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ABSTRACT: BACKGROUND: Bleeding remains a potentially lethal complication of cardio-pulmonary bypass (CPB) surgery. The purpose of this study was to obtain a better insight into in vitro thrombin generation in the context of CPB. METHODS: We used Calibrated Automated Thrombography to assess blood coagulation of 10 low-risk patients operated for valve replacement with CPB, under 2 experimental conditions, one implicating platelets as platelet dysfunction has been described to occur during CPB. RESULTS: Our main finding was that CPB-induced coagulopathy was differently appreciated depending on the presence or absence of platelets: the decrease in thrombin generation was much less pronounced in their presence (mean endogenous thrombin potential change values before and after CPB were -3.9% in the presence of platelets and -39.6% in their absence). CONCLUSION: Our results show that experimental conditions have a profound effect in the study of in vitro thrombin generation in the context of CPB.
Thrombosis Journal 08/2012; 10(1):15. · 1.31 Impact Factor
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ABSTRACT: The thrombin generation test (TGT) has demonstrated utility in evaluating overall hemostatic capacity both in bleeding and thrombotic disorders. Although the test is currently well accepted as a research tool, its role in clinical practice has not yet been defined through large prospective multicenter clinical studies. Such prospective studies have been limited by the lack of official standardization of the assay and its large inter-laboratory variability. This international study assessed the intra- and inter-assay imprecision of TGT as well as the inter-centre variability of results in one US and four European centres. Contact-inhibited plasmas from six healthy volunteers, one mild haemophilia A patient, and five patients with heterozygous prothrombin G20210 mutation were assayed. We demonstrated that, using identical equipement, standardized reagents, a carefully selected reference plasma for normalization of results and the same test procedure as described in our DVD, the assay variability was highly reduced compared to previously published data. Our results emphasize the importance of preheating on TGT results and the variability of the assay. In conclusion, our data demonstrated that the standardized TGT methodology evaluated in this study effectively reduces the variability of the assay to acceptable limits and may be used in clinical trials.
Thrombosis Research 08/2012; · 2.44 Impact Factor
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ABSTRACT: As a potent anticoagulant agent, rivaroxaban exposes a risk of bleeding. An effective way to reverse its effects is needed. Objectives were to study efficacy and safety of recombinant activated factor VII (rFVIIa) and prothrombin complex concentrate (PCC) to reverse the anticoagulant effect of an overdose of rivaroxaban in a rabbit model of bleeding and thrombosis.
First, a dose-ranging study assessed the minimal rivaroxaban dose that increased bleeding. Then, 48 anesthetized and ventilated rabbits were randomized into four groups: control (saline), rivaroxaban (rivaroxaban and saline), rFVIIa (rivaroxaban and rFVIIa), and PCC (rivaroxaban and PCC). The Folts model was applied: a stenosis and an injury were carried out on the carotid artery, inducing thrombosis, detected as cyclic flow reductions, which were recorded over 20 min. Then the following were measured: ear immersion bleeding time, clotting times, anti-Xa activity, thrombelastometric parameters, and thrombin generation test. Ultimately, a hepatosplenic section was performed and the total amount of blood loss after 15 min was evaluated as primary endpoint.
Rivaroxaban increased blood loss (17 g [8-32] vs. 7 g [5-18] for control (median [range]), P = 0.0004), ear bleeding time, clotting times, thrombelastographic clotting time, and decreased thrombin generation. In contrast, rFVIIa decreased ear bleeding time (92 s [65-115] vs. 140 s [75-190], P < 0.02), but without efficacy on blood loss. PCC and rFVIIa decreased activated partial thromboplastin time as well as thrombelastographic clotting time. Regarding safety, neither rFVIIa nor PCC increased cyclic flow reductions.
rFVIIa and PCC partially improved laboratory parameters, but did not reverse rivaroxaban induced-bleeding.
Anesthesiology 01/2012; 116(1):94-102. · 5.36 Impact Factor
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ABSTRACT: Background: As a potent anticoagulant agent, rivaroxaban exposes a risk of bleeding. An effective way to reverse its effects is needed. Objectives were to study efficacy and safety of recombinant activated factor VII (rFVIIa) and prothrombin complex concentrate (PCC) to reverse the anticoagulant effect of an overdose of rivaroxaban in a rabbit model of bleeding and thrombosis.
