Red Clots Research Articles

Triple Aspiration versus Conventional Aspiration Techniques: A Randomized In Vitro Evaluation.

A single-aspiration maneuver using a large-volume syringe is a common and effective technique for aspiration thrombectomy. Multiple aspiration cycles using large aspiration syringes have been proposed as a means to improve the efficacy over single aspiration. In this study, we sought to investigate the efficacy of a "triple aspiration technique" in which a large-volume syringe is cycled 3 times before catheter retraction during aspiration thrombectomy. A 3D-printed adult vasculature was used as a benchtop thrombectomy platform. Fibrin-rich and red blood cell-rich clots were prepared in centrifuge tubes using human plasma, red blood cells, and calcium chloride. Next, clots were placed in the carotid terminus of the model, and the performances of 3 different aspiration techniques-triple syringe, single syringe, and continuous pump aspiration-were compared in a randomized manner (1:1:1). Outcomes of interest included first-pass efficacy (FPE), complete clot removal (final modified TICI 2c/3), the number of thrombectomy attempts to achieve modified TICI 2c/3, vacuum pressure, and distal embolization. The distal emboli were detected using a 70-μm cell strainer placed at the outflow of the model and quantified using an image-processing algorithm. The vacuum pressures were measured using a pressure transducer. A total of 102 replicates were performed, 34 for each technique. The triple-aspiration technique provided a significantly higher rate of FPE than the syringe and pump aspiration techniques (67.6% versus 41.1%, P = .02). Additionally, the triple-aspiration technique achieved complete clot removal with a significantly lower mean number of thrombectomy attempts compared with single-syringe aspiration (1.2 [SD, 0.5] versus 1.8 [SD, 0.8], P = .005). The triple-aspiration technique generated significantly higher mean vacuum pressure than both the single-syringe and vacuum pump aspiration (28.3 [SD, 0.2] versus 27.2 [SD, 0.3], P = .002 and 26.2 [SD, 0.4], P = .001, respectively). The differences in complete clot removal and distal embolization parameters were not statistically significantly different across the groups. Our findings suggest that the triple aspiration technique can improve FPE rates and vacuum pressure in aspiration thrombectomy. Further studies are needed to examine the safety and efficacy of triple aspiration in the clinical setting.

Safety and efficacy of stent retrievers plus contact aspiration in patients with acute ischaemic anterior circulation stroke and positive susceptibility vessel sign in France (VECTOR): a randomised, single-blind trial

Positive susceptibility vessel sign (SVS) in patients with acute ischaemic stroke has been associated with friable red blood cell-rich clots and more effective recanalisation using stent retrievers versus contact aspiration. We compared the safety and efficacy of stent retrievers plus contact aspiration (combined technique) versus contact aspiration alone as the first-line thrombectomy technique in patients with acute ischaemic anterior circulation stroke and SVS-positive occlusions. Adaptive Endovascular Strategy to the Clot MRI in Large Intracranial Vessel Occlusion (VECTOR) was a prospective, randomised, open-label study with blinded evaluation. Patients with SVS-positive anterior circulation occlusions on pretreatment MRI and arterial puncture within 24 h of symptom onset were enrolled from 22 centres in France. A centralised web-based method was used by interventional neuroradiologists for dynamic randomisation by minimisation. Patients were randomly assigned 1:1 to the combined technique or contact aspiration alone. The primary outcome was expanded Thrombolysis in Cerebral Infarction (eTICI) grade 2c or 3 reperfusion after three or fewer passes on post-treatment angiogram, adjudicated by a blinded independent central imaging core laboratory. The intention-to-treat population was used to assess the primary and secondary outcomes. This trial is registered with ClinicalTrials.gov (NCT04139486) and is complete. Between Nov 26, 2019, and Feb 14, 2022, 526 patients were enrolled, of whom 521 constituted the intention-to-treat population (combined technique, n=263; contact aspiration alone, n=258). The median age of participants was 74·9 years (IQR 64·4-83·3); 284 (55%) were female and 237 (45%) male. The primary outcome did not differ significantly between groups (152 [58%] of 263 patients for the combined technique vs 135 [52%] of 258 for contact aspiration; odds ratio [OR] 1·27; 95% CI 0·88-1·83; p=0·19). Procedure-related adverse events occurred in 32 (12%) of 263 patients in the combined technique group and 27 (11%) of 257 in the contact aspiration group (OR 1·14; 0·65-2·00; p=0·65). The most common adverse event was intracerebral haemorrhage (146 [56%] of 259 patients for the combined technique vs 123 [49%] of 251 for contact aspiration; OR 1·32; 0·91-1·90; p=0·13). All-cause mortality at 3 months occurred in 57 (23%) of 251 patients in the combined technique group and 48 (19%) of 247 in the contact aspiration group (OR 1·19; 0·76-1·86; p=0·45), none of which was treatment-related. The results of the VECTOR trial do not show superiority of the combined stent retriever plus contact aspiration technique over contact aspiration alone in patients with SVS-positive occlusion with respect to achieving eTICI 2c-3 within three passes. These findings support the use of either the combined technique or contact aspiration alone as the initial thrombectomy strategy in patients with acute anterior circulation stroke with SVS on pretreatment MRI. Cerenovus.

