In vitro testing of a funnel-shaped tip catheter model to decrease clot migration during mechanical thrombectomy

Abstract

one limitation of mechanical thrombectomy (Mt) is clot migration during procedure. this might be caused by abruption of the trapped thrombus at the distal access catheter (DAc) tip during stentretriever retraction due to the cylindrical shaped tip of the DAc. Aiming to solve this problem, this study evaluates the proof-of-concept of a new designed funnel-shaped tip, in an experimental in vitro setting. two catheter models, one with a funnel-shaped tip and one with a cylindrical-shaped tip, were compared in an experimental setup. for Mt a self-made vessel model and thrombi generated from pig's blood were used. MT was performed 20 times for each device using two different stent-retrievers, 10 times respectively. For the funnel-shaped model: for both stent-retrievers (Trevo XP ProVue 3/20 mm; Trevo XP ProVue 4/20 mm) MT was successful at first pass in 9/10 (90%), respectively. For the cylindricalshaped model: MT was successful at first pass in 5/10 (50%) with the smaller stent-retriever and in 6/10 (60%) with the larger stent-retriever. The experiments show a better recanalization rate for funnelshaped tips, than for cylindrical-shaped tips. these results are indicating a good feasibility for this new approach, thus the development of a prototype catheter seems reasonable.Mechanical thrombectomy (MT) has become the standard technique in the treatment of acute ischemic stroke in large vessel occlusion (LVO). Multiple randomized controlled trials (RCTs) demonstrated a safe and efficient use of MT in comparison to intravenous tissue plasminogen activator (IV t-PA) use alone 1-6 .Recently updated international and national guidelines 7,8 recommend MT for patients suffering from acute stroke up to 24 hours after the onset of symptoms, as well as for patients with wake-up strokes with an unknown time window, thus emphasizing the increasing relevance of endovascular treatment. The so-called "big five" 1-5 reports for MT in LVO show a good recanalization rate of 71%. A meta-analysis of 12 studies reports a successful recanalization rate (TICI 2b/3 score) of 81% for MT with stent-retriever in acute M2 occlusion 9 . Different techniques are possible for MT, like Direct Aspiration First Pass Technique (ADAPT), Stent-retriever Assisted Vacuum-locked Extraction (SAVE) or primary combined approach (PCA) of an aspiration catheter and stent-retriever 6,10 .Even though MT in combination with IVT is the state-of-the-art treatment for LVO, there are still limitations. Balami et al. 11 report an embolization to new vascular territories in 1-8.6% for most randomized controlled trials (RCTs) and in 1-12.5% for the non-RCTs. This can be caused by clot migration to proximal vessels during the retraction of the stent-retriever or persistence in the same vessel. Furthermore, the clot can break and dissipate www.nature.com/scientificreports www.nature.com/scientificreports/ learning algorithms to produce pixel based segmentations are available online 18,19 . Images were further processed and transformed into grayscale images. Then a binary im...

A Novel Thrombectomy Device: An In Vitro Evaluation of a Prototype Catheter

“…Since the thrombus is disproportionally larger than the diameter of common cylindrical catheters, there is a risk that it will be abraded against the catheter wall. We have now been able to confirm the superiority of the funnel-shaped extension from previously published preliminary tests with the new prototype catheter [11] .…”

“…Therefore, the Department of Neuroradiology at the University Hospital Mainz, Germany, developed a novel catheter designed to prevent thrombus loss and fragmentation at the catheter wall during stent retriever retraction. A recent proof-ofprinciple-study showed a better recanalization rate for the funnel-shaped tip compared to a standard cylindrical tip [11] . Our prototype catheter (PC) was developed on this basis.…”

In vitro testing of a funnel-tip catheter model to decrease clot migration and to evaluate clot effects in mechanical thrombectomy

“…A total of 160 MTs were carried out. Results from the preliminary study Tanyildizi et al 2 were included in the Chandler loop group. Please refer to the owchart (Fig.…”

“…We compared the funnel-shaped tip featuring a larger inner-opening diameter (d = 2.5mm) to a standard tip (d = 1.5mm) model, in terms of functionality and e cacy for mechanical thrombectomy in an in vitro setup. In our rst in vitro study, we observed higher recanalization rates of up to 90% using the modi ed funnel-shaped tip compared to 50 to 60% for the standard tip 2 . Consequently, the proof-of-concept for a newly designed funnel-shaped tip was deemed viable for continuing further in vitro experiments, this time including a greater case number (N = 160) and…”

“…Although the use of proximal balloon occlusion during thrombectomy has been suggested to signi cantly reduce this problem, clot migration into distal territories still remains unresolved. This might be caused by clot abruption at the wall of the cylindrical tip during stent retriever retraction into standard distal access catheters (DAC) 2 . Due to an overlap of thrombus material during retraction into the narrow opening tip, the thrombus is compressed and elongated, increasing the risk of fragmentation 6,7 .…”