Clot Fragmentation Research Articles

Macrowire for Intracranial Thrombectomy: A Video Description.

Mechanical thrombectomy has become the cornerstone to achieve reperfusion in large vessel occlusion causing acute ischemic stroke. Since the advent of intracranial thrombectomy, the procedural setup has been to deliver aspiration catheter over microwire and microcatheter to the intracranial occlusion (ADAPT) or to deliver the stent-retriever through the microcatheter (SOLUMBRA) to perform thrombectomy.1 In both these techniques the quintessential aspect is crossing the clot/thrombus, which increases the chances of clot fragmentation or disruption.2 We demonstrate delivering an ultra-large bore (Sofia 0.088, Microvention, Aliso Viejo, CA, USA) to the intracranial occlusion over a macrowire (Aristotle Colossus OD: 0.035' × 200 cm, Scientia Vascular, UT, USA) alone with no use of microcatheter or microwire. The utilization of macrowire to perform thrombectomy provides enough support to guide the large or ultra large bore catheter to the clot interface without the need to cross the clot. As this technique involves no crossing of clot it prevents clot disruption and distal embolization. There are other possible benefits which are under study in MINT Registry3 and include making thrombectomy more time and cost efficient.

Novel Self-Expandable Laser-Cut Device for Effective Thrombus Retrieval: Overcoming Limitations in Thrombectomy for Deep Vein Thrombosis, Peripheral Artery Disease and Pulmonary Embolism

Pulmonary embolism (PE) is a serious complication of deep vein thrombosis (DVT) and peripheral artery disease, often leading to fatal outcomes. The first line of treatment for DVT and PAD is anticoagulation: preventing the thrombus, occlusion of blood vessels, and propagation of PE especially in the case of DVT where limb or life-threatening complications are at risk. Clots retrieved from vessels include mechanical and manual interventions such as catheter-directed thrombolysis and thrombectomy. Yet the risks involved with thrombotic and embolic vascular occlusions are high because they cause occlusion of blood flow in crucial vessels; this may lead to tissue damage, organ failure, and death. Most of the existing thrombectomy devices do not remove the organized thrombus completely while prevention of clot fragmentation is also lacking. The study presents a new, self-expanding laser-cut clot retrieval device specifically designed to remove both hard and soft thrombi with no trauma at all to the vessel wall. This is one of the promising advancements in thrombectomy that overcomes the disadvantages of other existing technologies and offers a stronger approach for the removal of occlusions in the vascular system associated with DVT, PAD, and PE. The simulation test in vitro and a trackability test have been conducted with the developed device together with its delivery system for validation. These tests were envisaged to demonstrate how the device can operate, for example, navigate through the vasculature, and retrieve thrombi safely and accurately.

X-ray Attenuating Vesicles with Neutrophil Extracellular Trap (NET) Specificity: Synthesis and Testing in a Model System.

X-ray attenuating contrast agents for imaging thrombi directly during endovascular thrombectomy (EVT) are urgently needed for shortening the wait time for treatment and for reducing the chances of blood clot fragmentation. Neutrophil extracellular traps (NETs) are a product of an innate immune system response by which neutrophils release decondensed chromatin strands decorated with granule and cytosolic proteins, including neutrophil elastase and citrullinated histone H3 (CitH3). NETs are frequently found within fibrous thrombi in pathology and represent a promising target for thrombi-specific imaging agents due to their common occurrence in human cerebrovascular thrombi. We designed and tested 200 nm lipid vesicles (LV) formulated in the presence of a combination of hydrophilic and hydrophobic computed tomography (CT) contrast agents with resultant efficacy of X-ray attenuation corresponding to 312 ± 54 mg/mL iodine. The LV incorporated trans-cyclooctene-terminated pegylated distearoylphosphatidylethanolamine (TCO-PEG-DSPE) for rapid conjugation of methyltetrazine(mTz)-modified monoclonal immunoglobulin G (IgG) with anti-citH3 binding specificity. By using differential fluorescent labeling of the antibody and lipid components, we determined that 80 ± 3% of mTz-linked IgG coprecipitated with the LV after conjugation in contrast to 0.1-0.2% of control IgG. The engineered NET-specific LV were tested in vitro using differentiated human HL60 promyeloblasts (dHL60) as a standard model of NETing neutrophils. Using fibrin meshwork-incorporated dHL60 as well as monolayer cell cultures, we determined that anti-citH3 LV showed specific and high-affinity binding to dHL60 cells, which were stimulated to undergo NETosis. This work suggests the high promise of NET-specific agents in providing thrombus-specific imaging contrast during EVT.