Abstract TP214: In-Silico versus In-Vitro Evaluation of a New Stent-Retriever Design: A Novel Approach to Pre-Clinical Device Development

Introduction: In-vitro evaluation (analysis in a bench top flow model) is the gold standard for pre-clinical investigation of devices being developed for endovascular thrombectomy (EVT). In-silico evaluation (computer simulated analysis in a virtual stroke model) has the potential to test and optimize large number of stent-retriever design variations in a relatively time and cost-effective manner. We aim to validate the utility of in-silico evaluation when compared with in-vitro evaluation for the SuperNova Stent-retriever. Methods: In-silico analysis was performed using a virtual thrombectomy model, built using data from a fine-grained finite-element model, to estimate the probability of successful recanalization. Neurovascular anatomy of the virtual model was built based on digital subtraction angiography of an in-vitro model (Sim Agility, Mentice, Inc). Gravity Medical Technology’s SuperNova Stent-retriever was the device under investigation. Multiple thrombectomy scenarios were defined and validation analysis was performed. Results: We defined multiple thrombectomy scenarios including 1 cm red blood clot in M1 artery, 2 cm bifurcation M1-M2 red blood clot (Y-shaped clot), 1 cm white blood clot in M1 artery, and 1 cm white blood clot in superior M2 artery. The figure below demonstrates a pictorial representation of the first scenario- 1 cm red blood clot in M1 artery followed by mechanical thrombectomy simulation using the SuperNova stent-retriever. Per our in-vitro analysis (10 thrombectomy experiments), the rate of first pass effect and the rate of complete recanalization after a maximum of 3 passes using SuperNova stent-retriever was 50% and 90%, respectively. Preliminary data suggests 97% concordance. Conclusion: In-silico analysis has the potential to improve and expedite pre-clinical thrombectomy device development. Further studies are required to better understand the scope and potential of this technology.

Abstract 249: In‐silico Versus In‐Vitro Evaluation of a New Stent‐Retriever Design: A Novel Approach to Pre‐clinical Development

Introduction In‐vitro evaluation (analysis in a bench top flow model) is the gold standard and a regulatory requirement for pre‐clinical investigation of devices being developed for endovascular thrombectomy (EVT). In‐silico evaluation (computer simulated analysis in a virtual stroke model) has the potential to test and optimize large number of stent‐retriever design variations in a relatively time and cost‐effective manner. Further, new design concepts can be tested across multiple anatomical scenarios. We aim to validate the utility of in‐silico evaluation when compared with in‐vitro evaluation for the SuperNova Stent‐retriever. Methods In‐silico analysis was performed using a virtual thrombectomy model, built using data from a fine‐grained finite‐element model, to estimate the probability of successful recanalization and emboli in new/distal territory. Neurovascular anatomy of the virtual model was built based on digital subtraction angiography of an in‐vitro model (Sim Agility, Mentice, Inc). Gravity Medical Technology’s SuperNova Stent‐retriever was the device under investigation‐ physical device for in‐vitro analysis and virtual replica for in‐silico analysis (built using finite element analysis incorporating various physical metrics of the stent‐retriever). Experiments performed for in‐vitro analysis were replicated for in‐silico analysis. Multiple thrombectomy scenarios were defined and validation analysis was performed. Data was analyzed using SPSS 23 (IBM, Armonk, NY) Results We defined multiple thrombectomy scenarios including 1 cm red blood clot in M1 artery, 2 cm bifurcation M1‐M2 red blood clot (Y‐shaped clot), 1 cm white blood clot in M1 artery, and 1 cm white blood clot in superior M2 artery. The figure below demonstrates a pictorial representation of the first scenario‐ 1 cm red blood clot in M1 artery followed by mechanical thrombectomy simulation using the SuperNova stent‐retriever. Per our in‐vitro analysis (10 thrombectomy experiments), the rate of first pass effect and the rate of complete recanalization after a maximum of 3 passes using SuperNova stent‐retriever was 50% and 90%, respectively. Complete data from in‐silico analysis is being generated and will be presented at the conference. Preliminary data suggests high degree of concordance. Conclusion In‐silico analysis has the potential to improve and expedite pre‐clinical thrombectomy device development. Further studies are required to better understand the scope and potential of this technology.

