Bleeding Tendency In Patients Research Articles

Multimodal mechanisms of pathogenic variants in the signal peptide of FIX leading to hemophilia B

AbstractSignal peptide (SP) is essential for protein secretion, and pathogenic variants in the SP of factor IX (FIX) have been identified in hemophilia B (HB). However, the underlying mechanism for the genotype-phenotype correlation of these variants has not been well studied. Here, we systematically examined the effects of 13 pathogenic point variants in the SP of FIX using different approaches. Our results showed that these point variants lead to HB by missense variants and/or aberrant premessenger RNA (pre-mRNA) splicing. The missense variants in a hydrophobic core (h-region) mainly affected the cotranslational translocation function of the SP, and those in C-terminal containing cleavage site (c-region) caused FIX deficiency mainly by disturbing the cotranslational translocation and/or cleavage of the SP. Almost absolute aberrant pre-mRNA splicing was only observed in variants of c.82T>G, but a slight change of splicing patterns was found in variants of c.53G>T, c.77C>A, c.82T>C, and c.83G>A, indicating that these variants might have different degrees of impact on pre-mRNA splicing. Although two 6-nt deletion aberrant pre-mRNA splicing products caused FIX deficiency by disturbing the SP cleavage, they could produce some functional mature FIX, and vitamin K could increase the secretion of functional FIX. Taken together, our data indicated that pathogenic variants in the SP of FIX caused HB through diverse molecular mechanisms or even a mixture of several mechanisms, and vitamin K availability could be partially attributed to varying bleeding tendencies in patients carrying the same variant in the SP.

Brain-derived neurotrophic factor (BDNF) associated with platelet activity and bleeding tendency in patients with Gaucher disease

Brain-derived neurotrophic factor (BDNF) associated with platelet activity and bleeding tendency in patients with Gaucher disease

Brain-Derived Neurotrophic Factor (BDNF) Is Associated with Platelet Activity and Bleeding Tendency in Patients with Gaucher Disease.

Bleeding tendency, a prominent feature of patients with Gaucher disease (GD), is associated with abnormal platelet function. Brain-derived neurotrophic factor (BDNF) is a protein with neuroprotective potential stored in alpha granules of circulating platelets. Here we studied BDNF levels in 50 patients with type I GD (GD1) and their correlation with platelet activity and bleeding tendency. Flow cytometry was used to test unstimulated and stimulated measurement of platelet surface-activated expression of αIIbβ3 integrin, P-selectin and lysosomal-associated membrane protein (LAMP3/CD63). Serum and plasma BDNF levels were quantified using ELISA. The bleeding history was recorded by a bleeding questionnaire. Serum BDNF levels were positively correlated with platelet count and moderately correlated with unstimulated and stimulated platelet P-selectin expression. Patients with more than one bleeding manifestation were shown to have lower serum BDNF levels, albeit similar platelet count. Plasma BDNF levels were significantly elevated in splenectomized patients and showed a moderate positive correlation with stimulated platelet CD63 expression. These observations demonstrate the first association between BDNF levels in the peripheral blood with platelet dysfunction and increased bleeding manifestation. The role of measuring serum BDNF for assessing platelet alpha degranulation defects and bleeding risk in patients with GD and the general population needs further study.

Cancer-associated coagulation disorders

Diagnosis and treatment of paraneoplastic coagulation disorders are achallenge in daily practice. While prophylactic anticoagulation to prevent venous thromboembolism (VTE) is standard of care in all surgical and acutely ill medical cancer patients, particularly careful evaluation of risks and benefits using validated risk assessment models is required during outpatient chemotherapy. Low-molecular-weight heparin and direct oral factor Xa inhibitors are available to treat established cancer-associated VTE, adhering to algorithms for bleeding risk stratification. In patients with overt disseminated intravascular coagulation, therapeutic measures should strictly follow clinical symptoms. An acquired von Willebrand syndrome may evoke asevere bleeding tendency in patients with myeloproliferative neoplasms or plasma cell dyscrasias. In 15% of cases, acquired hemophiliaA, due to the formation of inhibitory autoantibodies against coagulation factor VIII, is associated with malignancy.

