Double Stent-Retriever Technique in Endovascular Treatment of Middle Cerebral Artery Saddle Embolus

Double Stent Retriever Technique for Mechanical Thrombectomy: A Systematic Review and Meta-Analysis

BACKGROUND

Mechanical thrombectomy using a double stent retriever technique has recently been described for the treatment of acute ischemic stroke, but its efficacy and safety are not well-established.

PURPOSE

The aim of this systematic review and meta-analysis was to evaluate reports of the use of a double stent retriever technique during the endovascular treatment of patients with ischemic stroke.

DATA SOURCES

The PubMed, EMBASE, Web of Science, and Scopus databases were searched to identify all studies (clinical trials, cohort series, and case reports) investigating the utility of a double stent retriever technique for the treatment of stroke. The study is reported in accordance with PRISMA 2020 guidelines and was prospectively registered in PROSPERO (CRD42023482691).

STUDY SELECTION

Seventeen studies involving a total of 128 patients with large-vessel occlusions predominantly in the anterior circulation (93.0%) were identified.

DATA ANALYSIS

Outcomes of interest were the prevalence of successful recanalization (modified TICI ≥2b) and a first-pass effect following the double stent retriever technique as well as complications such as iatrogenic dissections and SAH. Data were pooled using a random effects model.

DATA SYNTHESIS

The double stent retriever technique was used as a rescue strategy in occlusions refractory to conventional endovascular treatment in 68.7% (88/128) of patients and as a first-line strategy in 31.3% (40/128) of patients. The double stent retriever technique achieved an overall final modified TICI ≥2b in 92.6% cases, with a first-pass effect of 76.6%. The complication rate remained low, with 0.37% dissection and 1.56% SAH.

LIMITATIONS

Limitations of the study include the following: 1) a large number of case reports or small series, 2) a meta-analysis of proportions with no statistical comparison with a control group, and 3) the lack of access to patient-level data.

CONCLUSIONS

Our findings suggest that double stent retriever thrombectomy may be safe and associated with good recanalization outcomes, but prospective comparative studies are needed to determine which patients may benefit from this endovascular procedure.

Mechanical Thrombectomy Using Double Stent Retriever Technique for Acute Ischemic Stroke Following Embolism From the Pulmonary Vein Stump After Left Upper Lobectomy: A Case Report

Acute ischemic stroke (AIS) following pulmonary lobectomy, which is traditionally attributed to air embolism and atrial fibrillation (AF), may occur after thrombus formation in the pulmonary vein stump (PVS). Herein, we document the mechanical thrombectomy (MT) of a carotid bifurcation occlusion post-left upper lobectomy (LUL) to manage AIS. A 76-year-old male with a history of diabetes, dyslipidemia, and a treated dural arteriovenous fistula at the transverse sigmoid junction, with no history of AF, successfully underwent LUL for a pulmonary tumor. The patient independently walked on postoperative day 1. He developed right hemiparesis and total aphasia on the morning of the second day after surgery, which was discovered by the nursing staff. A magnetic resonance imaging (MRI) confirmed an occlusion of the left common carotid artery (CCA). Tissue plasminogen activator (t-PA) was not administered owing to recent surgery. An urgent MT using multiple MT techniques carried out 90 minutes after the discovery of symptoms only achieved partial recanalization. Subsequently, a double stent retriever technique (DSRT) addressed the occlusion in the common and cervical internal carotid artery (ICA). Following this, a T occlusion was encountered, which was addressed with a combined approach using a single stent retriever (SR), achieving a thrombolysis in cerebral infarction (TICI) grade 2b result. However, postoperative aphasia and severe right hemiparesis remained. Postoperative imaging showed a significant left cerebral hemisphere infarction and a thrombus in the PVS. Oral edoxaban was administered, and PVS thrombosis did not recur. The patient was transferred to a rehabilitation facility 190 days post-embolization with a modified Rankin Scale score of 4. In this report, we demonstrate the challenging case of the DSRT in addressing AIS after LUL, which led to the formation of a massive thrombus and occlusion of the carotid artery, as revealed by the PVS. This case emphasizes the importance of collaborative efforts between thoracic surgeons and all staff involved in stroke care in managing such complex scenarios.