Clot-based time attenuation curve as a novel imaging predictor of mechanical thrombectomy functional outcome in acute ischemia stroke.

To investigate whether a novel assessment of thrombus permeability obtained from perfusion computed tomography (CTP) can act as a more accurate predictor of clinical response to mechanical thrombectomy (MT) in acute ischemic stroke (AIS). We performed a study including two cohorts of AIS patients who underwent MT admitted to a single-center between April 2018 and February 2022: a retrospective development cohort (n = 71) and a prospective independent validation cohort (n = 96). Thrombus permeability was determined in terms of entire thrombus time-attenuation curve (TAC) on CTP. Association between thrombus TAC distributions and histopathological results was analyzed in the development cohort. Logistic regression was used to assess the performance of the TAC for predicting 90-day modified Rankin Scale (mRS) score, and good outcome was defined as a mRS score of ≤ 2. Basic clinical characteristics was used to build a routine clinical model. A combined model gathered TAC and basic clinical characteristics was also developed. The performance of the three models is compared on the independent validation set. Two TAC distributions were observed-unimodal (uTAC) and linear (lTAC). TAC distributions achieved strong correlations (|r|= 0.627, p < 0.001) with histopathological results, in which uTAC associated with fibrin- and platelet-rich clot while lTAC associated with red blood cell-rich clot. The uTAC was independently associated with poor outcome (odds ratio, 0.08 [95% confidence interval (CI), 0.02-0.31]; p < 0.001). TAC distributions yielded an AUC of 0.78 (95% CI, 0.70-0.87) for predicting clinical outcome. When combined clinical characteristics, the performance was significantly improved (AUC, 0.85 [95% CI, 0.76-0.93]; p < 0.001) and higher than routine clinical model (AUC, 0.69 [95% CI, 0.59-0.83]; p < 0.001). Thrombus TAC on CTP were found to be a promising new imaging biomarker to predict the outcomes of MT in AIS. This study revealed that clot-based time attenuation curve based on admission perfusion CT could reflect the permeability and composition of thrombus and, also, provide valuable information to predict the clinical outcomes of mechanical thrombectomy in patients with acute ischemia stroke. • Two time-attenuation curves distributions achieved strong correlations (|r|= 0.627, p < 0.001) with histopathological results. • The unimodal time-attenuation curve was independently associated with poor outcome (odds ratio, 0.08 [0.02-0.31]; p < 0.001). • The time-attenuation curve distributions yielded a higher performance for detecting clinical outcome than routine clinical model (AUC, 0.78 [0.70-0.87] vs 0.69 [0.59-0.83]; p < 0.001).

Direct Aspiration versus Combined Technique for Distal Medium-Vessel Occlusions: Comparison on a Human Placenta Model.

Mechanical thrombectomy appears to be a promising option for distal medium-vessel occlusions, for which intravenous thrombolysis is effective but may be insufficient when used alone. This study aimed to determine the optimal technique for these distal mechanical thrombectomies using the human placenta model. Twenty-four procedures were performed, allowing comparison of direct aspiration (n = 12) versus the combined technique (n = 12). Two positions of the aspiration catheter were tested for each of these techniques: in direct contact with the clot and at a distance from it (5-10 mm). Two types of clots were tested: red blood cell-rich clots and fibrin-rich clots. First-pass recanalization and induced arterial collapse and traction were assessed. The first-pass recanalization was less frequent for direct aspiration than for the combined technique, without reaching statistical significance (41.7% versus 75.0%, P = .098). Full collapse (P < .001) and extended arterial traction (P = .001) were significantly less frequent for direct aspiration. For direct aspiration with the aspiration catheter not in direct contact with the clot, there was not a single first-pass recanalization and there was systematic arterial collapse, resulting in a no-flow in the aspiration syringe. The combined technique appears to be more harmful, and although direct aspiration has a lower rate of first-pass recanalization, it seems appropriate to try direct aspiration as a first-line procedure. However, if the aspiration catheter cannot reach the clot, it is not useful or even risky to try aspiration alone. These results need to be confirmed by clinical studies.

