Evolution of thrombectomy approaches and devices for acute stroke: a technical review

Current Approaches and Methods to Understand Acute Ischemic Stroke Treatment Using Aspiration Thrombectomy

Acute ischemic stroke occurs when a blood clot occludes a cerebral artery. Mechanical interventions, primarily stent retrievers and aspiration thrombectomy, are used currently for removing the occluding clot and restoring blood flow. Aspiration involves using a long catheter to traverse the cerebral vasculature to reach the blood clot, followed by application of suction through the catheter bore. Aspiration is also used in conjunction with other techniques such as stent retrievers and balloon guide catheters. Despite the wide use of aspiration, our physical understanding of the process and the causes of the failure of aspiration to retrieve cerebral clots in certain scenarios is not well understood. Experimental and computational studies can help develop the capability to provide deeper insights into the procedure and enable development of new devices and more effective treatment methods. We recapitulate the aspiration-based thrombectomy techniques in clinical practice and provide a perspective of existing engineering methods for aspiration. We articulate the current knowledge gap in the understanding of aspiration and highlight possible directions for future engineering studies to bridge this gap, help clinical translation of engineering studies, and develop new patient-specific stroke therapy.

Comparison of 4 mm-sized and 3 mm-sized Stent Retrievers in Mechanical Thrombectomy for M2 Occlusion

INTRODUCTION

A stent retriever (SR) is widely used in mechanical thrombectomy (MT) for M2 segment occlusion. However, the suitable size of SR in M2 occlusion remains unclear. Therefore, we aimed to compare 4 mm-sized SR with 3 mm-sized SR in M2 occlusion.

METHODS

Patients who underwent MT with SR for M2 occlusion were dichotomized into 4×20 mm SR and 3×20 mm SR groups. Then, 1:1 propensity score matching was performed. The M2 segment was divided into proximal and distal segments according to the occlusion site. Subgroup analysis was then performed for each cohort.

RESULTS

A total of 111 patients were enrolled, with 4×20 mm SR and 3×20 mm SR applied in 72 (64.9%) and 39 (35.1%) cases, respectively. In propensity score matching, mean number of stent passages for reperfusion was significantly lower in the 4×20 mm SR group than in the 3×20 mm SR group (1.5 ± 0.8 vs. 2.1 ± 1.1; p = 0.004). First-pass reperfusion (FPR) was more highly achieved in the 4×20 mm SR group than in the 3×20 mm SR group (52.6% vs. 42.1%; p = 0.007). In both proximal and distal occlusion cohorts, the 4 mm SR group showed lower mean number of SR passage (p = 0.004 and p = 0.003, respectively) and higher FPR rate than the 3 mm SR group (p = 0.003 and p = 0.007, respectively).

CONCLUSION

In MT for M2 occlusion, 4×20 mm SR enables an effective procedure with lesser SR passage for reperfusion and a higher rate of FPR than 3×20 mm SR.

In vitro testing of a funnel-tip catheter with different clot types to decrease clot migration in mechanical thrombectomy

BACKGROUND

Mechanical thrombectomy is the standard treatment for acute ischemic stroke in patients with large vessel occlusion and can be performed up to 24h after symptom onset. Despite high recanalization rates, embolism in new territories has been reported in 8.6% of the cases. Causes for this could be clot abruption during stent retrieval into the smaller opening of a standard distal access catheter, and antegrade blood flow via collaterals despite proximal balloon protection. A funnel-shaped tip with a larger internal diameter was developed to increase the rate of first-pass recanalization and to improve the safety and efficacy of mechanical thrombectomy.

METHODS

This in vitro study compared the efficacy of a funnel-shaped tip with a standard tip in combination with different clot compositions. Mechanical thrombectomy was performed 80 times for each tip, using two stent retrievers (Trevo XP ProVue 3/20 mm, 4/20 mm) and four different clot types (hard vs. soft clots, 0-24h vs. 72h aged clots).

RESULTS

Significantly higher first-pass recanalization rates (mTICI 3) were observed for the funnel-shaped tip, 70.0% versus 30.0% for the standard tip (absolute difference, 32; relative difference 57.1%; P < .001), regardless of the clot type and stent retriever. Recanalization could be increased using harder Chandler loop clots versus softer statically generated clots, as well as 0-24h versus 72h aged clots, respectively.

CONCLUSION

The funnel-shaped tip achieved higher first-pass recanalization rates than the smaller standard tip and lower rates of clot abruption at the tip. Clot compositions and aging times impacted recanalization rates.

Mechanical thrombectomy with a new intermediate balloon catheter combining the BGC and DAC features: Initial clinical experience with the iNedit device

INTRODUCTION

The iNedit balloon distal access catheter is a novel thrombectomy device. It has an inner diameter of 0.058″, proximal outer diameter of 2.13 mm, and distal outer diameter of 1.67mm. It is compatible with a 0.088″ guide catheter and includes a balloon located 5 cm from the catheter tip, enabling proximal flow restriction and combined therapy with stent retrievers. We investigate the appraisal of the use, safety, and efficacy of the iNedit catheter in the first-in-human study.

METHODS

In the preliminary cases that demanded training on the product previous to a multicentric study, prospective data were collected on 22 consecutive patients treated with the iNedit catheter to perform thrombectomy for acute ischemic stroke due to large vessel occlusion within 24 h. The outcome measures consisted of several evaluations of user experience rated on a 5-point scale ranging from 1 (bad) to 5 (excellent), as well as assessments of procedural safety outcomes such as artery perforation and arterial occlusion, procedural efficacy outcomes including first-pass effect (Thrombolysis In Cerebral Infarction [TICI] 2c/3) and final recanalization (TICI 2b/3), and clinical efficacy outcomes such as a 3-month 0-2 modified Rankin Scale (mRS).

RESULTS

The mean age was 72 ± 12 years old; median National Institute Health Stroke Scale was 17 (11-19). Sites of primary occlusion were: 2 internal carotid artery, 12 M1-MCA, 7 M2-MCA, and one P1. Median score evaluation of the appraisal of use was 4- IQR [4-5]. The median number of passes was 1 [IQR 1-2]. First pass complete recanalization rate was 50% and the final recanalization rate was 94.45%. No artery perforation and arterial occlusion. Good functional outcome mRS 0-2 was achieved in 50% of patients.

CONCLUSIONS

In this initial clinical experience, iNedit device achieved a high rate of first-pass effect and final recanalization rate with no safety concerns, thus favoring a high percentage of good clinical outcomes.

Aristotle 24 microwire early experience

Larger microcatheters are being used with increasing frequency in routine neurovascular procedures. Navigating catheters safely and effectively to the target intracranial vessels can be a challenge when using conventional 0.014″ microwires. A new family of 0.024″ Aristotle 24 microwires (Scientia Vascular, West Valley City, UT) specifically designed for intracranial navigation were recently introduced. These microwires offer significant technical advantages over the standard 0.014″ microwires, including a reduced ledge gap, improved torquability and support, and overall safety. This video case series contains several illustrative cases to demonstrate the features of the novel Aristotle 24 microwire for use in endovascular neurointervention.

Impact of aspiration catheter size on clinical outcomes in aspiration thrombectomy

BACKGROUND

Direct aspiration thrombectomy is a well-established method for mechanical thrombectomy in acute ischemic stroke. Yet, the influence of aspiration catheter internal diameter (ID) on aspiration thrombectomy efficacy is incompletely understood.

METHODS

A systematic literature review and meta-regression analysis was completed to evaluate the impact of primary aspiration thrombectomy outcomes based on the ID of the aspiration catheter. Primary outcome measures were: final recanalization of modified Thrombolysis In Cerebral Ischemia (mTICI) 2b-3 with aspiration only and with rescue modalities, first pass effect (FPE), need for rescue modalities, intracranial hemorrhagic complication rates, and functional outcomes of 90-day modified Rankin Scale (mRS) of 0-2.