Anesthesiology 12/2011; 116(1):94–102. · 5.36 Impact Factor
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Pierre Sié,
Charles M Samama,
Anne Godier,
Nadia Rosencher,
Annick Steib,
Juan V Llau,
Philippe Van der Linden,
Gilles Pernod, Thomas Lecompte,
Isabelle Gouin-Thibault,
Pierre Albaladejo
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ABSTRACT: Direct oral anticoagulants (DOAs)--inhibitors of thrombin or factor-Xa--are expected to replace vitamin K antagonists in most of their indications. Patients receiving long-term treatment with DOAs are likely to be exposed to elective or emergency surgery or invasive procedures. Owing to the present lack of experience in such conditions, we cannot make recommendations, but only propose perioperative management for optimal safety regarding the risk of bleeding and thrombosis. DOAs may increase surgical bleeding, they have no validated antagonists, they cannot be monitored by simple standardized laboratory assays and their pharmacokinetics vary significantly between patients. Although DOAs differ in many respects, the proposals in the perioperative setting need not be specific to each. For procedures with low haemorrhagic risk, a therapeutic window of 48 hours (last administration 24 hours before surgery, restart 24 hours after) is proposed. For procedures with medium or high haemorrhagic risk, we suggest stopping DOAs 5 days before surgery to ensure complete elimination in all patients. Treatment should be resumed only when the risk of bleeding has been controlled. In patients at high thrombotic risk (e.g. those in atrial fibrillation with a history of stroke), bridging with heparin (low molecular-weight heparin, or unfractionated heparin, if the former is contraindicated) is proposed. In an emergency, the procedure should be postponed for as long as possible (minimum 1-2 half-lives) and non-specific antihaemorrhagic agents, such as recombinant human activated factor VIIa or prothrombin complex concentrates should not be given for prophylactic reversal due to their uncertain benefit-risk.
Archives of cardiovascular diseases 12/2011; 104(12):669-76. · 0.66 Impact Factor
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ABSTRACT: We report dysmegakaryopoiesis in a case of familial platelet disorder with predisposition to acute myeloid leukemia (familial platelet disorder/acute myeloid leukemia phenotype Mendelian Inheritance in Man number 601 399). Slight reduction of the number of megakaryocytes with high nucleocytoplasmic ratio, strongly basophilic cytoplasm and poorly lobulated nuclei are suggestive of megakaryocytic dysplasia.
Journal of Pediatric Hematology/Oncology 09/2011; 33(7):e264-6. · 1.16 Impact Factor
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ABSTRACT: The study aimed to describe French off-label use of rFVIIa for intractable bleeding in major cardiovascular surgery.
Retrospective observational analysis of data from 2005 to October 2007 (no formal guidelines were available) was employed. The collect request form was elaborated by a multidisciplinary committee.
Data on 109 patients--37 mechanical cardiac assist devices--were collected, with repeated injection for 24%. Bleeding stopped, decreased or continued in 43%, 37% and 20% of the cases, respectively. For patients treated in the intensive care unit (ICU), hourly bleeding decreased from 365 ± 212 to 115 ± 106 ml h(-1) (p<0.001). The median number of transfused products was 25 (2-90) before and 6 (0-48) after rFVIIa (p<0.001). Most patients had been well compensated with fibrinogen (>1g.l(-1)) and platelets (>50 G.l(-1)) before rFVIIa. The bleeding outcome (cessation, decrease or no change) was associated with the infused dose (81 ± 31, 71 ± 24, 64 ± 23 μg.kg(-1); p = 0.044) and did not differ whether rFVIIa was administered in the operating room (49%) or ICU (51%). Thrombotic events occurred in 13% of patients without assist devices and in 27% of those with them (but without obvious intra-device clotting). The overall 28-day survival rate was 60% and associated with bleeding outcome (p = 0.002).
rFVIIa rescue therapy was followed by control of bleeding in a substantial number of the patients with seemingly acceptable safety; however, thrombotic risk remains a matter of concern. Our observational study suggests that the dose to be tested prospectively is at least 80 μg.kg(-1).
European journal of cardio-thoracic surgery: official journal of the European Association for Cardio-thoracic Surgery 05/2011; 40(6):1320-7. · 2.40 Impact Factor
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American Journal of Hematology 02/2011; 87(1):105-6. · 4.67 Impact Factor
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Veronique Regnault,
Christine Perret-Guillaume,
Anna Kearney-Schwartz,
Jean-Pierre Max,
Carlos Labat,
Huguette Louis,
Denis Wahl,
Bruno Pannier, Thomas Lecompte,
Georges Weryha,
Pascal Challande,
Michel E Safar,
Athanase Benetos,
Patrick Lacolley
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ABSTRACT: To investigate in women older than 60 whether aortic stiffness or pulse pressure (PP) is associated with selected procoagulant or anticoagulant factors and to examine whether pulsatile stretch influences these factors in human vascular smooth muscle cells (VSMCs) in vitro.
