White blood cell subtypes and neutrophil extracellular traps content as biomarkers for stroke etiology in acute ischemic stroke clots retrieved by mechanical thrombectomy.

Background: Lymphocytes, macrophages, neutrophils, and neutrophil extracellular traps (NETs) associate with stroke risk factors and form a thrombus through different mechanisms. We investigated the total WBCs, WBC subtypes and NETs composition in acute ischemic stroke (AIS) clots to identify possible etiological differences that could help us further understand the process of thrombosis that leads to AIS.

Methods: AIS clots from 100 cases each of atherothrombotic (AT), cardioembolic (CE) and cryptogenic stroke etiology were collected per-pass as part of the CÚRAM RESTORE registry of AIS clots.

A Review of the Advancements in the Modelling of Acute Ischemic Stroke and Its Treatment.

neurovascular models of large vessel occlusions (LVOs) causing acute ischemic stroke (AIS) are used extensively for pre-clinical testing of new treatment devices. They enable physicians and engineers to examine device performance and the response of the occlusion to further advance design solutions for current unmet clinical needs. These models also enable physicians to train on basic skills, to try out new devices and new procedural approaches, and for the stroke team to practice workflows together in the comfort of a controlled environment in a non-clinical setting.

Aspects of ischemic stroke biomechanics derived using ex-vivo and in-vitro methods relating to mechanical thrombectomy.

Establishing the underlying biomechanics of acute ischemic stroke (AIS) and its treatment is fundamental to developing more effective clinical treatments for one of society's most impactful diseases. Recent changes in AIS management, driven by clinical evidence of improved treatments, has already led to a rapid rate of innovation, which is likely to be sustained for many years to come. These unprecedented AIS triage and treatment innovations provide a great opportunity to better understand the disease.

Systematic Review on Endovascular Access to Intracranial Arteries for Mechanical Thrombectomy in Acute Ischemic Stroke.

Purpose: In acute ischemic stroke for large vessel occlusions, delayed or failed access to intracranial occlusions has a negative impact on procedural and clinical outcomes. The aim of this review is to identify and quantify access failures and challenges in mechanical thrombectomy.

Methods: A systematic literature review of PubMed and Scopus databases from January 2014 to October 2020 was performed.

Measuring the effect of thrombosis, thrombus maturation and thrombolysis on clot mechanical properties in an in-vitro model.

Changes in acute ischemic stroke thrombi structure and composition may result in significant differences in treatment responsiveness. Ischemic stroke patients are often treated with a thrombolytic agent to dissolve thrombi, however these patients may subsequently undergo mechanical thrombectomy to remove the occlusive clot. We set out to determine if rt-PA thrombolysis treatment of blood clots changes their mechanical properties, which in turn may impact mechanical thrombectomy.

Characterization of the 'White' Appearing Clots that Cause Acute Ischemic Stroke.

Objectives: Most clots retrieved from patients with acute ischemic stroke are 'red' in color. 'White' clots represent a less common entity and their histological composition is less known. Our aim was to investigate the composition, imaging and procedural characteristics of 'white' clots retrieved by mechanical thrombectomy.

Quantitative 3D analysis of tissue damage in a rat model of microembolization.

There is a discrepancy between successful recanalization and good clinical outcome after endovascular treatment (EVT) in acute ischemic stroke patients. During removal of a thrombus, a shower of microemboli may release and lodge to the distal circulation. The objective of this study was to determine the extent of damage on brain tissue caused by microemboli.

A new compressible hyperelastic model for the multi-axial deformation of blood clot occlusions in vessels.

Mechanical thrombectomy can be significantly affected by the mechanical properties of the occluding thrombus. In this study, we provide the first characterisation of the volumetric behaviour of blood clots. We propose a new hyperelastic model for the volumetric and isochoric deformation of clot.

Blood clot fracture properties are dependent on red blood cell and fibrin content.

Thrombus fragmentation during endovascular stroke treatment, such as mechanical thrombectomy, leads to downstream emboli, resulting in poor clinical outcomes. Clinical studies suggest that fragmentation risk is dependent on clot composition. This current study presents the first experimental characterization of the composition-dependent fracture properties of blood clots, in addition to the development of a predictive model for blood clot fragmentation.

Per-pass analysis of acute ischemic stroke clots: impact of stroke etiology on extracted clot area and histological composition.

Background: Initial studies investigating correlations between stroke etiology and clot composition are conflicting and do not account for clot size as determined by area. Radiological studies have shown that cardioembolic strokes are associated with shorter clot lengths and lower clot burden than non-cardioembolic clots.

Objective: To report the relationship between stroke etiology, extracted clot area, and histological composition at each procedural pass.