Histological, Immunohistochemical, Biomechanical, and Wettability Evaluations of the Leukocyte- and Platelet-Rich Fibrin Membranes Derived from Canine Blood.

This study aimed to perform histological, immunohistochemical, biomechanical, and wettability assessments of leukocyte- and platelet-rich fibrin (L-PRF) membranes obtained from the blood of healthy dogs. Ten client-owned Labrador Retriever dogs were enrolled. Blood samples were obtained from the external jugular vein using a vacuum tube without anticoagulant, which was immediately centrifuged at 400g for 12 min in a dedicated centrifuge. The L-PRF clot was removed from the tube, and the red clot was released from the buffy coat using a spatula. The membrane was produced using a PRF box. Histological examination identified the three portions of the L-PRF membranes. The first portion was composed mainly of red blood cells with the presence of a low number of leukocytes among them. The second portion was composed of white blood cells, mainly neutrophils. The third portion was composed of the fibrin network which was characterized by acidophilic staining. The immunohistochemical analysis showed that vascular endothelial growth factor and platelet-derived growth factor were expressed in all samples at different intensities, both in cellular components and fibrin mesh. The tensile test and wettability assessments were measured in membranes 30 min and 3 h after production. The 30 min L-PRF membranes supported twice the ultimate tensile strength compared to 3 h L-PRF membranes. The wettability of the 30 min sample membranes was statistically higher than the 3 h sample membranes. In conclusion, the centrifugation protocol allowed production of the L-PRF membrane using canine blood and this was confirmed by histological and immunohistochemical analysis. The mechanical resistance and wettability of the L-PRF membrane were significantly reduced over time.

Abstract 99: Clot Composition And Reperfusion Outcomes In 1430 Mechanical Thrombectomy Patients: Analysis Of The Stroke Thromboembolism Registry Of Imaging And Pathology

Background: Understanding clot composition may allow for better technical planning and improved outcomes in mechanical thrombectomy (MT). We sought to correlate clot composition with reperfusion outcomes in MT. Methods: Clinical, imaging, and clot data from patients enrolled in the STRIP Registry from September 2016 to September 2020 were analyzed. Samples were fixed in 10% phosphate-buffered formalin and stained with hematoxylin and eosin and Martius Scarlett Blue. Percent composition, richness, and gross appearance were evaluated. Outcome measures included the rate of First-Pass Effect (mTICI2c/3, FPE) and the number of device passes. Results: A total of 1430 patients (mean age, 68.4±13.5years; median [IQR] baseline NIHSS,17.2 [10.5-23]; IV-tPA use, 36%; Stent-Retrievers [SR], 27%; Contact Aspiration [CA], 27%; Combined SR + CA, 43%) were included. The median [IQR] number of passes was 1 [1-2]. FPE was achieved in 39.3% of the cases. There was no association between percent histological composition or clot richness and FPE in the overall population. However, the combined technique resulted in lower FPE rates for RBC-rich (P&lt;0.0001), platelet-rich (P=0.003), and mixed (P&lt;0.0001) clots. Fibrin-rich and platelet-rich clots required a higher number of passes compared to RBC-rich and mixed clots (median, 2 and 1.5 vs.1, respectively, P=0.02). CA displayed a trend towards a higher number of passes with fibrin-rich clots (2 vs.1, P=0.12). By gross appearance, mixed/heterogeneous clots had lower FPE rates than red and white clots. Conclusion: Despite the lack of correlation between clot histology and FPE in the overall population, our study adds to the growing body of evidence supporting the notion that clot composition influences reperfusion treatment strategy outcomes. Additional studies are needed.