Aortic pulse wave velocity (PWV) and carotid PP were studied in 123 apparently healthy postmenopausal women. PWV, PP, von Willebrand factor, and free tissue factor pathway inhibitor (TFPI), but not mean arterial pressure, increased with age. Free TFPI and PWV were positively correlated, even after adjustment for age and PP and other confounding parameters. In vitro, 5% or 10% pulsatile stretch (at 1 Hz) enhanced TFPI synthesis and secretion by VSMCs in a time-independent manner (1 to 48 hours) without changes in protein level of smooth muscle myosin heavy chain. Application of 5% static stretch had no effect.
In postmenopausal women, free TFPI increases as vascular wall function deteriorates and PP increases. These findings are supported by the increase in TFPI synthesized by VSMCs in response to cyclic stress in vitro. They suggest that VSMCs require pulsatility to interfere with the coagulation process and highlight the relevance of plasma free TFPI levels to cardiovascular diseases.
Arteriosclerosis Thrombosis and Vascular Biology 02/2011; 31(5):1226-32. · 6.37 Impact Factor
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ABSTRACT: Essential thrombocythemia and polycythemia vera are myeloproliferative disorders (MPD) with an elevated thrombotic risk. Leukocytosis has recently emerged as a new risk factor and there is increasing evidence that polymorphonuclear neutrophils (PMN) are involved. Procoagulant activity (PCA) of PMN in MPD has not yet been investigated. PCA of PMN from 22 patients with JAK2(V617F) positive MPD and 26 healthy subjects was studied using calibrated automated thrombography: in vitro thrombin generation induced with 1 pM tissue factor in the presence of added procoagulant phospholipids. There were no differences between patients and controls regarding the ability of PMN to increase thrombin generation. More surprisingly, basal thrombin generation in acellular MPD-plasma was found decreased for as yet unknown reasons. The presence of an active protein C pathway or platelets might provide a better insight into the coagulation phenotype in MPD.
Blood Cells Molecules and Diseases 02/2011; 46(3):235-8. · 2.35 Impact Factor
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ABSTRACT: Recombinant activated factor VII (rFVIIa), which is used off-label as an adjuvant therapy for uncontrolled and life-threatening bleeding, might also attenuate intractable bleeding related to macrovascular arterial lesions. Here we evaluated the efficacy of rFVIIa in sealing a large arterial wound in haemostatically competent rabbits.
Sixty male New Zealand rabbits were randomly divided into vehicle control and 80 and 200 μg kg⁻¹ rFVIIa groups (n = 20 animals each). A standardized wound of the isolated right carotid artery was made in all rabbits with an 18-G catheter. Bleeding, which was limited by mild compression, was assessed every minute. At 5 min, an intravenous bolus of vehicle or human rFVIIa was given and the animals were further observed for 1 h. Efficacy was assessed from the bleeding duration and blood mass lost. Statistical significance was defined as P less than 0.05. All investigators were blinded to the treatment the animals received.
The bleeding duration and blood mass lost were significantly reduced in both rFVIIa dosage groups as compared with the vehicle control group. For the vehicle, 80 and 200 μg kg⁻¹ rFVIIa groups, the median bleeding durations were 56 min (range 7-60 min), 15 min (range 5-60 min) and 10 min (range 5-60 min), respectively; and the median blood mass losses were 22.5 g (range 1-58 g), 12 g (range 0-36 g) and 5 g (range 0-31 g), respectively. The prothrombin time was shorter in the rFVIIa groups. Visual inspection of the carotid artery and microscopic analysis of the liver and kidney revealed neither gross thrombi nor entrapped microthrombi in any rabbit.
Recombinant FVIIa at 80 or 200 μg kg⁻¹ promoted the sealing of a large and slightly compressed arterial wound in rabbits. These results suggest a potential role for the drug in the management of massive bleeds due to an arterial lesion when surgical intervention is not immediately and readily available. Safety should remain a matter of concern.
