Mechanical Thrombolysis and Stenting in Acute Ischemic Stroke

Application of Nanotechnology in Thrombus Therapy

A thrombus is a blood clot that forms in the lumen of an artery or vein, restricting blood flow and causing clinical symptoms. Thrombosis is associated with many life-threatening cardiovascular diseases. However, current clinical therapeutic technologies still have many problems in targeting, enrichment, penetration, and safety to meet the thrombosis treatment needs. Therefore, researchers devote themselves to developing nanosystems loaded with antithrombotic drugs to address this paradox in recent years. Herein, the existing thrombosis treatment technologies are first reviewed; and then, their advantages and disadvantages are outlined based on a brief discussion of thrombosis's definition and formation mechanism. Furthermore, the need and application cases for introducing nanotechnology are discussed, focusing on thrombus-specific targeted ligand modification technology and microenvironment-triggered responsive drug release technology. Then, nanomaterials that can be used to design antithrombotic nanotherapeutic systems are summarized. Moreover, a variety of drug delivery technologies driven by nanomotors in thrombosis therapy is also introduced. Last of all, a prospective discussion on the future development of nanotechnology for thrombosis therapy is highlighted.

P2Y12 inhibitors for the neurointerventionalist

The use of antiplatelets is widespread in clinical practice. However, for neurointerventional procedures, protocols for antiplatelet use are scarce and practice varies between individuals and institutions. This is further complicated by the quantity of antiplatelet agents which differ in route of administration, dosage, onset of action, efficacy and ischemic and hemorrhagic complications. Clarifying the individual characteristics for each antiplatelet agent, and their associated risks, will increasingly become relevant as the practice of mechanical thrombectomy, stenting, coiling and flow diversion procedures grows. The aim of this review is to summarize the existing literature for the use of P2Y12 inhibitors in neurointerventional procedures, examine the quality of the evidence, and highlight areas in need of further research.

Mesenchymal Stem Cell Transplantation for Ischemic Diseases: Mechanisms and Challenges

Ischemic diseases are conditions associated with the restriction or blockage of blood supply to specific tissues. These conditions can cause moderate to severe complications in patients, and can lead to permanent disabilities. Since they are blood vessel-related diseases, ischemic diseases are usually treated with endothelial cells or endothelial progenitor cells that can regenerate new blood vessels. However, in recent years, mesenchymal stem cells (MSCs) have shown potent bioeffects on angiogenesis, thus playing a role in blood regeneration. Indeed, MSCs can trigger angiogenesis at ischemic sites by several mechanisms related to their trans-differentiation potential. These mechanisms include inhibition of apoptosis, stimulation of angiogenesis via angiogenic growth factors, and regulation of immune responses, as well as regulation of scarring to suppress blood vessel regeneration when needed. However, preclinical and clinical trials of MSC transplantation in ischemic diseases have shown some limitations in terms of treatment efficacy. Such studies have emphasized the current challenges of MSC-based therapies. Treatment efficacy could be enhanced if the limitations were better understood and potentially resolved. This review will summarize some of the strategies by which MSCs have been utilized for ischemic disease treatment, and will highlight some challenges of those applications as well as suggesting some strategies to improve treatment efficacy.

Efficacy and Safety of Endovascular Treatment in Acute Tandem Carotid Occlusions: Analysis of a Single-Center Cohort

Introduction

Acute ischemic strokes with tandem occlusions, which represent 10–20% of all ischemic strokes, have a particularly poor prognosis. Since emergent treatment of tandem lesions has not been specifically addressed in randomized trials, there is an absence of standardized management.

Objective

We sought to assess the efficacy and safety of acute endovascular treatment in stroke due to tandem occlusions in our center and compare the results with previous reports.

Methods

From a prospective registry we analyzed data of 99 consecutive patients (males: 77.7%, mean age ± SD: 67.5 ± 9.5 years) with stroke due to tandem occlusions who underwent treatment with emergent carotid stenting and intracranial mechanical thrombectomy. Successful recanalization was defined as a TICI score of 2b-3 and a good functional outcome was defined as a modified Rankin scale score ≤2 at 90 days. Symptomatic intracranial hemorrhage (sICH) was considered when associated with worsening on the National Institutes of Health Stroke Scale (≥4 points).