Reduced platelet forces underlie impaired hemostasis in mouse models of MYH9-related disease.

MYH9-related disease patients with mutations in the contractile protein nonmuscle myosin heavy chain IIA display, among others, macrothrombocytopenia and a mild-to-moderate bleeding tendency. In this study, we used three mouse lines, each with one point mutation in the Myh9 gene at positions 702, 1424, or 1841, to investigate mechanisms underlying the increased bleeding risk. Agonist-induced activation of Myh9 mutant platelets was comparable to controls. However, myosin light chain phosphorylation after activation was reduced in mutant platelets, which displayed altered biophysical characteristics and generated lower adhesion, interaction, and traction forces. Treatment with tranexamic acid restored clot retraction in the presence of tPA and reduced bleeding. We verified our findings from the mutant mice with platelets from patients with the respective mutation. These data suggest that reduced platelet forces lead to an increased bleeding tendency in patients with MYH9-related disease, and treatment with tranexamic acid can improve the hemostatic function.

Global hemostatic profiling in patients with decompensated cirrhosis and bacterial infections

Background & AimsBacterial infections in cirrhosis are associated with increased bleeding risk. To assess the factors responsible for bleeding tendency in patients with bacterial infections, we conducted a prospective study comparing all 3 aspects of hemostasis (platelets, coagulation, and fibrinolysis) in hospitalized patients with decompensated cirrhosis with vs. without bacterial infections.MethodsPrimary hemostasis assessment included whole blood platelet aggregation and von Willebrand factor (VWF). Coagulation assessment included procoagulant factors (fibrinogen, factor II, V, VII, VIII, IX, X, XI, XII, XIII), natural anticoagulants (protein C, protein S, antithrombin) and thrombomodulin-modified thrombin generation test. Fibrinolysis assessment included fibrinolytic factors (plasminogen, t-PA, PAI-1, α2-AP, TAFIa/ai) and plasmin-antiplasmin complex (PAP).ResultsEighty patients with decompensated cirrhosis were included (40 with and 40 without bacterial infections). Severity of cirrhosis and platelet count were comparable between groups. At baseline, patients with cirrhosis and bacterial infections had significantly lower whole blood platelet aggregation, without significant differences in VWF. Regarding coagulation, bacterial infections were associated with reduced procoagulant factors VII and XII, and a significant reduction of all natural anticoagulants. However, thrombomodulin-modified thrombin generation was comparable between the study groups. Finally, although mixed potentially hypo-fibrinolytic (lower plasminogen) and hyper-fibrinolytic (higher t-PA) changes were present in bacterial infections, a comparable level of PAP was detected in both groups. Upon resolution of infection (n = 29/40), platelet aggregation further deteriorated whereas coagulation and fibrinolysis factors returned to levels observed in patients without bacterial infections.ConclusionIn hospitalized patients with decompensated cirrhosis, bacterial infections are associated with reduced whole blood platelet aggregation and a significant decrease of all natural anticoagulants, which may unbalance hemostasis and potentially increase the risk of both bleeding and thrombosis.Lay summaryBacterial infections are a common issue in hospitalized patients with decompensated cirrhosis (i.e. patients hospitalized due to severe complications of advanced chronic liver disease). Patients with decompensated cirrhosis who acquire infections may be at increased risk of bleeding complications following invasive procedures (that is a procedure in which the body is penetrated or entered, for instance by a needle or a tube). As bleeding complications in decompensated cirrhosis are associated with a high risk of further decompensation and death, there is an urgent need to understand the factors responsible for such increased bleeding tendency. Herein, we investigated the alterations of hemostasis (that is the physiological process responsible for clot formation and stability) in patients with decompensated cirrhosis and bacterial infections. We found that development of bacterial infections in these patients is associated with alterations of hemostasis (particularly of platelets and clotting cascade) that may increase the risk of both bleeding and thrombotic complications.