Double stent-retriever as the first-line approach in mechanical thrombectomy: a randomized in vitro evaluation

BACKGROUND

A repeated number of passes during mechanical thrombectomy leads to worse clinical outcomes in acute ischemic stroke. Initial experiences with the simultaneous double stent-retriever (double-SR) technique as the first-line treatment showed promising safety and efficacy results.

OBJECTIVE

To characterize the potential benefits of using the double-SR as first-line technique as compared with the traditional single-SR approach.

METHODS

Three types of clot analogs (soft, moderately stiff, and stiff) were used to create terminal internal carotid artery (T-ICA=44) and middle cerebral artery (MCA=88) occlusions in an in vitro neurovascular model. Sixty-six cases were randomized into each treatment arm: single-SR or double-SR, in combination with a 0.071" distal aspiration catheter. A total of 132 in vitro thrombectomies were performed. Primary endpoints were the rate of first-pass recanalization (%FPR) and procedural-related distal emboli.

RESULTS

FPR was achieved in 42% of the cases. Overall, double-SR achieved a significantly higher %FPR than single-SR (52% vs 33%, P=0.035). Both techniques showed similar %FPR in T-ICA occlusions (single vs double: 23% vs 27%, P=0.728). Double-SR significantly outperformed single-SR in MCA occlusions (63% vs 38%, P=0.019), most notably in saddle occlusions (64% vs 14%, P=0.011), although no significant differences were found in single-branch occlusions (64% vs 50%, P=0.275). Double-SR reduced the maximal size of the clot fragments migrating distally (Feret diameter=1.08±0.65 mm vs 2.05±1.14 mm, P=0.038).

CONCLUSIONS

This randomized in vitro evaluation demonstrates that the front-line double-SR technique is more effective than single-SR in achieving FPR when treating MCA bifurcation occlusions that present saddle thrombus.

Dual-Stent retriever thrombectomy for extensive dural sinus thrombosis

INTRODUCTION

First line treatment for cerebral venous thrombosis (CVT) is systemic anticoagulation. In cases with symptoms of elevated ICP, endovascular thrombectomy (EVT) is pursued. We describe two cases in which dual stent-retrievers were used for EVT.

OBJECTIVES

The use of dual stent-retrievers has been described in arterial stroke when clot is present in the M1 artery and both M2 branches as a rescue therapy after 1 stent-retriever failed to remove the clot. We applied this same thinking to our EVT patients.

METHODS

A 17-year-old female with imaging demonstrating occlusion of the superior sagittal sinus (SSS), dominant right transverse sinus (TS), right sigmoid sinus (SS), and upper right internal jugular vein (IJV). A 20-year-old female with a magnetic resonance venography (MRV) noting CVT in the dominant lateral left TS, SS, and upper left IJV.

RESULTS

Both were taken for EVT due to severity of symptoms. Two 6 × 40 mm stent-retrievers were deployed into the CVT and then remove with continuous aspiration with significant recanalization.

CONCLUSIONS

The average diameter of the dural sinuses is 8 mm compared to the average size of the middle cerebral artery 3-4 mm. The largest available SR in the United States is 6 mm, and the largest outer diameter of available aspiration catheters is 2-3 mm. Due to the larger size of the dural sinuses, using two SRs can result in more efficient recanalization and less radiation.

Double stent retriever technique for rescue recanalization in refractory large vessel occlusions

Acute ischemic stroke patients with large vessel occlusion (LVO) involving bifurcation usually have a difficult and high clot burden. By using conventional technique often resulting in a reduction in the possibility of successful recanalization. The double stent retriever technique can be considered for rescue recanalization. We reported a case of refractory terminal left internal carotid occlusion that was treated using double stent retriever technique. Two microcatheter were advanced across the occlusion were one to the superior branch of middle cerebral artery and another was on inferior branch. Both stent retrievers were pulled back together and complete recanalization was achieved. This technique were reported in some case series to be effective and based on our initial experience using this technique it seems the expansion improved after deployment of the second stent retriever and it traps the clot within its stent struts, to facilitate clot retrieval. Therefore, double stent retriever technique can be one of the choices for rescue recanalization in refractory clot occlusion and it may potentially help other clinicians in similar situations.

