Mirza Mahmood, Ulfert Christian, McCarthy Ray, Brouwer Patrick
From the Research Department, Johnson and Johnson Medtech Neurovascular, Galway, Ireland.
Cardiol Rev. 2025 Jun 27. doi: 10.1097/CRD.0000000000000977.
Endovascular thrombectomy has revolutionized acute ischemic stroke treatment, significantly improving recanalization rates. However, up to 20% of cases involve recalcitrant clots that fail to recanalize or require multiple passes, negatively impacting clinical outcomes. This review explores the multifaceted nature of these challenging clots, including insights from preclinical, imaging, and clinical studies, with strategies to overcome them. Ex-vivo clot characterization reveals red blood cell-poorness in clots as a common feature in fibrin-rich, platelet-rich, neutrophil extracellular traps-rich, collagenous or bacteria-rich clots. Preclinical models have evolved alongside ex-vivo clot analysis, demonstrating properties such as increased stiffness, toughness, hardness, and stickiness that hinders retrieval. Imaging markers such as absence of the hyperdense artery sign or susceptibility vessel sign correlate with recalcitrant clots, although reliable predictors of recalcitrant clots remain elusive. Recent innovations, including specifically designed tough clot stent-retrievers such as Nimbus and technologies to improve complete clot ingestion such as super-bore aspiration catheters and cyclic aspiration have shown promise. Yet, a substantial proportion of cases still have difficulty or fail to achieve recanalization. Techniques such as rescue stenting and dual-stent-retriever approaches offer additional strategies but carry risks of vascular injury and complications. Major research limitations include clot deformation during retrieval and the inability to remove some clots. Furthermore, some interactions are poorly understood, such as the biological interaction between the clot and vessel wall or with circulating thrombo-influencing proteins. Overcoming these challenges can pave the pathway for creative solutions to elegantly improve the recanalization of tough clots.
血管内血栓切除术彻底改变了急性缺血性中风的治疗方式，显著提高了再通率。然而，高达20%的病例涉及顽固血栓，这些血栓无法再通或需要多次尝试，对临床结果产生负面影响。本综述探讨了这些具有挑战性的血栓的多方面性质，包括来自临床前、影像学和临床研究的见解，以及克服这些血栓的策略。体外血栓特征显示，在富含纤维蛋白、富含血小板、富含中性粒细胞胞外陷阱、富含胶原蛋白或富含细菌的血栓中，红细胞缺乏是血栓的一个共同特征。临床前模型随着体外血栓分析的发展而不断演进，显示出诸如硬度增加、韧性增强、硬度增大和粘性增加等特性，这些特性阻碍了血栓的取出。诸如高密度动脉征或磁敏感血管征缺失等影像学标志物与顽固血栓相关，尽管顽固血栓的可靠预测指标仍然难以捉摸。最近的创新，包括专门设计的用于处理顽固血栓的支架取栓器，如Nimbus，以及用于改善完全血栓摄取的技术，如超大腔抽吸导管和循环抽吸，已显示出前景。然而，仍有相当一部分病例在再通方面存在困难或未能实现再通。诸如补救性支架置入术和双支架取栓器方法等技术提供了额外的策略，但存在血管损伤和并发症的风险。主要的研究局限性包括取栓过程中血栓变形以及无法取出某些血栓。此外，一些相互作用尚不清楚，例如血栓与血管壁之间或与循环中影响血栓形成的蛋白质之间的生物学相互作用。克服这些挑战可为巧妙改善顽固血栓再通的创造性解决方案铺平道路。