RESULTS

30 studies were identified with 3228 patients. Meta-regression analysis revealed a significant association between increasing aspiration catheter ID and FPE (p=0.032), between ID and final recanalization with aspiration only (p=0.05), and between ID size and recanalization including cases with rescue modalities (p=0.002). Further, subgroup analysis indicated that catheters with an ID ≥0.064 inch had a lower rate of need for rescue than smaller catheters (p=0.013). Additionally, catheters with an ID ≥0.068 inch had a higher rate of intracranial bleeding complications (p=0.025). Lastly, no significant association was found in functional outcomes overall.

CONCLUSIONS

Larger aspiration catheters are associated with a higher rate of FPE, final recanalization with only an aspiration catheter, and in cases with rescue modalities, though with a higher rate of hemorrhagic complications. These findings confirm that aspiration catheter size functions as a variable in aspiration thrombectomy, which should be considered in future study and trial design.

Meniscus Sign in Patients with Anterior Circulation Large Vessel Occlusion Stroke does not Predict Outcome

PURPOSE

The angiographic appearance of the occlusion site was suggested to influence outcomes of stroke patients with large vessel occlusion (LVO) who undergo endovascular treatment (EVT). We aimed to study the impact of the meniscus sign (MS) on outcomes of stroke patients with anterior circulation LVO.

METHODS

Based on two prospective registries of acute ischemic stroke, we selected patients with carotid‑T, M1 or M2 occlusion who underwent EVT. Clinical characteristics and outcomes were collected from the registries or from individual records. Two independent observers blinded to outcomes assessed the presence of MS in digital subtraction angiography before thrombectomy. Angiographic and clinical outcomes of patients with and without MS were compared.

RESULTS

We included 903 patients, with median age of 78 years, 59.8% were male, median baseline NIHSS was 14 and 39.5% received intravenous thrombolysis. Patients with MS (n = 170, 18.8%) were more frequently female, presented with higher NIHSS scores and more frequently underwent intravenous thrombolysis. Presence of MS was significantly associated with cardioembolic etiology. Successful reperfusion, number of passes, first pass effect, procedural time, symptomatic intracerebral hemorrhage, in-hospital mortality and favorable 3‑month functional outcome were similar in the groups of patients with and without MS. In the multivariable analyses, MS was not associated with successful reperfusion (odds ratio, OR = 1.08, 95% confidence interval, CI = 0.76-1.55), first pass effect (OR = 0.96, 95%CI = 0.48-1.92) or favorable 3‑month outcome (OR = 1.40, 95%CI = 0.88-2.24).

CONCLUSION

The presence of MS in acute ischemic stroke patients with anterior circulation large vessel occlusion who undergo EVT does not appear to influence angiographic or clinical outcomes.

Endovascular treatment for acute ischaemic stroke due to medium vessel occlusion: data from ANGEL-ACT registry

OBJECTIVES

To investigate the safety and efficacy of endovascular treatment (EVT) for acute medium vessel occlusion (MeVO) in the anterior circulation and to explore the independent predictors of the 90-day good outcome for such patients.

METHODS

Data from ANGEL-ACT Registry were analysed in our study. The outcomes, such as the modified Rankin Scale (mRS) at 90 days, successful recanalisation rate and symptomatic intracranial haemorrhage (SICH) rate, were compared between MeVO and acute large vessel occlusions (LVO). Then, the independent predictors of the good outcome at 90 days in MeVO patients were determined by the logistic regression analyses.

RESULTS

We included 1032 subjects in the analysis, of which, 147 were MeVO and 885 were LVO. mRS at 90 days distribution (3 (0-4) vs 3 (0-5), common odds ratio (OR) =1.00, 95% confidence interval (CI) 0.73 to 1.38, p=0.994), SICH rate (4.8% vs 8.9%; OR=0.59, 95% CI 0.26 to 1.34, p=0.205) and successful recanalisation rate (89.8% vs 89.7%; OR=1.00 95% CI 0.51 to 1.93, p=0.992) were similar between the MeVO and LVO groups after adjusting for the confounders. We identified that baseline neutrophil-to-lymphocyte ratio ≤4.1 (OR=2.13, 95% CI 1.14 to 3.99, p=0.019), baseline National Institutes of Health Stroke Scale ≤14 (OR=1.96, 95% CI 1.02 to 3.80, p=0.045) and mechanical thrombectomy passes ≤1 (OR=2.16, 95% CI 1.14 to 4.11, p=0.021) were independent predictors of the 90-day good outcome in MeVO patients undergoing EVT.

CONCLUSIONS

Patients with MeVO achieved similar 90-day mRS, SICH rate and successful recanalisation rate after EVT compared with patients with LVO. Several independent predictors of 90-day good outcome in MeVO patients undergoing EVT were determined, which should be highly considered in MeVO stroke management.

REACT Aspiration Catheters: Clinical Experience and Technical Considerations

Aspiration catheters are widely used in mechanical thrombectomy procedures to treat acute ischemic stroke due to large vessel occlusion. The key performance requirements for aspiration catheters are ease of navigation and effective aspiration. In this work, we review the clinical experience and in vitro studies of REACT aspiration catheters (Medtronic, Minneapolis, MN, USA). In vitro experiments showed that REACT catheters exhibit solid performance in navigation and aspiration. Previous studies reported that the recanalization capacity of the aspiration catheters can be influenced by the devices’ inner diameter and tip distensibility, the catheter-to-vessel diameter ratio, the negative pressure delivered by the vacuum generator, the cyclical aspiration mode, the proximal flow arrest, and the angle of interaction between catheter and clot. REACT catheters can be navigated through the vasculature without any support from a microcatheter/ microwire in favorable anatomical configurations. In challenging situations, mostly encountered when crossing the ophthalmic segment of the internal carotid artery, the use of the stentriever anchoring technique or delivery assist catheter can facilitate the navigation. Three clinical studies reporting on 299 patients who underwent mechanical thrombectomy with REACT catheters were included in this review. Successful recanalization (modified treatment in cerebral ischemia score 2b–3) was achieved in 89–96% of cases, no procedural complications related to REACT catheters were reported, and functional independence (modified Rankin Scale 0–2) at 90-days was 24–36%. In vitro experimental evaluations and clinical studies support the safety and effectiveness of the REACT catheters.

Acute embolic stroke with large-vessel occlusion: does contact aspiration thrombectomy show superiority?

AIM

To compare the efficacy between contact aspiration thrombectomy and stent retriever thrombectomy in the treatment of acute embolic stroke patients with large vessel occlusion.

MATERIALS AND METHODS

Between January 2019 and June 2020, data from consecutive acute ischaemic stroke patients who underwent either endovascular contact aspiration or stent retriever thrombectomy were analysed at one institution. The primary outcome was the full 90-day modified Rankin Scale (mRS) score. Ordinal logistic regression analysis was used to assess the association between thrombectomy approach and functional outcomes.

RESULTS

A total of 156 patients were analysed. Among them, 57 (36.5%) patients underwent primary aspiration thrombectomy, while 99 (63.5%) patients underwent primary stent retriever thrombectomy. The median procedure time was significantly shorter in patients treated with aspiration (37 versus 56 minutes; p<0.001). Compared with those of patients who underwent stent retriever thrombectomy, successful recanalisation rates and favourable functional outcome rates were higher in patients who underwent the aspiration approach (94.7% versus 77.8%, p=0.006; 49.1% versus 27.3%, p=0.006, respectively). Ordinal logistic regression analysis showed that aspiration thrombectomy was independently associated with a good functional outcome (adjusted common odds ratio, 0.30, 95% confidence interval: 0.16-0.60, p<0.001).

CONCLUSION

Among the specific patients with large vessel occlusion in acute embolic stroke, the use of aspiration thrombectomy compared with stent retriever thrombectomy resulted in a greater likelihood of favourable neurological outcomes; however, because of study limitations, these findings should be interpreted as preliminary and require further study to confirm these results.