Single-session catheter-directed lysis using adjunctive clot fragmentation with power pulse spray only is a fast, safe, and effective option for acute pulmonary embolism

ObjectiveSingle-session, catheter-directed thrombolysis (CDT) with adjunctive power pulse spray (PPS) only, without thrombectomy, was evaluated for its safety and effectiveness. We performed a single-center, retrospective analysis of prospectively collected data. MethodsPatients with high-risk or intermediate-risk pulmonary embolism (PE) who met the inclusion criteria and underwent a single session of CDT-PPS were included in the study. The primary outcomes assessed were technical and clinical success and major adverse events. Secondary outcomes included effectiveness based on pre- and postintervention clinical examination, radiographic findings, and reversal of right ventricular dysfunction at 48 hours and 4 weeks after discharge on echocardiography and computed tomography pulmonary angiography. The length of stay in the intensive care unit and overall admission were also analyzed. A return to premorbid exercise tolerance was evaluated at 12 months after the procedure. ResultsBetween May 2016 and January 2023, 104 patients at the Wollongong Hospital were diagnosed with high- or intermediate-risk PE and underwent CDT-PPS. Of the 104 patients, 49 (47%) were considered to have high-risk PE and 55 (53%) intermediate-risk PE. Eleven patients (11%) had absolute contraindications and 49 patients (47%) had relative contraindications to systemic thrombolysis. Technical success was achieved in 102 patients (98%). Survival was 99% at 48 hours, 96% at 4 weeks, and 91% at 12 months. At 4 weeks, echocardiography showed 98% of patients had no evidence of right heart dysfunction, and computed tomography pulmonary angiography showed complete resolution of PE in 72%. There were no major adverse events at 48 hours. The median intensive care unit length of stay was 1 day, and the overall length of stay was 6 days. At 12 months, 96% had returned to their premorbid status. ConclusionsThe CDT-PPS technique is fast, safe, and effective in the treatment of high- and intermediate-risk PE, even in patients with a high bleeding risk, and should be considered as first-line management when the skills and resources are available. Further multicenter prospective studies are needed to corroborate these results.

Abstract WMP89: Reperfusion Pattern as a Predictor of Final Infarct Growth in Patients With Anterior Large Vessel Occlusion Ischemic Stroke

Aim: The first pass effect (FPE) and complete sudden recanalization (cSR) have been identified as an indicator of favorable clinical outcome. We aimed to compare final infarct volume (FIV) according to different reperfusion pattern. Methods: We included consecutive patients admitted with an anterior LVO stroke (intracranial internal carotid artery, MCA-M1) who underwent endovascular treatment between January 2018 and April 2022. Patients with partial or no-reperfusion (eTICI 0-2b) were excluded. Final complete reperfusion (TICI 2c-3) was categorized as achieved at first pass (FPE) or in subsequent passes as sudden (cSR: from TICI 0-1 to TICI 2c-3 in a single pass) or progressive (PR: interim partial recanalization). FIV was quantified using an automatic segmentation tool (Methinks AI) on 24-hour NCCT. Aggregated infarct distribution heatmaps were generated to compare FIV distribution. Results: Of 316 consecutive patients, complete reperfusion was achieved in 202 patients (63.9%). Reperfusion patterns were as follows: FPE (109/202, 54.0%), cSR (28/202, 13.9%) and PR (65/202, 32.1%). The mean FIV was 28.1mL (95%CI 19.1-37.1), 49.5mL (95%CI 18.8-80.2) and 58.4mL (95% CI 37.6-79.2) in FPE patients, cSR and PR patients, respectively (p=0.014). After adjusting for confounders, FPE and cSR patterns were independently associated with a reduced FIV (FPE: -61.7%, 95%CI -77.2% to -35.8%, p<0.001; cSR: -39.7%, 95%CI -63.8% to 0.6%, p=0.05). The rate of excellent clinical outcome (mRS 90d 0-1) was higher in FPE (36.1%) and cSR (35.7%) groups compared to the PR group (20.3%, p=0.081). Conclusion: Improved clinical outcomes in patients with FPE and cSR patterns seem to be influenced by reduced infarct volume in a stepwise manner (FIV FPE<cSR<PR). PR may reflect clot fragmentation and embolization, contributing to infarct growth and worse outcomes. Reperfusion patterns should be explored for selecting target populations for adjunctive neuroprotective therapies during EVT.