Results

A successful recanalization rate was achieved in 87.8 and 48.5% of the patients had a good functional outcome. sICH and mortality rates were 12.1 and 20.2%, respectively, and 21.2% of the patients received combined treatment with intravenous thrombolysis, which did not affect neither the prognosis nor the recanalization or sICH rates. The time from symptom onset to recanalization and the degree of recanalization were the main factors associated with prognosis and the occurrence of sICH.

Conclusions

Our results suggest that endovascular treatment with emergent carotid stenting and intracranial thrombectomy in patients with acute stroke due to tandem occlusions is an effective and safe procedure.

Mechanical Thrombectomy with Solitaire Stent Retrieval for Acute Cardioembolic Stroke

Objective

Few studies have reported the outcome of mechanical thrombectomy with Solitaire stent retrival (MTSR) in subtypes of acute ischemic stroke. The purpose of this study was to evaluate the efficacy and result of MTSR in acute cardioembolic stroke.

Methods

Twenty consecutive patients with acute cardioembolic stroke were treated by MTSR. The angiographic outcome was assessed by thrombolysis in cerebral infarction (TICI) grade. TICI grade 2a, 2b, or 3 with a measurable thrombus that was retrieved was considered as a success when MTSR was performed in the site of primary vessel occlusion, and TICI grade 2b or 3 was considered as a success when final result was reported. Clinical and radiological results were compared between two groups divided on the basis of final results of MTSR. Persistent thrombus compression sign on angiogram was defined as a stenotic, tapered arterial lumen whenever temporary stenting was performed. The clinical outcomes were assessed by the modified Rankin Scale (mRS) at 3 months.

Results

The failure rate of MTSR was 20% (4/20) and other modalities, such as permanent stenting, were needed. Final successful recanalization (TICI grade 2b or 3) was 80% when other treatments were included. The rate of good outcome (mRS≤2) was 35% at the 3-month follow-up. Failure of MTSR was significantly correlated with persistent thrombus compression sign (p=0.001).

Conclusion

Some cases of cardioembolic stroke are resistant to MTSR and may need other treatment modalities. Careful interpretation of angiogram may be helpful to the decision.

The golden 35 min of stroke intervention with ADAPT: effect of thrombectomy procedural time in acute ischemic stroke on outcome

Introduction

In acute ischemic stroke (AIS), extending mechanical thrombectomy procedural times beyond 60 min has previously been associated with an increased complication rate and poorer outcomes.

Objective

After improvements in thrombectomy methods, to reassess whether this relationship holds true with a more contemporary thrombectomy approach: a direct aspiration first pass technique (ADAPT).

Methods

We retrospectively studied a database of patients with AIS who underwent ADAPT thrombectomy for large vessel occlusions. Patients were dichotomized into two groups: ‘early recan’, in which recanalization (recan) was achieved in ≤35 min, and ‘late recan’, in which procedures extended beyond 35 min.

Results

197 patients (47.7% women, mean age 66.3 years) were identified. We determined that after 35 min, a poor outcome was more likely than a good (modified Rankin Scale (mRS) score 0–2) outcome. The baseline National Institutes of Health Stroke Scale (NIHSS) score was similar between ‘early recan’ (n=122) (14.7±6.9) and ‘late recan’ patients (n=75) (15.9±7.2). Among ‘early recan’ patients, recanalization was achieved in 17.8±8.8 min compared with 70±39.8 min in ‘late recan’ patients. The likelihood of achieving a good outcome was higher in the ‘early recan’ group (65.2%) than in the ‘late recan’ group (38.2%; p<0.001). Patients in the ‘late recan’ group had a higher likelihood of postprocedural hemorrhage, specifically parenchymal hematoma type 2, than those in the ‘early recan’ group. Logistic regression analysis showed that baseline NIHSS, recanalization time, and atrial fibrillation had a significant impact on 90-day outcomes.

Conclusions

Our findings suggest that extending ADAPT thrombectomy procedure times beyond 35 min increases the likelihood of complications such as intracerebral hemorrhage while reducing the likelihood of a good outcome.

