Mechanistic View of Risk Factors for Venous Thromboembolism

Risk of Recurrent Venous Thromboembolism After an Initial Episode: Risk Stratification and Implications for Long-term Treatment

PURPOSE OF REVIEW

Venous thromboembolism (VTE) is a common condition with significant associated morbidity and mortality. Recurrent VTE after an initial episode is a preventable medical condition. The following review discusses data supporting recurrence risk estimates after an initial VTE episode as well as treatment strategies to mitigate risk of recurrent VTE.

RECENT FINDINGS

This review particularly highlights methods for stratifying the risk of recurrent VTE and recent studies that have evaluated direct oral anticoagulants for the prevention of recurrent VTE. Risk assessment for VTE recurrence should guide anticoagulation duration. In patients who present with unprovoked VTE events, there remains a high risk of recurrence that is significantly mitigated with extended duration anticoagulation with either a vitamin K antagonist or direct oral anticoagulant.

Targeted sequencing to identify novel genetic risk factors for deep vein thrombosis: a study of 734 genes

Essentials Deep vein thrombosis (DVT) has a large unknown genetic component. We sequenced coding areas of 734 hemostasis-related genes in 899 DVT patients and 599 controls. Variants in F5, FGA-FGG, CYP4V2-KLKB1-F11, and ABO were associated with DVT risk. Associations in KLKB1 and F5 suggest a more complex genetic architecture than previously thought. SUMMARY: Background Although several genetic risk factors for deep vein thrombosis (DVT) are known, almost all related to hemostasis, a large genetic component remains unexplained. Objectives To identify novel genetic determinants by using targeted DNA sequencing. Patients/Methods We included 899 DVT patients and 599 controls from three case-control studies (DVT-Milan, Multiple Environmental and Genetic Assessment of risk factors for venous thrombosis [MEGA], and the Thrombophilia, Hypercoagulability and Environmental Risks in Venous Thromboembolism [THE-VTE] study) for sequencing of the coding regions of 734 genes involved in hemostasis or related pathways. We performed single-variant association tests for common variants (minor allele frequency [MAF] ≥ 1%) and gene-based tests for rare variants (MAF ≤ 1%), accounting for multiple testing by use of the false discovery rate (FDR). Results Sixty-two of 3617 common variants were associated with DVT risk (FDR < 0.10). Most of these mapped to F5,ABO,FGA-FGG, and CYP4V2-KLKB1-F11. The lead variant at F5 was rs6672595 (odds ratio [OR] 1.58, 95% confidence interval [CI] 1.29-1.92), in moderate linkage with the known variant rs4524. Reciprocal conditional analyses suggested that intronic variation might drive this association. We also observed a secondary association at the F11 region: missense KLKB1 variant rs3733402 remained associated conditional on known variants rs2039614 and rs2289252 (OR 1.36, 95% CI 1.10-1.69). Two novel variant associations were observed, in CBS and MASP1, but these were not replicated in the meta-analysis data from the International Network against Thrombosis (INVENT) consortium. There was no support for a burden of rare variants contributing to DVT risk (FDR > 0.2). Conclusions We confirmed associations between DVT and common variants in F5,ABO,FGA-FGG, and CYP4V2-KLKB1-F11, and observed secondary signals in F5 and CYP4V2-KLKB1-F11 that warrant replication and fine-mapping in larger studies.

Cooperative PSGL-1 and CXCR2 signaling in neutrophils promotes deep vein thrombosis in mice

Inflammation is a major contributor to deep vein thrombosis (DVT). Flow restriction of the inferior vena cava (IVC) in mice induces DVT like that in humans. In this model, P-selectin-dependent adhesion of neutrophils and monocytes leads to release of neutrophil extracellular traps (NETs) and expression of tissue factor. However, it is not known what signals cause myeloid cells to generate these procoagulant effectors. Using ultrasonography and spinning-disk intravital microscopy in genetically engineered mice, we found that engagement of P-selectin glycoprotein ligand-1 (PSGL-1) and the chemokine receptor CXCR2 on rolling neutrophils propagated signals that cooperated to induce β2 integrin-dependent arrest in flow-restricted IVCs. Unlike previous reports, PSGL-1 signaling in neutrophils did not require L-selectin, and it used tyrosine 145 rather than tyrosines 112 and 128 on the adaptor Src homology domain-containing leukocyte phosphoprotein of 76 kDa. PSGL-1 and CXCR2 signaling cooperated to increase the frequency and size of thrombi, in part by stimulating release of NETs. Unlike in neutrophils, blocking PSGL-1 or CXCR2 signaling in monocytes did not affect their recruitment into thrombi or their expression of tissue factor. Our results demonstrate that neutrophils cooperatively signal through PSGL-1 and CXCR2 to promote DVT.