Safety and efficacy of endovascular thrombectomy for primary and secondary MeVO

BackgroundMedium-vessel occlusions (MeVO) are emerging as a new target for endovascular treatment (EVT). Primary MeVO occur de novo, while secondary MeVO arise from large vessel occlusion (LVO) through clot migration or fragmentation - spontaneously, following intravenous thrombolysis or EVT. We aimed to evaluate efficacy and safety of EVT in primary and EVT-induced secondary MeVO. MethodsRetrospective single-center study on consecutive EVT-treated acute ischemic stroke, from 2019-to-2021. We considered: (1) exclusive-LVO, patients with LVO and – in case of residual distal occlusion – no rescue endovascular procedure; (2) primary MeVO: initial A2, A3, M2 non-dominant, M3, P2, P3 occlusions; (3) EVT-induced secondary MeVO, presenting LVO with subsequent (treated) EVT-induced MeVO. We compared (univariable/multivariable logistic regression) EVT efficacy (eTICI≥2b, 3-month modified Rankin Scale [mRS] 0-2) and safety (EVT-complications [vessel dissection, perforation, persistent-SAH], symptomatic ICH) in all MeVO versus exclusive-LVO, primary MeVO versus exclusive-LVO, EVT-induced secondary MeVO versus exclusive-LVO and EVT-induced secondary MeVO versus primary MeVO. ResultsWe included 335 patients: 221 (66.0 %) exclusive-LVO and 114 (34.0 %) MeVO (55 [48.2 %] primary, 59 [51.8 %] secondary). Compared to exclusive-LVO, primary MeVO had higher rates of EVT complications (aOR 3.77 [95%CI 1.58-9.00],p=0.003), lower rates of eTICI≥2b (aOR 0.32 [95%CI 0.12-0.88],p=0.027) and mRS 0-2 (aOR 0.28 [95%CI 0.13-0.63],p=0.002). EVT-induced secondary MeVO had no major differences in efficacy and safety outcomes compared to exclusive-LVO, but a better mRS 0-2 (aOR 8.00 [95%CI 2.12-30.17],p=0.002) compared to primary MeVO. ConclusionsPrimary and EVT-induced secondary MeVO showed different safety/efficacy EVT-related profiles. Dedicated randomized data are needed to identify the best acute reperfusion strategy in the two categories.

Abstract 047: Solumbra ‘PINCHING’ technique for medium vessel occlusions (MeVOs): A Single Center Experience

Introduction Various techniques have been evolved and used by different operators for mechanical thrombectomies for improved procedural performance, lower intraoperative times and better recanalization rates The widely used, isolated stent‐retriever and contact aspiration technique for medium vessel occlusions (MeVOs) carries a high risk for clot fragmentation, spasm and distal migration. The stent–aspiration (Solumbra) technique uses a large bore aspiration catheter with a stent retriever device for potential synergistic effects. However, its use is limited in distal thrombectomies. Hereby, we assess the efficacy and safety of solumbra ‘Pinching’ technique by using a smaller profile aspiration catheter for MeVO thrombectomy. Methods We retrospectively analyzed our prospective institutional database for medium vessel occlusions (M2, M3 MCA/ A2, A3 ACA/ P2 PCA) who underwent endovascular mechanical thrombectomy using stent retriever or aspiration or combined (solumbra) technique. The technique involves deploying a stent retriever through microcatheter and large bore aspiration catheter like ACE 68 (Penumbra, Inc.), followed by both microcatheter and aspiration removal, clot localization and blind navigation of a correctly sized lower profile (3MAX or 4MAX, Penumbra, Inc.) aspiration catheter over stent bare wire to “pinch” the primal end of the clot. Besides various demographic parameters, we collected final recanalization rates with first pass effect [using modified Thrombolysis in Cerebral Infarction (TICI) score]. All the intra‐procedural complications (haemorrhage, vasospasm) were analysed. Clinical outcome was analysed using modified ranking score (mRS) on 7th day post procedure/ discharge(whichever is earlier) and at 90 days. Results Total 26 MeVOs were successfully treated in twenty‐five patients with solumbra ‘Pinching’ technique since January 2022 (Male: female 16:7, mean age 58.6 years, mean NIHSS 9.1). Majority of the procedures were done for primary MeVOs and 72% consisted of M2 MCA occlusions. Whether to use a 3MAX or 4MAX aspiration catheter was determined by eyeballing the appropriate calibre for target vessels. Final first pass mTICI 2c/3 recanalization was achieved in 24 patients (88%). Minor Intra‐procedural complications were observed in 13 patients. Favorable modified ranking score (mRS 0‐2) was achieved in approximately 80% patients at the end of 7 days/discharge and 14 out of 16 follow up patients achieved good clinical outcome at 90 days Conclusion Solumbra ‘Pinching’ technique, using a low profile aspiration catheter like 3 MAX or 4 MAX (Penumbra, Inc.) with a stent retriever, can be effectively used in management of acute ischaemic stroke secondary to a MeVOs with significantly enhancing the first‐pass recanalization with lesser risk of intimal injury, dissection and secondary embolization.