Microcatheter tracking in thrombectomy procedures: A finite-element simulation study

BACKGROUND AND OBJECTIVE

Mechanical thrombectomy is a minimally invasive procedure that aims at removing the occluding thrombus from the vasculature of acute ischemic stroke patients. Thrombectomy success and failure can be studied using in-silico thrombectomy models. Such models require realistic modeling steps to be effective. We here present a new approach to model microcatheter tracking during thrombectomy.

METHODS

For 3 patient-specific vessel geometries, we performed finite-element simulations of the microcatheter tracking (1) following the vessel centerline (centerline method) and (2) as a one-step insertion simulation, where the microcatheter tip was advanced along the vessel centerline while its body was free to interact with the vessel wall (tip-dragging method). Qualitative validation of the two tracking methods was performed with the patient's digital subtraction angiography (DSA) images. In addition, we compared simulated thrombectomy outcomes (successful vs unsuccessful thrombus retrieval) and maximum principal stresses on the thrombus between the centerline and tip-dragging method.

RESULTS

Qualitative comparison with the DSA images showed that the tip-dragging method more realistically resembles the patient-specific microcatheter-tracking scenario, where the microcatheter approaches the vessel walls. Although the simulated thrombectomy outcomes were similar in terms of thrombus retrieval, the thrombus stress fields (and the associated fragmentation of the thrombus) were strongly different between the two methods, with local differences in the maximum principal stress curves up to 84%.

CONCLUSIONS

Microcatheter positioning with respect to the vessel affects the stress fields of the thrombus during retrieval, and therefore, may influence thrombus fragmentation and retrieval in-silico thrombectomy.

Bifurcation occlusions and endovascular treatment outcome in acute ischemic stroke

BACKGROUND

A thrombus in the M1 segment of the middle cerebral artery (MCA) can occlude this main stem only or extend into the M1-M2 bifurcation. The occlusion pattern may affect endovascular treatment (EVT) success, as a bifurcated thrombus may be more prone to fragmentation during retrieval.

OBJECTIVE

To investigate whether bifurcated thrombus patterns are associated with EVT procedural and clinical outcomes.

METHODS

Occlusion patterns of MCA thrombi on CT angiography from MR CLEAN Registry patients were classified into three groups: main stem occlusion, bifurcation occlusion extending into one M2 branch, and bifurcation occlusion extending into both M2 branches. Procedural parameters, procedural outcomes (reperfusion grade and embolization to new territory), and clinical outcomes (24-48 hour National Institutes of Health Stroke Scale [NIHSS_FU] score, change in NIHSS scores between 24 and 48 hours and baseline ∆ [NIHSS], and 90-day modified Rankin Scale [mRS] scores) were compared between occlusion patterns.

RESULTS

We identified 1023 patients with an MCA occlusion of whom 370 (36%) had a main stem occlusion, 151 (15%) a single branch, and 502 (49%) a double branch bifurcation occlusion. There were no statistically significant differences in retrieval method, procedure time, number of retrieval attempts, reperfusion grade, and embolization to new territory between occlusion patterns. Patients with main stem occlusions had lower NIHSS_FU scores than patients with single (7 vs 11, p=0.01) or double branch occlusions (7 vs 9, p=0.04). However, there were no statistically significant differences in ∆ NIHSS or in 90-day mRS scores.

CONCLUSIONS

In our population, EVT procedural and long-term clinical outcomes were similar for MCA bifurcation occlusions and MCA main stem occlusions.

First Experience with the Nimbus Stentretriever

Purpose

To share our first experience with the Nimbus stentretriever, a multizone device designed to assist neurointerventionalists in handling fibrin-rich clots in endovascular stroke treatment.

Methods

We retrospectively analyzed the data of patients who were treated with the Nimbus stentretriever at our high-volume stroke center between May 2021 and May 2022. We evaluated the number of passes before Nimbus was used, the number of passes with nimbus, as well as the recanalization success before and after Nimbus according to the modified treatment in cerebral ischemia (mTICI) scale. Also, patient characteristics, procedural times and clinical outcomes were documented.

Results

A total of 21 consecutive patients were included in the study. An mTICI 2b/3 could be achieved in 76.2% and mTICI 2c/3 could be achieved in 57.1%. The mean number of passes was 3.4 before the use of Nimbus, 2.2 with Nimbus, and 5.4 for all passes with and without Nimbus and 4 occlusions (19.0%) were successfully recanalized with direct aspiration after the use of Nimbus. We observed seven subarachnoid hemorrhages (33.3%) and two cases of vasospasm.