Delayed Plasma Clot Lysis in Adult Patients with Primary Immune Thrombocytopenia (ITP)

Introduction: Primary immune thrombocytopenia (ITP) is an orphan disease characterized by very low platelet counts. Patients have heterogeneous bleeding phenotypes, which are not only determined by platelet counts, also a paradoxically increased thrombotic risk has been observed.Aim: To investigate, whether the fibrinolysis inhibitors plasminogen activator inhibitor-1 (PAI-1) and α2-antiplasmin are associated with impaired plasma clot lysis in primary ITP patients in comparison to non-immunologic thrombocytopenic controls (TPC) and healthy controls (HC). Furthermore, associations with bleeding severity and previous thrombotic events were investigated.Methods: Patients from the Vienna ITP biobank (EC 1843/2016), a multi-centric study including adult patients with primary ITP were investigated and compared to age- and sex-matched control groups: TPC with thrombocytopenia after chemotherapy and HC. Informed consent was obtained from all individuals before study inclusion. A clot formation and lysis assay (CLA) was performed according to the recommendations of the ISTH SSC. Platelet poor plasma samples were measured in duplicates for each patient and control. PAI-1 (PAI-1 Actibind ELISA, Technoclone, Vienna, Austria) and α2-antiplasmin by the chromogenic STA Stachrom antiplasmin assay (Diagnostic Stago, Asnieres, France) were measured. Bleeding severity was measured using the ITP-specific ITP-ISTH BAT (Rodeghiero et al. 2013).Results: In total, 37 primary ITP patients, 18 TPC and 156 healthy controls were analyzed (Table 1). Primary ITP patients had a higher BMI than HC. Bleeding severity was higher and more ITP patients had a thrombosis history compared to HC, whereas there was no difference in comparison to TPC. PAI-1 activity was highest in ITP patients, with a statistically significant difference in comparison to HC. α2-antiplasmin activity was higher in ITP patients than in TPC, whereas there was no difference in comparison to HC.After adjustment for sex, age, BMI and fibrinogen, primary ITP patients had a reduced clot formation rate (V max) and significantly delayed plasma clot lysis compared to TPC and HC (Table 2). Also, the lag phase and time to peak absorbance (TTP) were prolonged with a significant difference in comparison to HC.To investigate outliers of PAI-1 and α2-antiplasmin, we calculated cut-offs at the 75 th percentile of healthy controls (PAI-1: ≥ 3.1 U/mL, α2-antiplasmin: ≥ 107.0 %). 14 (37.8 %) ITP patients had PAI-1 levels and 10 (27.0 %) ITP patients had α2-antiplasmin activity above the cut-off. ITP patients with high PAI-1 levels had mildly delayed clot lysis in comparison to those below with a significantly lower maximal lysis rate (mLR). ITP patients with α2-antiplasmin activity above the cut-off had a significantly shorter lag phase, faster V max and shorter TTP than patients below the cut-off, whereas there was no difference in clot lysis. No differences between ITP patients above or below the respective cut-offs of PAI-1 and α2-antiplasmin regarding their bleeding severity and thrombosis incidence were observed (Table 3).Conclusion: Primary ITP patients have a tendency towards increased PAI-1 activity, which is associated with considerably delayed plasma clot lysis. Albeit an association with the bleeding score could not be identified, this impaired lysis could be seen as a counter-regulation and at least contribute to the relatively mild bleeding tendency in patients with ITP. [Display omitted] DisclosuresPabinger: CSL Behring: Consultancy, Honoraria, Research Funding; NovoNordisk: Consultancy, Research Funding; Bayer: Consultancy, Honoraria; Takeda: Consultancy, Honoraria; Daiichi Sanchyo: Consultancy, Honoraria; Alexion: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria.