Abstract 208: Optimal Catheter Position and Aspiration Technique Improves Safety and Efficacy Using Next Generation Funnel Catheter

Introduction The Advanced Neurovascular Access (ANA5, Anaconda Biomed) is a novel stroke thrombectomy catheter comprising a distal self‐expanding covered funnel designed to locally restrict blood flow in the Internal Carotid Artery (ICA) and, when used in conjuction with available stent retreiver, reduce clot fragmentation during clot ingestion. The ANAIS study aimed to investigate the safety and efficacy of the ANA5 device (‘Funnel’) in different deployment locations and aspiration conditions. Methods Prospective, single‐arm, multi‐center study to assess the safety and performance of ANA5 in combination with a stent retriever in patients with Acute Ischemic Stroke (ANAIS). An independent imaging corelab and Clinical Events Committee assessed the different predefined outcomes. Patients with anterior circulation vessel occlusion admitted within 24 hours from symptom onset were eligible. The primary efficacy endpoint was successful recanalization, defined as mTICI ≥2b in the target vessel within three passes of the Funnel device. The primary safety endpoint was a composite of symptomatic Intracranial Hemorrhage within 24 hours and any device related severe adverse event. The impact of the funnel deployment location in the different ICA segments (C1 to C4 or above) and the condition of the aspiration on angiographical outcome was also evaluated. Results A total of 39 subjects who complied with all inclusion/exlusion criteria were treated by 10 different physicians in 3 stroke centers. Mean age was 69.9 ±13.2 years, 52.5% women, and the median National Institutes of Health Stroke Scale on admission was 16.0 [12.5‐19.5]. Initial occlusion location was: TICA 25.0%, M1‐MCA 52.5% and M2‐MCA 22.5%. The rate of succesful reperfusion within 3 passes was 74.4% (29/39) (primary efficacy endpoint). First pass effect (FPE) mTICI 2b‐3 and 2c‐3 was 56.4% (22/39) and 48.7% (19/39), respectively. Zero sICHs at 24h or SADE at 5 days were reported (primary safety endpoint). At 90 days, the rate of modified Rankin Scale score 0‐2 was: 57.9% (22/38). The efficacy of the thrombectomy procedure using the Funnel increases when: 1. The funnel was deployed in the higher ICA segments (below ophtalmic artery) with diameter between 3.5‐5.0mm, ensuring full apposition of the funnel to the vessel wall: C1(n=10): 40.0% vs. C2 or higher (n=29): 86.2% (p < 0.002). 2. Continuous aspiration was applied during the full retrieval of the stentriever in the Funnel (89.3% (n=28) vs. 36.4% (n=11), p < 0.0005). 3. When both continuous aspiration and appropriate ICA location were achieved, the Clinical efficacy endpoint improved to 95.5% (n=22), and FPE mTICI 2b‐3 and 2c‐3 were 72.7% and 59.1% respectively. Conclusion The use of the next generation Funnel Device in the ANAIS study results in a high rate of successful recanalization with an optimal safety profile and favorable 90 days clinical outcomes. The performance improved when the Funnel was deployed above the C1 cervical segment of the ICA, and continuous aspiration was applied during the full stent retrieval.

When should we involve interventional radiology in the management of acute pulmonary embolism?

