Increased Number of Passes and Double Stent Retriever Technique Induces Cumulative Injury on Arterial Wall After Mechanical Thrombectomy in a Swine Model.

The number of stentriever passes during endovascular thrombectomy impacts clinical outcomes in acute ischemic stroke. Previous studies suggest that the simultaneous double stent retriever technique (DSRT) could improve the efficacy and reduce the number of passes. We aim to analyze the degree of vessel wall injury according to the number of passes and technique (single vs. simultaneous devices). Histological changes were evaluated in renal arteries (RAs) of swine models after thrombectomy (1, 2, or 3 passes) with single stent (SSRT) and DSRT. Thrombectomy passes were performed in 12 RA: 3 samples from each artery were studied by optical microscopy to assess a vascular damage score. All thirty-six samples showed endothelial denudation and different degrees of damage in the deepest layers of the arterial wall; however, all arteries remained patent by the time of assessment. In all cases, the degree of vascular injury increased with the number of passes. Compared with a SSRT, DSRT showed a higher severity of histological damage corresponding to the damage caused by 1.4 SSRT passes. However, in distal arteries, vascular damage was relatively similar when comparing SSRT with multiple passes and DSRT with one pass. The degree of vessel injury increases with the number of passes. Even though histological damage per pass was 1.4 higher with DSRT than SSRT, short-term vessel patency was not compromised after up to 3 DSRT passes. Further studies are needed to characterize the risk-benefit ratio of the DSRT in routine clinical practice.

Understanding the Radial Force of Stroke Thrombectomy Devices to Minimize Vessel Wall Injury: Mechanical Bench Testing of the Radial Force Generated by a Novel Braided Thrombectomy Assist Device Compared to Laser-Cut Stent Retrievers in Simulated MCA Vessel Diameters.

BACKGROUND: Recent reports have raised various concerns about the risk of vessel wall injury while withdrawing current laser-cut stent retrievers during active strut apposition to the vessel walls. The development of braided thrombectomy assist devices in conjunction with aspiration systems may be gentler on the fragile brain vessels and more optimized with regard to the radial force (RF) for vessel diameters of proximal (M1) and distal (M2) large vessel occlusions (LVOs). METHODS: Mechanical bench testing of the RF was performed using a radial compression station mounted on a tensile testing machine. The total RF in newtons (N) generated in vessels with diameters ranging from 2.25 to 3 mm as seen in proximal LVOs (∼M1), and in vessel diameters ranging from 1.5 to 2.24 mm as seen in distal LVOs (∼M2), was measured. The outer diameter of each stent was recorded, and an RF ≤1 N was grouped as "low," while an RF >1 N was grouped as "high" for this analysis. RESULTS: The total RFs of all laser-cut stent retrievers were all higher in the simulated M2 vessels (>1 N) than in the M1 vessels (<1 N), whereas the total RFs of the braided thrombectomy assist devices were uniformly low in both the simulated M1 and the simulated M2 vessels. CONCLUSIONS: Novel braided thrombectomy assist devices in conjunction with aspiration systems have lower RFs than existing laser-cut stent retrievers in M1 and M2 vessel diameters. Further in vivo studies are needed to delineate the impact of lowering the RF on vessel wall integrity.