Myeloproliferative neoplasms are acquired hematological malignancies, mainly affecting the adult and whose morbidity and mortality stems from haemostasis disorders. The most frequently encountered complications include thrombosis, affecting preferentially the arterial territory, but also atypical locations such as splanchnic vein thrombosis. The pathophysiology of these thromboses is complex and involves different actors: blood cells, endothelium and flow conditions. Numerous studies have been conducted to identify risk factors for thrombosis. To date, only two risk factors have been validated through prospective studies (age over 60 years old, history of thrombotic events) and allow classification of patients as "low risk" and "high risk" as the basis for current treatment recommendations. Haemorrhagic manifestations, less frequent than thrombosis, are mainly related to an alteration of primary haemostasis and are therefore manifested by mucocutaneous bleeding. In these patients, platelet dysfunctions and/or acquired Willebrand syndromes can be found. The pathophysiology of thrombosis and platelet dysfunction during myeloproliferative neoplasms remains to date partially unknown. In this review, we offer to focus on physiopathological mechanisms as well as the latest advances in their understanding. (C) 2020 Societe Nationale Francaise de Medecine Interne (SNFMI). Published by Elsevier Masson SAS. All rights reserved.

Les néoplasies myéloprolifératives sont un ensemble d’hémopathies acquises touchant le plus souvent l’adulte et dont la morbi-mortalité découle, en grande partie, de troubles de l’hémostase. Les complications les plus fréquemment retrouvées sont des thromboses affectant préférentiellement le territoire artériel, mais également des localisations plus atypiques telles que des thromboses des veines splanchniques. La physiopathologie en est complexe et fait intervenir différents acteurs : cellules sanguines, endothélium, conditions de flux. De nombreuses études ont été menées afin d’identifier les facteurs de risque de thromboses. À ce jour, seuls deux facteurs de risque sont validés sur des études prospectives (âge supérieur à 60 ans et un antécédent d’évènements thrombotiques) et permettent la classification des patients en « bas risque » ou « haut risque », base des recommandations thérapeutiques actuelles. Les manifestations hémorragiques, moins fréquentes que les thromboses, sont principalement liées à une altération de l’hémostase primaire et se manifestent par des saignements cutanéo-muqueux. On retrouve chez ces patients des thrombopathies et des syndromes de Willebrand acquis. La physiopathologie des thromboses et thrombopathies au cours des néoplasies myéloprolifératives reste toutefois à ce jour partiellement méconnue. Dans cette revue, nous nous proposons de faire le point sur les différents mécanismes physiopathologiques ainsi que sur les dernières avancées dans la compréhension de ceux-ci.

Myeloproliferative neoplasms are acquired hematological malignancies, mainly affecting the adult and whose morbidity and mortality stems from haemostasis disorders. The most frequently encountered complications include thrombosis, affecting preferentially the arterial territory, but also atypical locations such as splanchnic vein thrombosis. The pathophysiology of these thromboses is complex and involves different actors: blood cells, endothelium and flow conditions. Numerous studies have been conducted to identify risk factors for thrombosis. To date, only two risk factors have been validated through prospective studies (age over 60 years old, history of thrombotic events) and allow classification of patients as \"low risk\" and \"high risk\" as the basis for current treatment recommendations. Haemorrhagic manifestations, less frequent than thrombosis, are mainly related to an alteration of primary haemostasis and are therefore manifested by mucocutaneous bleeding. In these patients, platelet dysfunctions and/or acquired Willebrand syndromes can be found. The pathophysiology of thrombosis and platelet dysfunction during myeloproliferative neoplasms remains to date partially unknown. In this review, we offer to focus on physiopathological mechanisms as well as the latest advances in their understanding.

Acute traumatic coagulopathy (ATC) is an acute and endogenous mechanism triggered by the association of trauma and hemorrhage. Several animal models have been developed, but some major biases have not yet been identified. Our aim was to develop a robust and clinically relevant murine model to study this condition. Anesthetized adult Sprague Dawley rats were randomized into 4 groups: C, control; T, trauma; H, hemorrhage; TH, trauma and hemorrhage (n = 7 each). Trauma consisted of laparotomy associated with four-limb and splenic fractures. Clinical variables, ionograms, arterial and hemostasis blood tests were compared at 0 and 90 min. ATC and un-compensated shock were observed in group TH. In this group, the rise in prothrombin time and activated partial thromboplastin was 29 and 40%, respectively. Shock markers, compensation mechanisms and coagulation pathways were all consistent with human pathophysiology. The absence of confounding factors, such as trauma-related bleeding or dilution due to trans-capillary refill was verified. This ethic, cost effective and bias-controlled model reproduced the specific and endogenous mechanism of ATC and will allow to identify potential targets for therapeutics in case of trauma-related hemorrhage.

Les patients obèses morbides ont une hypercoagulabilité biologique en rapport avec une inflammation de bas grade. Le but de notre étude était de comparer l'état de coagulabilité de patients obèses morbides avant et 1 an après chirurgie bariatrique (CB) à l'aide d'un test de génération de thrombine, une méthode validée d'étude globale de la coagulation in vitro. Tous les patients opérés d'une CB dans un centre hospitalo-universitaire entre le 1er septembre 2014 et le 1er janvier 2016 (n = 100) étaient éligibles pour cette étude prospective. Le critère de jugement principal était le potentiel endogène de thrombine générée (PET) à 1 an comparé au préopératoire. Après exclusions, 90 patients étaient inclus. À un an postopératoire, la variation d'IMC était de 14,2 ± 6,5 ; le fibrinogène diminuait de 4,2 ± 0,7 à 3,7 ± 0,8 g/L (p < 0,001). Le PET ( %) diminuait de 111 (95–128) à 83 (71–105) (p < 0,001). En analyse multivariée, la baisse de fibrinogène (Δ relative) était associée significativement (p < 0,001) à une diminution de l'ETP (Δ relative) : β=0,36 (IC95 % : 0,06–0,26) indépendamment de la perte de poids. Notre étude retrouve une baisse significative du potentiel de thrombine générée un an après CB reliée significativement à la réduction de l'état inflammatoire.