Bioluminescence imaging of transplanted human endothelial colony-forming cells in an ischemic mouse model

Ischemic strokes are devastating events responsible for high mortality and morbidity worldwide each year. Endothelial colony-forming cell (ECFC) therapy holds promise for stroke treatment; however, grafted ECFCs need to be monitored better understand their biological behavior in vivo, so as to evaluate their safety and successful delivery. The objectives of this study are to visualize the fate of infused human cord blood derived ECFCs via bioluminescence imaging (BLI) in an ischemic stroke mouse model and to determine the therapeutic effects of ECFC transplantation. ECFCs derived from human umbilical cord blood were infected with lentivirus carrying enhanced green fluorescent protein (eGFP) and firefly luciferase (Luc2) double fusion reporter gene. Labeled ECFCs were grafted into a photothrombotic ischemic stroke mouse model via intra-arterial injection though the left cardiac ventricle. The homing of infused cells and functional recovery of stroke mice were evaluated using BLI, neurological scoring, and immunohistochemistry. Significantly, BLI signals were highest in the brain on day 1 and decreased steadily until day 14. GFP-positive cells were also found surrounding infarct border zones in brain sections using immunohistochemical staining, suggesting that ECFCs properly homed to the ischemic brain tissue. Using a modified neurological severity score assay and histological analysis of brain slices with CD31 immunostaining in brain tissue, double cortin analysis, and the TdT-mediated dUTP nick end labeling (TUNEL) assay, we demonstrated functional restoration, improved angiogenesis, neurogenesis, and decreased apoptosis in ischemic mice after ECFC infusion. Collectively, our data support that ECFCs may be a promising therapeutic agent for stroke.

Sonothrombolysis

Thrombo-occlusive disease is a leading cause of morbidity and mortality. In this chapter, the use of ultrasound to accelerate clot breakdown alone or in combination with thrombolytic drugs will be reported. Primary thrombus formation during cardiovascular disease and standard treatment methods will be discussed. Mechanisms for ultrasound enhancement of thrombolysis, including thermal heating, radiation force, and cavitation, will be reviewed. Finally, in-vitro, in-vivo and clinical evidence of enhanced thrombolytic efficacy with ultrasound will be presented and discussed.

The Penumbra 5MAX ACE Catheter Is Safe, Efficient, and Cost Saving as a Primary Mechanical Thrombectomy Device for Large Vessel Occlusions in Acute Ischemic Stroke

BACKGROUND

Reperfusion of large vessel occlusions in acute stroke can improve patient outcomes. The purposes of this study were to assess the safety and efficacy of the Penumbra 5MAX ACE catheter for revascularization of large vessels and to compare its cost to the cost of stent retrievers.

METHODS

In this retrospective, single-center case review study, data were captured on consecutive patients treated with the Penumbra 5MAX ACE as first-line therapy during an 11-month period. Good functional outcome was defined as a modified Rankin Scale score of ≤2 at discharge. Results were directly compared with previously published data for stent retrievers, and length of stay was analyzed in relation to revascularization.

RESULTS

The 31 patients studied had a mean age of 66.3 ± 17.8 years and a mean National Institutes of Health Stroke Scale score of 19.4 ± 5.7. Intravenous tissue recombinant plasminogen activator therapy was initiated in 35.5% (11/31) of patients. A Thrombolysis in Cerebral Infarction (TICI) grade of 2b-3 reperfusion after endovascular therapy was achieved in 26/31 (83.9%) of cases; TICI grade 3 was achieved in 19/31 (61.3%) patients. The average time from groin puncture to TICI grade 2b-3 reperfusion was 40 minutes. The average estimated cost for aspiration with the 5MAX ACE alone was $4,916 per case compared with an estimated cost of $9,620 if a stent retriever was used as the primary device. Our actual average cost per case, including all adjunctive devices used in the neurointerventional procedure, was $6,997. Good functional outcome was achieved in 19/31 (61.3%) patients. Two patients experienced symptomatic intracerebral hemorrhage (6.5%), and 1 (3.2%) patient died. The length of stay was significantly shorter among patients with TICI grade 2b-3 reperfusion compared to patients with TICI grade <2 (6.8 ± 5.34 days vs 15.8 ± 11.32 days, respectively; P<0.05).

