokinase dose, recanalization rate, and time to recanalization were compared between the groups.

RESULTS

Median NIHSS scores were higher in group A compared with group B on admission (19 versus 12.5; P = .018) but were not significantly different at day 1 (14 versus 10; P = .6). Intra-arterial thrombolysis was used in significantly fewer patients of group A than group B (53% versus 87%, respectively; P = .017), and median urokinase dose was lower in group A than in group B (250,000 IU versus 700,000 IU; P = .006). Time to recanalization was significantly shorter in group A compared with group B (median time to recanalization 52.5 minutes versus 90 minutes, respectively; P = .001). Recanalization rate was higher in group A than group B (94% versus 78%; P = .17).

CONCLUSIONS

Addition of retrievable stents to the multimodal endovascular approach for acute ischemic stroke treatment significantly reduces time to recanalization and further increases the recanalization rate.

Fibrinolysis and Beyond: Bridging the Gap between Local and Systemic Clot Removal

Recanalization methods in ischemic stroke have been progressively expanded over the past years. In addition the continuous development of specialized mechanical devices for thrombectomy a broad spectrum of new drugs has been tested: Both options, novel drugs as well as new devices, can be employed independently of each other, but in most cases a combination of the two with the standard treatment of intravenous fibrinolysis is applied. Until recently, a large number of case series have been performed to investigate the effects of various drugs and interventions, but only a few trials have been conducted to determine the optimal conditions for combining both procedures. This review surveys the different systemic and endovascular vessel reopening practices and their major bridging techniques.

Treatment of acute ischemic stroke: feasibility of primary or secondary use of a self-expanding stent (Neuroform) during local intra-arterial thrombolysis

INTRODUCTION

We evaluated the feasibility of employing a self-expanding stent (Neuroform) in treatment of acute cerebral ischemia and compared the results of primary and secondary stenting.

METHODS

We analyzed the treatment results of 14 acute ischemic stroke patients (11 men and three women; median age, 65 years) who were treated with Neuroform stents. Seven patients received stent placement for primary recanalization and a further seven for secondary recanalization. We performed between-group comparisons of all of overall procedure duration, recanalization rate immediately after stenting, need for additional measures after stenting, final recanalization rate, occurrence of hemorrhagic transformation, early re-occlusion rate after 24 h, and 3-month functional recovery rate (mRS ≤2).

RESULTS

The median interval from femoral puncture to stent placement was 61.5 min and was significantly shorter in the primary than in the secondary group (55 vs. 95 min, p = 0.004). The recanalization rate immediately after stenting was 42.9% and was greater in the primary than in the secondary group (71.4% vs. 14.3%, p = 0.1). Thirteen patients required various additional therapeutic measures. The final recanalization rate was 78.6%, attributable to improvements in the recanalization rate of the secondary group (71.4% vs. 85.7%). Early hemorrhagic transformation was noted in four patients, but only one patient became symptomatic (symptomatic hemorrhage, 7.1%). Good functional recovery was noted in eight patients (57.1%).

CONCLUSION

Placement of a self-expanding stent during endovascular recanalization of acute ischemic stroke was both feasible and safe. Primary use of this method may enhance early recanalization.

In vivo evaluation of the first dedicated combined flow-restoration and mechanical thrombectomy device in a swine model of acute vessel occlusion

BACKGROUND AND PURPOSE

The use of self-expanding retrievable stents is an emerging and promising treatment strategy for acute stroke treatment. The concept combines the advantages of stent deployment with immediate flow-restoration and of mechanical thrombectomy with definitive thrombus removal. The present study was performed to gain more knowledge about the principle of combined flow restoration and thrombectomy in an established animal model using radiopaque thrombi evaluating efficiency, thrombus-device interaction and possible complications of the first dedicated flow-restoration and mechanical thrombectomy device.

MATERIALS AND METHODS

The Solitaire FR (4 × 20 mm) was evaluated in 15 vessel occlusions in an established animal model in swine. Flow-restoration effect at T0, T5, and T10; recanalization rate after retrieval; thromboembolic events; and complications were assessed. Radiopaque thrombi (10-mm length) were used for visualization of thrombus-device interaction during application and retrieval.

RESULTS

Immediate flow restoration was achieved in 80% of occlusions. Mean percentage of recanalization compared with the initial vessel diameter at T0 was 30.8%; at T5, 30.7%; and at T10, 25.4%. Re-occlusion occurred in 20.0% between T0 and T5 and in 13.3% between T5 and T10. Complete recanalization (TICI 3) after retrieval was achieved in 86.7%. In 2 cases (13.3%), partial recanalization was achieved, with the remaining thrombus in a side branch (TICI 2b). No thromboembolic event was observed. The assessment of thrombus-device interaction illustrated the compression of the thrombus against the vessel wall during deployment leading to partial flow restoration. During retrieval, the thrombus was retained by the stent struts even during the passage of vessel curvatures.

CONCLUSIONS

The Solitaire FR is a safe and effective combined flow-restoration and thrombectomy device in vivo. Partial flow restoration is achieved by thrombus compression immediately after deployment, but flow restoration decreases afterward until final retrieval results in maximal recanalization.

Stent-assisted mechanical recanalization for treatment of acute intracerebral artery occlusions

BACKGROUND AND PURPOSE

The purpose of this study was to demonstrate a new approach to the use of a self-expanding stent in the treatment of acute ischemic stroke.