Conclusion

In our series, the use of Nimbus resulted in successful recanalization in half of the patients after otherwise unsuccessful thrombectomy maneuvers; therefore, it should be considered as a rescue option if the maneuver with conventional stent retrievers was unsuccessful.

First-line Double Stentriever Thrombectomy for M1/TICA Occlusions : Initial Experiences

BACKGROUND

Mechanical thrombectomy is the standard of care for acute ischemic stroke due to large-vessel occlusion; however, mechanical thrombectomy fails to achieve adequate recanalization in nearly one third of these cases. Rescue therapy using two stentrievers simultaneously yields good results in clots refractory to single stentriever treatment. We aimed to determine the safety and efficacy of first-line double stentriever thrombectomy for acute occlusion of the M1 segment of the middle cerebral artery and/or terminal internal carotid artery (TICA).

METHODS

This single-center study prospectively enrolled consecutive patients with a single M1/TICA occlusion to undergo double stentriever thrombectomy between May and October 2020. Outcomes included successful recanalization (modified thrombolysis in cerebral infarction, TICI 2b/3), first-pass effect, procedure times, number of device passes, symptomatic intracerebral hemorrhage, National Institutes of Health Stroke Scale Score (NIHSS) at discharge, 90-day functional independence (modified Rankin scale 0-2), and 90-day mortality.

RESULTS

We analyzed 39 patients median age 79 years (range 42-96 years); 23 (58.9%) female; 19 (48.7%) with TICA occlusions; 5 (12.8%) with mRS 3-5 at admission; mean NIHSS at admission, 17 ± 4.39). Mean time from symptom onset to final angiogram was 238.0 ± 94.6 min; mean intervention duration was 36.0 ± 24.2 min. The mean number of device passes was 1.5 ± 1.07. All patients had final TICI 2b/3, and 27 (69%) had TICI 2c/3 after the first pass. We observed 3 (7.9%) cases of intracerebral symptomatic hemorrhages. At 90 days, 16 (41%) patients were functionally independent and 9 (23%) had died. The percentage of patients with good clinical outcome at 90 days was 55.5% in the first-pass subgroup.

CONCLUSION

Our findings suggest that first-line double stentriever thrombectomy is safe and effective for M1/TICA occlusions.

Increased Number of Passes and Double Stent Retriever Technique Induces Cumulative Injury on Arterial Wall After Mechanical Thrombectomy in a Swine Model

The number of stentriever passes during endovascular thrombectomy impacts clinical outcomes in acute ischemic stroke. Previous studies suggest that the simultaneous double stent retriever technique (DSRT) could improve the efficacy and reduce the number of passes. We aim to analyze the degree of vessel wall injury according to the number of passes and technique (single vs. simultaneous devices). Histological changes were evaluated in renal arteries (RAs) of swine models after thrombectomy (1, 2, or 3 passes) with single stent (SSRT) and DSRT. Thrombectomy passes were performed in 12 RA: 3 samples from each artery were studied by optical microscopy to assess a vascular damage score. All thirty-six samples showed endothelial denudation and different degrees of damage in the deepest layers of the arterial wall; however, all arteries remained patent by the time of assessment. In all cases, the degree of vascular injury increased with the number of passes. Compared with a SSRT, DSRT showed a higher severity of histological damage corresponding to the damage caused by 1.4 SSRT passes. However, in distal arteries, vascular damage was relatively similar when comparing SSRT with multiple passes and DSRT with one pass. The degree of vessel injury increases with the number of passes. Even though histological damage per pass was 1.4 higher with DSRT than SSRT, short-term vessel patency was not compromised after up to 3 DSRT passes. Further studies are needed to characterize the risk-benefit ratio of the DSRT in routine clinical practice.