European Journal of Anaesthesiology 01/2011; 28(1):51-6. · 2.23 Impact Factor
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ABSTRACT: Low-molecular-weight heparins (LMWHs) and fondaparinux are antithrombin dependent anticoagulant drugs considered to need no laboratory monitoring because of their reputedly predictable anticoagulant effect. However it has been suggested in the literature the existence of an inter-individual variability in response to LMWHs that would be not fully attributable to pharmacokinetics causes.
In order to separate pharmacokinetic from pharmacodynamics effects we studied in 12 platelet-depleted plasmas from normal donors the inhibitory effect on TG determined with the CAT of added UFH, 5 LMWHs and 2 oligosaccharides with anti-Xa activity only.
A concentration-dependent inhibition of thrombin generation was found with all molecules tested. The concentration-response relation was very different when the concentrations were expressed in anti-Xa unit but became very similar when expressed in anti-thrombin units regarding LMWHs. Most importantly, we noticed a large inter-individual variability of the inhibitory effects with all molecules tested, UFH and LMWHs alike. The IC40 value varied at least twofold between the highest and the lowest responder. For any given anti-Xa level of any heparin and of pentasaccharide the inhibition of the ETP showed scattering of around 25%.
In contrast to what is generally assumed the inter-individual variation of the in vitro pharmacodynamics response is equally high for UFH and any LMWH (~25%) and even for the synthetic pentasaccharide. This questions the rationale for standard dosage, the more so as in clinical practice pharmacokinetic variation (e.g. due to body weight) will add to this pharmacodynamic variability.
Thrombosis Research 01/2011; 127(1):29-34. · 2.44 Impact Factor
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ABSTRACT: Pathogenesis of idiopathic pulmonary arterial hypertension (iPAH) includes endothelial dysfunction and in situ thrombosis. A hypercoagulable state has also been postulated but never demonstrated. Our objective was to determine whether patients with iPAH had a hypercoagulable state using calibrated automated thrombography (CAT), a new tool to phenotype coagulation in vitro.
16 patients with iPAH and 29 controls were studied. In vitro platelet dependent coagulation phenotyping by CAT monitored the activity of thrombin generation over time. Plasma levels of soluble thrombomodulin, tissue factor pathway inhibitor (TFPI) and von Willebrand factor (VWF) were measured as endothelial biomarkers.
Endogenous thrombin potential (ETP) in the absence of activated protein C (APC) tended to be increased in patients compared to controls (1769 versus 1656 nM.min; p=0.053). ETP was higher in the presence of APC 25 nM (ETP-APC) in patients (781 versus 494 nM.min; p=0.005). Five patients had ETP-APC higher than the 95th centile of controls. Other CAT parameters (lag time, peak thrombin and time to peak) were all consistent with some degree of hypercoagulability in patients. Regarding endothelial plasma biomarkers sTM was lower (28.4 versus 40.6 μg/l, p=0.0108) in patients; TFPI antigen and activity (respectively: 14.3 versus 10.5 μg/l, p=0.0167; 1.155 versus 1.070, p=0.0021) and VWF (1300 versus 976%, p=0.0108) were higher in patients.
We have demonstrated that at least some patients with iPAH have a hypercoagulable phenotype.
Thrombosis Research 09/2010; 126(6):e418-22. · 2.44 Impact Factor
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ABSTRACT: Cathepsin G (Cath G), a serine-protease found in neutrophils, has been reported to have effects that could either facilitate or impede coagulation. Thrombin generation (CAT method) was chosen to study its overall effect on the process, at a plasma concentration (240 nM) observed after neutrophil activation. Coagulation was triggered by tissue factor in the presence of platelets or phospholipid vesicles. To help identify potential targets of Cath G, plasma depleted of clotting factors or of inhibitors was used. Cath G induced a puzzling combination of two diverging effects of varying intensities depending on the phospholipid surface provided: accelerating the process under the three conditions (shortened clotting time by up to 30%), and impeding the process during the same thrombin generation time-course since thrombin peak and ETP (total thrombin potential) were decreased, up to 45% and 12%, respectively, suggestive of deficient prothrombinase. This is consistent with Cath G working on at least two targets in the coagulation cascade. Our data indicate that coagulation acceleration can be attributed neither to platelet activation and nor to activation of a clotting factor. When TFPI (tissue factor pathway inhibitor) was absent, no effect on lag time was observed and the anticoagulant activity of TFPI was decreased in the presence of Cath G. Consistent with the literature and the hypothesis of deficient prothrombinase, experiments using Russel's Viper Venom indicate that the anticoagulant effect can be attributed to a deleterious effect on factor V. The clinical relevance of these findings deserves to be studied.