Ablation of collagen VI leads to the release of platelets with altered function

AbstractHemostatic abnormalities and impaired platelet function have been described in patients affected by connective tissue disorders. We observed a moderate bleeding tendency in patients affected by collagen VI–related disorders and investigated the defects in platelet functionality, whose mechanisms are unknown. We demonstrated that megakaryocytes express collagen VI that is involved in the regulation of functional platelet production. By exploiting a collagen VI–null mouse model (Col6a1−/−), we found that collagen VI–null platelets display significantly increased susceptibility to activation and intracellular calcium signaling. Col6a1−/− megakaryocytes and platelets showed increased expression of stromal interaction molecule 1 (STIM1) and ORAI1, the components of store-operated calcium entry (SOCE), and activation of the mammalian target of rapamycin (mTOR) signaling pathway. In vivo mTOR inhibition by rapamycin reduced STIM1 and ORAI1 expression and calcium flows, resulting in a normalization of platelet susceptibility to activation. These defects were cell autonomous, because transplantation of lineage-negative bone marrow cells from Col6a1−/− mice into lethally irradiated wild-type animals showed the same alteration in SOCE and platelet activation seen in Col6a1−/− mice. Peripheral blood platelets of patients affected by collagen VI–related diseases, Bethlem myopathy and Ullrich congenital muscular dystrophy, displayed increased expression of STIM1 and ORAI1 and were more prone to activation. Altogether, these data demonstrate the importance of collagen VI in the production of functional platelets by megakaryocytes in mouse models and in collagen VI–related diseases.

Assessing bleeding risk in 18 children with Osteogenesis imperfecta

Assessing bleeding risk in 18 children with <i>Osteogenesis imperfecta</i>

A case-control study indicates that coagulation imbalance is associated with arteriosclerosis and markers of endothelial dysfunction in kidney failure

Endothelial dysfunction, one of many causes of arterial changes in end-stage kidney disease (kidney failure), is a likely link between early vascular aging and the risk of thrombosis or bleeding in this condition. To evaluate this, we compared links between arterial stiffness and endothelial/coagulation factors in 55 patients receiving hemodialysis therapy and 57 age-/sex-matched control individuals. Arterial stiffness was assessed from carotid-femoral pulse wave velocity, and coagulation status from the endogenous thrombin generating potential. Markers of endothelial dysfunction (von Willebrand factor, tissue factor pathway inhibitor), neutrophil extracellular traps and tissue factor-positive extracellular vesicles were higher in patients with kidney failure. Prothrombin fragments 1 and 2, and D-dimer markers of invivo coagulation activation were also higher. However, invitro in the presence of platelets, endogenous thrombin generating potential was lower and its downregulation by activated protein C impaired. Antiplatelet drugs did not affect these parameters. In multiple regression analysis, prothrombin fragments 1 and 2, D-dimer, factor VIII and monocyte-derived tissue factor-positive extracellular vesicles correlated with higher carotid-femoral pulse wave velocity. In patients with kidney failure, invivo hypercoagulability occurred with reduced thrombin generation in platelet-rich plasma, likely explaining the opposing thrombotic and bleeding tendencies in patients with kidney failure. Importantly, arteriosclerosis is more closely related to a prothrombotic state. Thus, coagulation changes plus arterial stiffness highlight a major therapeutic challenge for anticoagulant and antiplatelet drug use.

Characterization of missense mutations in the signal peptide and propeptide of FIX in hemophilia B by a cell-based assay

AbstractMany mutations in the signal peptide and propeptide of factor IX (FIX) cause hemophilia B. A FIX variants database reports 28 unique missense mutations in these regions that lead to FIX deficiency, but the underlying mechanism is known only for the mutations on R43 that interfere with propeptide cleavage. It remains unclear how other mutations result in FIX deficiency and why patients carrying the same mutation have different bleeding tendencies. Here, we modify a cell-based reporter assay to characterize the missense mutations in the signal peptide and propeptide of FIX. The results show that the level of secreted conformation-specific reporter (SCSR), which has a functional γ-carboxyglutamate (Gla) domain of FIX, decreases significantly in most mutations. The decreased SCSR level is consistent with FIX deficiency in hemophilia B patients. Moreover, we find that the decrease in the SCSR level is caused by several distinct mechanisms, including interfering with cotranslational translocation into the endoplasmic reticulum, protein secretion, γ-carboxylation of the Gla domain, and cleavage of the signal peptide or propeptide. Importantly, our results also show that the SCSR levels of most signal peptide and propeptide mutations increase with vitamin K concentration, suggesting that the heterogeneity of bleeding tendencies may be related to vitamin K levels in the body. Thus, oral administration of vitamin K may alleviate the severity of bleeding tendencies in patients with missense mutations in the FIX signal peptide and propeptide regions.