Morphological aspects of diaphragm dysfunction in COVID-19-associated pneumonia

To assess morphological changes in the diaphragm and phrenic nerve in patients who died from COVID-19. In a case-control study, an analysis was made of autopsy material of the diaphragm and phrenic nerve of those who died from COVID-19 infection complicated by SARS-CoV-2-associated pneumonia, confirmed in vivo by the presence of SARS-CoV-2 RNA (Group 1, n=12), and those who died with a diagnosis of acute cerebrovascular accident of the ischemic type without parenchymal respiratory failure (Group 2, n=3). The main histopathological features in the diaphragm of the 1st group were the edema of the pericellular spaces of muscle fibers, edema of perivascular spaces, diapedese hemorrhages, plethora in arteriolas, in most veins and capillaries, red blood clots were revealed; in the diaphragmatic nerve - swelling of the perineral space, severe edema around the nerve fibers inside the nerve trunk. In the diaphragm of group 2, edema of pericellular spaces of muscle fibers and edema of perivascular spaces were less pronounced (p<0.001), hemorrhages were not determined; in the diaphragmatic nerve, moderate edema of the perineral space, mild swelling inside the nerve trunk around the nerve fibers was revealed (p<0.001). The glycogen content in the muscle cells of group 1 is significantly lower compared to group 2 (p<0.001). The study confirms the characteristic pathological picture of organ damage in COVID-19. However, the leading pathological mechanism of organ damage requires further investigation.

Theme and Variation: Structuring Thrombus Formation from Jugular/Arterial Puncture Wounds to Occlusive Clots in a Mouse Model

Hemostasis in veins and arteries has been assumed to be different processes, e.g., white vs. red clots. We took the unbiased experimental approaches of 3D EM across full clot volumes and high-resolution heat mapping of platelet activation state to probe for commonalities and variations using controlled mouse models. Remarkably, the thrombi formed, 5 min post-puncture, in the jugular vein and femoral artery showed considerable consistency in organization. There were vaulted cavities within the puncture wound and apparent extravascular capping of the puncture hole to produce bleeding cessation. Notable differences in the venous thrombi were a greater activation of platelets lining the surfaces of the vaulted columns, an outcome that we attribute to lowr flow rates resulting in the longer retention of activating signals, and in the "hanging drop” nature of the arterial thrombi anchored to the extrema with an outward, extravascular bulge of the thrombus. We attribute these variations to arterial vessel wall properties and higher flow rates. At 20 min post-puncture, the intravascular crown of the venous wound thrombi was enriched in loosely adherent platelets in a low activation state. Similarly, the outer portion of the intravascular arterial thrombus was rich in low activation platelets including obviously discoid platelets. Strikingly, the arterial thrombus was subject to rebleeding and ate 20 min displayed fractured extravascular features indicative of an unstable clot. The puncture wound thrombi form in the relatively small volume of the immediate wound site. In contrast, occlusive clots fill the cylindrical volume of the vessel. To us, the overall structure of the wound thrombi suggested a predictive hypothesis for induced occlusive clotting. We propose that 1) the exposed intima lining the arterial vessel wall provides a cylindrical substratum for the generation of a tightly adherent platelet layer anchoring the forming clot and 2) the central volume of the clot resembles the intravascular crown of the puncture wound thrombus. Hence, the prediction of a central volume of the occlusive clot consisting of loosely adherent to discoid shaped platelets. That was result found for FeCl3 induced femoral clots by wide area-TEM (WA-TEM) i.e., a central volume rich in discoid shaped platelet and few red blood cells were trapped in the tightly adherent rim of the clot.. Using sequential block face SEM, we have begun to image and volume render carotid clots by sequential block face SEM. Analysis of 5,000 sequential images from the downstream half of the carotid clot, showed that the structure gradually tapered in a conical manner and contains few red blood cells. We propose that there are indeed organizational themes shared by the puncture wound thrombus in venous or arterial settings and the occlusive clot in which vascular damage is restricted to the endothelial cell layer. Work was supported by NIH grants (BS) R01 HL155519 and P20 HL146373 (Joel Bennett, principal investigator), R35 HL150118 (SWW) and by intramural NIBIB research program (RDL). An occlusive FeCl3 clot in the carotid artery of a C57BL/6 mouse imaged by sequential block face SEM over a length of 1.2 millimeters.A. cross section of the clot 200 microns in from the mid-occlusion starting point for sectioning. B. Zoom of A) to illustrate the low level of trapped red blood cells within the clot. C. cross section of the clot 900 microns in from the starting point showing how the clot has now tapered down and fills a minor portion of the artery. D. Rendering of 1.2 millimeters of the clot (blue), vessel wall (green) and in gray a single plane image. Flow was from left to right. Note that the clot progressively tapers to a point in the downstream direction.Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Towards rainbow portable Cytophone with laser diodes for global disease diagnostics

