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1. P-023 Optimizing radial force of stent retrievers to minimize vessel wall injury: mechanical bench testing of radial force generated by a novel braided stent retriever compared to laser-cut stent retrievers in the M1 and m2 vessels

   Katz, Jeffrey M ; Chebl, Alex A ; Janardhan, Vikram ; Janardhan, Vallabh ( July 2018 , Journal of neurointerventional surgery)

   Purpose: 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 vesselsmore »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. Funding Source: This study was funded in part by a research grant (NSF Award: 1819491; PI: Vallabh Janardhan, MD) from the National Science Foundation (NSF). Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. Conference Proceeding: This paper was presented in part at the 15th Annual Meeting of the Society of Neuro-Interventional Surgery (SNIS), July 23-26, 2018 in San Francisco, CA.« less
2. Radial Force of Braided Thrombectomy-Assist Devices Vis-à-Vis Laser-cut Stent Retrievers in the ICA and Basilar.

   Chebl, Alex A ; Katz, Jeffrey M ; Janardhan, Vikram ; Janardhan, Vallabh. ( November 2018 , Society of Vascular & Interventional Neurology (SVIN))

   Background: Recent reports have raised concern about the risk of vessel wall injury (VWI) when pulling out current laser-cut stent retrievers with active strut apposition to the vessel walls. Development of braided stroke thrombectomy-assist devices for use in conjunction with aspiration systems may be gentler in the internal carotid (ICA) and basilar vessels (with regards to radial force) compared to existing laser-cut stent retrievers. Methods: Radial force (RF) bench testing was performed using a radial compression station (Blockwise Engineering, Phoenix, AZ). The average total radial force (RF) in Newtons (N) generated (average of 3 readings) in vessel diameters (d) (Rangemore »3.25 to 4.00mm) seen in proximal LVOs of the anterior circulation (such as in the internal carotid artery - ICA), and vessel diameters (d) (Range 2.50 to 3.25mm) seen in the posterior circulation (such as in the basilar artery - BA) was measured. The Solitaire Platinum Revascularization Device (Medtronic, Irvine, CA) was used as the predicate device. All thrombectomy and thrombectomy-assist devices were compared in terms of the RF being higher or lower (%) to the predicate device. Results: The results of the radial force testing are shown in the table below. The total radial force (RF) of the SHELTER® Retriever (part of Insera System, Insera Therapeutics, Inc., Dallas, TX), a braided thrombectomy-assist device is significantly lower (@ d=2.5mm: 58%) than the predicate device (@ d=2.5mm: 100%) and other laser-cut stent retrievers (@ d=2.5mm: 103% to 152%). Thrombectomy devices with lower OD had higher radial forces than larger devices. Conclusion: Novel braided stroke thrombectomy-assist devices for use in conjunction with aspiration systems have lower radial force compared to existing laser-cut stent retrievers in the ICA and BA vessel diameters. Further studies in-vivo need to assess the impact of lower radial force on minimizing VWI. Funding Source: This study was funded in part by a research grant (NSF Award: 1819491; PI: Vallabh Janardhan, MD) from the National Science Foundation (NSF). Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. Conference Proceeding: This paper was presented in part at the 2018 Annual Meeting of the Society of Vascular & Interventional Neurology (SVIN), November 14-17, 2018 in San Diego, CA« less
3. Complete clot ingestion with cyclical ADAPT increases first-pass recanalization and reduces distal embolization.

   Arslanian, Rose A ; Marosfoi, Miklos ; Caroff, Jildaz ; King, RM ; Raskett, Christopher ; Puri, Ajit S ; Gounis, Matthew ; Chueh, Ju-Yu. ( August 2019 , Journal of neurointerventional surgery)

   BACKGROUND: Evidence is mounting that first-pass complete recanalization during mechanical thrombectomy is associated with better clinical outcomes in patients presenting with an emergent large vessel occlusion. We hypothesize that aspiration achieving complete clot ingestion results in higher first-pass successful recanalization with quantitative reduction in distal emboli. METHODS: A patient-specific cerebrovascular replica was connected to a flow loop. Occlusion of the middle cerebral artery was achieved with clot analogs. Independent variables were the diameter of the aspiration catheter (0.054-0.088in) and aspiration pattern (static versus cyclical). Outcome measures were the first-pass rates of complete clot ingestion, the extent of recanalization, and themore »particle-size distribution of distal emboli. RESULTS: All aspiration catheters were successfully navigated to the occlusion. Complete clot ingestion during aspiration thrombectomy resulted in first-pass complete recanalization in every experiment, only achieved in 21% of experiments with partial ingestion (P<0.0001). Aspiration through the large bore 0.088in device resulted in the highest rates of complete clot ingestion (90%). Cyclical aspiration significantly increased the rate of complete clot ingestion (OR21 [1.6, 266]; P=0.04). In all experiments, complete clot ingestion resulted in fewer and smaller distal emboli. CONCLUSIONS: Complete clot ingestion results in fewer distal emboli and the highest rates of first-pass complete recanalization. The rate of complete ingestion during aspiration thrombectomy is a function of both the inner diameter of the aspiration catheter and use of cyclical aspiration. Funding Source: This study was funded in part by a research grant (NSF Award: 1819491) from the National Science Foundation (NSF). Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. Conference Proceeding: This paper was presented in part at the 2018 Annual Meeting of the Society of Vascular & Interventional Neurology (SVIN), November 14-17, 2018 in San Diego, CA« less
4. Customizable Uniform and Cyclical Aspiration Thrombectomy Using a Digital Smart Pump: An In-Vitro Feasibility Study.