Congenital platelet disorders and health status–related quality of life

BackgroundPatients with congenital blood platelet disorders (CPDs) demonstrate a predominantly mucocutaneous bleeding tendency. Repeated bleeds throughout life can have a significant impact on health status–related quality of life (HR‐QoL), but few studies have investigated HR‐QoL in patients with CPDs. ObjectivesTo determine HR‐QoL in patients with suspected or confirmed CPDs as compared with the general Dutch population and to assess the association between bleeding phenotype and HR‐QoL. MethodsData were derived from the Thrombocytopathy in the Netherlands (TiN) study, a cross‐sectional study of individuals suspected for a congenital platelet defect. TiN patients with an increased ISTH Bleeding Assessment Tool (ISTH‐BAT) score (>3 in men and > 5 in women) were included for analysis. HR‐QoL was assessed with the Short Form (SF)‐36 survey. Bleeding symptoms were evaluated with the ISTH‐BAT, resulting in a bleeding score. ResultsOne hundred fifty‐six patients were analyzed, of whom 126 (81%) were women. Sixty‐two patients (40%) had a confirmed CPD. Compared to the general Dutch population, patients with a suspected or confirmed CPD reported decreased physical functioning, limitations in daily activities due to physical health problems, limitations in social activities, decreased energy levels and fatigue, pain, and lower general health status. HR‐QoL was not correlated with the ISTH‐BAT score and was similar in patients with a confirmed CPD and those in whom a CPD could not be diagnosed. ConclusionA bleeding tendency in patients with a suspected or confirmed CPD significantly impacts HR‐QoL, independent of a confirmed explanatory diagnosis.

Recombinant Human Thrombopoietin Increases Platelet Numbers and Reduces the Risk of Bleeding Events in Thrombocytopenic Patients with Chronic Hepatitis B Virus Infection: A Multicenter Observational Study