Pulmonary embolism (PE) is a common disease associated with high morbidity and mortality. Currently, guidelines recommend systemic thrombolysis in patients with haemodynamic instability (high-risk PE) or patients with intermediate-high-risk PE with haemodynamic deterioration. Nevertheless, more than half of high-risk PE patients do not receive systemic thrombolysis due to a perceived increased risk of bleeding. In these cases, percutaneous catheter-directed therapy (CDT) or surgical embolectomy should be considered. CDT has emerged and appears to be an effective alternative in treating PE, with a hypothetical lower risk of bleeding than systemic thrombolysis, acting directly in the thrombus with a much lower dose of thrombolytic drug or even without thrombolytic therapy. CDT techniques include catheter-directed clot aspiration or fragmentation, mechanical embolectomy, local thrombolysis, and combined pharmaco-mechanical approaches. A few observational prospective studies have demonstrated that CDT improves right ventricular function with a low rate of haemorrhage. Nevertheless, the evidence from randomised controlled trials is scarce. Here we review different scenarios where CDT may be useful and trials ongoing in this field. These results may change the upcoming guidelines for management and treatment of PE, establishing CDT as a recommended treatment in patients with acute intermediate-high-risk PE.

The First Local Experience of Use of Extracorporeal Circulatory Support with PROTEKDuo Dual-Lumen Cannula in a Patient with Acute Right Ventricular Failure

Acute right ventricular failure is a life-threatening condition that can occur as a result of a sudden increase in total pulmonary vascular resistance, in particular, as a result of pulmonary embolism. Most patients with thromboembolism are treated with thrombolytic therapy, but in some cases open thrombextraction is preferred. Removal of blood clots from the pulmonary vascular bed and cardiopulmonary bypass can lead to spasm of the pulmonary artery and to the elevation of total pulmonary resistance, which, in turn, increases the afterload on the right ventricle and can lead to a dramatic decrease in its mechanical function.
 The aim. The aim of this report is to present the first experience of using the right ventricular bypass with the PROTEKDuo cannula for the purpose of temporary mechanical support of the right ventricle.
 Case presentation. We studied a 63-year-old patient who underwent Studer technique for bladder adenocarcinoma. On the 14th day an acute massive pulmonary embolism occurred with a drop in hemodynamics and the presence of a floating clot on the right atrium. Thrombolysis carried significant risks due to possible bleeding and clot fragmentation in the right atrium with subsequent embolization of the pulmonary arteries. In these circumstances, open thrombectomy under hypothermic arrest was performed. Intraoperatively, the patient developed acute right ventricular failure resistant to all conservative therapy, therefore, right ventricular bypass was connected using PROTEKDuo, which made it possible to overcome the phenomena of acute right ventricular failure in the postoperative period.
 Conclusions. Our experience with right ventricular bypass using the PROTEKDuo dual-lumen cannula demonstrates another useful option for saving patients with isolated right ventricular failure.

Urethral Sheath to Evacuate Blood Clots through Mitrofanoff Appendicovesicostomy

Background: the Mitrofanoff appendicovesicostomy provides a catheterizable submucosal tunnel between umbilicus and bladder (or neobladder). In patients with a closed bladder neck, the Mitrofanoff channel is the only way to access the bladder. We describe our case of a 17 year-old girl with a Mitrofanoff appendicovesicostomy and a previous surgical closure of the bladder neck and who developed a large bladder clot due to hematuria after a surgical cystolithotomy in an augmented bladder; Methods: after an unsuccessful trans-appendicovesicostomy bladder washing, the endoscopic evaluation was performed using a 14 Ch rigid cystoscope and surrounded by its own urethral sheath. The clot was progressively fragmented through the cystoscope under direct vision. Clot fragments were aspirated to obtain a complete evacuation; Results: the urethral sheath prevented damages to the appendicovesicostomy, allowing at the same time repeated accesses of the cystoscope into the neobladder and ensuring the procedural success. The postoperative period was uneventful, and the neobladder catheter was removed after two days. Neither channel stenosis nor anastomosis dehiscence nor incontinence were reported after five months; Conclusions: the use of urethral sheath 14 Ch through an appendicovesicostomy preserves both the stoma and the channel, making possible endoscopic procedures such as blood clot evacuation into the neobladder.

Sonothrombolysis with an acoustic net-assisted boiling histotripsy: A proof-of-concept study