Crossing double stent retriever technique for refractory terminal internal carotid artery occlusion

Mechanical thrombectomy is highly effective for the recovery of acute ischemic stroke with large vessel occlusion. However, refractory occlusions are still encountered despite the use of currently available devices. In this article, we present a case of refractory terminal internal carotid artery occlusion treated with the "crossing double stent retriever technique." Two thrombectomy procedures with the combined technique using a stent retriever and aspiration catheter failed to recanalize the terminal internal carotid artery occlusion that involved the dominant anterior cerebral artery. We then applied the crossing double stent retriever technique as a rescue technique. Two microcatheters were advanced across the occlusion: one to the anterior cerebral artery and the other to the middle cerebral artery. First, a Trevo NXT 4 mm stent retriever was deployed from the anterior cerebral artery. Next, an additional Trevo NXT 4 mm stent retriever was deployed from the middle cerebral artery, and full immediate restoration of flow was achieved on angiography. Intraprocedural radiological images showed that the 2 microcatheters traversed different pathways, and the 2 stent retrievers completely covered the entire vessel with apparent in-stent clot sign. Both stent retrievers were then pulled back together, and a hard clot was retrieved. Subsequent angiography revealed complete recanalization. The crossing double stent retriever technique seems an effective rescue technique for treating refractory terminal internal carotid artery occlusion, especially with the anatomical feature of branching of the dominant anterior cerebral artery. This technique can facilitate the device-clot-vessel interaction by engaging the clot via 2 different device pathways.

Predictors of Early Neurological Deterioration in Stroke Due to Vertebrobasilar Occlusion

Background and Aims: This study explores the predictors of early neurological deterioration (END) in patients with vertebrobasilar occlusion (VBO) in both primary endovascular therapy (EVT) and medical management (MM) groups. Methods: Patients diagnosed with VBO from 2010 to 2018 were included. Comparative and multivariate analyses were used to identify predictors of all-cause END in the EVT group, and END due to ischemia progression (END-IP) in the MM group. Results: In 174 patients with VBO, 43 had END. In the primary EVT group (N = 66), 17 all-cause END occurred. Distal basilar occlusion (odds ratio (OR), 14.5 [95% confidence interval (CI), 1.4-154.4]) and reperfusion failure (eTICI < 2b67 (OR, 5.0 [95% CI, 1.3-19.9]) were predictive of END in multivariable analysis. In the MM group (N=108), 17 END-IP occurred. Higher systolic blood pressure (SBP) at presentation (per 10 mmHg increase, OR, 1.5 [95% CI, 1.1-2.0]), stroke onset-to-door time <24 h (OR, 5.3 [95% CI, 1.1-2.0]), near-total occlusions (OR, 4.9 [95% CI, 1.2-19.6]), lower posterior circulation-Alberta Stroke Program Early CT scores (OR, 1.6 [95% CI, 1.0-2.5]), and lower BATMAN collateral scores (OR, 1.6 [95% CI, 1.1-2.2]) were predictive of END-IP. Conclusions: In patients with stroke due to VBO, potential predictors of END can be identified. In the primary EVT group, failure to achieve reperfusion and distal basilar occlusion were associated with all-cause END. In the MM group, higher SBP at presentation, onset-to-door time less than 24 h, incomplete occlusions, larger infarct cores, and poorer collaterals were associated with END-IP.

Device size selection can enhance Y-stentrieving efficacy and safety as a rescue strategy in stroke thrombectomy

BACKGROUND

Despite advancements in stroke treatment, refractory clots are relatively common, prompting the exploration of alternative techniques. Bifurcation occlusions pose specific intraprocedural challenges, occasionally dealt with by two stentrievers deployed in Y-configuration. Previous studies have portrayed this strategy as feasible, yet little is known about its safety and efficacy, and how to best select retrievers.

OBJECTIVE

To determine whether device selection influences the efficacy and safety of Y-stentrieving.

METHODS

We performed a multicentric, retrospective analysis of patients undergoing Y-stentrieving rescue for bifurcation occlusions. Demographics, devices, procedural metrics, neurological severity, reperfusion, disability, and safety were assessed.