Introduction Hepatitis B virus (HBV) is a widespread virus that severely affects people's health, especially in China. HBV has infected over 400 million people worldwide (Liaw YF et al, Lancet, 2009), of which 93 million are Chinese (Hou J.L. et al, 2015). People infected with hepatitis B virus may develop chronic HBV infection, leading to a high risk of liver cirrhosis or hepatocellular carcinoma. Thrombocytopenia can be observed in patients with chronic HBV infection, especially in patients with liver cirrhosis. Thrombocytopenia plays a key role in thrombin generation and possibly bleeding tendencies in patients with chronic HBV infection. Those patients are at a higher risk of bleeding comparing to the patients without thrombocytopenia, which may lead to a higher mortality. However, its pathogenesis is considered to be complicated and remains poorly understood. Currently, there are not many effective treatments for chronic HBV infection patients with concomitant thrombocytopenia. Moreover, due to the invasiveness of procedures or inadequate effectiveness, the current treatments still have limited applications. Recombinant human thrombopoietin (rh-TPO) can promote megakaryocyte development and platelet production, resulting in an elevation in platelet counts both in vitro and in vivo, though there is still no information available for its effect in chronic HBV infection patients with concomitant thrombocytopenia.Methods The aim of the study is to explore the effectiveness and safety of rh-TPO in the treatment of thrombocytopenia in patients with chronic HBV infection. This was a multicenter, observational study conducted in China between January 2003 and May 2018. Patients with chronic HBV infection (defined as seropositive for HBV surface antigen (HBsAg) for more than 6 months and/or had serum HBV DNA levels greater than 500 copies/ml) accompanied with thrombocytopenia (defined as a platelet count of <100 000 per cubic millimeter) were enrolled and divided into 2 groups by the occurrence of liver cirrhosis. Each patient received nucleoside analog (NA) alone treatment, or NA plus prednisone or NA plus rh-TPO treatment. Platelet counts, occurrence of bleeding events and adverse events were evaluated before and after treatment.Results Through our research, we have noticed that among patients with chronic HBV infection associated thrombocytopenia, patients with liver cirrhosis had significantly lower platelet counts compared to those without liver cirrhosis, especially in cirrhotic patients with splenomegaly. After treatment, patients treated with NA plus prednisone and patients treated with NA plus rh-TPO had significantly higher platelet count elevations than those treated with NA alone, respectively. Chronic HBV infection patients with liver cirrhosis reacted superior to both prednisone and rh-TPO treatment compared to patients without liver cirrhosis, especially in those without splenomegaly. During the observations before and after treatment, fewer bleeding events were observed in patients treated with rh-TPO or prednisone, compared to the NA alone group. No severe bleeding events occurred during the treatment. 22 variables considered relevant to the presence of bleeding events were tested using univariate analysis. The platelet counts, prothrombin time (PT), prothrombin activity (PTA) and methods of treatment were significantly associated with bleeding events. The platelet counts, and methods of treatment were risk factors associated with bleeding events in multivariate analysis. The adverse events among patients receiving different methods of treatment were mild and balanced. Liver function and HBV replication were not worsened after treatment. No severe adverse events were observed during the treatment with rh-TPO, and no patients stopped treatment due to adverse events during the observation.Conclusion Treatment with rh-TPO could elevate the platelet counts and reduce the risk of bleeding events in chronic HBV infection patients with thrombocytopenia. The treatment with rh-TPO was more effective in patients with liver cirrhosis, especially in those without splenomegaly. No severe adverse events were observed during rh-TPO treatment, proving the safety of rh-TPO in the use of treatment in chronic HBV infection associated thrombocytopenia. DisclosuresNo relevant conflicts of interest to declare.

Abnormal plasma clot formation and fibrinolysis reveal bleeding tendency in patients with partial factor XI deficiency

AbstractIndividuals with factor XI (FXI) deficiency have a variable bleeding risk that cannot be predicted from plasma FXI antigen or activity. This limitation can result in under- or overtreatment of patients and risk of bleeding or thrombosis. Previously, plasma clot fibrinolysis assays showed sensitivity to bleeding tendency in a small cohort of patients with severe FXI deficiency. Here, we determined the ability of plasma clot formation, structure, and fibrinolysis assays to predict bleeding tendency in a larger, independent cohort of patients with severe and partial FXI deficiency. Patients were characterized as nonbleeders or bleeders based on bleeding after tonsillectomy and/or dental extraction before diagnosis of FXI deficiency. Blood was collected in the absence or presence of the contact pathway inhibitor corn trypsin inhibitor (CTI). Clotting was triggered in platelet-poor plasma with tissue factor, CaCl2, and phospholipids in the absence and presence of thrombomodulin or tissue plasminogen activator. Clot formation and fibrinolysis were assessed by turbidity and confocal microscopy. CTI-treated plasmas from bleeders showed significantly reduced clot formation and decreased resistance to fibrinolysis compared with plasmas from controls or nonbleeders. Differences were enhanced in the presence of CTI. A model that combines activated partial thromboplastin time with the rate of clot formation and area under the curve in fibrinolysis assays identifies most FXI-deficient bleeders. These results show assays with CTI-treated platelet-poor plasma reveal clotting and clot stability deficiencies that are highly associated with bleeding tendency. Turbidity-based fibrinolysis assays may have clinical utility for predicting bleeding risk in patients with severe or partial FXI deficiency.