Use of the Rocket Technique after Failure of the Direct Aspiration First-Pass Technique in Acute Stroke Thrombectomy

The technical feasibility of the rocket technique was evaluated for patients treated for stroke where the direct aspiration first-pass technique (ADAPT) failed to reach the occlusion site. This single-center retrospective study included data on consecutive patients with a large vessel occlusion of the anterior circulation who underwent mechanical thrombectomy. Of 138 patients, 100 met the inclusion criteria. In 84 patients, a large 0.072-inch inner lumen aspiration catheter was able to reach the occlusion site when deployed with a coaxial microcatheter. In 16 patients, this technique failed, and the microcatheter was replaced with a compliant balloon inflated at the extremity of the aspiration catheter (rocket technique). In 15 of these 16 patients, the rocket technique brought the catheter into contact with the thrombus. In conclusion, when deployment of the ADAPT with a coaxial microcatheter fails to reach the clot site, the rocket technique can safely advance the aspiration catheter to the clot.

Trackability of distal access catheters: an in vitro quantitative evaluation of navigation strategies

BACKGROUND

In mechanical thrombectomy (MT), distal access catheters (DACs) are tracked through the vascular anatomy to reach the occlusion site. The inability of DACs to reach the occlusion site has been reported as a predictor of unsuccessful recanalization. This study aims to provide insight into how to navigate devices through the vascular anatomy with minimal track forces, since higher forces may imply more risk of vascular injuries.

METHODS

We designed an experimental setup to monitor DAC track forces when navigating through an in vitro anatomical model. Experiments were recorded to study mechanical behaviors such as tension buildup against vessel walls, DAC buckling, and abrupt advancements. A multiple regression analysis was performed to predict track forces from the catheters' design specifications.

RESULTS

DACs were successfully delivered to the target M1 in 60 of 63 in vitro experiments (95.2%). Compared to navigation with unsupported DAC, the concomitant coaxial use of a microcatheter/microguidewire and microcatheter/stent retriever anchoring significantly reduced the track forces by about 63% and 77%, respectively (p<0.01). The presence of the braid pattern in the reinforcement significantly reduced the track forces regardless of the technique used (p<0.05). Combined coil and braid reinforcement configuration, as compared with coil alone, and a thinner distal wall were predictors of lower track force when navigating with unsupported DAC.

CONCLUSIONS

The use of microcatheter and stent retriever facilitate smooth navigation of DACs through the vascular tortuosity to reach the occlusion site, which in turn improves the reliability of tracking when positioning the DAC closer to the thrombus interface.

Aspiration thrombectomy using a novel 088 catheter and specialized delivery catheter

BACKGROUND

We describe the first-in-human experience using the Route 92 Medical Aspiration System to perform thrombectomy in the initial 45 consecutive stroke patients enrolled in the SUMMIT NZ trial. This aspiration system includes a specifically designed delivery catheter which enables delivery of 0.070 inch and 0.088 inch aspiration catheters.

METHODS

The SUMMIT NZ trial is a prospective, multicenter, single-arm study with core lab imaging adjudication. Patients presenting with acute ischemic stroke from large vessel occlusion are eligible to enrol. The study has had three phases which transitioned from use of the 0.070 inch to the 0.088 inch catheter.

RESULTS

Vessel occlusions were located in the internal carotid artery (27%), M1 (60%) and M2 (13%). Median baseline National Institutes of Health Stroke Scale (NIHSS) was 16 (IQR 10). Across the three phases, the first-pass reperfusion rate of modified Thrombolysis In Cerebral Infarction (mTICI) ≥2b was 62% using the Route 92 Medical system; this rate was 29% in phase 1, 56% in phase 2, and 80% in phase 3. The first-pass reperfusion rate of mTICI ≥2c was 42% overall, 29% in phase 1, 33% in phase 2, and 55% in phase 3. A final reperfusion rate of mTICI ≥2b was achieved in 96% of cases, with 36% of cases using adjunctive devices. Patients had an average improvement of 6.7 points in NIHSS from baseline at 24 hours, and at 90 days 48% were functionally independent (modified Rankin Scale 0-2).

CONCLUSIONS

In this early experience, the Route 92 Medical Aspiration System has been effective and safe. The system has design features that improve catheter deliverability and have the potential to increase first-pass reperfusion rates in aspiration thrombectomy.

Combined Approach to Stroke Thrombectomy Using a Novel Short Flexible Aspiration Catheter with a Stent Retriever : Preliminary Clinical Experience

BACKGROUND

Large-bore aspiration catheters enabling greater flow rates and suction force for mechanical thrombectomy might improve outcomes in patients with stroke secondary to large-vessel occlusion. Complete or near-complete reperfusion after a single thrombectomy pass (first-pass effect) is associated with improved clinical outcomes. We assessed the efficacy and safety of novel MIVI Q™ aspiration catheters in combination with stent-retriever devices.

METHODS

We retrospectively analyzed demographics, procedure characteristics, and clinical data from consecutive patients with acute anterior large-vessel occlusion treated with a combined approach using MIVI Q™ aspiration catheters and stent retrievers. Reperfusion was defined according to the modified thrombolysis in cerebral infarction (mTICI) score. Clinical outcomes were measured by the National Institute of Health Stroke Scale (NIHSS) and modified Rankin scale (mRS) scores.

RESULTS

We included 52 patients (median age, 75 y IQR: 64-83); 31 (59.6%) women; 14 (26.9%) with terminal internal carotid artery occlusions, 26 (50%) middle cerebral artery (MCA) segment M1 occlusions, and 12 (23.1%) MCA segment M2 occlusions; median NIHSS score at admission was 19 (IQR: 13-22). After the first pass, 25 (48%) patients had mTICI ≥ 2c. At the end of the procedure, 47 (90.4%) had mTICI ≥ 2b and 35 (67.3%) had mTICI ≥ 2c. No serious device-related adverse events were observed. Symptomatic intracranial hemorrhage developed in 1 patient. Mean NIHSS score was 13 at 24 h and 5 at discharge. At 90 days, 24 (46.2%) patients were functionally independent (mRS 0-2).

CONCLUSION

This preliminary study found good efficacy and safety for MIVI Q™ aspiration catheters used in combination with stent-retriever devices.

Comparison of Risk Factors, Safety, and Efficacy Outcomes of Mechanical Thrombectomy in Posterior vs. Anterior Circulation Large Vessel Occlusion

Background and Purpose: It is believed that stroke occurring due to posterior circulation large vessel occlusion (PCLVO) and that occurring due to anterior circulation large vessel occlusion (ACLVO) differ in terms of their pathophysiology and the outcome of their acute management in relation to endovascular mechanical thrombectomy (MT). Limited sample size and few randomized controlled trials (RCTs) with respect to PCLVO make the safety and efficacy of MT, which has been confirmed in ACLVO, difficult to assess in the posterior circulation. We therefore conducted a meta-analysis to study to which extent MT in PCLVO differs from ACLVO. Materials and Methods: We searched the databases PubMed, Cochrane, and EMBASE for studies published between 2010 and January 2021, with information on risk factors, safety, and efficacy outcomes of MT in PCLVO vs. ACLVO and conducted a systematic review and meta-analysis; we compared baseline characteristics, reperfusion treatment profiles [including rates of intravenous thrombolysis (IVT) and onset-to-IVT and onset-to-groin puncture times], recanalization success [Thrombolysis In Cerebral Infarction scale (TICI) 2b/3], symptomatic intracranial hemorrhage (sICH), and favorable functional outcome [modified Rankin Score (mRS) 0-2] and mortality at 90 days. Results: Sixteen studies with MT PCLVO (1,172 patients) and ACLVO (7,726 patients) were obtained from the search. The pooled estimates showed higher baseline National Institutes of Health Stroke Scale (NIHSS) score (SMD 0.32, 95% CI 0.15-0.48) in the PCLVO group. PCLVO patients received less often IVT (OR 0.65, 95% CI 0.53-0.79). Onset-to-IVT time (SMD 0.86, 95% CI 0.45-1.26) and onset-to-groin puncture time (SMD 0.59, 95% CI 0.33-0.85) were longer in the PCLVO group. The likelihood of obtaining successful recanalization and favorable functional outcome at 90 days was comparable between the two groups. PCLVO was, however, associated with less sICH (OR 0.56, 95% CI 0.37-0.85) but higher mortality (OR 1.92, 95% CI 1.46-2.53). Conclusions: This meta-analysis indicates that MT in PCLVO may be comparably efficient in obtaining successful recanalization and 90 day favorable functional outcome just as in ACLVO. Less sICH in MT-treated PCLVO patients might be the result of the lower IVT rate in this group. Higher baseline NIHSS and longer onset-to-IVT and onset-to-groin puncture times may have contributed to a higher 90 day mortality in PCLVO patients.

