A new approach to mechanical thrombectomy: The SAVE technique

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As mechanical thrombectomy continues to be established as the standard of care for the treatment of patients with large vessel occlusion stroke, investigators strive to refine their approaches to determine the safest and fastest option, with the best outcome. To this end, Marios Psychogios (University Medical Center Goettingen, Germany) and Volker Maus (University Hospital Cologne, Germany) along with their respective teams have developed the SAVE technique which has proved to be fast and appears to be very effective in terms of first-pass complete reperfusion.

Marios Psychogios

What is the SAVE technique?

Psychogios: The proposed approach for clot retrieval combines a more distally placed stent retriever (proximal third along the clot; 2/3 distally to the clot) and a proximally placed aspiration catheter which act as a unit, offering a distal (stent retriever) and proximal capture of the clot (aspiration catheter) while being withdrawn simultaneously under continuous proximal aspiration into the cervical guide catheter as described by Maus et al.1

The essential point of our technique is that, contrary to previous approaches, where the stent was fully retrieved inside the aspiration catheter, we wedge the thrombus between the aspiration catheter tip and the stent retriever based on the idea of increasing clot entrapment. After reaching the “wedge position” and seeing no flow within the aspiration tube, permanent aspiration with the pump is switched to the guide catheter/sheath while negative pressure is retained within the aspiration catheter with the use of a 60mL vacuum-lock syringe. The proximal aspiration with the guide catheter/sheath enables control of fragments during the critical moments of withdrawal of the embolus/stent retriever/aspiration-catheter unit inside the guide catheter/sheath. Pump aspiration on the guide catheter/sheath stays on for another 10–15 seconds after removal of the stent retriever/aspiration catheter unit in order to minimise distal emboli or emboli to new territory.

How did you come up with the idea for the SAVE technique?

Volker Maus

Maus: Historically, we came up with the idea of this wedging technique in a patient where the use of the “Solumbra-technique” (retraction of the stent retriever within the aspiration catheter) failed many times and the thrombus was only extracted when wedging the clot as described above. This experience led to the development of the SAVE technique that comprises a combination of various techniques and aspects (modified Solumbra/ARTS with distal stent placement, wedging of the clot and unit removal; “active push deployment” or “push and fluff” technique; “bare wire” technique; and proximal/extracranial pump-aspiration). The SAVE technique was finalised after discussions between the stroke groups in Goettingen and Cologne, led by Marios Psychogios and Anastasios Mpotsaris.

What is current experience with the SAVE technique?

Psychogios: In our first publication, 32 patients were included and first-pass mTICI 3 reperfusion was reached in 72%. The overall rate of mTICI 3 was 78%. Successful reperfusion (mTICI ≥2b) was achieved in all patients (100%). The rate of favourable clinical outcome (mRS 0–2) was 59%. At the moment we have performed over 130 cases with the SAVE technique in Goettingen and while the overall percentages have dropped, the results (internal core-lab) are still very good compared to the current literature: first-pass mTICI 3 47%, first-pass mTICI 2c–3 60%, overall mTICI 3 58%, overall mTICI 2c–3 76%, overall mTICI 2b–3 94%, 2% emboli to new territory, groin-to-reperfusion (first mTICI>=2b) 35min and median number of passes one (IQR 1-2). The results are even more important if we consider that 40% of our cases have been done by neurointerventionalists with <two years’ experience in neurointerventions. This means that while the SAVE technique consists of multiple steps, if one sticks to the plan and follows all the steps, the reperfusion outcome is going to be very good. Other benefits of our technique include the low number of needed passes and the minimisation of distal emboli as shown by the high rate of mTICI 2c–3 reperfusions.

How does the SAVE technique compare to other mechanical thrombectomy techniques?

Maus: Similarly to our technique, Massari et al. described an Aspiration-Retriever Technique for Stroke (ARTS)2 which was initially used as a bailout method in cases of failed ADAPT attempts and is based in a more thrombus-centred implantation of the stent retriever. This technique exhibited a similar overall successful reperfusion rate of 97.6%; however, their first-pass favourable reperfusion rate, defined as mTICI 2b/3, in 43% of their patients was inferior to our results. Furthermore, their reported mean time from groin puncture to reperfusion was longer. The “Solumbra” technique described by Humphries et al. demonstrated high successful reperfusion rates of 88% with a rate of first-pass reperfusion of 37% (mTICI 2b/3) which were both also inferior to our technique. Large studies using ADAPT report high successful reperfusion rates with fast procedure times, however, the rates of complete reperfusion (mTICI 2c–3) or successful first-pass reperfusion are lower, as shown in the ASTER trial.3

Do you have any tips and tricks for operators wanting to implement the SAVE technique?

Psychogios: Implementing the SAVE technique yields to promising complete first-pass reperfusion rates and should therefore be considered in stroke centres as we know that complete reperfusion has an impact on clinical outcome of ELVO patients.

Using a radiopaque stent retriever helps with the “active-push” or “push and fluff” part of the SAVE technique. We have started using a balloon-guide catheter, as an additional flow-control tool for minimisation of distal emboli and emboli to new territory. Our own tests have shown that, contrary to our initial beliefs, even an 8F guide sheath with pump-aspiration does not lead to flow reversal within the internal carotid artery (when clogged with a 6F aspiration-catheter). Thus, internal carotid artery flow-arrest with a balloon-guide-catheter might be the better addition to our technique.

As the stent retriever has direct contact with the vessel walls during retrieval it should not be withdrawn through an acutely placed extracranial stent as this may cause entanglements of the stent struts. This problem can be solved by executing angioplasty of the proximal stenosis initially with a balloon, then performing thrombectomy intracranially with SAVE and finally placing an extracranial stent (retrograde approach) if necessary or by advancing the guide catheter distally to the carotid stent if you simultaneously perform intracranial thrombectomy and internal carotid artery stenting as described in our REWISED technique.4

References

  1. Maus V, Behme D, Kabbasch C, Borggrefe J, Tsogkas I, Nikoubashman O, Wiesmann M, Knauth M, Mpotsaris A, Psychogios MN. Maximizing first-pass complete reperfusion with save. Clinical neuroradiology. 2017
  2. Massari F, Henninger N, Lozano JD, Patel A, Kuhn AL, Howk M, Perras M, Brooks C, Gounis MJ, Kan P, Wakhloo AK, Puri AS. Arts (aspiration-retriever technique for stroke): Initial clinical experience. Interventional neuroradiology : journal of peritherapeutic neuroradiology, surgical procedures and related neurosciences. 2016;22:325-332
  3. Lapergue B, Blanc R, Gory B, Labreuche J, Duhamel A, Marnat G, Saleme S, Costalat V, Bracard S, Desal H, Mazighi M, Consoli A, Piotin M. 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. 2017;318:443-452
  4. Behme D, Knauth M, Psychogios MN. Retriever wire supported carotid artery revascularization (rewised care) in acute ischemic stroke with underlying tandem occlusion caused by an internal carotid artery dissection: Technical note. Interventional neuroradiology : journal of peritherapeutic neuroradiology, surgical procedures and related neurosciences. 2017;23:289-292
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