Whilst sonothrombolysis is a promising and noninvasive ultrasound technique for treating blood clots, bleeding caused by thrombolytic agents used for dissolving clots and potential obstruction of blood flow by detached clots (i.e., embolus) are the major limitations of the current approach. In the present study, a new sonothrombolysis method is proposed for treating embolus without the use of thrombolytic drugs. Our proposed method involves (a) generating a spatially localised acoustic radiation force in a blood vessel against the blood flow to trap moving blood clots (i.e., generation of an acoustic net), (b) producing acoustic cavitation to mechanically destroy the trapped embolus, and (c) acoustically monitoring the trapping and mechanical fractionation processes. Three different ultrasound transducers with different purposes were employed in the proposed method: (1) 1-MHz dual focused ultrasound (dFUS) transducers for capturing moving blood clots, (2) a 2-MHz High Intensity Focused Ultrasound (HIFU) source for fractionating blood clots and (3) a passive acoustic emission detector with broad bandwidth (10 kHz to 20 MHz) for receiving and analysing acoustic waves scattered from a trapped embolus and acoustic cavitation. To demonstrate the feasibility of the proposed method, in vitro experiments with an optically transparent blood vessel-mimicking phantom filled with a blood mimicking fluid and a blood clot (1.2 to 5 mm in diameter) were performed with varying the dFUS and HIFU exposure conditions under various flow conditions (from 1.77 to 6.19 cm/s). A high-speed camera was used to observe the production of acoustic fields, acoustic cavitation formation and blood clot fragmentation within a blood vessel by the proposed method. Numerical simulations of acoustic and temperature fields generated under a given exposure condition were also conducted to further interpret experimental results on the proposed sonothrombolysis. Our results clearly showed that fringe pattern-like acoustic pressure fields (fringe width of 1 mm) produced in a blood vessel by the dFUS captured an embolus (1.2 to 5 mm in diameter) at the flow velocity up to 6.19 cm/s. This was likely to be due to the greater magnitude of the dFUS-induced acoustic radiation force exerted on an embolus in the opposite direction to the flow in a blood vessel than that of the drag force produced by the flow. The acoustically trapped embolus was then mechanically destructed into small pieces of debris (18 to 60 μm sized residual fragments) by the HIFU-induced strong cavitation without damaging the blood vessel walls. We also observed that acoustic emissions emitted from a blood clot captured by the dFUS and cavitation produced by the HIFU were clearly distinguished in the frequency domain. Taken together, these results can suggest that our proposed sonothrombolysis method could be used as a promising tool for treating thrombosis and embolism through capturing and destroying blood clots effectively.

Impact of stent-retriever tip design on distal embolization during mechanical thrombectomy: a randomized in vitro evaluation

BackgroundRepeated number of passes, clot fragmentation, and distal embolization during mechanical thrombectomy (MT) lead to worse clinical outcomes in acute ischemic stroke. This study aimed to assess the recanalization and...

Development of a clot-adhesive coating to improve the performance of thrombectomy devices

BackgroundThe first-pass complete recanalization by mechanical thrombectomy (MT) for the treatment of stroke remains limited due to the poor integration of the clot within current devices. Aspiration can help retrieval...

Abstract Number ‐ 151: Impact of Stent‐Retriever Tip Design on Distal Embolization during Mechanical Thrombectomy

Introduction Mechanical thrombectomy (MT) is a widely performed procedure for acute ischemic stroke (AIS) due to large vessel occlusion. Repeated number of passes, clot fragmentation, and distal embolization during MT lead to worse clinical outcomes. We aim to evaluate the impact of different stent‐retriever (SR) distal tip designs on distal emboli generation during MT. Methods Fragment‐prone clot analogs (diameter = 3.53±0.14mm; length = 6.74±0.61mm) were used to create proximal middle cerebral artery (MCA‐M1) occlusions in an in vitro neurovascular model featuring a complete circle of Willis. The anatomical replica was connected to a flow loop with circulating saline at physiological flow rate and temperature; 100‐µm filters were placed at the neurovascular outflow points of the model to collect generated distal emboli. After initial embolization, experiments were randomized into one of the three treatment arms based on SR tip design: open‐end (Open‐SR: Solitaire 6.0×40mm), closed‐end (Closed‐SR: Embotrap II 5.0×33mm), and filter‐end (Filter‐SR: NeVa NET 5.5×37mm). A balloon guide catheter was inflated at the internal carotid artery C1 level immediately after SR deployment, and the SR was pulled out under continuous proximal pump aspiration. A total of 90 cases were performed (30 cases/treatment arm). A single attempt was performed per case and after each pass, distal emboli collected in the outflow filters were analyzed by an image processing algorithm. Successful first pass recanalization (FPR) was confirmed if no residual clot was observed at the initial location or in a distal branch of the model. Primary study endpoints were: FPR rate (%FPR), the size of the largest embolus (largest‐E), the total emboli count (total‐E), the total count of emboli larger than 1mm (total>1mm‐E), and the total area of the filter covered by emboli (area‐E). Results FPR was achieved in 57.8% of cases (52/90): Filter‐SR achieved a non‐significantly higher %FPR (70%) than closed‐SR (50%) and open‐SR (53.3%) (p = 0.244). In comparison to open‐ and closed‐SR, filter‐SR significantly reduced the largest‐E (open‐SR = 1.66±0.68mm vs. closed‐SR = 1.77±0.90mm vs. filter‐SR = 1.22±0.77mm; p = 0.013) as well as the total>1mm‐E (open‐SR = 2.27±2.33 vs. closed‐SR = 3.97±5.68 vs. filter‐SR = 0.93±1.28; p = 0.002), and the area‐E (open‐SR = 18.22±14.47mm2 vs. closed‐SR = 23.98±22.39mm2 vs. filter‐SR = 10.14±8.81mm2; p = 0.013). The differences between distal tip designs were not clearly evidenced in the total‐E (open‐SR = 22.7±10.75 vs. closed‐SR = 23.13±13.16 vs. filter‐SR = 20.63±12.77; p = 0.464). No significant differences were found between open‐ and closed‐SR (p>0.05 in all metrics). Conclusions When facing fragment‐prone clots with low SR engagement, the filter‐SR significantly reduces the number of large clot fragments (>1mm), the size of the largest embolus, and the overall surface area of clot fragments that embolize distally during an MT procedure.