In vivo, Cytophone has demonstrated the capability for the early diagnosis of cancer, infection, and cardiovascular disorders through photoacoustic detection of circulating disease markers directly in the bloodstream with an unprecedented 1,000-fold improvement in sensitivity. Nevertheless, a Cytophone with higher specificity and portability is urgently needed. Here, we introduce a novel Cytophone platform that integrates a miniature multispectral laser diode array, time-color coding, and high-speed time-resolved signal processing. Using two-color (808 nm/915 nm) laser diodes, we demonstrated spectral identification of white and red clots, melanoma cells, and hemozoin in malaria-infected erythrocytes against a blood background and artifacts. Data from a Plasmodium yoelii murine model and cultured human P. falciparum were verified in vitro with confocal photothermal and fluorescent microscopy. With these techniques, we detected infected cells within 4 h after invasion, which makes hemozoin promising as a spectrally selective marker at the earliest stages of malaria progression. Along with the findings from our previous application of Cytophone with conventional lasers for the diagnosis of melanoma, bacteremia, sickle anemia, thrombosis, stroke, and abnormal hemoglobin forms, this current finding suggests the potential for the development of a portable rainbow Cytophone with multispectral laser diodes for the identification of these and other diseases.

Single Cutaneous Metastasis from Mucinous Adenocarcinoma of Prostate with Bladder Invasion: An Unusual Localization

Mucinous adenocarcinoma of the prostate is an extremely rare histological variant of prostate cancer. The malignancy potential, tumor grading, clinical course and prognosis of affected patients remain controversial. There are no data on the evolution of metastatic mucinous adenocarcinoma of the prostate. Our case describes the rapid and unfortunate evolution of a prostatic mucinous adenocarcinoma invading bladder with skin metastasis in a 47-year-old patient, who was hospitalized because of intermittent gross hematuria accompanied by bulky and dark red clots for more than two months. The diagnosis was confirmed after a prostatic Magnetic resonance imaging (MRI) and a transurethral resection of the prostate and bladder with anatomopathological study and immunohistochemical complement. The evolution was marked initially by the appearance cutaneous metastasis during his hospitalization and hepatic and splenic metastases 3 months after his initial extension workup which was negative; our patient is currently on his 2nd cycle of chemotherapy for palliative purposes. The aim of our article is to highlight the most important diagnostic features and specific aspects in the primary diagnosis of this tumor, which every urologist should keep in mind, and we will focus on the prognosis and the interest of an early and especially multidisciplinary management.

MicroCT Can Characterize Clots Retrieved With Mechanical Thrombectomy From Acute Ischemic Stroke Patients-A Preliminary Report.

BackgroundCharacterization of the clot occluding the arteries in acute ischemic stroke received ample attention, in terms of elucidating the relationship between the clot composition, its etiology and its amenability for pharmacological treatment and mechanical thrombectomy approaches. Traditional analytical techniques such as conventional 2D histopathology or electron microscopy sample only small parts of the clot. Visualization and analysis in 3D are necessary to depict and comprehend the overall organization of the clot. The aim of this study is to investigate the potential of microCT for characterizing the clot composition, structure, and organization.MethodsIn a pilot study, we analyzed with microCT clots retrieved from 14 patients with acute ischemic stroke. The following parameters were analyzed: overall clot density, clot segmentation with various density thresholds, clot volume.ResultsOur findings show that human clots are heterogeneous in terms of CT intra-clot density distribution. After fixation in formalin, the clots display a shift toward negative values. On average, we found the mean HU values of red clots retrieved from patients to be −153 HU, with SD = 23.8 HU, for the intermediate clots retrieved from patients −193 HU, SD = 23.7 HU, and for the white clots retrieved from patients −229 HU, SD = 64.8 HU.ConclusionOur study shows that volumetric and density analysis of the clot opens new perspectives for clot characterization and for a better understanding of thrombus structure and composition.

ERS statement on chronic thromboembolic pulmonary hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) is a rare complication of acute pulmonary embolism, either symptomatic or not. The occlusion of proximal pulmonary arteries by fibrotic intravascular material, in combination with a secondary microvasculopathy of vessels &lt; 500 μm, leads to increased pulmonary vascular resistance and progressive right heart failure. The mechanism responsible for the transformation of red clots into fibrotic material remnants has not yet been elucidated. In patients with pulmonary hypertension, the diagnosis is suspected when a ventilation/ perfusion lung scan shows mismatched perfusion defects, and confirmed by right heart catheterisation and vascular imaging. Today, in addition to lifelong anticoagulation, treatment modalities include surgery, angioplasty and medical treatment according to the localisation and characteristics of the lesions. This statement outlines a review of the literature and current practice concerning diagnosis and management of CTEPH. It covers the definitions, diagnosis, epidemiology, follow-up after acute pulmonary embolism, pathophysiology, treatment by pulmonary endarterectomy, balloon pulmonary angioplasty, drugs and their combination, rehabilitation and new lines of research in CTEPH. It represents the first collaboration of the European Respiratory Society, the International CTEPH Association and the European Reference Network-Lung in the pulmonary hypertension domain. The statement summarises current knowledge, but does not make formal recommendations for clinical practice.