Suction force rather than aspiration flow correlates with recanalization in hard clots: an in vitro study model

BACKGROUND

ANA Advanced Neurovascular Access provides a novel funnel component designed to reduce clot fragmentation and facilitate retrieval in combination with stent-retrievers (SRs) in stroke patients by restricting flow and limiting clot shaving. In previous publications ANA presented excellent in vitro/in vivo efficacy data, especially with fibrin-rich hard clots. We aimed to determine the main physical property responsible for these results, namely suction force versus aspiration flow.

METHODS

We evaluated in a bench model the suction force and flow generated by ANA and compared them to other neurovascular catheters combined with a SR (Solitaire). Aspiration flow was evaluated with a flow rate sensor while applying vacuum pressure with a pump. Suction force was determined using a tensile strength testing machine and a purposely designed tool that completely seals the device tip simulating complete occlusion by a hard clot. Suction force was defined as the force needed to separate the device from the clot under aspiration. All experiments were repeated five times, and mean values used for comparisons.

RESULTS

Aspiration flow increased with the inner diameter of the device: ANA 1.85±0.04 mL/s, ACE68 3.74±0.05 mL/s, and 8F-Flowgate2 5.96±0.30 mL/s (P<0.001). After introducing the SR, the flow was reduced by an average of 0.57±0.12 mL/s. Due to its larger distal surface, ANA suction force (1.69±0.40 N) was significantly higher than ACE68 (0.26±0.04 N) and 8F-Flowgate2 (0.42±0.06 N) (P<0.001). After introducing the SR, suction force variation was not relevant except for ANA that increased to 2.64±0.41 N.

CONCLUSION

Despite lower in vitro aspiration flow, the ANA design showed a substantially higher suction force than other thrombectomy devices.

Development of a Novel Wasp-Inspired Friction-Based Tissue Transportation Device

Currently existing tubular transportation systems for the extraction of large tissue masses during Minimal Invasive Surgery (MIS) are subjected to a large amount of operating limitations. In this study, a novel transportation mechanism (patented) was developed inspired by the egg-laying structure of wasps. The developed mechanism consists of an outer tube within which six reciprocating semi-cylindrical blades are present and tissue is transported using a friction differential between the blades. Two motion sequences were developed: (1) 1–5 motion sequence, in which one blade moves forward, while the remaining five blades move backward and (2) 2–4 motion sequence, in which four blades move backward while two blades move forward. A proof-of-principle experiment was performed to investigate the effects of tissue elasticity, tissue heterogeneity, and the motion sequence on the transportation rate [mg/s], transportation efficiency [%], and transportation reliability [%]. The mean transportation rate and reliability was highest for the 9 wt% gelatine phantoms at 4.21 ± 0.74 mg/s and the 1–5 sequence at 100%, respectively. The prototype has shown that the friction-based transportation principle has the potential of becoming a viable and reliable alternative to aspiration as a transportation method within MIS.

Y-Stent Rescue Technique for Failed Thrombectomy in Patients With Large Vessel Occlusion: A Case Series and Pooled Analysis

Objective: Y-stent thrombectomy is a recent rescue technique for failed thrombectomy in patients with emergent large vessel occlusion. We presented case series of using Y-stent rescue technique at different sites and investigate its feasibility and safety through pooled analysis of collected case report or series. Methods: Twenty-eight cases were screened from stroke databank who underwent thrombectomy between January 2015 and June 2019. Clinical, procedural, and follow-up data were investigated and pooled analysis of published literature was analyzed. Results: The occlusion sites include carotid terminus in 14 patients; siphon segment in 3; middle cerebral artery (MCA) in 4; basilar terminus in 7. The overall recanalization rate reached 85.7% (arterial occlusive lesion score 2-3); and final reperfusion rate 85.7% (modified Thrombolysis in Cerebral Infarction 2b-3). After literature review, totally, 52 cases were included. Good clinical outcome was achieved in 26 (50%) and mortality in 7 (17.3%). There is no significant difference on the SAH complication at different sites. Literature review shows no difference between each site in the reperfusion and complication rate. Conclusion: Our case series results suggest that high recanalization rate can be effectively achieved with Y-stent rescue technique for patients with refractory emergent large vessel occlusion. The safety of using this technique at different sites needs further investigation for patients.

Implications of achieving TICI 2b vs TICI 3 reperfusion in patients with ischemic stroke: a cost-effectiveness analysis

BACKGROUND

The benefit of endovascular thrombectomy (EVT) in stroke patients with large-vessel occlusion (LVO) depends on the degree of recanalization achieved. We aimed to determine the health outcomes and cost implications of achieving TICI 2b vs TICI 3 reperfusion in acute stroke patients with LVO.

METHODS

A decision-analytic study was performed with Markov modeling to estimate the lifetime quality-adjusted life years (QALY) of EVT-treated patients, and costs based on the degree of reperfusion achieved. The study was performed with a societal perspective in the United States' setting. The base case calculations were performed in three age groups: 55-, 65-, and 75-year-old patients.

RESULTS

Within 90 days, achieving TICI 3 resulted in a cost saving of $3676 per patient and health benefit of 11 days in perfect health as compared with TICI 2b. In the long term, for the three age groups, achieving TICI 3 resulted in cost savings of $46,498, $25,832, and $15 719 respectively, and health benefits of 2.14 QALYs, 1.71 QALYs, and 1.23 QALYs. Every 1% increase in TICI 3 in 55-year-old patients nationwide resulted in a cost saving of $3.4 million and a health benefit of 156 QALYs. Among 65-year-old patients, the corresponding cost savings and health benefit were $1.9 million and 125 QALYs.

CONCLUSION

There are substantial cost and health implications in achieving complete vs incomplete reperfusion after EVT. Our study provides a framework to assess the cost-benefit analysis of emerging diagnostic and therapeutic techniques that might improve patient selection, and increase the chances of achieving complete reperfusion.

Analysis of the Anatomical Factors Affecting Ability to Navigate Penumbra Catheter through Internal Carotid Siphon

Objective

The efficacy and safety of aspiration thrombectomy using Penumbra catheter with acute large vessel occlusion in the anterior circulation have been reported in previous studies. In some cases, the carotid siphon (CS) is elongated, and with this anatomy, especially where there is bifurcation of the ophthalmic artery (OA), navigation of Penumbra catheters into distal internal carotid artery (ICA) is interrupted, which is known as the 'ledge effect'. We investigate the anatomical characteristics of CS that cause interruption of navigation of the Penumbra catheter.

Methods

Between January 2015 and March 2018, mechanical thrombectomy using Penumbra 60 was performed on 51 patients with middle cerebral artery (MCA) or intracranial ICA occlusion. Patients were divided into two groups: The 'ledge-effect' group those in whom the Penumbra catheter was unable to be navigated into the distal ICA through the CS, and 'no ledge-effect' group those in whom this was possible. The anatomical characteristics of CS, the diameter of ICA, diameter of OA, OA/ICA ratio and radius of the CS were evaluated using angiographical imaging.

Results

The 'ledge-effect' group numbered eight cases (17%). Only the value of the CS radius was significantly smaller in the ledge-effect group (p = 0.0019), other parameters were not significantly different between the groups. The cutoff radius value was 3.62 mm.

Conclusion

The most notable anatomical factor affecting possibility of navigation of the Penumbra catheter through the CS was the CS radius. This could be useful information when devices used in mechanical thrombectomy are selected.

Comparative Safety and Efficacy of Modified TICI 2b and TICI 3 Reperfusion in Acute Ischemic Strokes Treated With Mechanical Thrombectomy

BACKGROUND

Mechanical thrombectomy (MT) is the current standard of care for acute ischemic stroke (AIS) patients with emergent large-vessel occlusions (ELVO). Successful reperfusion of ELVO is traditionally defined by modified Thrombolysis in Cerebral Infarction (mTICI) grades of 2b or 3.

OBJECTIVE

To evaluate the comparative safety and efficacy of mTICI 2b and mTICI 3 reperfusion in AIS patients treated with MT.