CONCLUSION

These findings suggest that direct aspiration with the large-bore 5MAX ACE catheter can be considered a first-line approach to mechanical thrombectomy for large vessel occlusions. Our results demonstrated high rates of successful reperfusion in a timely manner with excellent clinical outcomes, although our sample size was small. In addition, this direct-aspiration technique has important cost-savings potential compared to stent retrievers.

Type of anesthesia and differences in clinical outcome after intra-arterial treatment for ischemic stroke

BACKGROUND AND PURPOSE

Intra-arterial treatment (IAT) in patients with acute ischemic stroke (AIS) can be performed with or without general anesthesia (GA). Previous studies suggested that IAT without the use of GA (non-GA) is associated with better clinical outcome. Nevertheless, no consensus exists about the anesthetic management during IAT of AIS patients. This study investigates the association between type of anesthesia and clinical outcome in a large cohort of patients with AIS treated with IAT.

METHODS

All consecutive patients with AIS of the anterior circulation who received IAT between 2002 and 2013 in 16 Dutch hospitals were included in the study. Primary outcome was functional outcome on the modified Rankin Scale at discharge. Difference in primary outcome between GA and non-GA was estimated using multiple ordinal regression analysis, adjusting for age, stroke severity, occlusion of the internal carotid artery terminus, previous stroke, atrial fibrillation, and diabetes mellitus.

RESULTS

Three hundred forty-eight patients were included in the analysis; 70 patients received GA and 278 patients did not receive GA. Non-GA was significantly associated with good clinical outcome (odds ratio 2.1, 95% confidence interval 1.02-4.31). After adjusting for prespecified prognostic factors, the point estimate remained similar; statistical significance, however, was lost (odds ratio 1.9, 95% confidence interval 0.89-4.24).

CONCLUSIONS

Our study suggests that patients with AIS of the anterior circulation undergoing IAT without GA have a higher probability of good clinical outcome compared with patients treated with general anesthesia.

Acute stroke imaging: feasibility and value of MR angiography with high spatial and temporal resolution for vessel assessment and perfusion analysis in patients with wake-up stroke

RATIONALE AND OBJECTIVES

Magnetic resonance (MR) imaging (MRI) provides information that can be used to estimate the symptom onset in patients with wake-up stroke (WUS). Time-resolved MR angiography (MRA) is the fastest available MR sequence technique for vessel assessment, and the different phases acquired can provide information about cerebral perfusion. The aim of this study was to evaluate the diagnostic performance of time-resolved MRA both for the assessment of vessel morphology and for the feasibility of perfusion.

MATERIALS AND METHODS

Nineteen patients with WUS were included. Image quality and vessel pathologies were evaluated and correlated to time-of-flight-MRA (n = 14), computed tomography-angiography (n = 4), sonography (n = 12), and conventional angiography (n = 6). The temporal delay of signal enhancement in all pixels of the time-resolved MRA measurement after contrast injection was evaluated and compared to dynamic susceptibility contrast-enhanced (DSC) perfusion imaging (n = 13).

RESULTS

Time-resolved MRA resulted in the diagnosis of large vessel disease in 14 of 19 patients, involving the internal carotids (n = 4), the vertebral arteries (n = 3), and the circle of Willis (n = 10). All severe vascular pathologies which influence patients' acute stroke therapy were obtained by time-resolved MRA. Overestimation of stenoses in two of 14 patients resulted in sensitivity and specificity of 100% and 71%, respectively. Time-to-peak (TTP) estimations were hampered by movement artifacts in four patients (31%). Compared to DSC, the area of TTP delay was comparable in size and localization without relevant overestimation or underestimation.

CONCLUSIONS

Time-resolved MRA is a valuable technique in patients with WUS with high sensitivity and high negative predictive value. Cerebral perfusion estimation can be performed in selected cases for therapy decision but can be hampered by patient movement.

State-of-the-art endovascular treatment of acute ischemic stroke

Stroke is the third leading cause of death in the USA. An estimated 795,000 new or recurrent stroke events occur annually, mostly ischemic in nature. Arterial recanalization and subsequent reperfusion performed shortly after symptom onset can help to restore brain function in acute ischemic stroke (AIS). The only treatment currently approved by the United States Food and Drug Administration is intravenous tissue plasminogen activator, administered within 4.5 h of symptom onset. However, this short window often precludes effective intervention. Mechanical neurothrombectomy devices offer many potential advantages over pharmacologic thrombolysis, including more rapid achievement of recanalization, enhanced efficacy in treating large-vessel occlusions, and a potentially lower risk of hemorrhagic events. The goal of this chapter is to describe the state-of-the-art neurothrombectomy devices and stenting techniques for endovascular treatment of acute ischemic stroke, as well as to highlight recent advances in reperfusion therapies. Ongoing clinical trials, some with randomized, controlled designs, are included.