Thrombosis and Haemostasis 09/2010; 104(3):514-22. · 5.04 Impact Factor
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Audrey Bidet,
Brigitte Tardy Poncet,
Dominique Desprez,
Emmanuel de Maistre,
Emilie Presles, Thomas Lecompte,
Cecile Lavenu-Bombled,
Marie Genevieve Huisse,
Martine Wolf,
Pierre Morange,
Evelyne Racadot,
Christine Mouton,
Lelia Grunebaum,
Claire Pouplard,
Bernard Tardy
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ABSTRACT: We undertook a survey of French university hospital hematological laboratories to ascertain the clinical characteristics of patients with suspected HIT, the laboratory tests performed, and the therapeutic strategy adopted in current practice.
A standardized medical records database for patients with suspected HIT was sent to 19 laboratories. During two months, all consecutive patients for whom a biological test was performed were included.
169 patients were included, 27 (16%) patients having a final diagnosis of HIT. At the time HIT was suspected, the heparin duration and the level of thrombocytopenia were similar in HIT- positive and HIT-negative groups. The use of unfractionated heparin, a therapeutic heparin dose regimen and the presence of thrombotic complications were significantly more frequent in HIT-positive patients. When the heparin dose regimen was taken into account, only thrombotic complications under a therapeutic dose regimen were significantly increased in HIT-positive patients. Eighty-six percent of patients presented at least one alternative diagnosis of thrombocytopenia without significant difference between the two groups. Laboratory tests were performed after a mean of 0.3days and mainly consisted of antigen assays. At the time HIT was suspected, heparin was stopped in 56 (33%) patients, being replaced mainly by danaparoid. Only three laboratories declared they usually received all the necessary clinical information to establish the likelihood of HIT.
In current practice in France, the clinical probability of HIT is rarely established, leading to systematic requests for laboratory HIT tests.
Thrombosis Research 02/2010; 125(6):e294-9. · 2.44 Impact Factor
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ABSTRACT: Oral absorption of low-molecular-weight heparin (LMWH) is limited by its molecular size and negative charge. It has been shown previously that orally administered polymeric nano- or microparticles containing encapsulated LMWH have led to gastrointestinal absorption of heparin in rabbits.
Based on these investigations, pellets containing two LMWHs, enoxaparin (MW 4500 Da) or bemiparin (MW 3600 Da), and EudragitRS30D (ERS), were prepared using extrusion/ spheronization technique. Uncoated or coated (ERS) pellets were evaluated in vitro and in vivo on rabbits.
Enoxaparin pellets showed fast in vitro release in phosphate buffer (pH 7.4) and prolonged in vivo drug absorption after a single oral dose of 600 anti-Xa IU/ kg of body weight, leading to relative bioavailabilities ranging from 9.7 +/- 1.9% to 12.8 +/- 2.7% and anti-Xa activity over the curative dose. Bemiparin included in matrix pellets of ERS and coated with ERS exhibited in vitro prolonged release up to 4 hours and in vivo anti-Xa activity below the therapeutic minimum value of 0.1 IU/mL.
This study presents LMWH in a pellet dosage form, which compared to nano- or microparticles, may offer a more convenient and industrializable way of manufacture leading to an easier scale-up process.
Drug Development and Industrial Pharmacy 12/2009; 35(12):1503-10. · 1.49 Impact Factor
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Gilles Pernod,
Christine Biron-Andreani,
Pierre-Emmanuel Morange,
Françoise Boehlen,
Joël Constans,
Francis Couturaud,
Ludovic Drouet,
Brigitte Jude, Thomas Lecompte,
Gregoire Le Gal,
Nathalie Trillot,
Denis Wahl
La Revue du praticien 10/2009; 59(8):1044-6.
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European Journal Of Haematology 08/2009; 84(1):92-3. · 2.61 Impact Factor
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ABSTRACT: Levetiracetam is an antiepileptic drug widely prescribed. We report here for the first time, an alteration of platelet function attributable to this drug. This effect has never been reported before. The responsibility of levetiracetam seems to be probable: restoration of platelet functionality was observed after withholding this treatment and this effect has been described for a structurally related molecule, piracetam.
Epilepsy research 06/2009; 86(1):94-6. · 2.48 Impact Factor
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European Journal of Anaesthesiology 05/2009; 26(4):344-5. · 2.23 Impact Factor