METHODS

Consecutive ELVO patients who underwent MT at 6 high-volume centers were included in this analysis. Standard safety (3-mo mortality, symptomatic intracranial hemorrhage [sICH]) and efficacy (absolute and relative reduction in NIHSS-scores during hospitalization, functional-improvement [shift analysis in mRS-scores], and functional-independence [mRS-scores of 0-2] at 3-mo) were compared between patients who had mTICI 2b and mTICI 3 reperfusion post MT.

RESULTS

A total of 416 ELVO patients achieved successful reperfusion with mTICI 2b (n = 216) and mTICI 3 (n = 200) following MT. The mTICI 3 group had significantly (P < .05) greater absolute (11 vs 9 points) and relative (77% vs 63%) reduction in NIHSS-scores during hospitalization, lower sICH (6% vs 12%), and higher 3-mo functional-independence (55% vs 44%) rates. Successful reperfusion with mTICI 3 was independently (P < .05) associated with greater absolute and relative reduction in NIHSS-scores during hospitalization as well as higher odds of 3-mo functional improvement (common odds ratios: 1.67; 95% confidence interval: 1.10-2.56) and functional independence (odds ratio: 2.08; 95% confidence interval: 1.22-3.53) in multivariable regression models adjusting for confounders.

CONCLUSION

Successful reperfusion with mTICI 3 was associated with greater neurological improvement during hospitalization and better 3-mo functional outcomes in comparison to mTICI 2b reperfusion.

Anesthetic Management of Emergency Endovascular Thrombectomy for Acute Ischemic Stroke, Part 1: Patient Characteristics, Determinants of Effectiveness, and Effect of Blood Pressure on Outcome

In the United States, stroke ranks fifth among all causes of death and is the leading cause of serious long-term disability. The 2018 American Heart Association stroke care guidelines consider endovascular thrombectomy to be the standard of care for patients who have acute ischemic stroke in the anterior circulation when arterial puncture can be made within 6 hours of symptom onset or within 6-24 hours of symptom onset when specific eligibility criteria are satisfied. The aim of this 2-part review is to provide practical perspective on the clinical literature regarding anesthesia care of patients treated with endovascular thrombectomy. Part 1 (this article) reviews the development of endovascular thrombectomy and the determinants of endovascular thrombectomy effectiveness irrespective of method of anesthesia. The first aim of part 1 is to explain why rapid workflow and maintenance of blood pressure are necessary to help support the ischemic brain until, as a result of endovascular thrombectomy, reperfusion is accomplished. The second aim of part 1, understanding the nonanesthesia factors determining endovascular thrombectomy effectiveness, is necessary to identify numerous biases present in observational reports regarding anesthesia for endovascular thrombectomy. With this background, in part 2 (the companion to this article), the observational literature is briefly summarized, largely to identify its weaknesses, but also to develop hypotheses derived from it that have been recently tested in 3 randomized clinical trials of sedation versus general anesthesia for endovascular thrombectomy. In part 2, these 3 trials are reviewed both from a functional outcomes perspective (meta-analysis) and a methodological perspective, providing specifics regarding anesthesia and hemodynamic management. Part 2 concludes with a pragmatic approach to anesthesia decision making (sedation versus general anesthesia) and acute phase anesthesia management of patients treated with endovascular thrombectomy.

Numerical modelling of blood clot extraction by aspiration thrombectomy. Evaluation of aspiration catheter geometry

Aspiration thrombectomy is one of the most effective systems for blood clot removal and vessel recanalization. We present the results of a study involving the modelling and extraction of blood clots in the arteries of the human body using the following computer tools: Bond-Graph methodology for the fluid domain and Multi-Body Simulation for the mechanical domain. The modelling for the mechanical domain focuses on the clot and the distal end section of an aspiration device. Our final model considers an elastic characterization of the blood clot with progressive detachment from the vessel wall. We conclude that the results of such modelling could potentially improve the effectiveness of blood clot removal by reducing the risk of clot fragmentation. Such modelling could also potentially provide an adjunct technique in improving recanalization of arteries over a range of given parameters (mechanical properties of the vessel, mechanical properties of the blood clot, blood clot length, suction pressure, catheter - clot distance, catheter shape, catheter diameter and vessel occlusion).

A Direct Aspiration First Pass Technique vs Standard Endovascular Therapy for Acute Stroke: A Systematic Review and Meta-Analysis

BACKGROUND

The direct aspiration first pass technique (ADAPT) is a recent endovascular treatment for ischemic stroke due to large vessel occlusion that has been gaining popularity due to the rapidity of the technique and the potential for cost savings in comparison to standard thrombectomy methods such as stent retrievers. However, few studies have directly compared these 2.

OBJECTIVE

To compare ADAPT with stent retrievers for thrombectomy via systematic review and meta-analysis.

METHODS

Ovid Medline, PubMed, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, ACP Journal Club, and Database of Abstracts of Review of Effectiveness limited to English through September 2016 were systematically searched. Eligible studies included those in which patient cohorts underwent ADAPT for acute stroke. Recanalization efficiency, clinical outcomes, and complication rates of ADAPT were compared with the current standard of endovascular thrombectomy techniques.

RESULTS

Seventeen studies on ADAPT and 5 randomized controlled trials on endovascular therapy were included. ADAPT achieved higher rates of complete revascularisation (89.4% vs 71.7%, P < .001) but similar clinical outcomes compared to front-line endovascular therapy. Seventy-one point four percent of ADAPT cases were successfully recanalized with aspiration alone, and a trend towards reduced time from groin puncture to recanalization time was noted (44.77 vs 61.46 min, P = .088).

CONCLUSION

The pooled results are comparable with recent randomized studies that demonstrate the benefit of endovascular therapy over intra-arterial medical therapy. Future direct comparative studies and randomized trials are required to confirm the benefit of the ADAPT strategy compared to standard endovascular therapy for acute ischemic stroke.

Understanding the Radial Force of Stroke Thrombectomy Devices to Minimize Vessel Wall Injury: Mechanical Bench Testing of the Radial Force Generated by a Novel Braided Thrombectomy Assist Device Compared to Laser-Cut Stent Retrievers in Simulated MCA Vessel Diameters

Background

Recent reports have raised various concerns about the risk of vessel wall injury while withdrawing current laser-cut stent retrievers during active strut apposition to the vessel walls. The development of braided thrombectomy assist devices in conjunction with aspiration systems may be gentler on the fragile brain vessels and more optimized with regard to the radial force (RF) for vessel diameters of proximal (M1) and distal (M2) large vessel occlusions (LVOs).

Methods

Mechanical bench testing of the RF was performed using a radial compression station mounted on a tensile testing machine. The total RF in newtons (N) generated in vessels with diameters ranging from 2.25 to 3 mm as seen in proximal LVOs (∼M1), and in vessel diameters ranging from 1.5 to 2.24 mm as seen in distal LVOs (∼M2), was measured. The outer diameter of each stent was recorded, and an RF ≤1 N was grouped as "low," while an RF >1 N was grouped as "high" for this analysis.

Results

The total RFs of all laser-cut stent retrievers were all higher in the simulated M2 vessels (>1 N) than in the M1 vessels (<1 N), whereas the total RFs of the braided thrombectomy assist devices were uniformly low in both the simulated M1 and the simulated M2 vessels.

Conclusions

Novel braided thrombectomy assist devices in conjunction with aspiration systems have lower RFs than existing laser-cut stent retrievers in M1 and M2 vessel diameters. Further in vivo studies are needed to delineate the impact of lowering the RF on vessel wall integrity.

Breakage and Retrieval of an Aspiration Catheter Coil with a Stent Retriever During Mechanical Thrombectomy

BACKGROUND

Some mechanical thrombectomy techniques for acute ischemic stroke use a combination of an aspiration catheter and stent retriever. We experienced a rare case of aspiration catheter coil breakage and subsequent retrieval using a stent retriever.

