Background: The Regulation of Coagulation in Orthopedic Surgery to Prevent Deep Venous Thrombosis and Pulmonary Embolism (RECORD) 1 to 4 trials compared rivaroxaban 10 mg daily with commonly used doses of enoxaparin and demonstrated similar rates of VTE and bleeding. Objective: To evaluate bleeding events between patients who received enoxaparin or rivaroxaban for prevention of venous thromboembolism (VTE) following total hip arthroplasty (THA) or total knee arthroplasty (TKA). Methods: Retrospective cohort that compared patients undergoing THA and TKA who received enoxaparin (enoxaparin) with those who received rivaroxaban (rivaroxaban) and also with those who received enoxaparin in the RECORD 1 to 4 trials (enoxaparin RECORD). The primary outcome was any postoperative bleeding, defined as a composite of major and clinically relevant nonmajor bleeding based on the definitions in the RECORD 1 to 4 trials. Results: There was a lower rate of any postoperative bleeding (2.2% vs 6.8%, P = 0.004) in patients who received enoxaparin compared with rivaroxaban, and bleeding rates between the enoxaparin group and the enoxaparin RECORD groups were similar (2.2% vs 2.5%, P = 0.085). Major bleeding in the enoxaparin group (0.2%) was not significantly different from that in the rivaroxaban group (1.4%, P = 0.12) or the RECORD group (0.2%, P = 0.93). Clinically relevant nonmajor bleeding was also lower in the enoxaparin group compared with the rivaroxaban group (2.0% vs 5.5%, P = 0.012). Conclusions: The use of enoxaparin for VTE prophylaxis following THA and TKA was associated with a lower rate of the primary outcome (any postoperative bleeding) compared with the use of rivaroxaban in a similar cohort of patients.

Hypercoagulable states occur when the process of hemostasis is disturbed. It manifests as a deep vein thrombosis or a pulmonary embolism. It is also one of the most common cardiovascular diseases. There are two factors- genetic and acquired. Inherent factors involve coagulation inhibitor deficiency, prothrombin gene mutation and activated protein C resistance. Acquired factors include antiphospolipid syndrome, pregnancy, overweight etc. The analytic part of the thesis is focused on the effect of a low molecular weight heparin. It was shown in many theses that the LMWH could have a negative impact on a parturition complications or a week of parturition, a birth weight. The results of statistical analysis show that there is a coherence between the week of parturition and the type of parturition. What is more, the anticoagulation drug therapy shows a positive effect on the week of parturion. The data used in the thesis originate in laboratory information management system of Clinical Haematology ward in the hospital Nemocnice České Budějovice a.s.

