Paper:
Experimental evaluation of the NeVa™ thrombectomy device, a novel stent retriever conceived to improve efficacy of organized clot removal
Authors:
Machi, Ulm, Bernava, Brina, Lovbad, Jourdan
Journal:
Journal of Neuroradiology – 2017
Background and Purpose:
Although stent-retrievers are recognized as the most effective devices in thrombectomy, they still fail when occlusion is due to organized, firm clots. The aim of this study is to present a preclinical evaluation of the Neva device in removing these more challenging clot types.
Methods:
Experimental thrombectomies were done in a vascular phantom using 4 and 6 mm large hard clots in the MCA or terminal ICA of the phantom. NeVa M1 was used in the MCA and NeVa T was used in the terminal ICA. The interaction of the devices with the thrombus and the behavior of the device during retrieval were evaluated using fluoroscopy and magnified video imaging in 10 thrombectomies.
For describing results:
- Optimal clot integration (OCI) was defined as clots entering the drop zones
- Effective clot removal (ECR) was defined as complete removal of clot from the phantom
Efficacy Analysis:
NeVa demonstrated the highest rate of optimal clot integration (OCI) and effective clot removal (ECR) – 70% – when compared to 10 competitive devices that were tested in a previous study with the same phantom and protocol, performed by the same author1.
Average number of passes was 1.8 for NeVa M1 (4.0 x 30 mm) and 1.9 for NeVa T (4.5 x 37 mm)
NeVa devices maintained constant wall apposition and resisted stretch deformation during retrievals even when retrieved over the sharp angles of the rigid vascular phantom
Mechanical Analysis:
As with all stent retriever devices, NeVa radial force is reduced significantly in 3.5 mm vessels compared to 1.5 mm vessels
NeVa devices demonstrated significant radial pressure compared to other tested devices
Safety:
Some degree of vasospasm was noted, often fully recovered within 30-60 min after retrieval
Histology of vessels from animal study demonstrated endothelial loss and minimal disruption of the internal elastic lamina and lower injury score of 2.63 – 2.88 was recorded compared to Stryker Trevo 4.3 – 4.5²
Results:
NeVa device showed a high rate of “optimal clot integration” and “effective clot removal”
¹ Machi P, Jourdan F, Ambard D, Reynaud C, Lobotesis K, Sanchez M, et al. Experi-mental evaluation of stent retriever’s mechanical properties and effectiveness.J Neurointervent Surg 2016:1–7
² Nogueira RG, Levy EI, Gounis M, Siddiqui AH. The Trevo device: preclinicaldata of a novel stroke thrombectomy device in two different animal models ofarterial thrombo-occlusive disease. J Neurointerv Surg 2012;4:295–300