CASE DESCRIPTION

A 79-year-old man suddenly developed somnolence, global aphasia, and right hemiplegia. Magnetic resonance imaging revealed acute infarction of the left frontal lobe and occlusion of the left common carotid artery. Thus, using an aspiration catheter and a stent retriever, mechanical thrombectomy was performed. The stent retriever was deployed from the middle cerebral artery to the internal carotid artery and retracted into the aspiration catheter placed in the internal carotid artery proximal to the thrombus. The catheter was bent during retraction of the stent retriever. After thrombus aspiration, the internal carotid and anterior and middle cerebral arteries were successfully reperfused; however, the stent retriever captured a broken section of the winding coil of the aspiration catheter. We suspected that an X-ray marker on the stent retriever broke the winding coil at the bent segment of the aspiration catheter and the stent captured the broken coil.

CONCLUSIONS

The combined use of an aspiration catheter and a stent retriever may cause unexpected device breakage, especially when the catheter is bent.

ANCD thrombectomy device: in vitro evaluation

Introduction

Endovascular treatment of stroke, although highly effective, may fail to reach complete recanalization in around 20% of cases. The Advanced Thrombectomy System (ANCD) is a novel stroke thrombectomy device designed to reduce clot fragmentation and facilitate retrieval by inducing local flow arrest and allowing distal aspiration in combination with a stent retriever. We aimed to assess the preclinical efficacy of ANCD.

Methods

Soft red blood cell (RBC)-rich (n=20/group) and sticky fibrin-rich (n=30/group) clots were used to create middle cerebral artery (MCA) occlusions in two vascular phantoms. Three different treatment strategies were tested: (1) balloon guide catheter + Solitaire (BGC+SR); (2) distal access catheter + SR (DAC+SR); and (3) ANCD+SR, until complete recanalization was achieved or to a maximum of three passes. The recanalization rate was determined after each pass.

Results

After one pass, ANCD+SR resulted in an increased recanalization rate (94%) for all clots together compared with BGC+SR (66%; p<0.01) or DAC+SR (80%; p=0.04). After the final pass the recanalization rate increased in all three groups but remained higher with ANCD+SR (100%) than with BGC+SR (74%; p<0.01) or DAC+SR (90%; p=0.02). The mean number of passes was lower with ANCD+SR (1.06) than with BGC+SR (1.46) or DAC+SR (1.25) (p=0.01). A logistic regression model adjusted for treatment arm, clot type, and model used showed that both RBC-rich clots (OR 8.1, 95% CI 1.6 to 13.5) and ANCD+SR (OR 3.9, 95% CI 1.01 to 15.8) were independent predictors of first-pass recanalization.

Conclusion

In in vitro three-dimensional models replicating MCA-M1 occlusion, ANCD+SR showed significantly better recanalization rates in fewer passes than other commonly used combinations of devices.

Factors impacting on technical success in stroke thrombectomy: experience of a UK neuro-interventional unit

AIM

To investigate factors that could impact on recanalisation and reperfusion in patients undergoing mechanical thrombectomy and to assess the technical success over time.

MATERIALS AND METHODS

Two hundred consecutive patients who underwent thrombectomy for a proximal anterior circulation occlusion were dichotomised into equal groups (groups 1 and 2) based on the date that immediate access to emergency general anaesthesia (GA) commenced.

RESULTS

Recanalisation success using thrombolysis in cerebral infarction (TICI) 2b/3 or TICI 2c/3 significantly improved in group 2 (67% versus 93%, p<0.0001; 52% versus 78%, p=0.0002). Symptomatic haemorrhage also reduced from 9% to 4%. Despite similar presentation Alberta Stroke Program Early (computed tomography) CT Scores (ASPECTS), post-procedural ASPECTS was significantly increased in group 2 (7; [interquartile range {IQR} 4-9] versus 8 [IQR 7-9]; p=0.0034). The number of patients with a post procedural ASPECTS of 8-10 increased (46% versus 64%, p=0.0155) and the difference in ASPECTS between pre- and post-thrombectomy CT was significantly lower (2 [IQR 1-4] versus 1 [IQR 0-2], p<0.0001). GA use increased from 8% to 56% (p=0.0001) as did use of distal aspiration (59% versus 87%, p=0.0001) mostly in combination with a stent-retriever. Failed access fell from 8% to 3%. When GA was used, successful recanalisation (TICI 2b/3) was achieved more frequently (90.5% versus 76.7%; OR 3.04, 1.2-7.69, p=0.0187).

CONCLUSION

Technical results for thrombectomy are improving over time. Technique modification, operator experience, and judicious use of GA may be contributing.

Frontline Contact Aspiration Treatment for Emergent Large Vessel Occlusion: A Review Focused on Practical Techniques

Endovascular thrombectomy (EVT) as the standard care for acute stroke due to large vessel occlusion has recently been validated through several randomized controlled trials (RCTs). Contact aspiration (CA) and stent retriever (SR) are the two major EVT methods currently used. Because the RCTs have mostly evaluated SR devices, there was a demand to test CA in relation to SR as a frontline EVT treatment method. Recently, the Contact Aspiration vs Stent Retriever for Successful Recanalization (ASTER) study, the first RCT to compare CA and SR, demonstrated similar efficacy between them as a frontline EVT for patients with large vessel occlusions. This facilitates further investigation to confirm better frontline EVT for patients with acute stroke. In this review, we discuss past and recent developments in CA techniques, focusing on related literature. Additionally, we describe practical skills to overcome technical difficulties that can be encountered during the CA procedure. Finally, we review the evolution of device technologies, including a newer version of using a large-bore aspiration catheter.

The Wall Apposition Evaluation for a Mechanical Embolus Retrieval Device

A computational evaluation approach to the wall apposition of a cerebral mechanical emboli retrieval device (MERD) is presented. The typical enclosed multilattice structure, manufactured from the thin-walled Nitinol tube, consists of repeated “V”-shaped unit cells. During interventional thrombectomy, the MERD system is delivered inside an artery stenosis segment to capture emboli and restore cerebral blood flow. The wall apposition, which deteriorates during embolus capture, occurs during system migration along the tortuous intracranial vessel. The commercial finite element analysis (FEA) solver ABAQUS 6.10 Standard and user subroutine (UMAT/Nitinol) are utilized to study the ability to remain in close contact with the curved vessel wall during migration. In this numerical analysis, the influence of the contacting interference loadings on structure deformation and strain field distribution is obtained and analyzed. The results indicate that the middle segment of the MERD seriously contracts or collapses inside the curved vessel. In addition, the peak strain is in the apex flow-prone region and maintains at the safe range.

A Guide-Wired Helical Microrobot for Mechanical Thrombectomy: A Feasibility Study

In this paper, we present a novel guide-wired helical microrobot for mechanical thrombectomy in cardiovascular system, especially for calcified thrombus therapeutics. We designed and fabricated a prototype of the helical shape microrobot equipped with a freely rotatable spherical joint connected to a catheter guidewire, that enables drilling capability to remove calcified objects in vascular. The guidewire helps supporting and maneuvering the microrobot against blood flow during thrombus removal procedure. In addition to the microrobot, an enhanced electromagnetic navigation system (ENS) is implemented to utilize high frequency operation based on resonant effect, which enables powerful drilling force of the microrobot. The in-vitro experimental results illustrate that the suggested method could successfully enhance the locomotion and the drilling force of the helical microrobot that would be sufficient for future mechanical thrombectomy application in cardiovascular therapeutics.

Mechanical Thrombectomy: Emerging Technologies and Techniques

BACKGROUND

The treatment of acute ischemic stroke due to large vessel occlusion (LVO) has revolutionized in the last decade. We sought to compile the most relevant literature published about the evolution in treating this disabling and fatal disease.

METHODS

A literature review of recent studies describing early treatment options like intravenous tissue plasminogen activator to the latest mechanical thrombectomy (MT) techniques was performed. We described in a chronological order the evolution of LVO treatment.

RESULTS

Recanalization rates with newer techniques and MT devices approach a 90% of effectiveness. Timely interventions have also resulted in better clinical outcomes with approximately 50% of patient achieving functional independence at 90 days. At least 14 new third generation thrombectomy devices are currently being evaluated in in vitro and clinical studies.

CONCLUSIONS

The treatment of LVO with MT is feasible and safe. MT is standard of care in treating acute ischemic stroke due to LVO.