Rationnel: Bien qu'elles constituent la majorité des thromboses veineuses des membres inférieurs, les thromboses veineuses profondes (TVP) distale et les thromboses veineuses superficielles (TVS) ont été peu étudiées et leur significativité clinique et leur prise en charge sont débattues.Méthodes: Cette thèse collige les résultats des travaux effectués par J.P. Galanaud sur les TVP distales et les TVS à partir des études épidémiologiques OPTIMEV, POST et RIETE.Résultats commentés: TVP distale: La TVP distale n'a pas le même profil de facteur de risque que la TVP proximale. Sa mortalité associée à court terme est plus faible que celle des TVP proximales mais supérieure à celle de témoins confirmant qu'il s'agit d'une entité cliniquement significative. Les différences de profil de population et de complications entre ces deux types de TVP suggèrent que le rapport bénéfice/risque du traitement anticoagulant est différent. Il n'est donc pas légitime d'extrapoler les résultats des essais des TVP proximales aux TVP distales. Des essais spécifiques sont donc nécessaires.TVS: En cas de TVS le risque de TVP concomitante est élevé. Un examen écho-doppler doit être réalisé et devra au moins explorer l'ensemble du réseau profond du membre inférieur affecté. Sexe masculin et antécédents de TVP/Embolie pulmonaire constituent des facteurs prédictifs indépendants de récidive. Si certaines TVS peuvent être traitées avec succès sans traitement anticoagulant, celles associées à un cancer ou à une atteinte saphéno-fémorale sont à haut risque de récidive y compris après un traitement anticoagulant curatif. / Background: Though they represent the majority of all lower limbs thromboses, isolated distal deep-vein thrombosis (DVT) (without symptomatic pulmonary embolism (PE)) and isolated superficial vein thrombosis (SVT) (without DVT or PE) have been poorly studied. Their clinical significance and management are under debate.Methods: Data from epidemiological multicenter prospective studies OPTIMEV, POST, RIETEResults and comments: Isolated distal DVT: Distal and proximal DVTs exhibit a different risk factor profile, the latter being more associated with chronic risk factors. Three-month mortality of distal DVT patient is lower than that of proximal DVT ones but is higher than that of controls. This evidences that distal DVT is a clinically significant finding. Differences in population profile and outcomes suggests that the benefit/risk ratio of anticoagulant treatment is not similar. Data from proximal DVT clinical trials should no longer be extrapolated to distal DVT.Isolated SVT: In case of SVT the risk of concomitant DVT is high. A compression ultrasonographic exam should be performed and at least explore the whole deep venous system of the affected limb. Male gender and history of DVT/Pulmonary embolism are independent predicators of recurrence. Some SVT can be safely treated without anticoagulants. On contrary, in patients with cancer or a sapheno-femoral junction involvement, the risk of deep venous recurrence is high even upon full therapeutic dose of anticoagulants.

Bakgrund: Djup ventrombos (DVT) är en allvarlig komplikation postoperativt och kan leda till ett livshotande tillstånd för patienten. Graderade kompressionsstrumpor (GCS) används på många postoperativa avdelningar tillsammans med andra profylaktiska åtgärder för att förebygga utvecklingen av DVT. Kompressionsstrumpor används även till att förebygga posttrombotiskt syndrom (PTS) efter en DVT. PTS kan utvecklas på grund av att de venösa klaffarna skadas vid en DVT, till följd stockar sig blodet och ödem bildas vilket leder till försämrad näring- och syretillförsel till vävnaderna. Syfte: Syftet var att genom en litteraturstudie undersöka om kompressionsstrumpor hade någon effekt för att förebygga DVT postoperativt samt om kompressionsstrumpor hade någon effekt att förebygga PTS efter en DVT. Metod: Litteraturstudie som baserads på 11 RCT studier. Resultat: GCS utan andra profylaktiska åtgärder visade sig ha en god effekt för att undvika utvecklingen av DVT på patienter som genomgått en operation. Däremot visade sig användandet av GCS i kombination med andra beprövade profylax inte ha någon större effekt för att reducera uppkomsten av DVT ytterligare. Resultatet angående GCS effekt för att undvika utvecklingen av PTS visade ingen entydighet. Slutsats: GCS har en förebyggande effekt för att undvika uppkomsten av DVT. Användningen av GCS i kombination med andra profylax potentierar däremot inte effekten av preventionen för DVT. GCS verkan för att förebygga uppkomsten av PTS är inte entydigt och flera studier behövs för att se evidens kring detta. / ABSTRACT  Background: Deep vein thrombosis (DVT) is a serious complication postoperatively and can lead to a life threatening condition for the patient. Graded compression stockings (GCS) are used in many post-operative departments along with other prophylactic measures to prevent the development of DVT. Compression stockings are also used to prevent postthrombotic syndrome (PTS) after a DVT. PTS can develop because the venous valves are damaged by a DVT, as a result, the blood is stored and edema is formed, which leads to poor nutritional and oxygen supply to the tissues. Aim: The aim of the literature study was to investigate whether compression stockings had any effect in preventing DVT postoperatively, and also whether the compression stockings had any effect in preventing PTS after a DVT. Method: Literature study based on 11 RCT studies. Results: GCS without other prophylactic measures was found to have a good effect in avoiding the development of DVT in patients who underwent surgery. However, the use of GCS in combination with other proven prophylaxis was found to have no significant effect in further reducing the onset of DVT. The results regarding the GCS effect to avoid the development of PTS showed no unambiguity. Conclusion: GCS has a preventive effect to avoid the onset of DVT. However, the use of GCS in combination with other prophylaxis does not potentiate the effect of prevention for DVT. The effect of GCS in preventing the onset of PTS is not unambiguous and several studies are needed to see evidence of this.