METHODS

Twenty-two consecutive patients with acute intracerebral artery occlusions were treated with a self-expandable intracranial stent, which was withdrawn in its unfolded state. For this technique, we used the Solitaire AB/FR, which is the only intracranial stent that is fully recoverable. Eight patients had an occlusion of the basilar artery, 12 had a middle cerebral artery occlusion, and 2 had terminal carotid artery occlusions; 6 of these had to be treated first for an acute occlusion originating in the internal carotid artery. Recanalization results were assessed by follow-up angiography immediately after the procedure. Neurologic status was evaluated before and after treatment (90-day follow-up) according to the National Institutes of Health Stroke Scale and modified Rankin scale.

RESULTS

Successful revascularization was achieved in 20 of 22 (90.9%) patients (thrombolysis in cerebral infarction [TICI] 2a/b and 3), a TICI 3 state was accomplished in 12 patients, and partial recanalization or slow distal branch filling with filling of more than two-thirds of the vessel territory was achieved in 8 patients (TICI 2b). There was immediate flow restoration in 21 of 22 (95.4%) cases after deployment of the device. The stent was removed in its unfolded state in all patients. The mean time from stroke symptom onset to recanalization was 277 minutes, with a standard deviation of 118 minutes. Mean National Institutes of Health Stroke Scale score on admission was 19.4, with a standard deviation of 5.7. Almost two-thirds of the patients (63.6%) improved by > 10 points on the National Institutes of Health Stroke Scale at discharge, and 50% showed a modified Rankin scale score of ≤ 2 at 90 days (59% with a modified Rankin scale ≤ 3). Mortality was 18.1%. In 1 case, an asymptomatic intracranial hemorrhage was detected on control computed tomography, and 2 patients had a symptomatic intracranial hemorrhage.

CONCLUSIONS

Withdrawal of an unfolded, fully recoverable, intracranial stent yielded very promising angiographic and clinical results. It combines the advantages of prompt flow restoration and mechanical thrombectomy.

Solitaire flow-restoration device for treatment of acute ischemic stroke: safety and recanalization efficacy study in a swine vessel occlusion model

BACKGROUND AND PURPOSE

The extended time window and theoretic reduction in hemorrhage make mechanical strategies an attractive approach in the treatment of patients with ischemic stroke. My purpose was to evaluate the recanalization efficacy and safety of the Solitaire FR Revascularization Device in a swine vessel occlusion model.

MATERIALS AND METHODS

For recanalization efficacy, radio-opaque clots were used in 6 ascending pharyngeal arteries of the swine. Safety was assessed in 8 renal arteries with 3 passes of the device. Four vessels were harvested at 30 days, and 4, at 90 days, with microscopic examination to assess vessel damage.

RESULTS

On deployment, immediate flow was seen in 3/6 vessels; and on retrieval, TIMI-3 recanalization was seen in 6/6. Vasospasm, which resolved on follow-up angiography with no distal emboli or vessel damage, was noted. In the renal vessels, safety evaluation findings were unremarkable, with the exception of 2 vessels harvested from a kidney at 90 days. These 2 vessels appeared without damage on microscopy; however, angiography showed shrinkage of the entire kidney, which was attributed to damage and stenosis of the main renal artery at the site of the guide-catheter insertion, likely leading to a chronic low-flow state and resultant atrophy of the entire kidney.

CONCLUSIONS

The Solitaire Device showed good recanalization efficacy with acceptable safety. The unique stent-like design allows immediate flow restoration, a distinct advantage of the device. On the basis of this study, the device has good potential as a tool in the treatment of patients with ischemic stroke.

Mechanical thrombectomy with the Solitaire AB device in large artery occlusions of the anterior circulation: a pilot study

BACKGROUND AND PURPOSE

To describe the safety and effectiveness of a self-expanding and fully retrievable stent (Solitaire AB; ev3 Inc, Plymouth, MN) in revascularization of patients with acute ischemic stroke.

METHODS

Prospective, single-center study of 20 patients with an acute ischemic stroke attributable to a large artery occlusion of the anterior circulation within the first 8 hours from symptoms onset (median National Institutes of Health Stroke Scale, 19 [interquartile range, 15-23]). The occlusion site was middle cerebral artery in 12 patients, proximal internal carotid artery/middle cerebral artery tandem occlusion in 3 patients, and terminus internal carotid artery in 5 patients. Thrombectomy was used as rescue therapy in 2 patients who were refractory to intra-arterial plasminogen activator, and in 3 patients in whom successful recanalization with the MERCI retriever was not achieved.

RESULTS

Successful revascularization defined as thrombosis in cerebral ischemia grade 2b or 3 was achieved in 18 of 20 (90%) treated vessels, and 16 patients showed immediate restoration of flow after stent deployment. The mean number of passes for maximal recanalization was 1.4, and the median (quartiles) time from groin puncture to recanalization was 50 (38-71) minutes. No case required adjuvant therapy after deployment of the embolectomy device. No significant procedural events occurred. Symptomatic intracranial hemorrhage was found in 2 (10%) patients, 4 (20%) patients died during the 90-day follow-up period, and 45% of patients showed good functional outcome at 3 months (modified Rankin Scale score <or=2).

CONCLUSIONS

These results suggest that the Solitaire AB device can rapidly, safely, and effectively retrieve clots from the middle cerebral artery and terminus internal carotid artery within 8 hours from symptoms onset.