Posterior Circulation Occlusions May Be Associated with Distal Emboli During Thrombectomy : Factors for Distal Embolization and a Review of the Literature

Background

Distal embolization or movement of the thrombus to previously uninvolved vasculature are feared complications during stroke thrombectomy. We looked at associated factors in a consecutive series of patients who underwent thrombectomy with the same endovascular device.

Methods

We included all patients with acute ischemic stroke in the anterior or posterior circulation, who underwent thrombectomy with the same thrombectomy device for acute stroke from 2013 to 2016. Distal embolization was defined as any movement of the thrombus into a previously uninvolved portion of the cerebral vasculature or the presence of thrombotic material further downstream in the affected vessel, which occurred after the initial angiogram. We studied patient-related as well as technical factors to determine their association with distal emboli.

Results

In this study 167 consecutive acute stroke patients treated with the emboTrap® device (Cerenovus, Irvine, CA, USA) were included with a median National Institutes of Health Stroke Scale (NIHSS) of 15 (range 2–30) and mean age of 67 years (SD 13.1 years). Of the patients in our cohort 20 (11.9%) experienced distal emboli, with 2.3% into a new territory and 9.6% into a territory distal to the primary occlusion. On univariate analysis, age, intravenous tissue plasminogen activator (tPA), posterior circulation occlusions, and general anesthesia were associated with distal emboli. On multivariate analysis, only posterior circulation occlusions (odds ratio OR 4.506 95% confidence interval CI 1.483–13.692, p = 0.008) were significantly associated with distal emboli. Distal embolization was not significantly associated with worse functional outcomes at 3 months, increased mortality or increased bleeding risk.

Conclusion

Posterior circulation occlusions were significantly associated with distal emboli during thrombectomy, possibly due to the lack of flow arrest during such procedures. New techniques and devices should be developed to protect against embolic complications during posterior circulation stroke thrombectomy.

Blood pressure levels post mechanical thrombectomy and outcomes in non-recanalized large vessel occlusion patients

Objective

Permissive hypertension may benefit patients with non-recanalized large vessel occlusion (nrLVO) post mechanical thrombectomy (MT) by maintaining brain perfusion. Data evaluating the impact of post-MT blood pressure (BP) levels on outcomes in nrLVO patients are scarce. We investigated the association of the post-MT BP course with safety and efficacy outcomes in nrLVO.

Methods

Hourly systolic BP (SBP) and diastolic BP (DBP) values were prospectively recorded for 24 hours following MT in consecutive nrLVO patients. Maximum, minimum, and mean BP levels were documented. Three-month functional independence (FI) was defined as modified Rankin Scale (mRS) scores of 0–2.

Results

A total of 88 nrLVO patients were evaluated post MT. Patients with FI had lower maximum SBP (160±19 mmHg vs 179±23 mmHg; P=0.001) and higher minimum SBP levels (119±12 mmHg vs 108±25 mmHg; P=0.008). Maximum SBP (183±20 mmHg vs 169±23 mmHg; P=0.008) and DBP levels (105±20 mmHg vs 89±18 mmHg; P=0.001) were higher in patients who died at 3 months while minimum SBP values were lower (102±28 mmHg vs 115±16 mmHg; P=0.007). On multivariable analyses, both maximum SBP (OR per 10 mmHg increase: 0.55, 95% CI 0.39 to 0.79; P=0.001) and minimum SBP (OR per 10 mmHg increase: 1.64, 95% CI 1.04 to 2.60; P=0.033) levels were independently associated with the odds of FI. Maximum DBP (OR per 10 mmHg increase: 1.61; 95% CI 1.10 to 2.36; P=0.014) and minimum SBP (OR per 10 mmHg increase: 0.65, 95% CI 0.47 to 0.90; P=0.009) values were independent predictors of 3-month mortality.

Conclusions

Our study demonstrates that wide BP excursions from the mean during the first 24 hours post MT are associated with worse outcomes in patients with nrLVO.

Clinical and Angiographic Outcomes with the Combined Local Aspiration and Retriever in the North American Solitaire Stent-Retriever Acute Stroke (NASA) Registry

Background

Various techniques are used to enhance the results of mechanical thrombectomy with stent-retrievers, including proximal arrest with balloon guide catheter (BGC), conventional large bore proximal catheter (CGC), or in combination with local aspiration through a large-bore catheter positioned at the clot interface (Aspiration-Retriever Technique for Stroke [ARTS]). We evaluated the impact of ARTS in the North American Solitaire Acute Stroke (NASA) registry.

Summary

Data on the use of the aspiration technique were available for 285 anterior circulation patients, of which 29 underwent ARTS technique, 131 CGC, and 125 BGC. Baseline demographics were comparable, except that ARTS patients are less likely to have hypertension or atrial fibrillation. The ARTS group had more ICA occlusions (41.4 vs. 22% in the BGC, p = 0.04 and 26% in CGC, p = 0.1) and less MCA/M1 occlusions (44.8 vs. 68% in BGC and 62% in CGC). Time from arterial puncture to reperfusion or end of procedure with ARTS was shorter than with CGC (54 vs. 91 min, p = 0.001) and was comparable to the BGC time (54 vs. 67, p = 0.11). Final degree of reperfusion was comparable among the groups (TICI [modified Thrombolysis in Cerebral Infarction] score 2b or higher was 72 vs. 70% for CGC vs. 78% for BGC). Procedural complications, mortality, and good clinical outcome at 90 days were similar between the groups.

Key Messages

The ARTS mechanical thrombectomy in acute ischemic stroke patients appears to yield better results as compared to the use of CGCs with no significant difference when compared to BGC. This early ARTS technique NASA registry data are limited by the earlier generation distal large bore catheters and small sample size. Future studies should focus on the comparison of ARTS and BGC techniques.

Recent Trends in Clot Retrieval Devices: A Review

Stroke is the second leading cause of death worldwide and in Europe. Even with gold standard medical management of acute ischemic stroke, which is intravenous (IV) thrombolysis by administration of recombinant tissue plasminogen activator (rt-PA), the mortality rate remains the same. Intra-arterial (IA) thrombolysis therapy also did not achieve significant results and was not approved by the US Food and Drug Administration (FDA) because of limited sample size. This encouraged scientists and engineers to develop endovascular clot retrieval devices for the mechanical recanalization of the occluded arteries in stroke patients. Although the initial designs of clot retrieval devices failed, efforts to improve these devices continue. Recently clot retrieval devices were approved by the FDA as first-line treatment along with IV rt-PA. This article gives an in-depth review of different clot retrieval devices which includes MERCI (the first), the Penumbra Aspiration System, EmboTrap^®II, stent retrievers, and the way forward with the new FDA clearance of the devices as first-line treatment for acute ischemic stroke along with IV rt-PA. The review also includes a comparison of clot retrieval devices to gold standard treatment.

Neuroprotective strategies and the underlying molecular basis of cerebrovascular stroke

Stroke is a leading cause of disability in the US. Although there has been significant progress in the area of medical and surgical thrombolytic technologies, neuroprotective agents to prevent secondary cerebral injury and to minimize disability remain limited. Only limited success has been reported in preclinical and clinical trials evaluating a variety of compounds. In this review, the authors discuss the most up-to-date information regarding the underlying molecular biology of stroke as well as strategies that aim to mitigate this complex signaling cascade. Results of historical research trials involving N-methyl-d-aspartate and α-amino-3-hydroxy-5-methyl-4-isoxazole propionate receptor antagonists, clomethiazole, antioxidants, citicoline, nitric oxide, and immune regulators have laid the groundwork for current progress. In addition, more recent studies involving therapeutic hypothermia, magnesium, albumin, glyburide, uric acid, and a variety of other treatments have provided more options. The use of neuroprotective agents in combination or with existing thrombolytic treatments may be one of many exciting areas of further development. Although past trials of neuroprotective agents in ischemic stroke have been limited, significant insights into mechanisms of stroke, animal models, and trial design have incrementally improved approaches for future therapies.

