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

The 'Slingshot' technique: balloon-guide assisted tracking of distal systems past tortuosity and ledges in thrombectomy

BACKGROUND

We describe and analyze a novel technique by which inflation of a proximal balloon guide catheter (BGC) permits tracking of distal catheter systems past vessel tortuosity and ledges like the ophthalmic segment of the internal carotid artery (ICA). Inflation of the BGC counteracts slippage when deployed, and careful advancement of the system builds up energy that is translated forward, allowing users to cross segments otherwise inaccessible by endovascular techniques.

METHODS

A retrospective review of our institutional neurovascular database was conducted, and we identified nine patients for whom the novel 'Slingshot' technique was used for mechanical thrombectomy. Patient characteristics, outcomes, and procedural steps were collected and analyzed with regards to safety and efficacy of the technique.

RESULTS

The Slingshot technique was successful in all nine cases to navigate the distal system to the target location. For all cases, conventional tracking of the catheter failed, and the Slingshot technique was used as a rescue. No intraoperative complications such as vessel dissection or perforation were observed. First pass recanalization was achieved in seven (78%) cases with successful reperfusion (thrombolysis in cerebral infarction ((TICI) ≥2B) in all cases. Patient outcome was favorable with National Institutes of Health Stroke Scale (NIHSS) score improvement from a median of 16 to 3 postoperatively.

DISCUSSION

For neurovascular procedures in which advancement of an intermediate catheter or other equipment is limited by ledges or tortuosity, the Slingshot technique is a safe and effective way to reach the intended target position and does not require additional catheters or devices.

Feasibility and Safety of Double-Wire Technique for Microcatheter Navigation Beyond Tortuous Internal Carotid Siphon: A Propensity Score-Matched Study

BACKGROUND

Severe vessel tortuosity may prevent a microcatheter from reaching a distal vessel. However, the double-wire technique (DWT) may facilitate the procedure. The present study evaluated the feasibility and safety of guiding a 0.027-inch microcatheter into a distal vessel beyond the tortuous internal carotid siphon (ICS) using the DWT.

METHODS

We retrospectively reviewed 61 consecutive unruptured anterior circulation aneurysms in 61 patients who underwent treatment using flow diverter or intrasaccular flow disruption with a 0.027-inch microcatheter at our institution between October 2021 and August 2024. The DWT was used for patients in whom difficulties were encountered in advancing the microcatheter beyond the ICS with a single wire. Patients were divided into 2 groups, those who required the DWT (DWT group) and those who did not (non-DWT group). To investigate whether DWT use was associated with the degree of tortuosity of the ICS, a propensity score-matched analysis was used to control for background factors.

RESULTS

Ultimately, 11 (18.0%) used DWT to guide a 0.027-inch microcatheter into the distal vessel of the ICS, achieving 100% success rate. After matching, the radius of ICS was significantly smaller in the DWT group than in the non-DWT group (2.7 mm vs. 3.7 mm, P = 0.039). No significant difference in the complication rate was found between the 2 groups.

CONCLUSIONS

Although a 0.027-inch microcatheter is difficult to guide beyond a tortuous ICS to a distal internal carotid artery using only a single wire, the application of the DWT may allow the catheter to be guided without increased complications.

Zoom71 navigation: Does tip orientation matter?

BACKGROUND

Aspiration thrombectomy is one of the mainstays for stroke interventions. The Zoom 71 (Z71) aspiration catheter is unique with its angled tip. This study describes the orientation of the angled tip as it is navigated around the carotid siphon in relation to trackability.

METHOD

Prospectively collected cases involving large vessel occlusions of the anterior circulation intervened upon using the Z71 were retrospectively analyzed. 71 passes in 50 patients were analyzed with respect to Z71 tip orientation. 3 anatomical "turns" were defined as follows: "1": proximal cavernous, "2"- ophthalmic turn, and "3"-ICA terminus to M1. The tip was described as "Toward" Vs "Away" with respect to the inner curve of each turn. The tip getting "caught" was also analyzed.

RESULTS

There was no preferential angled tip orientation of the Z71 as it was navigated around "Turn 1", 51 % "Away" vs 44 % "Toward", p= 0.54; "2", 46.5 % "Away" vs 53.5 % "Toward", p= 0.55; and "3", 43.7 % "Away" vs 46.5 % "Toward", p=0.63. The tip was not caught in Turn 1. It was caught up in "2" in 15.5 % of passes. "Away" at "2" got caught up in 21 % of passes vs 10.5 % for "Toward", p= 0.22. Z71 got caught up in "3" in 4.7 % of passes. "Away" was associated with getting caught in 6.5 % of passes vs 3 % for "Toward", p=0.52. Zoom 88 (Z88) usage as guide catheter may be associated with Z71 getting caught less in "2" compared to "Others", 9.3 % for Z88 vs 25 %, p= 0.07. This also applied to Turn 3, 0 % for Z88 vs 11.1 %, p=0.038.

CONCLUSION

There is no preferential angled tip orientation of the Z71 as it navigates around the carotid siphon. The tip orientation does not appear to significantly affect navigation. Usage of Z88 as guide catheter helps with Z71 trackability around the siphon.