Abstract TP144: Extracellular Vesicles Derived From Stroke Patient Clots Impair Cerebral Endothelial Cell Function

Introduction: Most patients undergoing thrombectomy fail for full reperfusion. The present study tested whether small extracellular vesicles (sEVs) from stroke patient clots impair cerebral endothelial cell (CEC) function, which may contribute to dysfunction of downstream CECs, leading to reduction of cerebral tissue perfusion. Methods: Per IRB-approved protocol, clots were collected from 60 patients (30 males) with acute ischemic stroke subjected to thrombectomy. Red and white clots were determined by immunochemistry. Clot-sEVs were isolated and characterized using ultracentrifugation, size distribution, and Western blot. The effects of clot-sEVs on human CEC (hCEC) permeability and proteins were measured using trans-endothelial assay and trans-endothelial electrical resistance (TEER) and Western blot, respectively. Nystatin, an inhibitor of caveolin-dependent endocytosis, was employed to study hCEC uptake of clot-sEVs. Results: Clot-sEVs had a mean size of 73±2nm. Cellular source analysis of clot-sEVs revealed that 22%, 30%, and 44% of sEVs from red clots and 28%, 28%, and 52% of sEVs from white clots were from neutrophils, endothelial cells, and platelets, respectively. Compared to sEVs derived from donor plasma (plasma-sEVs), treatment of hCECs with clot-sEVs significantly increased cell permeability (227% vs 100% of plasma-sEVs) and reduced TEER (66.6ω.cm 2 vs 87.3ω.cm 2 ). Clot-sEVs significantly increased pro-inflammatory and pro-coagulation proteins in the hCECs including ICAM1, VCAM1, TNF-a, HMBG1, tissue factor, and significantly reduced tight junction proteins ZO-1 and Claudin-5. The effects of white clot-sEVs on hCEC dysfunction were greater than red clot-sEVs. Nystatin significantly reduced hCEC uptake of clot-sEV from 232% to 142% and the clot-sEV-increased permeability. Moreover, Pearson correlation showed that the severity of clot-sEV impaired hCEC function was significantly correlated with final TICI scores of the individual patients (permeability vs TICI, r=-0.3348, p=0.02; TEER vs TICI, r=0,3666, p=0.01). Conclusion: Clot-sEVs contribute to hCEC dysfunction by augmenting pro-inflammatory and pro-coagulation proteins. Blocking uptake of clot-sEVs by recipient cells may improve patient outcomes.

Shedding Lights on Crude Venom from Solitary Foraging Predatory Ant Ectatomma opaciventre: Initial Toxinological Investigation

Some species of primitive predatory ants, despite living in a colony, exercise their hunting collection strategy individually; their venom is painful, paralyzing, digestive, and lethal for their prey, yet the toxins responsible for these effects are poorly known. Ectatomma opaciventre is a previously unrecorded solitary hunting ant from the Brazilian Cerrado. To overcome this hindrance, the present study performed the in vitro enzymatic, biochemical, and biological activities of E. opaciventre to better understand the properties of this venom. Its venom showed several proteins with masses ranging from 1–116 kDa, highlighting the complexity of this venom. Compounds with high enzymatic activity were described, elucidating different enzyme classes present in the venom, with the presence of the first L-amino acid oxidase in Hymenoptera venoms being reported. Its crude venom contributes to a state of blood incoagulability, acting on primary hemostasis, inhibiting collagen-induced platelet aggregation, and operating on the fibrinolysis of loose red clots. Furthermore, the E. opaciventre venom preferentially induced cytotoxic effects on lung cancer cell lines and three different species of Leishmania. These data shed a comprehensive portrait of enzymatic components, biochemical and biological effects in vitro, opening perspectives for bio-pharmacological application of E. opaciventre venom molecules.

