Aspiration and First Pass - Ep.1/2 - SLICE WorldWide 2022

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Aspiration technology, how big are we going?


Thrombolysis with the current dose of alteplase has been around since 1996. Few changes have occurred in the past 27 years since the publishing of the NINDS trial[1]. Notably, the time-window extension seen in 2008 with the ECASS III trial and the indication to treat unknown onset stroke based on multi-modal imaging in the extended time window[2,3].

However, since the 2015 landmark thrombectomy trials, much has changed in acute reperfusion therapies for LVO stroke, and many are still expected[4,5]. There is now evidence extending the time window to 24 hours, extending the population to large–core infarctions, and further evidence is expected for MeVO occlusions. This has all been made possible by rapid improvement in thrombectomy technology and AI-based software’s which have facilitated it.

This rapid development makes the endovascular treatment field very prone to change, and previous study results about which technique is more efficacious: thrombectomy with stent-retriever vs. aspiration, are rendered less evident[6]. Bringing a 0.88 catheter (Neuronmax size) in the M1 promises disruptive results for aspiration technology, while stent-retrievers are less prone to improvement.

Summary of initial results of large-bore aspiration

  • First-line aspiration was previously proven to be non-inferior to stent-retriever thrombectomy. Still, problems with incomplete reperfusion, trackability of large-bore devices, rate of first-pass reperfusion, and the need to use adjunctive devices have been constantly criticized by several authors who keep adhering to stent-retriever first or combination technique. 
  • The majority of the currently used aspiration catheters have 0.070-0.074 inch internal diameters, which corresponds to 1.8 mm, and it is smaller than the 3 mm lumen diameter of a standard M1 segment. Thereby explaining lower first-pass effect rates and more frequent distal embolization. 
  • Moreover, literature data support the previous theoretical considerations that aspiration technology could involve by increasing inner diameter (ID) size. Recanalization with aspiration only: is significantly more often encountered with larger ID sizes, first pass effect is more frequently encountered, and the need for adjunctive device use is less regularly encountered with higher ID sizes[7].
  • Fitzgerald et al. reported excellent trackability in a cadaver study using the Millipede 0.88 system with 100% first-pass effect compared to 40% for 6-Fr devices[8].
  • Caldwell et al. first published an initial experience with the Route 92 system. Provided, the 0.88 system could be advanced in the MCA, first-pass reperfusion was achieved in 80% of cases, and in 70% of cases, the system could be advanced without the need for a guidewire (theoretically limiting perforation rate). The technique seemed to evolve with experience, and the theoretical 42% more significant lumen of the system compared to a 0.070 catheter offers promising results[9].


Initial results with large-bore catheters seem promising, and the stroke field might be subject to a new revolution that will facilitate thrombectomy and shorten the procedural time. Further, well-designed randomized trials will have to clarify the usefulness of these devices after several teams get more familiar with their use. However, the story of mechanical thrombectomy is not over yet, and many steps have been made from the initial 6-Fr guide catheter – stent-retriever combo to currently available devices.

Further reading:

1. Group TNI of ND and S rt-PSS. Tissue Plasminogen Activator for Acute Ischemic Stroke. New England Journal of Medicine 1995;333:1581–8. doi:10.1056/NEJM199512143332401

2. Campbell BCV, Ma H, Ringleb PA, et al. Extending thrombolysis to 4·5–9 h and wake-up stroke using perfusion imaging: a systematic review and meta-analysis of individual patient data. The Lancet 2019;394:139–47. doi:10.1016/S0140-6736(19)31053-0

3. Hacke W, Kaste M, Bluhmki E, et al. Thrombolysis with Alteplase 3 to 4.5 Hours after Acute Ischemic Stroke. New England Journal of Medicine 2008;359:1317–29. doi:10.1056/nejmoa0804656

4. Goyal M, Menon BK, van Zwam WH, et al. Endovascular thrombectomy after large-vessel ischaemic stroke: A meta-analysis of individual patient data from five randomised trials. The Lancet 2016;387:1723–31. doi:10.1016/S0140-6736(16)00163-X

5. Jovin TG, Nogueira RG, Lansberg MG, et al. Thrombectomy for anterior circulation stroke beyond 6 h from time last known well (AURORA): a systematic review and individual patient data meta-analysis. The Lancet 2022;399:249–58. doi:10.1016/S0140-6736(21)01341-6

6. Lapergue B, Blanc R, Gory B, et al. Effect of endovascular contact aspiration vs stent retriever on revascularization in patients with acute ischemic stroke and large vessel occlusion: The ASTER randomized clinical trial. JAMA - Journal of the American Medical Association 2017;318:443–52. doi:10.1001/jama.2017.9644

7. Schartz D, Ellens N, Kohli GS, et al. Impact of aspiration catheter size on clinical outcomes in aspiration thrombectomy. J Neurointerv Surg Published Online First: 2022. doi:10.1136/jnis-2022-019246

8. Fitzgerald S, Ryan D, Thornton J, et al. Preclinical evaluation of Millipede 088 intracranial aspiration catheter in cadaver and in vitro thrombectomy models. J Neurointerv Surg 2021;13:447–52. doi:10.1136/neurintsurg-2020-016218

9. Caldwell J, McGuinness B, Lee SS, et al. Aspiration thrombectomy using a novel 088 catheter and specialized delivery catheter. J Neurointerv Surg 2022;14:1239–43. doi:10.1136/neurintsurg-2021-018318



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