Abstract Number ‐ 25: Acute Ischemic Stroke Intervention With Penumbra RED Reperfusion Catheters: Updated Subset Analysis From INSIGHT Registry

Introduction The prospective INSIGHT Registry is a multicenter ‘multi‐omic’ analysis of thrombi associated with acute hemorrhagic or ischemic stroke. This updated interim analysis evaluated the performance of Penumbra RED catheters used during aspiration thrombectomy for acute ischemic stroke (AIS). Methods All AIS cases in which Penumbra RED aspiration catheters (RED 62, 68, or 72) were utilized as a frontline treatment were included in the analysis. Retrieved clot fragments were classified based on their gross appearance. Key time metrics and procedural data were also collected, including first‐pass / post‐procedure modified Treatment in Cerebral Ischemia (mTICI) score. Results Of 400 patients enrolled across 25 US centers, 161 underwent thrombectomy with Penumbra RED catheters over ten months (Jul 2021 through Apr 2022). The mean patient age was 70.7 years, and 50.9% were female. The middle cerebral artery first segment (M1) was the most common primary occlusion site (60.4%; 96/159). IV t‐PA was administered before the procedure in 13.7% (22/161) of patients. The median time from stroke onset / last known well to mTICI≥ 2b was 5.0 hrs. [IQR 3‐11], and the median time from a puncture to mTICI≥ 2b was 23.0 mins [IQR 15‐31]. Firm‐red clots represented 45.3% (67/148), while soft‐red clots were found in 37.8% (56/148) of retrieved clots. In turn, firm‐white and soft‐white clots were seen in 11.5% (17/148) and 5.4% (8/148) of cases, respectively. Rates of the first pass and final mTICI≥ 2b scores by clot type are shown in Table 1. Conclusions Aspiration thrombectomy with Penumbra RED catheters resulted in good revascularization rates for all clot types.

Abstract Number ‐ 186: Keep it simple: MAC (Manual Aspiration with Contrast) Technique Endovascular Management of Acute ischemic Stroke

Introduction The availability of advanced large‐bore diameter aspiration catheters has improved recanalization rates and time. We report a prospectively collected clinical experience with a simple technique: MAC (Manual Aspiration Contrast Enhancement) as the primary method for vessel recanalization. Gently contrast injection while the aspiration catheter is advanced to the thrombus and subsequently creating a closed‐loop system with the contrast column within the catheter can result in better visualization during the aspiration, thus improving the FPE avoiding clot fragmentation, multiple passes and blind movements of catheter by a single operator. Methods 47 prospectively patients with ELVO and 3 cases of middle vessel occlusion (MVO) at four institutions were included in the study. The MAC technique was utilized in all patients. Procedural and clinical data were analyzed. Results MAC technique using SOFIA 6 Plus Catheter was successful in achieving first pass effect (FPE) and Thrombolysis in Cerebral Infarction (TICI) 2b‐ 3 revascularizations in 77% of cases. The average time from groin puncture to at least TICI 2b recanalization was 16 min. National Institutes of Health Stroke Scale (NIHSS) score average at onset of 16, and improved to a median NIHSS score at discharge of 5.5. One ICA rupture and two symptomatic intracerebral hemorrhages were recorded peri operatively. Conclusions MAC technique is a simple, fast, safe, and effective method that has reduced the requirements to multiple passes and also avoiding the use of expensive materials to reach the occlusion site. MAC is a replicable approach without additional training requirements.