Quantification of clot spatial heterogeneity and its impact on thrombectomy

BackgroundCompositional and structural features of retrieved clots by thrombectomy can provide insight into improving the endovascular treatment of ischemic stroke. Currently, histological analysis is limited to quantification of compositions and...

Stent Opening Visualization During Mechanical Thrombectomy; Relationship with the Retrieved Clot and Procedural Success

Purpose: The angiographic visualization of the stent during mechanical thrombectomy (MT) may provide information regarding the characteristics of the underlying occluding clot, device-clot interaction, and recanalization. The purpose of this study was to evaluate the open stent sign in relation to the retrieved clot and recanalization. Methodology78 patients treated with the stent retriever for acute stroke were retrospectively reviewed. The open stent sign was defined as full opening (>80% of normal vessel diameter) of the stent on DSA after deployment across the occlusion. The retrieved clot was visually classified as red or non-red clots. The relationship between the open stent sign and the patient characteristics, recanalization, retrieved clot, and clinical outcome were analyzed. ResultsOverall successful recanalization and good outcome was achieved in 68 (87.2%) and 35 (44.9%) patients, respectively. Open stent sign was seen in 52 patients (66.7%). Occlusions showing positive open stent sign was associated with significantly higher first pass effect (44.2% vs 19.2%, p=0.044) and successful recanalization rate (94.2% vs 73.1%, p=0.013) compared to negative open stent sign. The open stent sign was associated with higher incidence of red clot (75.0% vs 38.9%, p=0.008). On multivariate analysis, the open stent sign (OR 22.721, 95% CI 1.953-264.372, p=0.013) was a predictor of successful recanalization. ConclusionsThe visualization of the open stent during MT of acute ischemic stroke may provide added information in terms of clot characteristics and procedural success. The open stent sign is associated with red clots, higher first pass effect and successful recanalization.

Platelet-Rich Fibrin Decreases the Inflammatory Response of Mesenchymal Cells.

Chronic inflammation is a pathological process where cells of the mesenchymal lineage become a major source of inflammatory mediators. Platelet-rich fibrin (PRF) has been shown to possess potent anti-inflammatory activity in macrophages, but its impact on mesenchymal cells has not been investigated. The aim of this study was, therefore, to expose mesenchymal cells to inflammatory cytokines together with lysates generated from liquid platelet-poor plasma (PPP), the cell-rich buffy coat layer (BC; concentrated-PRF or C-PRF), and the remaining red clot layer (RC), following centrifugation of blood. Heating PPP generates an albumin gel (Alb-gel) that when mixed back with C-PRF produces Alb-PRF. Membranes prepared from solid PRF were also subjected to lysis. We report here that lysates of PPP, BC, and PRF decreased the cytokine-induced expression of interleukin 6 (IL6) and nitric oxide synthase (iNOS) in the bone marrow-derived ST2 cells. Consistently, PPP, BC, and PRF greatly decreased the phosphorylation and nuclear translocation of p65 in ST2 cells. The inflammatory response caused by Pam3CSK4 was reduced accordingly. Moreover, PPP, BC, and PRF reduced the enhanced expression of inflammatory mediators IL6 and iNOS in 3T3-L1 pre-adipocyte mesenchymal cells, and iNOS and CCL5 in murine calvarial cells. Surprisingly, PRF lysates were not effective in reducing the inflammatory response of human gingival fibroblasts and HSC2 epithelial cells. The data from the present study suggest that both liquid PRF and solid PRF exert potent anti-inflammatory activity in murine mesenchymal cells.

Causes and Management of Lower Gastro-Intestinal Bleeding

Gastrointestinal (GI) bleeding from the colon is a communal reason for hospitalization and is being more frequent in older patients. Gastrointestinal bleeding is known as any bleeding that takes place in the GIT from mouth to anus. Lower GI bleeding is defined as bleeding distal to the ligament of Treitz. Lower GI bleed is typically presented as hematochezia which is the passing of bright red blood clots or burgundy stools through the rectum. The causes of lower GI bleeding are changing over the past several decades from diverticulosis (which is the protrusion of the colon wall at the site of penetrating vessels), infectious colitis, ischemic colitis, angiodysplasia, inflammatory bowel disease, colon cancer, hemorrhoids, anal fissures, rectal varices, dieulafoy lesion, radiation-induced damage following cancer treatment to post-surgical. Management of lower GI bleeding is done through assessing the severity of symptoms and the condition of the overall case.