Large Artery Atherosclerotic Clots are Larger than Clots of other Stroke Etiologies and have Poorer Recanalization rates.

Objectives: There is a paucity of knowledge in the literature relating to the extent of clot burden and stroke etiology. In this study, we measured the Extracted Clot Area (ECA) retrieved during endovascular treatment (EVT) and investigated relationships with suspected etiology, administration of intravenous thrombolysis and recanalization.

Materials And Methods: As part of the multi-institutional RESTORE registry, the ECA retrieved during mechanical thrombectomy was quantified using ImageJ.

Investigating the Mechanical Behavior of Clot Analogues Through Experimental and Computational Analysis.

With mechanical thrombectomy emerging as the new standard of care for stroke treatment, clot analogues provide an extremely useful tool in the testing and design of these treatment devices. The aim of this study is to characterise the mechanical behavior of thrombus analogues as a function of composition. Platelet-contracted clot analogues were prepared from blood mixtures of various hematocrits.

Clot Analog Attenuation in Non-contrast CT Predicts Histology: an Experimental Study Using Machine Learning.

Exact histological clot composition remains unknown. The purpose of this study was to identify the best imaging variables to be extrapolated on clot composition and clarify variability in the imaging of thrombi by non-contrast CT. Using a CT-phantom and covering a wide range of histologies, we analyzed 80 clot analogs with respect to X-ray attenuation at 24 and 48 h after production.

Development of an in vitro model of calcified cerebral emboli in acute ischemic stroke for mechanical thrombectomy evaluation.

: BACKGROUND: Calcified cerebral emboli (CCEs) are a rare cause of acute ischemic stroke (AIS) and are frequently associated with poor outcomes. The presence of dense calcified material enables reliable identification of CCEs using non-contrast CT. However, recanalization rates with the available mechanical thrombectomy (MT) devices remain low.

Mechanical behavior of in vitro blood clots and the implications for acute ischemic stroke treatment.

Background: Clot mechanical properties are influenced by composition and the arrangement of components within the clot. This work investigates the effects of platelet-driven contraction on blood clot microstructure and mechanical behavior, and provides insight into some implications for mechanical thrombectomy.

Methods: Platelet-contracted clot analogues (PCCs) and non-contracted clot analogues (NCCs) were prepared from blood mixtures of various hematocrits (%H), that is, the volume percentage of red blood cells (RBCs) in the mixture.

Platelet-rich emboli are associated with von Willebrand factor levels and have poorer revascularization outcomes.

Background And Aims: Platelets and von Willebrand factor (vWF) are key factors in thrombosis and thus are likely key components of acute ischemic stroke (AIS) emboli. We aimed to characterize platelet and vWF levels in AIS emboli and to assess associations between their expression levels and clinical and procedural information.

Materials And Method: Histopathological and immunohistochemical analysis of emboli collected as part of the multi-institutional RESTORE registry was performed.

Quantitative estimation of thrombus-erythrocytes using MRI. A phantom study with clot analogs and analysis by statistic regression models.

Background: Thrombus composition has the potential to affect acute ischemic stroke (AIS) treatment.

Objective: To evaluate in an in vitro test the correlation of clot composition, especially erythrocytes (red blood cells (RBCs)), with the variation of signal intensity ratio (SIR) obtained with MRI sequences used for AIS, and qualification of the susceptibility vessel sign effect using clot analogs.

Materials And Methods: Nine ovine clots were fixed in a gelatin-manganese solution and studied by MRI (T2GE, T2-weighted gradient echo; SWI, susceptibility-weighted imaging; FLAIR, fluid attenuated inversion recovery).

Per-Pass Analysis of Thrombus Composition in Patients With Acute Ischemic Stroke Undergoing Mechanical Thrombectomy.

Background and Purpose- Mechanical thrombectomy may involve multiple attempts to retrieve the occluding thrombus. This study examined the composition of thrombus fragments retrieved with each pass of a device during the thrombectomy procedure. Second, the per-pass composition was compared with procedural and clinical data including angiographic outcome and stroke etiology.

Characterization of strut indentation during mechanical thrombectomy in acute ischemic stroke clot analogs.

Background: Although it is common practice to wait for an 'embedding time' during mechanical thrombectomy (MT) to allow strut integration of a stentriever device into an occluding thromboembolic clot, there is a scarcity of evidence demonstrating the value or optimal timing for the wide range of thrombus compositions. This work characterizes the behavior of clot analogs of varying fibrin and cellular compositions subject to indentation forces and embedding times representative of those imparted by a stentriever during MT. The purpose of this study is to quantify the effect of thrombus composition on device strut embedding, and to examine the precise nature of clot integration into a stentriever device at a microstructural level.