An in-vitro method for comparative analysis of aspiration catheter tracking performance

BACKGROUND AND PURPOSE

Mechanical thrombectomy (MT) for acute ischemic stroke (AIS) relies on efficient tracking of aspiration catheters through complex vascular anatomies. Differences in catheter design lead to variation in tracking performance which may only become apparent after use in patients. We developed an in-vitro methodology for evaluating aspiration catheter performance under a variety of pre-defined circumstances, that can be used during catheter development for design optimization.

METHODS

Validation of the in-vitro methodology involved testing four large bore aspiration catheters on recreated challenging vascular access routes derived from patient angiograms. Two experienced neurointerventionalists conducted the tests under controlled physiological and procedural conditions. Each catheter design was evaluated across 30 unique anatomy-procedural set-up combinations. A fifth, prototype large bore catheter was evaluated by trained engineers to assess the applicability of the in-vitro test.

RESULTS

Results from statistical analysis using a general linear model demonstrated the methodology's effectiveness in detecting significant tracking differences among catheter designs (p < 0.01). Minimal inter-operator variability was observed (p = 0.304), while procedural techniques significantly influenced tracking performance (p < 0.01). The tortuosity of the arterial access route notably impacted catheter performance (p < 0.01), with anatomical features revealing varying degrees of influence on desirable and undesirable catheter design aspects.

CONCLUSION

We successfully developed a test methodology for evaluating the trackability of large bore aspiration catheters intended for treating acute ischemic stroke with large vessel occlusions. This methodology offers a robust approach to pre-clinical design assessment, utilizing anatomical models that simulate real-world vascular challenges to enhance catheter optimization.

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.

Improving the Reachability of Contact Aspiration for Acute Ischemic Stroke Using a New Delivery Assist Catheter

OBJECTIVE

This study aimed to improve the reachability of large lumen catheter for contact aspiration during acute ischemic stroke by a new delivery assist catheter.

METHODS

This study included 58 patients with large-vessel stroke treated using endovascular procedures at our institution and affiliated hospitals between July 2021 and January 2023. Contact aspiration, especially contact aspiration using nonpenetrating of thrombus (CANP) technique, was adopted as first-line thrombectomy for localized internal carotid artery, middle cerebral artery proximal (M1 segment), and basilar artery without tandem occlusion in acute stroke. The new delivery assist catheter (AXS Offset catheter, Stryker, Fremont, CA, USA) was standardized after its release. Results of this improved contact aspiration technique using the new delivery assist catheter, including reachability, procedure time, and first-pass effect, were compared with conventional catheters.

RESULTS

Of the 58 patients, 43 underwent only thrombectomy for acute embolic stroke. CANP technique was attempted on 25 patients (25/43, 58.1%). Of these, a normal inner catheter (inner diameter: 0.021 or 0.027 inches) and the new delivery assist catheter were used on 10 (10/25, 40%) and 15 (15/25, 60%) patients, respectively. An aspiration catheter reached the thrombus for 5 patients (5/10, 50%) and 14 patients (14/15 93.3%) in the normal and new delivery assist catheter groups, respectively (P = 0.023). There was no significant difference in the results of contact aspiration due to the delivery catheter.

CONCLUSIONS

The new delivery assist catheter improved the reachability of the aspiration catheter to the thrombus and is an effective device for performing CANP technique.

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.

A Review of the Advancements in the in-vitro Modelling of Acute Ischemic Stroke and Its Treatment

In-vitro neurovascular models of large vessel occlusions (LVOs) causing acute ischemic stroke (AIS) are used extensively for pre-clinical testing of new treatment devices. They enable physicians and engineers to examine device performance and the response of the occlusion to further advance design solutions for current unmet clinical needs. These models also enable physicians to train on basic skills, to try out new devices and new procedural approaches, and for the stroke team to practice workflows together in the comfort of a controlled environment in a non-clinical setting. Removal of the occlusive clot in its entirety is the primary goal of the endovascular treatment of LVOs via mechanical thrombectomy (MT) and the medical treatment via thrombolysis. In MT, recanalization after just one pass is associated with better clinical outcomes than procedures that take multiple passes to achieve the same level of recanalization, commonly known as first pass effect (FPE). To achieve this, physicians and engineers are continually investigating new devices and treatment approaches. To distinguish between treatment devices in the pre-clinical setting, test models must also be optimized and expanded become more nuanced and to represent challenging patient cohorts that could be improved through new technology or better techniques. The aim of this paper is to provide a perspective review of the recent advancements in the in-vitro modeling of stroke and to outline how these models need to advance further in future. This review provides an overview of the various in-vitro models used for the modeling of AIS and compares the advantages and limitations of each. In-vitro models remain an extremely useful tool in the evaluation and design of treatment devices, and great strides have been made to improve replication of physiological conditions. However, further advancement is still required to represent the expanding indications for thrombectomy and thrombolysis, and the generation of new thrombectomy devices, to ensure that smaller treatment effects are captured.