Systematic Review on Endovascular Access to Intracranial Arteries for Mechanical Thrombectomy in Acute Ischemic Stroke

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.

Radiographic Anatomy of the Common Carotid Artery for Direct Carotid Puncture

BACKGROUND

Direct common carotid puncture (DCP) is conventionally used as a bailout technique in stroke patients. However, little is known about the relevant anatomy. Our objective was to examine the relationship of the common carotid artery (CCA) to surrounding structures based on different DCP trajectories passing through the artery's center.

METHODS

Fifty randomly selected head/neck CTAs were analyzed. The trajectory of DCP and relationship to the internal jugular vein (IJV) and thyroid were analyzed at 1 cm intervals above the clavicle on 7 axial sections. Using the trans-carotid sagittal plane as the 0° trajectory, we plotted 3 additional trajectories at 30° intervals and the relationship with the IJV and thyroid proximity was graded as following: 0=absent, 1=adjacent, and 2=crossing. The CCA tortuosity index was also analyzed for each vessel.

RESULTS

Analysis of 2800 trajectories across 100 CCAs showed that the IJV and thyroid were least encountered on the axial sections 2 cm above the clavicle, at 0° on the right (9 thyroids and 6 IJV), and at 90° on the left (0 Thyroids and 14 IJVs). The tortuosity index of the CCA was significantly lower above the clavicle than its entire length (P < 0.001).

CONCLUSIONS

DCP performed 2 cm above the clavicle at 0° on the right, and 90° on the left appears to minimize encounters with the IJV and thyroid gland, reducing potential complications. However, despite these findings, ultrasound guidance remains vital for DCP safety. Further focus on endovascular device safety in DCP is needed.

Percutaneous Closure Device for the Carotid artery: An integrated review and design analysis

Endovascular thrombectomies (EVTs) are the current standard of care therapy for treating acute ischemic strokes. While access through the femoral or radial arteries is routine, up to 20% of EVTs through these sites are unable to access the cerebral vasculature on the first pass. These shortcomings are commonly due to tortuous vasculature, atherosclerotic arteries, and type III aortic arch, seen especially in the elderly population. Recent studies have shown the benefits of accessing the cerebral vasculature through a percutaneous direct carotid puncture (DCP), which can reduce the time of the procedure by half. However, current vascular closure devices (VCDs) designed for the femoral artery are not suited to close the carotid artery due to the anatomical differences. This unmet clinical need further limits a DCP approach. Thus, to foster safe adoption of this potential approach, a VCD designed specifically for the carotid artery is needed. In this review, we outline the major biomechanical properties and shortcomings of current VCDs and propose the requirements necessary to effectively design and develop a carotid closure device.

Deep learning-based model for difficult transfemoral access prediction compared with human assessment in stroke thrombectomy

BACKGROUND

In mechanical thrombectomy (MT), extracranial vascular tortuosity is among the main determinants of procedure duration and success. Currently, no rapid and reliable method exists to identify the anatomical features precluding fast and stable access to the cervical vessels.

METHODS

A retrospective sample of 513 patients were included in this study. Patients underwent first-line transfemoral MT following anterior circulation large vessel occlusion stroke. Difficult transfemoral access (DTFA) was defined as impossible common carotid catheterization or time from groin puncture to first carotid angiogram >30 min. A machine learning model based on 29 anatomical features automatically extracted from head-and-neck computed tomography angiography (CTA) was developed to predict DTFA. Three experienced raters independently assessed the likelihood of DTFA on a reduced cohort of 116 cases using a Likert scale as benchmark for the model, using preprocedural CTA as well as automatic 3D vascular segmentation separately.

RESULTS

Among the study population, 11.5% of procedures (59/513) presented DTFA. Six different features from the aortic, supra-aortic, and cervical regions were included in the model. Cross-validation resulted in an area under the receiver operating characteristic (AUROC) curve of 0.76 (95% CI 0.75 to 0.76) for DTFA prediction, with high sensitivity for impossible access identification (0.90, 95% CI 0.81 to 0.94). The model outperformed human assessment in the reduced cohort [F1-score (95% CI) by experts with CTA: 0.43 (0.37 to 0.50); experts with 3D segmentation: 0.50 (0.46 to 0.54); and model: 0.70 (0.65 to 0.75)].

CONCLUSIONS

A fully automatic model for DTFA prediction was developed and validated. The presented method improved expert assessment of difficult access prediction in stroke MT. Derived information could be used to guide decisions regarding arterial access for MT.

Deep Learning-based Assessment of Internal Carotid Artery Anatomy to Predict Difficult Intracranial Access in Endovascular Recanalization of Acute Ischemic Stroke

BACKGROUND

Endovascular thrombectomy (EVT) duration is an important predictor for neurological outcome. Recently it was shown that an angle of ≤ 90° of the internal carotid artery (ICA) is predictive for longer EVT duration. As manual angle measurement is not trivial and time-consuming, deep learning (DL) could help identifying difficult EVT cases in advance.

METHODS

We included 379 CT angiographies (CTA) of patients who underwent EVT between January 2016 and December 2020. Manual segmentation of 121 CTAs was performed for the aortic arch, common carotid artery (CCA) and ICA. These were used to train a nnUNet. The remaining 258 CTAs were segmented using the trained nnUNet with manual verification afterwards. Angles of left and right ICAs were measured resulting in two classes: acute angle ≤ 90° and > 90°. The segmentations together with angle measurements were used to train a convolutional neural network (CNN) determining the ICA angle. The performance was evaluated using Dice scores. The classification was evaluated using AUC and accuracy. Associations of ICA angle and procedural times was explored using median and Whitney‑U test.