The role of patent foramen ovale (PFO) in stroke was debated for decades. Randomized clinical trials (RCTs) have shown fewer recurrent events after PFO closure in patients with cryptogenic stroke (CS). However, in clinical practice, treating stroke patients with coexisting PFO raises some questions. This brief review summarizes current knowledge and challenges in handling stroke patients with PFO and identifies issues for future research. The rationale for PFO closure was initially based on the concept of paradoxical embolism from deep vein thrombosis (DVT). However, RCTs did not consider such details, limiting their impact from a pathophysiological perspective. Only a few studies explored the coexistence of PFO and DVT in CS with varying results. Consequently, the PFO itself might play a role as a prothrombotic structure. Transesophageal echocardiography thus appears most appropriate for PFO detection, while a large shunt size or an associated atrial septum aneurysm qualify for a high-risk PFO. For drug-based treatment alone, studies did not find a definite superiority of oral anticoagulation over antiplatelet therapy. Remarkably, drug-based treatment in addition to PFO closure was not standardized in RCTs. The available literature rarely considers patients with transient ischemic attack (TIA), over 60 years of age, and competing etiologies like atrial fibrillation. In summary, RCTs suggest efficacy for closure of high-risk PFO only in a small subgroup of stroke patients. However, research is also needed to reevaluate the pathophysiological concept of PFO-related stroke and establish strategies for older and TIA patients and those with competing risk factors or low-risk PFO.

Venous thromboembolism (VTE), defined as deep vein thrombosis and/or pulmonary embolism is the second leading cause of mortality in cancer patients, second only to cancer itself. A number of reports suggest that circulating extracellular vesicles (EVs) may be increased in cancer patients with VTE. The aim of this study was to examine circulating EVs in high-risk ambulatory cancer patients, determine if levels are associated with hematological outcomes (VTE, major bleeding event), and to assess the impact of prophylactic antithrombotic therapy (Apixaban). We hypothesized that elevated levels of circulating large EVs will be predictive of cancer associated VTE and/or bleeding events and that treatment with Apixaban will reduce EV levels and incidence of cancer VTE. Plasma samples from patients at baseline, and 90-days follow-up from the Apixaban for the Prevention of Venous Thromboembolism in High-Risk Ambulatory Cancer patients (AVERT) trial were investigated. Total EVs were quantified by their pro-coagulant activity using the Zymuphen MP-Activity kit. Platelet, endothelial and tissue-factor EV levels were quantified by flow cytometry. We observed that circulating EVs exhibited significant associations with sex, age, and cancer type, however we did not observe any relationships with clinical outcomes. Thus, it appears that circulating EVs may not have a role in risk stratification for VTE in in high-risk ambulatory cancer patients.

