Adhesion of vessel wall to stentriever during combined technique for mechanical thrombectomy in acute ischemic stroke: A histomorphological study.

PURPOSE: Detection of vessel wall tissue in thrombus material in patients with ischemic stroke is judged as vascular injury. So far, several studies investigated components of the free clots after mechanical thrombectomy. The aim of this retrospective study was to investigate the involvement and role of the stentriever in vessel wall injury by analysis of the composition of adherent tissue to the stentriever during combined aspiration thrombectomy with stentriever. METHODS: Stentriever with adherent tissue and free clots in aspiration samples from patients undergoing mechanical thrombectomy (aspiration plus stentriever) were separately assessed for the occurrence of parts of vascular tissue together with clinical and interventional data as well as clinical outcome data. Specimens were analyzed histomorphologically and immunohistochemically. Findings, focused on parts of vessel wall were reported together with clinical data. RESULTS: Specimens from 21 identified patients were available. Parts of the vessel wall were detected in 7 out 21 (33%) samples. All specimens revealed fresh thrombus material without signs of organization or atheromatous tissue. In 90% of patients mTICI was greater than 2b without signs of secondary vessel injury. No vascular tissue was found in free clots of the aspiration samples. CONCLUSION: The examination of adherent tissue to the stentriever instead of the examination of free clots may affect the number of detected parts of vessel wall. Further studies in combination with vessel wall imaging may elucidate the origin of remnants of vessel wall.

Interventional stroke treatment - Is it also safe for arteries? Looking at thrombectomy wall damage through clot histology.

BACKGROUND AND PURPOSE: The aim of this study was to investigate whether morphological evidence of intracranial vascular injury can be found in the occluding thrombi of patients with ischemic stroke. METHODS: From 2015 until 2018 specimens of thrombi from patients with large vessel occlusion treated either by stent-assisted aspiration thrombectomy (TE) or by aspiration thrombectomy were prospectively collected. Thrombus specimens were formalin-fixed, paraffin-embedded and stained. Architectural features, presence of parts of vessel wall or atheromatous material, organisation of the thrombi, technique and number of thrombectomy manoeuvers were evaluated. RESULTS: Thrombus specimens from 302 patients were analyzed. 238 (80%) patients were treated with stent-assisted aspiration TE and 64 (20%) patients with aspiration TE only. 286 (95%) had fresh thrombi, 14 (4.6%) showed initial/complete thrombus organisation and multi-staged thrombi were found in 2 (<1%) patients. In 8 patients (2.6%) we found atypical thrombus content after a time interval longer 6 hours after onset and final thrombectomy manoeuvre: 4 with atheromatous material and 4 with parts of a vessel wall. In 1 patient with parts of vessel wall angiographically a dissection was detected. No parts of the vessel wall were found after sole aspiration thrombectomy. CONCLUSIONS: The overall risk of arterial vessel wall injury aspiration thrombectomy was low in our study. Aspiration thrombectomy and the procedure related with a retrieving device together with an ischemia time longer than 6 hours may increase the risk of vessel injury through the thrombectomy procedure. Further investigations are necessary to elucidate the influence of the mentioned aspects.