Stroke unit management and revascularisation in acute ischemic stroke

BACKGROUND

Stroke affects one in six people throughout their lifetimes and is the most frequent cause of disability in adults. Several recanalization therapies have emerged and the management of patients in stroke units has improved over the last decades.

SUMMARY

This article examines the current treatment options for stroke patients, summarizing the key clinical evidence, as well as listing the complications and practical issues related to each of these main treatment options.

KEY MESSAGES

Recent advances in the treatment of acute stroke include developments in intravenous thrombolysis (IVT), intra-arterial treatment and bridging therapies.

CLINICAL IMPLICATIONS

Treatment within a stroke unit reduces mortality and disability regardless of age, sex and stroke severity. IVT is widely available and reduces disability when initiated within 4.5 h after the onset of symptoms. The major limitations of IVT are the low recanalization rates and the narrow time frame. Intra-arterial treatment, especially when using newly developed stent-retrievers, achieves very high recanalization rates. It is restricted by its limited availability and by the longer time span required to initiate therapy. Bridging both therapies is a promising approach that combines the advantages of both therapies, but the superiority of this approach remains to be proven. Future strategies to reduce the burden of acute stroke in Europe should focus on immediate access to acute stroke care and dedicated stroke units for all patients.

Minimally invasive and rapid surgical embolectomy (MIRSE) as rescue treatment following failed endovascular recanalization for acute ischemic stroke

BACKGROUND

An intra-arterial (IA) mechanical thrombectomy has increased the recanalization rates for acute occlusion of proximal intracranial arteries. However, the current failure rate of endovascular recanalization remains at approximately 10%, resulting in the need for surgical rescue treatment. The authors applied a minimally invasive and rapid surgical embolectomy (MIRSE) as a final rescue treatment after the failure of endovascular recanalization, and investigated the incidence, technical feasibility, and treatment results.

METHODS

For two years, from 2012 to 2013, a total of 131 patients with acute occlusion of proximal intracranial arteries underwent an IA mechanical thrombectomy using a Penumbra System and a Solitaire stent, yet ten (7.6%) patients still experienced final recanalization failure. Four (40%) of these ten patients subsequently underwent a MIRSE consisting of a superciliary keyhole approach, arteriotomy to remove the embolus, and arteriotomy repair techniques using aneurysm clips as the final repair material, or a temporary compartmentalizing clip.

RESULTS

Four patients aged 39 to 78 years with an embolic occlusion in the middle cerebral artery (n = 1) and internal carotid artery (n = 3) were treated using a MIRSE. Complete recanalization was achieved in all four patients, and the time from skin incision to reperfusion was 40-50 minutes. The modified Rankin Scale (mRS) scores at 3 months after surgery were 1 (n = 2), 2 (n = 1), and 3 (n = 1), respectively.

CONCLUSIONS

A MIRSE can be an effective rescue treatment after the failure of endovascular recanalization therapies for acute occlusion of proximal intracranial arteries if the patient is within the therapeutic time window.

Intra-arterial therapy as a rescue strategy after clinically failed intravenous thrombolysis may increase the likelihood of a good outcome in patients with severe ischaemic stroke. A retrospective two centre study

The purpose of this study was to evaluate the efficacy and safety of intra-arterial therapy as a rescue strategy after clinically failed intravenous thrombolysis (IVT) in acute ischaemic stroke patients. We conducted a retrospective analysis of consecutive acute ischaemic stroke patients treated with rescue therapy. The results from this study group were compared with those obtained from a control group consisting of 260 consecutive patients treated with IVT alone. The study group consisted of 52 patients with a mean age of 63 years and a median NIHSS score at admission of 17. Recanalization was achieved in 92% with a symptomatic haemorrhage rate of 9.6%. Rescue patients admitted with a severe stroke (NIHSS score >12) had a significantly better outcome at 90 days compared to patients with the same score but treated with IVT alone. No difference was seen for patients with a lower score at admission. This study indicates that rescue therapy may increase the proportion of patients with independent outcome if presenting with a severe stroke (NIHSS score >12) without increasing the rate of symptomatic haemorrhage.