L'élastographie ultrasonore est une technique d'imagerie émergente destinée à cartographier les paramètres mécaniques des tissus biologiques, permettant ainsi d’obtenir des informations diagnostiques additionnelles pertinentes. La méthode peut ainsi être perçue comme une extension quantitative et objective de l'examen palpatoire. Diverses techniques élastographiques ont ainsi été proposées pour l'étude d'organes tels que le foie, le sein et la prostate et. L'ensemble des méthodes proposées ont en commun une succession de trois étapes bien définies: l'excitation mécanique (statique ou dynamique) de l'organe, la mesure des déplacements induits (réponse au stimulus), puis enfin, l'étape dite d'inversion, qui permet la quantification des paramètres mécaniques, via un modèle théorique préétabli. Parallèlement à la diversification des champs d'applications accessibles à l'élastographie, de nombreux efforts sont faits afin d'améliorer la précision ainsi que la robustesse des méthodes dites d'inversion. Cette thèse regroupe un ensemble de travaux théoriques et expérimentaux destinés à la validation de nouvelles méthodes d'inversion dédiées à l'étude de milieux mécaniquement inhomogènes. Ainsi, dans le contexte du diagnostic du cancer du sein, une tumeur peut être perçue comme une hétérogénéité mécanique confinée, ou inclusion, affectant la propagation d'ondes de cisaillement (stimulus dynamique). Le premier objectif de cette thèse consiste à formuler un modèle théorique capable de prédire l'interaction des ondes de cisaillement induites avec une tumeur, dont la géométrie est modélisée par une ellipse. Après validation du modèle proposé, un problème inverse est formulé permettant la quantification des paramètres viscoélastiques de l'inclusion elliptique. Dans la continuité de cet objectif, l'approche a été étendue au cas d'une hétérogénéité mécanique tridimensionnelle et sphérique avec, comme objectifs additionnels, l'applicabilité aux mesures ultrasonores par force de radiation, mais aussi à l'estimation du comportement rhéologique de l'inclusion (i.e., la variation des paramètres mécaniques avec la fréquence d'excitation). Enfin, dans le cadre de l'étude des propriétés mécaniques du sang lors de la coagulation, une approche spécifique découlant de précédents travaux réalisés au sein de notre laboratoire est proposée. Celle-ci consiste à estimer la viscoélasticité du caillot sanguin via le phénomène de résonance mécanique, ici induit par force de radiation ultrasonore. La méthode, dénommée ARFIRE (''Acoustic Radiation Force Induced Resonance Elastography'') est appliquée à l'étude de la coagulation de sang humain complet chez des sujets sains et sa reproductibilité est évaluée. / Ultrasound elastography is an emerging technology derived from the concept of manual palpation and dedicated to the mapping of biological tissue mechanical properties in a diagnostic context. Various elastographic approaches have been applied to the study of organs such as the liver, breast or prostate. All proposed techniques rely on a three-steps procedure: first, the tissue to be studied is mechanically excited, in a static or dynamic way. Induced displacements are then measured and used to estimate qualitatively or quantitatively mechanical properties of the medium. This step is called inversion. While application fields of elastography are constantly broadened, efforts are made to provide robust and accurate inversion algorithms. In this monography, theoretical and experimental works related to the development of new inversion methods dedicated to the study of mechanically inhomogeneous media in dynamic ultrasound elastography are provided. In the context of breast cancer diagnosis, a localized tumour can be assumed as a confined mechanical heterogeneity, also referred as an inclusion, which can disturb the propagation of shear waves (dynamic excitation). The first objective of this thesis is to provide a theoretical model to describe physical interactions occurring between incident shear waves and a tumour, here geometrically assumed as an ellipse. Once the theoretical model is validated, an inverse problem is formulated allowing further quantification of inclusion viscoelastic parameters. Aiming the development of realistic models, the previous work has been extended to the case of three dimensional spherical heterogeneities and adapted to the specific case of an acoustic radiation force excitation. Furthermore, the feasibility of assessing the medium rheological model (i.e., the frequency dependence of mechanical properties) is demonstrated. Finally, in the context of vascular diseases and blood coagulation, an inversion method based on the study of the mechanical resonance phenomenon induced by acoustic radiation force is proposed. The technique, termed ARFIRE (Acoustic Radiation Force Induced Resonance Elastography), is applied to human whole blood samples and the reproducibility of results is assessed.

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