RESULTS

Median EVT duration for cases with ICA angle > 90° was 48 min and with ≤ 90° was 64 min (p = 0.001). Segmentation evaluation showed Dice scores of 0.94 for the aorta and 0.86 for CCA/ICA, respectively. Evaluation of ICA angle determination resulted in an AUC of 0.92 and accuracy of 0.85.

CONCLUSION

The association between ICA angle and EVT duration could be verified and a DL-based method for semi-automatic assessment with the potential for full automation was developed. More anatomical features of interest could be examined in a similar fashion.

Clinical outcome, recanalization success, and time metrics in drip-and-ship vs. drive-the-doctor: A retrospective analysis of the HEI-LU-Stroke registry

Purpose

This study aimed at comparing clinical outcome, recanalization success and time metrics in the “drip and ship” (DS) vs. “drive the doctor” (DD) concept in a comparable setting.

Methods

This is a retrospective analysis of thrombectomy registries of a comprehensive stroke center (CSC) and a thrombectomy-capable stroke center (TSC). Patients, who were transferred from the TSC to the CSC, were classified as DS. Patients treated at the TSC by an interventionalist transferred from the CSC were classified as DD. Good outcome was defined as mRS 0–2 or equivalent to premorbid mRS at discharge. Recanalization (TICI 2b-3 or equivalent) and time metrics were compared in both groups.

Results

In total, 295 patients were included, of which 116 (39.3%) were treated in the DS concept and 179 (60.7%) in the DD concept. Good clinical outcome was similarly achieved in DS and DD (DS 25.0% vs. DD 31.3%, P = 0.293). mRS on discharge (DS median 4, DD median 4, P = 0.686), NIHSS improvement (DS median 4, DD median 5, P = 0.582) and NIHSS on discharge (DS median 9, DD median 7, P = 0.231) were similar in both groups. Successful reperfusion was achieved similarly in DS (75.9%) and DD as well (81.0%, P = 0.375). Time from onset to reperfusion (median DS 379 vs. DD 286 min, P = 0.076) and time from initial imaging to reperfusion were longer in DS compared to DD (median DS 246 vs. DD 162 min, P &lt; 0.001).

Conclusion

The DD concept is time saving while achieving similar clinical outcome and recanalization results.

[Neurothrombectomy 2022-Extension of indications and technical innovations]

For advanced territorial ischemia numerous retrospective and prospective studies have shown a positive effect of mechanical thrombectomy (MT) compared to best medicinal treatment alone. For patients with minor stroke (NIHSS < 6) there is currently a lack of evidence for MT. Appropriate study protocols must differentiate between patients with large vessel occlusion with disproportionately mild symptoms and more distal vascular occlusion and therefore correspondingly fewer clinical symptoms. The role of intravenous lysis treatment before MT as bridging lysis also currently retains its general recommendation, as large studies could not show a uniform noninferiority of MT alone. In addition, the use of intra-arterial lysis after successful MT offers a promising approach, which still needs to be evaluated. Novel aspiration catheters and stent-retrievers as well as competing thrombectomy techniques can be compared by the first pass effect, the successful recanalization with only one attempt at thrombectomy. Contact aspiration and stent-retriever thrombectomy under aspiration are equivalent and established thrombectomy procedures. For the latter, several detailed maneuver tactics are described for improvement of thrombectomy success. Also, in retrospective studies the combination with a balloon-guided catheter promises a further improvement of recanalization results. In the case of failure of supra-aortic vessel probing with inguinal access, radial access and direct carotid puncture are alternative access routes. Recent studies on ICA stenting with tandem occlusions showed a benefit of stents without an increased risk for symptomatic intracranial hemorrhage. The retrograde approach, to first treat the intracranial vessel occlusion and then the carotid stenosis, seems to be advantageous.

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.

Simplified classification of cavernous internal carotid artery tortuosity: a predictor of procedural complexity and clinical outcomes in mechanical thrombectomy

OBJECTIVES

Thromboaspiration catheters are increasingly used for the endovascular treatment of large vessel stroke (LVS), while tortuous vascular anatomy still remains one major challenge in mechanical thrombectomy. Prompt assessing and understanding cavernous internal carotid artery (cICA) tortuosity may help to predict procedural complexities of mechanical thrombectomy and thus improve the clinical outcomes.

METHODS

A retrospective review was performed on a cohort of LVS patients with thromboaspiration catheter. Simplified classification of cICA tortuosity was applied by measurement of the angle of the posterior genus (P) and the height from the peak of the posterior genu to the trough of the anterior genu (D). Statistical analyses were performed to analyze differences among the obtained types of cICA tortuosity regarding procedural characteristics and clinical outcomes.

RESULTS

A total of 150 patients with LVS proximal to the internal ICA terminus and middle cerebral artery (MCA) were included in this study, and three types of cICA tortuosity were defined by the simplified classification. The index, such as patients ages and hypertension, procedural fluoroscopy time, the degree of cICA tortuosity, first-pass success, final reperfusion, and 90-day mortality showed significant differences among the three types (P < 0.05), while 90-day good outcome (mRS 0-2) only presented significant difference between Type I and Type III (P < 0.05).

CONCLUSIONS

The study indicated that the grading of cICA tortuosity is highly correlated with procedural complexity and clinical outcome in mechanical thrombectomy. The proposed classification system may be helpful in pre-procedure prognostication complexity and clinical outcomes.Abbreviations:LVS: large vessel stroke; cICA: cavernous internal carotid artery; mRS: modified Rankin Scale; AIS: acute ischemic stroke; MCA: middle cerebral artery; M1: first division of middle cerebral artery; M2: second division of middle cerebral artery; M3: third division of middle cerebral artery; TICI: Thrombolysis In Cerebral Infarction; TICI 2b: two-thirds of occluded territory reperfusion; DSA: digital subtraction angiography; FT: fluoroscopy time.