Temporary endovascular bypass: a novel treatment for acute stroke

Recanalization Therapy for Acute Ischemic Stroke with Large Vessel Occlusion: Where We Are and What Comes Next?

In the past 5 years, the success of multiple randomized controlled trials of recanalization therapy with endovascular thrombectomy has transformed the treatment of acute ischemic stroke with large vessel occlusion. The evidence from these trials has now established endovascular thrombectomy as standard of care. This review will discuss the chronological evolution of large vessel occlusion treatment from early medical therapy with tissue plasminogen activator to the latest mechanical thrombectomy. Additionally, it will highlight the potential areas in endovascular thrombectomy for acute ischemic stroke open to exploration and further progress in the next decade.

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.

Primary Stenting for Acute Ischemic Stroke Using the Enterprise Intracranial Stent: 2-Year Results of a Phase-I Trial

BACKGROUND

The preliminary results of a prospective consecutive series of 20 patients who underwent Enterprise-assisted recanalization for acute ischemic stroke were recently reported. Recanalization to thrombolysis in myocardial infarction (TIMI) grade 2 (n = 6) or 3 (n = 12) flow was achieved in 18 patients (90% revascularization rate). Good outcome (modified Rankin Scale [mRS] score of ≤2) was obtained in 10 patients (50%) at 30 days. Here, we report the 2-year clinical follow-up data for patients enrolled in that prospective study.

METHODS

Study patients were scheduled for examinations 2 years postprocedure at which time mRS and Barthel indices were obtained.

RESULTS

Among 12 survivors at 2 years, 11 of the 20 (55%) study patients improved to mRS score ≤2 and 1 (5%) patient was disabled with an mRS 4. Of the 11 patients with mRS 0-2 scores, 10 patients had a Barthel index of 100, and the 11th had a Barthel index of 95. One patient improved from mRS 3 to 2 during the interval between the 6- and 12-month postintervention evaluations after intervention. Eight of 13 (62%) survivors underwent follow-up imaging at 6 months without evidence of instent stenosis or thrombosis.

CONCLUSION

At 2 years of follow-up, improvement in quality of life after acute stroke intervention was sustained; and 11 of 12 (92%) survivors had an excellent functional outcome. Improvement in functional status can occur even up to 1 year after stroke intervention. These results 2 years after acute stroke intervention demonstrate sustained benefit from acute intervention.

ABBREVIATIONS

AISacute ischemic strokeCTcomputed tomographicFDAFood and Drug AdministrationIVintravenousMCAmiddle cerebral arterymRSmodified Rankin ScaleNIHSSNational Institutes of Health Stroke Scale ScoreSWIFTSolitaire FR With the Intention For Thrombectomy (SWIFT)TIMIthrombolysis in myocardial infarctiontPAtissue plasminogen activatorTREVOThrombectomy REvascularization of large Vessel Occlusions.

Recanalization of acute intracranial artery occlusion using temporary endovascular bypass technique

PURPOSE

The purpose of this study is to present our preliminary experience of the temporary endovascular bypass (TEB) technique using an Enterprise stent for recanalization of acute intracranial artery (IA) occlusion.

MATERIALS AND METHODS

Patients treated by TEB were enrolled in this retrospective study from January 2009 to May 2010. All the procedures consist of temporary partial deployment and subsequent retrieval of Enterprise stent, supplemented by intra-arterial infusion of urokinase (UK) and/or tirofiban. According to the thrombolysis in cerebral infarction (TICI) classification, recanalization was evaluated with initial and postprocedural angiography. Safety was evaluated related to the procedure and clinical outcomes were assessed by National Institute of Health Stroke Scale (NIHSS) score at discharge and modified Rankin scale (mRS) score at 3 months.

RESULTS

Eleven patients (median NIHSS 12.8, mean age 61.6 years, male: female = 8:3) with acute IA occlusion were treated with TEB. All the patients presented with TICI 0, and the occluded vessel was the middle cerebral artery (n=7), the basilar artery (n=1), and the distal ICA occlusion (n = 3). IV infusion of tissue plasminogen activator (tPA) was done in 4 patients and mechanical thrombolysis with intra-arterial UK was performed in 9. Recanalization was achieved in 73% (8 patients; TICI ≥ 2). There were no procedure-related complications except for two asymptomatic intracranial hemorrhages. Improvement (≥ 4 points on the NIHSS) and good outcome (mRS ≤2) after 90 days was shown in six patients (55%). One patient died 6 days after procedure.

CONCLUSION

TEB may be a valuable treatment option in acute thromboembolic IA occlusion without stent implantation.