   Jagadeesan, Bharathi D ; Chebl, Alex A ; Janardhan, Vikram ; Janardhan, Vallabh ( November 2018 , Society of Vascular & Interventional Neurology (SVIN))

   Background: Aspiration is an important part of stroke thrombectomy (1). Pre-clinical studies have also suggested that uniform aspiration may need to be customized for varying vessel diameters and that cyclical (varying suction intensity) aspiration may be more effective (2). Methods: Suction intensity and duration are customized in an iPad app to create uniform aspiration (using the CLEAR TM App, Insera Therapeutics) or cyclical (using the CLEAR Pro TM App, Insera Therapeutics) aspiration. Customized aspiration initiated via the iPad app activates a Bluetooth-enabled smart pump (CLEAR Aspiration System TM, Insera Therapeutics) connected to a standard aspiration catheter with an inner diametermore »(ID) of 0.070" and length of 131 cm was studied. The suction intensity at the catheter tip is confirmed using a vacuum gauge (DuraChoice) and a previously defined technique (3), and any catheter luminal collapse is noted in an in-vitro flow model (United Biologics) simulating stroke thrombectomy. Results: Activating the smart pump to generate customized uniform and cyclical aspiration (suction range 0 to -29 in Hg) using an iPad app was successful. A vacuum gauge at the catheter tip confirmed the varying suction intensities generated by the smart pump without any catheter lumen collapse. Low, medium and high suction intensities of -13, -21, and -29 inHg on the digital smart pump resulted in a suction intensities at the catheter tip of -12.5, -20.5, and -28.5 inHg. Pause of 0 inHg on the digital smart pump resulted in similar intensity at catheter tip. There was similar transmission of suction intensities between the digital smart pump and the catheter tip for uniform and cyclical aspiration patterns. Conclusion: It is feasible to customize uniform and cyclical aspiration using a digital smart pump. Further studies need to evaluate the impact of customizing uniform and cyclical aspiration on varying vessel diameters, clot types, and clot burden. Funding Source: This study was funded in part by a research grant (NSF Award: 1819491; PI: Vallabh Janardhan, MD) from the National Science Foundation (NSF). Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. Conference Proceeding: This paper was presented in part at the 2018 Annual Meeting of the Society of Vascular & Interventional Neurology (SVIN), November 14-17, 2018 in San Diego, CA« less
5. Automated Balloon Guide Catheter Aspiration Using an iPad App and Bluetooth-enabled Smart Pump: In-vitro Study.

   Jagadeesan, Bharathi D ; Chebl, Alex A ; Janardhan, Vikram ; Janardhan, Vallabh. ( November 2018 , Society of Vascular & Interventional Neurology (SVIN))

   Multiple studies suggest that addition of cervical balloon guide catheter (BGC) aspiration to intracranial suction aspiration or thrombectomy improves outcomes (1). Currently, stroke thrombectomy when performed with cervical BGC/Guide catheter (GC) aspiration requires two (2) operators. Utilizing an automated smart pump could enable a single (1) operator to perform BGC-assisted thrombectomy while varying the suction intensity in different segments of the intracranial and cervical vasculature. Phase 1: Staged BGC aspiration (initially low, medium, then high - to avoid vessel collapse) is manually performed using a 60cc syringe and a 9F BGC. The suction intensity levels for low, medium, and highmore »(in inHg) are measured using a vacuum gauge (2). Phase 2: the Mean suction levels and duration from three sample measurements are entered into an iPad app (CLEARTM Pro, Insera Therapeutics, Inc.) to create a suction pattern. Phase 3: With a BGC positioned in an in-vitro flow model simulating stroke thrombectomy, the feasibility of automated staged BGC aspiration is assessed. The iPad app activates a bluetooth-enabled smart pump (CLEARTM Aspiration System, Insera Therapeutics, Inc.) connected to the BGC. Phase 1 testing was performed. Low suction ranged from 10-13 inHg (Mean: 12 inHg) with a duration ranging from 11-17s (Mean: 13s), Medium suction ranged from 15-18 inHg (Mean: 16 inHg) with a duration ranging from 8-11s (Mean: 9s), High suction ranged from 24-26 inHg (Mean: 25 inHg) with a duration ranging from 19-25s (Mean: 22s), The total duration of staged BGC aspiration ranged from 39-53s with a 60s safety pause or end of suction prior to another retrieval attempt. Phases 2 & 3 were successfully performed to create a customized BGC pattern and staged BGC aspiration was automated during simulated stroke thrombectomy. Automated staged BGC or GC aspiration is feasible using a customizable iPad app and a bluetooth-enabled smart pump. Funding Source: This study was funded in part by a research grant (NSF Award: 1819491; PI: Vallabh Janardhan, MD) from the National Science Foundation (NSF). Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. Conference Proceeding: This paper was presented in part at the 2018 Annual Meeting of the Society of Vascular & Interventional Neurology (SVIN), November 14-17, 2018 in San Diego, CA« less