Acute ischemic stroke (AIS) is the leading cause of disability and mortality worldwide. Mechanical thrombectomy is widely accepted as an important and effective treatment for AIS (1–5). However, mechanical thrombectomy is associated with many procedural (4–29%) or postoperative complications (0.6–9.3%) (6), which both neurointerventionists and stroke specialists are concerned about. The thrombectomy device plays a key role in these complications. Some complications are device-related, which occur with the primary thrombectomy device itself. As seen on angiography, there may be gross morphologic changes, such as arterial perforation (0.9–4.9%) (7–9), vasospasm (3.9–9.3%) (7, 10, 11), and kinking or dissection of the target arteries (0.6–3.9%) (7–10). On microscopic examination, there may be severe disruption of the intima. Other complications, such as distal embolization, are not directly device-induced but might be reduced with a better-designed thrombectomy device. Therefore, it is important to improve the devices to enhance their clot retrieval safety without sacrificing efficiency.

In this study, we report the evaluation of the safety and efficacy of Jrecan flow restoration device (Rui Kang Tong, Changsha, China), a new thrombectomy device designed to reduce complication risk, by comparison with the Trevo PROVUE Device in a canine model. We, therefore, tested the hypothesis that some thrombectomy safety problems could be resolved with a better stent retriever.

All procedures were conducted according to international guidelines at the Animal Experimental Center, Fuwai Hospital, Chinese Academy of Medical Sciences, and were approved by the Institutional Animal Ethics Committee [0077-3-14-HX(X)].

This study confirmed that the newly developed Jrecan^® flow restoration device reduced blood vessel damage and effectively prevented the occurrence of distal embolization on the premise of ensuring the efficiency of thrombectomy.

The damage caused by the stent to the blood vessel wall has always been a great concern for neurologists and is an urgent problem to be solved during the process of clinical thrombectomy. Recently, the preclinical trial of Trevo system on a swine thrombo-occlusion model (15) reported that severe intima disruption occurred under light microscopy (LM). Instead, a study using the Solitaire system on a swine renal artery model showed that only minimal intimal thickening occurred during follow-up studies under a microscope (16) after mechanical thrombectomy. It is speculated that direct compression of the device on the carotid artery endothelium and the force exerted on the vessel wall during the withdrawal of the device along the axis were the main factors that caused endothelial cell damage. In this study, our experiment demonstrated a lower pathological impairment score on the blood vessel wall of the Jrecan device compared with the Trevo device, which might be attributed to the structural modifications of the Jrecan^® flow restoration device. The main innovation was the optimized radial support force (Jrecan: 0.120 vs. Trevo: 0.122, N/mm), which could reduce the damage to the blood vessel while not affecting the thrombectomy efficiency. Another modification of Jrecan device was the mesh design with a horizonal trabecular structure, different from the vertical trabecular design of mesh in Trevo device. Theoretically, the vertical trabeculae with a small contact area to the blood vessel wall could be better embedded in thrombus, but the cutting force on the vessel wall during thrombectomy might be greater, resulting in a damage to the larger vessel wall (Figure 3).

In addition, the present study showed that the Jrecan^® device obtained a comparable recanalization rate to the Trevo system and was an effective thrombectomy tool for the treatment of acute thrombus occlusion model in canines. With respect to the side branch affection or distal vessel embolism during thrombectomy, the Jrecan^® device also showed similar safety when compared with the Trevo system. These effects were closely related to the improvement of the mesh area at the distal end and the optimized grid design with a large mesh area (11.7 mm²), which was beneficial to avoid the small thrombus from falling off, to reduce the incidence of distal embolization, and to make it more excellent in bending performance and smoother in recycling during the thrombectomy process.

The major limitation is that this study only observed the acute phase of injury after thrombectomy and did not involve the long-term effects of these endothelial injuries. Whether the acute injury to the blood vessel wall caused by thrombectomy would cause long-term negative effects is still a question worthy of in-depth study. Previous studies showed that the vessel wall injury caused by thrombectomy could be the source of acute platelet adhesion and aggregation, leading to acute arterial re-occlusion and late intimal hyperplasia (12). One of them showed that mild intimal thickening occurred at day 30, and minimal to mild intimal thickening occurred at day 90 after thrombectomy, but no evidence of medial or adventitial proliferation was found. Although this thickening led to an ~5% luminal narrowing in three vessels and 1% luminal narrowing in one vessel, the stenosis had no significant effect on clinical and histopathologic changes (16). In addition, the present study is a preclinical animal research and therefore cannot be extrapolated directly to humans. Intracranial human arteries are more tender, tortuous, and have a different vessel wall structure from extracranial arteries. Thirdly, the cerebral arteries of most patients with acute ischemic stroke are atherosclerotic, which is not the case in our study. Finally, we only tested the performance of the stent retriever for soft thrombus, whereas firm clot was more frequently encountered in clinical situations. Therefore, the effectiveness and safety of the Jrecan device need to be further evaluated in clinical trials.

In this animal experiment, both the Jrecan and the Trevo stent could effectively restore the blood flow of the occluded vessels and there was no significant difference. For device safety, the main injury caused by both thrombectomy devices for the blood vessels was intima injury, which is clinically acceptable. However, the Jrecan^® flow restoration device seemed to induce less vascular damage compared with the Trevo^TM PROVUE Device, which may give credit to its more suitable radial force provided by the wider cell design.

The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.

The animal study was reviewed and approved by Institutional Animal Ethics Committee of Animal Experimental Center, Fuwai Hospital, Chinese Academy of Medical Sciences [0077-3-14-HX(X)].

CL had full access to all the data in the study and takes responsibility for the integrity of the data, prepared all tables and figures in the manuscript, and prepared the manuscript draft with important intellectual input from JZ, Y-QZ, JL, Y-YZ, and H-CQ. W-JJ designed and conducted the study. A-FL and H-CQ helped conduct the study, provided input, and helped with patient recruitment and consent. All authors listed have made substantial, direct, and intellectual contribution to the work and approved it for publication.

This work was funded by National Key Basic Research Program of China (973 program) (grant no. 2013CB733805) and National Natural Science Foundation of China (grant nos. 81271536, 81070925, 81371540, 81101033, and 81871464).

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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