Diagnostic Value of Thrombus Size on T2(*)-weighted Gradient Echo Imaging in Acute Middle Cerebral Artery Occlusion

Objective

The T2^*-weighted gradient echo image susceptibility vessel sign (GRE SVS) is a well-known indicator of intraluminal thrombi in acute cerebral infarction. The purpose of this study was to evaluate the relationships between thrombus size on GRE SVS and recanalization after intravenous administration of tissue plasminogen activator (IV-tPA).

Materials and Methods

Fifty five patients with GRE SVSs on the M1 were enrolled. Examination of magnetic resonance image (MRI), including diffusion weighted imaging and MR angiography, was performed within 20 minutes of admission. Thrombus size on GRE was calculated using the Picture Archiving and Communication System upon initial MRI. Recanalization was assessed with follow-up MRI or transfemoral cerebral angiography within 24 hours of treatment.

Results

The patient group consisted of 37 males and 18 females with an average age of 63.74 ± 10.28 years (range: 43 - 77 years). The median NIHSS score was 13. Fifteen of these patients achieved recanalization (27.3%). The average thrombus cross-sectional area in the recanalization group was 38.54 ± 20.27 mm², and the corresponding size of the non-recanalization group was 53.38 ± 24.77 mm² (p = 0.043). In the receiver operator characteristic curve for thrombus cross-sectional area in relation to recanalization, the cut-off point was 47.28 mm². The sensitivity at this cut-off point was 73.3%, the specificity was 60%, and the area under the curve was 0.687.

Conclusion

Thrombus size on GRE is a simple diagnostic tool that can be easily measured, and thrombus size on GRE SVS was found to be associated with recanalization after IV-tPA.

Current Reperfusion Strategies for Acute Stroke

Stroke is the most common cause of permanent disability, the second most common cause of dementia, and the third most common cause of death in the Western world. The treatment of affected patients is a challenge because intravenous (IV) thrombolysis is often ineffective. IV thrombolysis on its own leads to a favorable clinical outcome in only 15% to 25% in patients with large-artery occlusion. Current reperfusion therapies enable high recanalization rates, high rate of favorable clinical outcome, and low complication rates. However, to achieve good clinical results, appropriate patient selection and the use of optimized stroke management system are obligate.

A feasibility study on femtosecond laser thrombolysis

OBJECTIVE

In this feasibility study, we investigate possible femtosecond laser thrombolysis.

BACKGROUND DATA

Because of low pulse energies, femtosecond laser surgery inherently minimizes side effects on the surrounding tissue. Moreover, current femtosecond laser sources as well as fiber technology allow consideration of catheter-based treatments.

METHODS

Two femtosecond laser systems (λ=800 nm, λ=1030 nm) along with a three dimensional (3D) scanner system (NA ~0.1) were used in this study. In vitro experiments were performed on porcine thrombi and blood vessels. Ablation thresholds were determined in air, by determining the pulse energy at which single shot ablation was visible under the optical microscope. Ablation rates were determined in physiological saline. Additionally, ablation of thrombi and blood vessels was monitored by means of a fiber spectrometer.

RESULTS

Depending upon the scan velocity, typical ablation rates for thrombi were ~0.04 mm(3)/sec. Ablation thresholds of thrombi and blood vessels differ by factors of 3 and 1.5 at laser wavelengths of 800 and 1030 nm, respectively. At a distance of 5 mm above the surface, second harmonic generation was observed in blood vessels, but not within thrombi.

CONCLUSIONS

The results show that a typical thrombus volume can be destroyed within a reasonable time frame. Because of the higher threshold difference of thrombi and blood vessels, the use of a laser wavelength of 800 nm is preferable. Furthermore, the detection of the second harmonic could provide a feedback mechanism to protect the vascular wall from mechanical and laser damage.

