A new aspiration device equipped with a hydro-separator for acute ischemic stroke due to challenging soft and stiff clots

Abstract

Objective: Fragile soft clots and stiff clots remain challenging in the treatment of acute ischemic stroke. This study aims to investigate the impact of clot stiffness on the efficacy of thrombectomy devices and a new aspiration catheter with a hydro-separator.

Methods: The Neurostar aspiration catheter has a novel hydro-separator technology that macerates clots by a stream of saline inside the catheter. The Neurostar catheter and two commercially available devices, the SOFIA aspiration catheter and Solitaire stent retriever, were tested in this study. We evaluated the efficacy of each device on clots with various stiffness in a simple in vitro model. We also assessed single-pass recanalization performance in challenging situations with large erythrocyte-rich clots and fibrin-rich clots in a realistic vascular model.

Results: We observed an inverse association between the clot stiffness and recanalization rates. The aspiration catheter, SOFIA ingested soft clots but not moderately stiff clots. When removing soft clots with the stent retriever, fragmentation was observed, although relatively stiff clots were well-integrated and removed. The Neurostar ingested soft clots similar to the aspiration catheter, and also aspirated stiff clots by continuous suction with hydro-separator. In the experiments with challenging clots, the Neurostar led to significantly higher recanalization rates than the stent retriever and aspiration catheter.

Conclusions: The stiffness of the clots affected the efficacy of endovascular thrombectomy based on the type of device. The Neurostar catheter with hydro-separator resulted in better success rates than a commercially available aspiration catheter and stent retriever in this experimental model.

Keywords: Acute ischemic stroke; aspiration; clot stiffness; endovascular thrombectomy; in vitro model.

Figure 1.

Neurostar Thrombectomy System. (a) Saline stream inside the tip of the Neurostar catheter to macerate the thrombus during aspiration (hydro-separator technology). (b) Neurostar Thrombectomy System. Aspiration is initiated by the footswitch, and negative pressure signal activates the Saline Drive Unit, creating a stream of saline on the tip of the catheter through a saline delivery tubing within the main lumen.

Figure 2.

Results of the compression test. Compression modulus (a) and compression strength (b) of artificial formed by varying agar concentrations. (Error bars indicate standard error of the means, asterisks mark significance levels of p < 0.05 (*), p < 0.01 (**), p < 0.001 (***), and p < 0.0001 (****)).

Figure 3.

Results of in vitro experiment using artificial clots with various stiffness. (a) Success rates of thrombectomy using the indicated device for clots of each agar concentration. (b) Top: Stent retriever deployed over the clot in the tubing. White bars indicate the degree of stent expansion. Bottom: Stent retriever and clot after the procedure. Fragmented clots remain in the tubing after the procedure when removing 1% clots. The integration of the stent retriever into clots reduces as the concentration increases.

Figure 4.

In vitro thrombectomy in challenging scenarios using a silicone vascular model. (a) Top: large erythrocyte-rich clot in the M1 segment. Bottom: fibrin-rich clot in the tortuous M1-M2 segment. Left: digital subtraction angiogram before the procedure. Right: video taken during the procedure for the evaluation of the clot and device behavior. (b) Success rates of clot removal using each device. * p < 0.05.