RESULTS

Y-configuration stents were used as a rescue maneuver after 2.16±1.5 failed attempts with other techniques in 20 patients. Successful reperfusion (modified Thrombolysis in Cerebral Infarction score 2b-3) was achieved in 70% of patients after the first Y-stentrieving attempt. The first stentriever more often had a larger diameter (5.15±0.92 vs 3.67±0.57 mm, p=0.017) and longer length (33.12±5.78 vs 20.67±1.15 mm, p=0.002) in successfully reperfused cases. Also, the diameter of the first device was associated with both any parenchymal (6.0 vs 4.71±0.99 mm, p=0.045) and symptomatic (6.0 vs 4.86±1.02 mm, p<0.001) hemorrhages. Exact logistic regression demonstrated that a longer length first stentriever independently predicted better angiographic outcomes (OR=1.26, p=0.036), and a 6 mm diameter first stentriever independently predicted more intracranial hemorrhages (OR=15.28, p=0.044). No periprocedural mortality was recorded.

CONCLUSION

Y-stentrieving is an effective and safe bail-out strategy for refractory bifurcation clots. Longer stents may promote better angiographic outcomes, whereas avoidance of disproportionately large retrievers may mitigate intracranial hemorrhage. Future studies should account for these factors when evaluating alternative stentriever techniques.

A Case of Acute Embolic Occlusion of the Common Carotid Artery in Which a Giant Thrombus Was Retrieved Using the Parallel Stent Retriever Technique

Objective

We report a case of embolic occlusion of the common carotid artery (CCA) in which a giant thrombus was retrieved using the parallel stent retriever technique.

Case Presentation

An 84-year-old woman without anticoagulant therapy despite a history of cardioembolic stroke presented to our hospital because of left hemiparesis after developing sudden vision loss in her right eye. Emergency angiography revealed a giant thrombus in the right CCA. After arresting flow in the CCA using a balloon-guided catheter (BGC), we deployed two stent retrievers in parallel from the internal carotid artery to the CCA, and slowly retrieved them simultaneously under manual aspiration through the BGC. As a result, complete recanalization was achieved.

Conclusion

Thrombi causing acute embolic occlusion of the CCA are often too large to be completely retrieved using conventional thrombectomy techniques. The parallel stent retriever technique may be effective in such cases.

Y-configuration double-stent-retriever thrombectomy for refractory thrombus in middle cerebral artery bifurcation: A case report

RATIONALE

Stent retriever mechanical thrombectomy is a recommended treatment for acute ischemic stroke. However, refractory thrombus in artery bifurcation can reduce the rate of successful revascularization.

PATIENT CONCERNS

A 72-year-old male, owing to the acute onset of almost complete right-sided hemiplegia and global aphasia, received bridging therapy. National Institutes of Health Stroke Scale score was 16 at the time of admission.

DIAGNOSES

Cerebral digital subtraction angiography revealed occlusion of the M1 segment of the left MCA.

INTERVENTIONS

Thrombectomy with 3 passes of the Solitaire FR device (Medtronic, Minneapolis, MN) was unsuccessful. Two stent retrievers were inserted in parallel by one microcatheter access point to each M2 branch, and then both stents were gradually retrieved out of the catheter while continuous suction was maintained.

OUTCOMES

After thrombectomy, subsequent follow-up angiograms showed mTICI 3 reperfusion of MCA. The patient has mRS 2 at discharge and the 3-month mRS score after stroke is 1 score.

LESSONS

The presented Y-configuration double-stent-retriever thrombectomy technique constitutes a safe and effective rescue treatment method for refractory thrombus in MCA bifurcation.

Impact of Clot Shape on Successful M1 Endovascular Reperfusion

Objectives: The susceptibility-vessel-sign (SVS) allows thrombus visualization, length estimation and composition, and it may impact reperfusion during mechanical thrombectomy (MT). SVS can also describe thrombus shape in the occluded artery: in the straight M1-segment (S-shaped), or in an angulated/traversing a bifurcation segment (A-shaped). We determined whether SVS clot shape influenced reperfusion and outcomes after MT for proximal middle-cerebral-artery (M1) occlusions.

Methods: Between May 2015 and March 2018, consecutive patients who underwent MT at one comprehensive stroke center and who had a baseline MRI with a T2^* sequence were included. Clinical, procedural and radiographic data, including clot shape on SVS [angulated/bifurcation (A-SVS) vs. straight (S-SVS)] and length were assessed. Primary outcome was successful reperfusion (TICI 2b-3). Secondary outcome were MT complication rates, MT reperfusion time, and clinical outcome at 90-days. Predictors of outcome were assessed with univariate and multivariate analyses.