SAT-444 - Heparin like effect increases risk of mortality and bleeding tendency in patients with severe alcoholic hepatitis during systemic Inflammatory Response (SIRS) and sepsis

SAT-444 - Heparin like effect increases risk of mortality and bleeding tendency in patients with severe alcoholic hepatitis during systemic Inflammatory Response (SIRS) and sepsis

Analysis of mean platelet volume and red blood cell distribution width in recurrent epistaxis

ObjectivesRecurrent epistaxis is one of the most common causes of emergency department visits. Although several localized and systemic conditions has been described, the exact cause is unknown in the majority of cases. In our study, we aimed to determine the effect of mean platelet volume (MPV) and red blood cell distribution width (RDW) levels on recurrent epistaxis. MethodOne hundred and thirty six patients with recurrent epistaxis and 170 healthy cases as control group were included in the study. Demographic data, vital signs and the results of complete blood counts were recorded. The patients who had clinical conditions that might affect the levels of MPV or RDW, were excluded. MPV and RDW levels were compared between the two groups. ResultsThe median level of MPV was 7.6 fL (IQR25–75%: 7.1–8.4) in the study group and 8.2 fL (IQR25–75%: 7.8–8.9) in the control group (p < 0.001). The median levels of RDW were found in the patient and control groups in order %15.4 (IQR25–75%: 14.5–15.4) and %14.3 (IQR25–75%: 13.4–15.4) (p < 0.001). Systolic blood pressure, leukocyte count, age, sex, RDW and MPV levels that were variables with p levels<0.2, were included in the multivariate analyses. It was determined that high RDW levels increased epistaxis (p < 0.001; OR:1.89 [95% CI:1.53–2.33]) and high MPV levels decreased epistaxis (p < 0.001; OR:0.54 [95% CI:0.39–0.72]). ConclusionLow MPV and high RDW levels caused an increased bleeding tendency in patients with recurrent epistaxis. Although exact mechanism is not known, referring those patients for the assessment of etiologic causes would be proper.

Acquired Von Willebrand syndrome in patients on long-term support with HeartMate II.

Impaired binding of Von Willebrand factor (VWF) to platelets and to collagen due to acquired Von Willebrand syndrome (AVWS) is associated with support from a ventricular assist device (VAD) and can contribute to bleeding tendencies in patients with VADs. The onset of AVWS has been shown to occur immediately after VAD implantation. Our aim was to determine long-term data on AVWS in VAD patients. We analysed 278 data sets of 74 patients on HeartMate II (HMII) support for 3-80 months after implantation (11.2 ± 12.1, median 6.3 months.). Ristocetin cofactor activity (VWF:RCo), collagen binding capacity (VWF:CB), VWF antigen (VWF:Ag) and the ratios of VWF:RCo/VWF:Ag and VWF:CB/VWF:Ag were determined. Further, the presence of high molecular weight (HMW) multimers of VWF was investigated. Abnormally low values of VWF:RCo/VWF:Ag and VWF:CB/VWF:Ag were found in 69% and 97% of blood samples, respectively. Only ten of 181 multimer analyses showed a normal pattern, and HMW multimers were present in both specimens in only one of the 74 patients. No significant changes in these parameters were observed over time. The VWF:CB/VWF:Ag ratio correlated with the multimer patterns, whereas the VWF:RCo/VWF:Ag ratio seemed to be less sensitive for AVWS. Our data indicate that AVWS is a typical phenomenon in patients with VAD support and that there are no time-dependent changes in these parameters apparent in most patients on long-term support with HMII.