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

BackgroundA 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...

942 PERCUTANEOUS TREATMENT OF ACUTE PULMONARY EMBOLISM: A CASE REPORT

Abstract Background Pulmonary embolism (P.E.) is defined as an acute occlusion/subocclusion of pulmonary vascular vessels with a ranging clinical manifestation. A reperfusion therapy (preferably systemic thrombolysis) represents the first line therapy for high-risk patients. However, a percutaneous treatment option should be considered when thrombolysis is contraindicated or has failed. Case report A 73 y.o. male, a former smoker with history of hypertension and dyslipidemia, was admitted for hemorrhagic stroke and was subsequently treated by neuro-surgical treatment. 7 days after admission, a cardiac arrest with pulseless electrical activity occurred but return of spontaneous circulation was rapidly achieved. For persistent hypotension vasopressor therapy was started. As first diagnostic work up, an EKG was performed showing sinus tachycardia and new onset of right bundle branch block; the echocardiography revealed a right ventricle dilatation with signs of pressure overload. At the computed tomography angiography of the pulmonary circulation, multiple and bilateral filling defects finally confirmed the diagnosis of acute high-risk P.E.. Given the absolute contraindication for thrombolysis and the good neurological prognosis, a catheter-directed therapy (CDT) was indicated by a multidisciplinary team evaluation. In the cath-lab, the angiography of pulmonary artery confirmed the presence of an occluding embolus in the left lower lobe artery and of a sub-occluding clot in the basal right lower lobe. Multiple aspirations were performed using a Flow Triever (Inari Medical, Irvine, CA) 20 Fr device advanced in the left and right pulmonary artery; a 16 Fr device, adopting child-in-mother technique, was also used, finally removing a large amount of thrombotic material (Fig.1). Restoration of the distal vascular segment perfusion was confirmed by a repeated angiography (Fig.2) and by the reduction of the invasive mean pulmonary artery pressure from 35 mmHg (pre-procedure) to 22 mmHg (post-procedure) (Fig.3). After the procedure, a rapid de-escalation of intravenous vasopressors was performed and the patient was transferred to the Intensive Care Unit, in stable conditions. Finally, the patient was discharged 7 days later, with the resolution of the EKG and echocardiography alterations. Conclusions The Flow Triever device for the interventional treatment of P.E. is a CE approved aspiration system (3 sizes aspiration catheters) including 3 catheters with self-expanding nitinol for mechanical clot fragmentation. Evidence on the safety and efficacy of CDT is limited to observational single studies, a few small randomized trials and small single-arm cohort studies. Outcomes depend on the chosen technique, patient characteristics and local expertise. In particular, the FLARE study showed a significant Right/Left Ventricle ratio reduction after the use of a Flow Triever system while keeping a low rate of complications. The FLASH study is ongoing and the interim analysis showed encouraging results. However, randomized studies focusing on clinical outcomes and comparing CDT to conventional standard therapy (i.e. systemic thrombolysis for high-risk PE and anticoagulation for intermediate risk disease) are needed.

Combined stent-retriever and aspiration intra-arterial thrombectomy performance for fragmentable blood clots: A proof-of-concept computational study

Mechanical thrombectomy (MT) treatment of acute ischemic stroke (AIS) patients typically involves use of stent retrievers or aspiration catheters alone or in combination. For in silico trials of AIS patients, it is crucial to incorporate the possibility of thrombus fragmentation during the intervention. This study focuses on two aspects of the thrombectomy simulation: i) Thrombus fragmentation on the basis of a failure model calibrated with experimental tests on clot analogs; ii) the combined stent-retriever and aspiration catheter MT procedure is modeled by adding both the proximal balloon guide catheter and the distal access catheter.The adopted failure criterion is based on maximum principal stress threshold value. If elements of the thrombus exceed this criterion during the retrieval simulation, then they are deleted from the calculation.Comparison with in-vitro tests indicates that the simulation correctly reproduces the procedures predicting thrombus fragmentation in the case of red blood cells rich thrombi, whereas non-fragmentation is predicted for fibrin-rich thrombi. Modeling of balloon guide catheter prevents clot fragments' embolization to further distal territories during MT procedure.