Results: A total of 62 patients were included. 56% (35/62) had an A-SVS. Clots were significantly longer in the A-SVS group (19 mm vs. 8 mm p = 0.0002). Groups were otherwise well-matched with regard to baseline characteristics. There was a significantly lower rate of successful reperfusion in the A-SVS cohort (83%) compared to the S-SVS cohort (96%) in multivariable analysis [OR 0.04 (95% CI, 0.002–0.58), p = 0.02]. There was no significant difference in long term clinical outcome between groups.

Conclusion: Clot shape as determined on T2^* imaging, in patients presenting with M1 occlusion appears to be a predictor of successful reperfusion after MT. Angulated and bifurcating clots are associated with poorer rates of successful reperfusion.

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.

Parallel Stent Retriever Technique for a Refractory Middle Cerebral Artery Embolism: A Technical Case Report

Objective

To report a patient who achieved complete recanalization using the parallel stent retriever (SR) technique for a refractory acute middle cerebral artery (MCA) embolism.

Case Presentation

An 86-year-old woman underwent an emergency thrombectomy for acute right MCA occlusion. Although thrombectomy has been attempted three times with the conventional technique using a single SR, no recanalization was achieved. Then, an innovative technique was used to deploy two SRs in parallel with the M1 segment of the MCA. Pulling them back simultaneously, the thrombus was retrieved, and complete recanalization was achieved.

Conclusion

The parallel SR technique is a feasible method and can be considered as one of the last treatment resorts for acute refractory embolisms at the major MCA trunk.

Dual SAVE technique for mechanical thrombectomy rescue on MCA bifurcation clots

The Stent retriever Assisted Vacuum-locked Extraction (SAVE) technique in mechanical thrombectomy consists of the simultaneous use of a stent retriever and a distal aspiration catheter, with the removal of both as a unit when performing the thrombectomy pass. This is a safe procedure that provides a high rate of first-pass reperfusion.1 In the distal M1 segment of the middle cerebral artery (MCA) occlusions, with the distal portion of the clot extending to the upper and lower MCA branches, mechanical thrombectomy can be challenging since the thrombus is not fully trapped, with risk of distal clot migration to the branch in which the retriever is not placed. In these cases the double stent-retriever technique has been described as a rescue strategy.2–4 We describe a case of the combined use of SAVE and double stent-retriever techniques as a rescue strategy in a patient with tandem occlusion of the proximal internal carotid artery and distal MCA—the D-SAVE technique. (video 1)

Experimental evaluation and training of stent clot retrieval: the confront clot scrambling method

The introduction of stent retrievers has changed the methods used for acute intracranial thrombectomy, but the training approach has not been discussed enough. We, therefore, aimed to establish a simple skill up method which can be used to train anytime and anywhere with low costs. Also, we introduce our experimental confront clot scrambling method (CCSM) which makes a profitable visualization in how the stent retriever works. The CCSM involved a sham clot set in the middle of a polyvinyl chloride tube, after which two stent retrievers were navigated from each side before being simultaneously withdrawn with the same force. The stent that removes the sham clot is determined to have stronger clot retrieval ability. Several adjunctive techniques were also compared. The push and fluff adjunctive technique was the most effective among all the stents. Generally, the former deployed stent was stronger than later one. Therefore, the later deployed stent with the push and fluff technique lets us know whether the physician's maneuver worked well or not. CCSM could directly evaluate the ability of adjunctive techniques with each stent retriever and demonstrate the physicians' skills. Because the actual endovascular clot retrieval requires extreme fine maneuvers against invisible vessels, repeat training is very important especially in beginners.

Utility of a Y-configured stentriever technique as a rescue method of thrombectomy for an intractable rooted thrombus located on the middle cerebral artery bifurcation: technical note

Mechanical thrombectomy with stentriever and/or aspiration is the new gold standard for the treatment of acute strokes with large-vessel occlusion. As many as 20% of cases remain refractory to current stentriever and/or aspiration devices. “Saddle clots” obstructing a bifurcation may be a particular challenge for recanalization with conventional techniques and devices. The authors describe an alternative technique to bifurcation occlusions resistant to the conventional mechanical thrombectomy approach in which they simultaneously deployed 2 stentrievers into both branches of an occluded bifurcation. This stentriever Y-configuration was very effective in managing a challenging intracranial bifurcation occlusion.