Thromboembolic Events After Traumatic Vertebral Fractures: An Analysis of 190,192 Patients

STUDY DESIGN

Retrospective cohort study OBJECTIVE.: To determine the rate of venous thromboembolism event (VTE) and risk factors for their occurrence in patients with vertebral fractures.

SUMMARY OF BACKGROUND DATA

Deep vein thrombosis or pulmonary embolism (VTE) events are a significant source of potentially preventable morbidity and mortality in trauma patients. In patients with traumatic vertebral fractures, a common high-energy injury sometimes resulting in spinal cord injury, there is debate about what factors may be associated with such VTEs.

METHODS

All patients with vertebral fractures in the American College of Surgeons National Trauma Data Bank Research Data Set (NTDB RDS) from years 2011 and 2012 were identified. Multivariate logistic regression was used to determine factors associated with the occurrence of VTE while considering patient factors, injury characteristics, and hospital course.

RESULTS

A total of 190,192 vertebral fractures patients were identified. The overall rate of VTE was 2.5%. In multivariate analysis, longer inpatient length of stay was most associated with increased VTEs with an odds ratio (OR) of up to 96.60 (95% CI: 77.67 - 129.13) for length of stay longer than 28 days (compared to 0 - 3 days). Additional risk factors in order of decreasing odds ratios were older age (OR of up to 1.65 [95% CI: 1.45 - 1.87] for patients age 70 - 79 years [compared to age 18 - 29 years]), complete spinal cord injuries (OR: 1.49 [95% CI: 1.31 - 1.68]), cancer (OR: 1.37 [95% CI: 1.25 - 1.50]), and obesity (OR: 1.32 [95% CI: 1.18 - 1.48]). Multiple associated non-spinal injuries were also associated with increased rates of VTE.

CONCLUSION

While the overall rate of VTE is relatively low after vertebral fractures, longer LOS and other defined factors to lesser extents were predisposing factors. By determining patients at greatest risk, protocols to prevent such adverse outcomes can be developed and optimized.

LEVEL OF EVIDENCE

3.

Prevalence of common hereditary risk factors for thrombophilia in Somalia and identification of a novel Gln544Arg mutation in coagulation factor V

Thrombophilia, commonly manifested as venous thromboembolism (VTE), is a worldwide concern but little is known on its genetic epidemiology in many parts of the globe particularly in the developing countries. Here we employed TaqMan genotyping and pyrosequencing to evaluate the prevalence of known common nucleotide polymorphisms associated with thrombophilia in a Somali population in the Puntland region of Somalia. We also employed next generation sequencing (NGS) to investigate other genetic variants in a Somali patient with deep venous thrombosis (DVT). As expected, we found no existence of factor V Leiden (rs6025) and prothrombin G20210A (rs1799963) in the Somali population. The G allele of ABO [261G/delG] polymorphism (rs8176719) was found at a frequency of 29%, similar to that observed in other African populations. We found the lowest so far reported frequency of MTHFR C677T (rs1801133) polymorphism in the Somali population (T allele frequency 1.5%). A novel and deleterious single nucleotide variation in exon 11 of coagulation factor V (c.1631A>G) causing Gln544Arg exchange in factor V was identified in a 29 years old Somali female with DVT. The same patient was heterozygous to VKORC1 Asp36Tyr polymorphism (rs61742245) that predisposes to warfarin resistance. In conclusion, this study shows that common hereditary factors for thromboembolism found in Caucasians are either less frequent or absent in the Somali population-similar to the situation in other Africans. NGS is possibly a better choice to detect genetic risk variants for thrombosis in this ethnic group.

Temporal trends in venous thromboembolism after radical cystectomy

PURPOSE

To determine whether the rate of venous thromboembolism (VTE) following radical cystectomy (RC) is changing overtime.