Switching strategy for mechanical thrombectomy of acute large vessel occlusion in the anterior circulation

BACKGROUND AND PURPOSE

We introduce the concept of a switching strategy for mechanical thrombectomy with period-to-period analysis. In period 1, forced arterial suction thrombectomy with a Penumbra reperfusion catheter was performed, even in difficult cases; in period 2, forced arterial suction thrombectomy was initially performed, with switching to Solitaire in difficult cases.

METHODS

We analyzed 135 consecutive patients treated with mechanical thrombectomy with acute large vessel occlusion in the anterior circulation, 61 from period 1 and 74 from period 2. We defined difficult case for both periods as ≥3 failed attempts at recanalization.

RESULTS

Period 2 showed a trend for better angiographic outcome of Thrombolysis in Cerebral Infarction 2b-3 (73.8%, period 1 versus 85.1%, period 2; P=0.10). In interperiod subgroup analysis of difficult cases, switching significantly outperformed nonswitching in Thrombolysis in Cerebral Infarction 2b-3 recanalization (52.7% versus 82.9%; P=0.030). Differences in puncture-to-recanalization time, symptomatic intracranial hemorrhage incidence, and procedure-related complications were not statistically significant.

CONCLUSIONS

A switching strategy using 2 mechanical thrombectomy techniques (forced arterial suction thrombectomy to Solitaire) may harbor better angiographic outcomes than a 1 technique only strategy (forced arterial suction thrombectomy).

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.

The Limitations of Thrombectomy with Solitaire™ AB as First-line Treatment in Acute Ischemic Stroke: A Single Center Experience

Objective

A self-expanding retrievable intracranial stent, such as Solitaire AB, is useful for mechanical thrombectomy, producing novel results in the treatment of acute ischemic stroke. On the other hand, difficult situations can arise after a thrombectomy when using as in first-line treatment.

Methods

This was a retrospective, single-center study of 23 patients with an acute ischemic stroke attributable to a large artery occlusion within the first eight hours from symptom onset. The occlusion sites were the T segment in five patients, proximal middle cerebral artery in six patients, distal middle cerebral artery in three patients, vertebral and/or basilar artery in five patients, proximal internal cerebral artery in one patient and tandem in three patients. All patients underwent a mechanical thrombectomy using the Solitaire™ stent system as the first-line treatment but required additional procedures due to the unsatisfactory results of a thrombectomy.

Results

Only six patients achieved complete recanalization by a thrombectomy using the Solitaire. Permanent stent deployment after the thrombectomy was performed in ten patients. Stent and balloon angioplasty was performed after a stent-based thrombectomy in six patients. Balloon angioplasty after thrombectomy was performed in one patient.

Conclusion

Mechanical thrombectomy with the Solitaire™ stent as a first-line treatment can produce unfortunate results that will require additional procedures.

The hyperdense vessel sign on CT predicts successful recanalization with the Merci device in acute ischemic stroke

BACKGROUND

The success of mechanical clot retrieval for acute ischemic stroke may be influenced by the characteristics of the occlusive thrombus. The thrombus can be partly characterized by CT, as the hyperdense vessel sign (HVS) suggests erythrocyte-rich clot whereas fibrin-rich clot may be isodense. We hypothesized that the physical clot characteristics that determine CT density may also determine likelihood of retrieval with the Merci device.

METHODS

We reviewed all acute stroke cases initially imaged with non-contrast CT before attempted Merci clot retrieval at a single center between 2004 and 2010. Each CT was blindly assessed for the presence or absence of the HVS, and post-retrieval angiograms were blindly assessed for reperfusion using the TICI scale.

RESULTS

Of 67 patients analyzed (mean age 69; median NIHSS 19; 61% female), the HVS was seen in 42, and no HVS was present in 25. Successful recanalization was achieved in 79% of patients with the HVS (33/42), but in only 36% (9/25) of patients without HVS (p=0.001). The HVS was the only significant predictor of recanalization while accounting for age, treatment with IV-tPA, clot location, stroke etiology, time to treatment, and number of retrieval attempts.

CONCLUSION

The HVS in acute ischemic stroke was strongly predictive of successful recanalization using the Merci device. The HVS may indicate thrombi that are less adhesive compared with isodense clots that are more resistant to mechanical retrieval. The absence of HVS on pre-treatment CT may thus suggest the need for a more aggressive or alternative therapeutic approach.