Endovascular treatment of acute ischemic stroke

Endovascular stroke therapy has revolutionized the management of patients with acute ischemic stroke in the last decade and has facilitated the development of sophisticated stroke imaging techniques and a multitude of thrombectomy devices. This article reviews the scientific basis and current evidence available to support endovascular revascularization and provides brief technical details of the various methods of endovascular thrombectomy with case examples.

Intracranial stents for treatment of acute ischemic stroke: evolution and current status

BACKGROUND

Intravascular stents have been applied to treat a variety of pathophysiologic conditions. With advances in stent design and delivery, stenting has become a viable treatment option in neurovascular disease. Recently, intracranial arterial stenting has received increasing interest as a modality to rapidly and effectively recanalize affected vessels in the setting of acute ischemic stroke.

METHODS

To examine the potential of stenting procedures for stroke, we compiled and analyzed relevant experimental and clinical studies in the available databases.

RESULTS

Our resulting discussion covers the brief history of stents, from their initial inception in the 1960s, to the developments of interventional cardiology, and finally to the treatment of acute occlusions of the neurovasculature. We also detail technological advances that have improved stent delivery to intracranial arteries and review the several clinical studies that feature stenting for the treatment of acute ischemic stroke.

CONCLUSION

Numerous clinical studies have revealed that stents are a quick and efficacious endovascular tool for acute ischemic stroke treatment. It appears likely that issues regarding design, safety, and feasibility of stent-based devices will experience further improvement and refinement, and from fruitful criticism of existing technologies and techniques, along with lessons from past mistakes, will arise safer and more effective devices.

Stenting in the treatment of acute ischemic stroke: literature review

Recanalization of acute large artery occlusions is a strong predictor of good outcome. The development of thrombectomy devices resulted in a significant improvement in recanalization rates compared to thrombolytics alone. However, clinical trials and registries with these thrombectomy devices in acute ischemic stroke (AIS) have shown recanalization rates in the range of 40-81%. The last decade has seen the development of nickel titanium self-expandable stents (SES). These stents, in contrast to balloon-mounted stents, allow better navigability and deployment in tortuous vessels and therefore are optimal for the cerebral circulation. SES were initially used for stent-assisted coil embolization of intracranial aneurysms and for treatment of intracranial stenosis. However, a few authors have recently reported feasibility of deployment of SES in AIS. The use of these devices yielded higher recanalization rates compared to traditional thrombectomy devices. Encouraged by these results, retrievable SES systems have been recently used in AIS. These devices offer the advantage of resheathing and retrieving of the stent even after full deployment. Some of these stents can also be detached in case permanent stent placement is needed. Retrievable SES are being used in Europe and currently tested in clinical trials in the United States. We review the recent literature in the use of stents for the treatment of AIS secondary to large vessel occlusion.

Temporary Endovascular Bypass: Rescue Technique During Mechanical Thrombolysis

BACKGROUND

The goal of mechanical thrombolysis is to re-establish blood flow to a completely occluded artery in patients who fail intravenous thrombolytic therapy or who are outside the therapeutic window.

OBJECTIVE

We present our single-institution experience with the use of temporary, partial deployment of a self-expanding intracranial stent as a rescue technique for the treatment of acute stroke. The use of the Enterprise stent represents an off-label use of a humanitarian device exemption device.

METHODS

We performed a retrospective review of a prospective database of acute stroke patients treated with intra-arterial techniques at the Thomas Jefferson University Comprehensive Stroke Center from July 2009 to July 2010.

RESULTS

Seven patients were included, and we obtained a 100% recanalization rate to Thrombolysis in Myocardial Infarction grade 2 and 3 with a 28% asymptomatic hemorrhagic transformation. No device-related complications were encountered.

CONCLUSION

Temporary, partial deployment of a self-expanding intracranial stent as a rescue procedure is feasible, effective, and safe in the setting of endovascular intervention for acute stroke, although our experience is limited. This technique was used only as a rescue procedure when more established procedures failed.

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.

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.

Recanalization therapy for acute ischemic stroke, part 2: mechanical intra-arterial technologies

Stroke therapy has been revolutionized in the past two decades with the widespread implementation of chemical thrombolysis for acute stroke. However, chemical thrombolysis continues to be limited in its efficacy secondary to relatively short time windows and a high associated risk of hemorrhage. In an attempt to minimize hemorrhagic complications and extend the available therapeutic window, mechanical devices designed specifically for thrombus removal, clot obliteration, and arterial revascularization have experienced a recent surge in development and utilization. As such, chemical thrombolytics now represent only one of many options in acute stroke therapy. These new mechanical devices have extended the potential treatment window and now provide alternatives to patients who do not respond to conventional intravenous thrombolysis. This review will discuss the development of these devices, supporting literature, and the individual strengths that each engenders towards a life-saving therapy for stroke.