The impact of thrombin generation and rotation thromboelastometry on assessment of severity of factor XI deficiency

The phenotype of bleeding in patients with severe FXI deficiency is unpredictable and unlike other bleeding disorders, it is not directly correlated with levels of FXI. In this study we analyzed whether the global coagulation assays can serve as a clinical tool in predicting bleeding tendency in patients with severe FXI deficiency undergoing surgery, taking into account the large inter-individual variability of FXI levels and genotypes. Thrombin generation (TG) was measured in 39 platelet-poor plasma with or without tissue factor (TF) and in the presence or absence of corn trypsin inhibitor (CTI). Rotation thromboelastometry (ROTEM) was performed with fresh whole blood of 26 patients applying NATEM and INTEM tests. TG induced by recalcification can distinguish between bleeding and non-bleeding patients with severe FXI deficiency particularly among those with FXI activity of 2–20IU/dl. The addition of TF or TF and CTI to the TG assay masked the ability to differentiate between XI activity, genotype as well as bleeding and non-bleeding patients. ROTEM assays failed to distinguish bleeding from non-bleeding patients but could do so between different FXI activity levels and genotypes. In conclusion, in the current study we found a sensitive tool to distinguish between bleeding and non-bleeding patients. In order to recommend TG as a predictive tool for treatment tailoring, a larger patient group is required.

Molecular analysis of patients with severe congenital factor X deficiency: First report from north and northwest of Iran.

Background Congenital FX deficiency is an extremely rare autosomal recessive disorder, mostly present in regions with a high rate of consanguinity, with an incidence of approximately 1:2,000,000 in the general population. The aim of this study was to evaluate the clinical manifestations and to provide a molecular analysis of 14 patients with homozygous factor X deficiency. Methods We evaluated the results of clinical and molecular characterization of 14 new cases (10 males, 4 females aged from 4 to 17 years) of FXD (FX activity <1%) in North and Northwest of Iran. FXD was diagnosed by clinical findings and routine laboratory tests. The PCR products of all the eight exons and their intron-exon boundaries were sequenced using DNA sequencer. Results Mean age of patients and mean age at diagnosis were 9 and 2.5 years, respectively. The molecular analysis revealed five different mutations, all of them were previously described. Molecular analysis showed five different homozygous and double heterozygous mutations including Arg-1Thr, Cys81Tyr, Gly78Asp, IVS1+3, and IVS2-3. Discussion The study of a large population of factor X patients from three institutions indicated that FXD was one of the most serious among rare bleeding disorders and that factor X gene mutation may be related to bleeding tendency in patients.

Thromboelastograph With Platelet MappingTM Predicts Postoperative Chest Tube Drainage in Patients Undergoing Coronary Artery Bypass Grafting

The goal of this study was to evaluate the ability of Thromboelastograph with Platelet Mapping (TEG-PM(TM)) to predict postoperative bleeding tendency in patients with a history of recent anti-platelet therapy undergoing coronary artery bypass grafting (CABG). A retrospective analysis. Association between predictor variables (MAADP [maximum amplitude produced by adenosine diphosphate], MAAA [maximum amplitude produced by arachidonic acid], percent of platelets inhibited by clopidogrel, percent of platelets inhibited by aspirin) and the outcomes as elevated chest tube drainage (CTD) and blood transfusion were investigated by logistic regression model. CTD was considered elevated if it was ≥ 600 mL within 12 hours after surgery. A university hospital. Patients on antiplatelet therapy scheduled to undergo CABG that had TEG-PM(TM) done as a point-of-care test. None. A total of 78 patients had preoperative TEG-PM(TM) test and on-pump CABG surgeries performed on the same day. Among them, 20 patients (25.6%) had elevated CTD. Decreased MAADP (odds ratio [OR] 0.94), increased percent inhibition of platelets by clopidogrel (OR 1.03), and lower body mass index (BMI) (OR 0.78) were significantly associated with elevated CTD. The same parameters were also associated with platelets transfusion: MAADP (OR 0.94), percent of inhibition of platelets by clopidogrel (OR 1.03) and BMI (OR 0.77). TEG-PM(TM) parameters and BMI are predictive of elevated CTD and platelets transfusion. A 1 mm decrease in MAADP increases the likelihood of elevated CTD and the likelihood of platelets transfusion by 6% whereas 1 unit decrease in BMI is associated with an increased likelihood of elevated CTD and platelets transfusion by 22% and 23% respectively.