Ribó, Marc

Introduction Difficult or impossible femoral access remains a significant burden for mechanical thrombectomy (MT) in stroke, affecting between 4.4% (impossible) to ∼10% of cases (time to first angiography [T1A] > 30 min) [1]. Visualization of CT angiography (CTA) or MR angiography are the only available diagnostic tools for neurointerventionalists (NIs) to qualitatively assess catheterization difficulty ahead of intervention. Visualization of 3D segmentation of the head‐and‐neck arteries from CTA may provide enhanced spatial information for catheter access difficulty assessment to the occlusion site, as well as large vessel occlusion (LVO) localization or carotid stenosis detection. Methods Three observers (2 expert NIs and 1 medical image engineer) assessed a sample of patients with anterior circulation stroke rating LVO location, femoral access difficulty according to a Likert scale (0 to 5) and assessment of radial access compared to femoral (easier or not). Raters were asked to answer the same form for each case twice, once after visualizing only the CTA and again after visualizing a deep‐learning, automated 3D segmentation of the head‐and‐neck arteries from CTA [2]. Cases were randomly sampled and blind to raters for both assessments. Likert scale values were normalized and averaged across observers, and correlation to T1A was studied. LVO localization accuracy and time needed for the analysis was also assessed. Results The final sample included N = 117 cases, where 22.98% presented difficult or impossible access. LVO location prevalence was 13/15/45/27% for extracranial ICA (eICA)/TICA/M1/M2, and 49/51% for right/left. Averaged Likert values presented significant linear correlation for both segmentation and CTA visualization, but this was much stronger in the former (R: 0.58 vs 0.30, p<0.001). Three‐dimensional visualization of segmented vessels allowed for an enhanced detection of difficult or impossible femoral access (ROC‐AUC: 0.85 vs 0.66). LVO detection was also superior after segmentation visualization (mean accuracy across observers: 0.81 vs 0.72) and time needed for assessment was on average 2.3 times shorter (44 s vs 100 s). In difficult or impossible patients, radial access was considered easier in 74% (63‐89%) of cases when visualizing the segmentation compared to 42% (35‐48%) when inspecting the CTA. Conclusion Visualization of deep‐learning 3D arterial segmentation resulted in enhanced difficult or impossible femoral access for MT, LVO detection and faster analysis over traditional pre‐procedural CTA inspection. Adding this visualization to the current workflow could enhance difficult access detection ahead of intervention.

Despite the proven benefit of stent retrievers, challenges to rapid revascularization of large vessel occlusions (LVO) persist. Current stent retrievers have limited effectiveness for removing organized thrombi. The NeVa device is a novel stent retriever designed with openings in the basket cell structure (“drop zones”) intended to capture organized thrombi within the central scaffold during retrieval. Prospective, multicenter, open label, single arm, FDA-regulated IDE study to evaluate the performance of the NeVa device for recanalizing occluded intracranial vessels including ICA, M1/M2 MCA, and vertebrobasilar arteries, within 8 hours of onset. Primary endpoint was rate of eTICI 2b-3 within 3 NeVa passes, tested for non-inferiority against a performance goal of 72% with a margin of -10%. Additional efficacy endpoints included first pass effect to eTICI 2b-3 (FPE) and 90-day mRS 0-2. Primary safety endpoint was 90-day mortality. (ClinicalTrials.gov NCT04514562) (Site-adjudicated revascularization results are reported here. Final core lab results will be presented at the conference.) From April 1, 2021 to April 28, 2022, 139 subjects were enrolled at 25 centers in the US and Europe. Mean age was 67 ± 13 years; 47% were female. Median NIHSS score was 16 (IQR: 12-20). Occlusions were 14 (10%) ICA, 85 (61%) M1, 38 (27%) M2, 1 (1%) Basilar and 1 (1%) PCA. Mean time to first pass was 19 ± 12 minutes. eTICI 2b-3 within 3 NeVa passes occurred in 87.8% (122/139; CI 81.1%,92.7%; non-inferiority p<0.0001; post hoc superiority p=0.002, tested against performance goal of 72%). FPE (to eTICI 2b-3) was observed in 67.6% (94/139), with first pass to eTICI 2b67-3 in 61.2% (85/139) and to eTICI 2c-3 in 43.9% (61/139). Median number of passes was 1 (IQR 1-2). Final eTICI 2b-3 rate was 94.2% (131/139); final eTICI 2c-3 rate was 65.5% (91/139). Good outcome (90-day mRS 0-2) was seen in 62.6% (87/139) and was 74.4% in patients with FPE (70/94 vs. 17/45 (37.8%) without FPE; p<0.0001). Mortality was 9.4% (13/139) with sICH in 8 (5.8%) subjects. The NeVa device is effective and safe for revascularization of LVO strokes and demonstrates high first pass success in this international multicenter study. First pass reperfusion (eTICI 2b-3) was strongly associated with functional independence.

Neurovascular catheter technology has rapidly evolved over the past decade. While performance characteristics are well known to the practitioner, the design features of these new-generation catheters and their implications on performance metrics remain a mystery to most clinicians due to the limited number of available resources. This knowledge gap hampers informed device choices and also limits collaboration between clinicians and engineers. To aid fellow neurointerventionalists, in this primer we have summarized the basic concepts of catheter design and construction.

Background In mechanical thrombectomy (MT), distal access catheters (DACs) are tracked through the vascular anatomy to reach the occlusion site. The inability of DACs to reach the occlusion site has been reported as a predictor of unsuccessful recanalization. This study aims to provide insight into how to navigate devices through the vascular anatomy with minimal track forces, since higher forces may imply more risk of vascular injuries. Methods We designed an experimental setup to monitor DAC track forces when navigating through an in vitro anatomical model. Experiments were recorded to study mechanical behaviors such as tension buildup against vessel walls, DAC buckling, and abrupt advancements. A multiple regression analysis was performed to predict track forces from the catheters’ design specifications. Results DACs were successfully delivered to the target M1 in 60 of 63 in vitro experiments (95.2%). Compared to navigation with unsupported DAC, the concomitant coaxial use of a microcatheter/microguidewire and microcatheter/stent retriever anchoring significantly reduced the track forces by about 63% and 77%, respectively (p<0.01). The presence of the braid pattern in the reinforcement significantly reduced the track forces regardless of the technique used (p<0.05). Combined coil and braid reinforcement configuration, as compared with coil alone, and a thinner distal wall were predictors of lower track force when navigating with unsupported DAC. Conclusions The use of microcatheter and stent retriever facilitate smooth navigation of DACs through the vascular tortuosity to reach the occlusion site, which in turn improves the reliability of tracking when positioning the DAC closer to the thrombus interface.