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.

Acute ischemic stroke treatment: State of the art

Stroke is among the leading causes of death and serious disability in the United States. Treatment of the acute ischemic stroke patient requires a multidisciplinary approach involving first-responders, emergency department personnel, neurologists, advanced imaging experts and endovascular specialists with neurosurgical support. Contemporary stroke treatment is a rapidly advancing field. New developments in pharmacologic and endovascular stroke therapy require thoughtful trial design and expeditious trial implementation to assess clinical outcomes. This manuscript reviews the state of the art in acute stroke therapy.

Blood pressure treatment in acute ischemic stroke: a review of studies and recommendations

PURPOSE OF REVIEW

Elevated blood pressure (BP) is frequent in patients with acute ischemic stroke. Pathophysiological data support its usefulness to maintain adequate perfusion of the ischemic penumba. This review article aims to summarize the available evidence from clinical studies that examined the prognostic role of BP during the acute phase of ischemic stroke and intervention studies that assessed the efficacy of active BP alteration.

RECENT FINDINGS

We found 34 observational studies (33,470 patients), with results being inconsistent among the studies; most studies reported a negative association between increased levels of BP and clinical outcome, whereas a few studies showed clinical improvement with higher BP levels, clinical deterioration with decreased BP, or no association at all. Similarly, the conclusions drawn by the 18 intervention studies included in this review (1637 patients) were also heterogeneous. Very recent clinical data suggest a possible beneficial effect of early treatment with some antihypertensives on late clinical outcome.

SUMMARY

Observational and interventional studies of management of acute poststroke hypertension yield conflicting results. We discuss different explanations that may account for this and discuss the current guidelines and pathophysiological considerations for the management of acute poststroke hypertension.

Reperfusion for acute ischemic stroke: arterial revascularization and collateral therapeutics

PURPOSE OF REVIEW

Reperfusion of the ischemic territory forms the basis of most acute stroke treatments. This overview of the literature relating to reperfusion in acute ischemic stroke published within the last year provides a snapshot of a rapidly evolving aspect of cerebrovascular disease.

RECENT FINDINGS

Arterial revascularization from systemic thrombolysis to combination endovascular procedures to achieve recanalization has proliferated. Stroke imaging continues to discern features of critical pathophysiology that may influence tissue fate and clinical outcome. Balancing the risk of hemorrhagic transformation against the therapeutic aim to salvage the ischemic penumbra remains a formidable challenge. Collateral therapeutics that enhance perfusion outside the ischemic core present novel dimension to acute stroke therapy, focused on ischemia and not just the clot or plaque.

SUMMARY

These timely findings illustrate the essential role of reperfusion in acute stroke, delineating aspects of arterial revascularization and collateral therapeutics to be refined in coming years.

Self-expanding stent for recanalization of acute embolic or dissecting intracranial artery occlusion

BACKGROUND AND PURPOSE

Stent placement may be an effective and last resort method for recanalization of recalcitrant intracranial artery occlusion. The purpose of this study was to evaluate the safety and efficacy of a self-expanding stent for the recanalization of acute embolic or dissecting intracranial artery occlusion.

MATERIALS AND METHODS

Nine patients (mean age, 66 years; NIHSS score, 10-23) with acute embolic (n = 8) or dissecting occlusion (n = 1) of the intracranial arteries (ICA terminus in 5, MCA in 3, and BA in 1) were treated with a recapturable self-expanding stent. The safety and efficacy of the stent for recanalization were evaluated retrospectively.

RESULTS

The emboli were entrapped against the vessel wall by the stent, resulting in immediate recanalization (TIMI 2) in all embolic occlusions. The dissecting occlusion was recanalized completely (TIMI 3). Adjunctive thrombolytics (n = 8, urokinase, 100,000-300,000 U) and/or GP IIb/IIIa antagonist (n = 7, tirofiban, 0.5-1 mg) were administered intra-arterially, and the degree of recanalization further improved in 4 embolic occlusions (TIMI 3). Acute in-stent thrombosis occurred in 2 patients, who received only urokinase without GP IIb/IIIa antagonist. Both of the reoccluded arteries were reopened, by stent recapture in 1 and by intra-arterial administration of GP IIb/IIIa antagonist in the other. Recapture was attempted in 7 cases, of which there were 3 successful outcomes. There was 1 asymptomatic hemorrhagic conversion at the infarction site. The mean improvement of the NIHSS score between baseline and discharge was 12.3 (range, 3-22).

CONCLUSIONS

Preliminary results of this study suggest that a self-expanding stent may be safe and efficient for recanalization of acute embolic or dissecting intracranial artery occlusion.