Forced Arterial Suction Thrombectomy Using Distal Access Catheter in Acute Ischemic Stroke

Historical innovations in mechanical thrombectomy devices and strategies for ischemic stroke have resulted in improved angiographic outcomes and better clinical outcomes. Various devices have been used, but the two most common approaches are aspiration thrombectomy and stent-retrieval thrombectomy. Aspiration thrombectomy has advanced from the traditional Penumbra system to forced arterial suction thrombectomy and a direct aspiration first-pass technique. Newer generation aspiration catheters with flexible distal tips and a larger bore have demonstrated faster and better recanalization relative to older devices. Recently, several species of distal access catheters have similar structural characteristics to the Penumbra reperfusion catheter. Therefore, we used the distal access catheter for forced arterial suction thrombectomy in three patients with acute ischemic stroke. In each case, we achieved fast and complete recanalization without significant complications. Forced arterial suction thrombectomy using a distal access catheter might provide another option for mechanical thrombectomy in patients with acute ischemic stroke.

Initial clinical experience using the two-stage aspiration technique (TSAT) with proximal flow arrest by a balloon guiding catheter for acute ischemic stroke of the anterior circulation

Background

Our initial experience using the two-stage aspiration technique (TSAT) with proximal flow arrest by a balloon guiding catheter is presented. In TSAT, aspiration is applied with the 5MAX ACE and also with the 3MAX catheter with a Penumbra aspiration pump, while arresting proximal flow by balloon inflation.

Methods

In patients treated with TSAT, clinical data including National Institutes of Health Stroke Scale (NIHSS) score at admission and the modified Rankin Scale (mRS) score at discharge, as well as procedural data including the Thrombolysis in Cerebral Infarction (TICI) score, procedural time, and complications were analyzed.

Results

Thirty-four consecutive patients (19 men (56%); mean age 73 years) were treated with TSAT using a balloon guiding catheter. The patients presented with a mean NIHSS score of 17.4 and 23 (68%) patients received IV tissue plasminogen activator. Median time from groin puncture to successful recanalization was 41 min (range 15–160 min). All patients were successfully revascularized; TICI 2b or better recanalization was achieved in 30 (88%) patients. No patient required an additional procedure such as use of a stent retriever. Procedure-related complications occurred in two (5.9%) patients (vessel injury and guidewire perforation). Symptomatic intracranial hemorrhage occurred in one patient and asymptomatic hemorrhagic infarction occurred in two patients. There were no cases of embolization to new territory (ENT). The mean NIHSS score at discharge improved to 6.1. Sixteen patients (47%) achieved a good outcome with an mRS score of 0–2 at discharge (mean hospitalization period 20 days).

Conclusions

TSAT with proximal flow arrest by a balloon guiding catheter is an effective and safe method to achieve good clinical and angiographic outcomes. This method may reduce ENT in the direct aspiration first-pass thrombectomy (ADAPT) technique.

Impact of ASPECT scores and infarct distribution on outcomes among patients undergoing thrombectomy for acute ischemic stroke with the ADAPT technique

Objective

To investigate the associations between Alberta Stroke Program Early CT Score (ASPECTS) or distribution and sidedness of acute infarction and clinical outcomes following intervention with a direct aspiration first pass technique (ADAPT).

Methods

A review was performed of patients who had undergone thrombectomy with ADAPT for emergent large vessel occlusions of the middle cerebral artery (MCA) between December 2012 and May 2015. Preintervention CT scans were reviewed by a blinded radiologist to calculate ASPECTS and determine the distribution of infarction. Clinical outcomes were compared for subsets of patients depending upon ASPECTS and regional infarction distribution (cortical, subcortical, or both).

Results

One hundred and fifty-four patients (50% female, mean age 67) underwent thrombectomy using ADAPT for MCA emergent large vessel occlusion. The median presenting National Institute of Health Stroke Scale score was 15. Fifty-five per cent of patients had left-side occlusions. Similar good outcomes were achieved for patients with perfect and non-perfect ASPECTS (modified Rankin Scale (mRS) 0–2: 63% vs 51%, respectively; p=0.20). Similar outcomes were also achieved for patients with ‘poor’ ASPECTS (≤6) compared with those with ASPECTS >6 (mRS 0–2: 52% vs 53%, respectively; p=0.91). Regional distribution and sidedness of core infarction on preintervention CT also did not correlate with worse outcomes.

Conclusions

Patients with moderate-sized core infarcts involving various distributions in either hemisphere can potentially achieve similar good outcomes compared with those with no core infarction at presentation. A treatment algorithm for acute ischemic stroke, which employs hardline ASPECTS thresholds or excludes patients with basal ganglia infarcts, might preclude patients who would potentially benefit from mechanical thrombectomy with ADAPT.

Endovascular treatment for AIS with underlying ICAD

Background

Acute large vessel occlusion (LVO) can result from thromboemboli or underlying intracranial atherosclerotic disease (ICAD). Although the technique for revascularization differs significantly for these two lesions (simple thrombectomy for thromboemboli and balloon angioplasty and stenting for ICAD), the underlying etiology is often unknown in acute ischemic stroke (AIS).

Objective

To evaluate whether procedural complications, revascularization rates, and functional outcomes differ among patients with LVO from ICAD or thromboembolism.

Methods

A retrospective review of thrombectomy cases from 2008 to 2015 was carried out for cases of AIS due to underlying ICAD. Thirty-six patients were identified. A chart and imaging review was performed to determine revascularization rates, periprocedural complications, and functional outcomes. Patients with ICAD and acute LVO were compared with those with underlying thromboemboli.

Results

Among patients with ICAD and LVO, mean National Institutes of Health Stroke Scale (NIHSS) score on admission was 12.9±8.5, revascularization (Thrombolysis In Cerebral Infarction, TICI ≥2b) was achieved in 22/34 (64.7%) patients, 11% had postprocedural intracerebral hemorrhage (PH2), and 14/33 (42.4%) had achieved a modified Rankin Scale (mRS) score of 0–2 at the 3-month follow-up. Compared with patients without underlying ICAD, there was no difference in NIHSS on presentation, or in the postprocedural complication rate. However, procedure times for ICAD were longer (98.5±59.8 vs 37.1±34.2 min), there was significant difference in successful revascularization rate between the groups (p=0.001), and a trend towards difference in functional outcome at 3 months (p=0.07).

Conclusions

Despite AIS with underlying ICAD requiring a more complex, technically demanding recanalization strategy than traditional thromboembolic AIS, it appears safe, and good outcomes are obtainable.

Endovascular thrombectomy for M2 occlusions: comparison between forced arterial suction thrombectomy and stent retriever thrombectomy

Background

To date there has been no direct comparison of two frequently used endovascular thrombectomy (EVT) methods (forced arterial suction thrombectomy (FAST) and stent retriever thrombectomy) in M2 occlusions. We review our experiences with EVT performed using FAST and stent retriever thrombectomy in such cases.

Methods

The subjects comprised 41 patients with an M2 occlusion who underwent EVT (25 with FAST, 16 with stent retriever thrombectomy). The patients' data were retrospectively analyzed to evaluate the technical characteristics and angiographic outcome of the two EVT techniques.

Results

Thrombolysis In Cerebral Infarction (TICI) grades 2b–3 using the first chosen technique did not differ significantly between the two techniques (FAST 64.0% vs stent retriever thrombectomy 81.2%, p=0.305). Time from groin puncture to reperfusion was significantly shorter for stent retriever thrombectomy (53.0 vs 38.5 min; p=0.045). Distal embolization occurred in three cases (12.0%) in the FAST group and in four (26.7%) in the stent retriever group (p=0.362). However, the two techniques did not differ significantly in the final TICI 2b–3 rate (72.0% vs 87.5%; p=0.441). A frequent angiographic finding regarding the failure of FAST was that the M2 occlusion was located immediately after severe acute angulation between M1 and M2.

Conclusions

Stent retriever thrombectomy may provide faster reperfusion than FAST, while the FAST technique might be associated with lower distal embolization and a higher reperfusion rate for the first thrombectomy attempt, but without any significant difference in clinical outcome. When choosing the EVT method for M2 occlusions, consideration of the location of the occlusion and tortuosity between M1 and M2 might be helpful to achieve a better angiographic outcome.