MATERIALS AND METHODS

The American College of Surgeons National Surgical Quality Improvement Program database was used to identify patients who underwent RC for bladder cancer from 2011 to 2016. VTE was defined as pulmonary embolism or deep vein thrombosis within 30 days of RC. VTE rate by year was assessed using the Cochran-Armitage test for trend. Associations between patient features and VTE were evaluated with multivariable logistic regression.

RESULTS

A total of 8,241 patients undergoing RC were identified, of whom 348 (4.2%) were diagnosed with VTE. VTE was diagnosed at a median of 13 days (IQR: 7-19) after RC, with 171 (49%) occurring after hospital discharge. Notably, the rate of VTE after RC was found to significantly decrease over time, from 5.1% in 2011 to 2.8% in 2016 (P = 0.001). On multivariable analysis, clinical factors significantly associated with increased odds of VTE included congestive heart failure (odds ratio [OR] = 2.83, P = 0.01), prolonged operative time (OR: 1.48-1.56, P = 0.02-0.01), and receipt of a perioperative blood transfusion (OR = 1.27; P = 0.04). When postoperative complications were adjusted for, sepsis/septic shock (OR = 2.37, P<0.001) and perioperative infection (OR = 1.74, P<0.001) were likewise found to be associated with VTE.

CONCLUSIONS

The rate of VTE after RC significantly decreased in recent years, potentially reflecting improvements in perioperative care. The specific casual factors underlying this trend, in addition to efforts to address identified risk factors for VTE, warrant continued study.

Comparison of the serum metabolic signatures based on 1H NMR between patients and a rat model of deep vein thrombosis

Deep vein thrombosis (DVT) and pulmonary embolism (PE) have high morbidity, reduce quality of life, and can cause death. Biomarkers or genetic risk factors have not been identified in patients with DVT. In present study, serum of 61 patients suffering from DVT and a rat DVT model (n = 10) were assayed by a proton nuclear magnetic resonance (¹H NMR) metabolomics technique combing with multivariate statistical analysis to identify the metabolites. The MetPA platform was used to identify differences in the metabolic pathways between the rat model and patients. The metabolomics results discovered that 11 different metabolites in rats and 20 different metabolites in DVT patients. Seven metabolites both altered in the rats and patients. Moreover, we observed changes in the metabolic pathways, including carbohydrate metabolism, lipid metabolism, and amino acid metabolism that were induced immediately by the thrombosis. Pathway of aminoacyl-tRNA biosynthesis perturbed only in the patients which was associated with the genetic risk factor of DVT. The study demonstrated that serum ¹H NMR metabolomics can be used to diagnose DVT in the clinic. The altered pathways related to thrombosis and genetics will provide a foundation and new strategies for understanding the pathological mechanism and pharmacological targets of DVT.

Platelets Drive Thrombus Propagation in a Hematocrit and Glycoprotein VI-Dependent Manner in an In Vitro Venous Thrombosis Model

OBJECTIVE

The objective of this study was to measure the role of platelets and red blood cells on thrombus propagation in an in vitro model of venous valvular stasis.

APPROACH AND RESULTS

A microfluidic model with dimensional similarity to human venous valves consists of a sinus distal to a sudden expansion, where for sufficiently high Reynolds numbers, 2 countercurrent vortices arise because of flow separation. The primary vortex is defined by the points of flow separation and reattachment. A secondary vortex forms in the deepest recess of the valve pocket characterized by low shear rates. An initial fibrin gel formed within the secondary vortex of a tissue factor-coated valve sinus. Platelets accumulated at the interface of the fibrin gel and the primary vortex. Red blood cells at physiological hematocrits were necessary to provide an adequate flux of platelets to support thrombus growth out of the valve sinus. A subpopulation of platelets that adhered to fibrin expose phosphatidylserine. Platelet-dependent thrombus growth was attenuated by inhibition of glycoprotein VI with a blocking Fab fragment or D-dimer.

CONCLUSIONS

A 3-step process regulated by hemodynamics was necessary for robust thrombus propagation: First, immobilized tissue factor initiates coagulation and fibrin deposition within a low flow niche defined by a secondary vortex in the pocket of a model venous valve. Second, a primary vortex delivers platelets to the fibrin interface in a red blood cell-dependent manner. Third, platelets adhere to fibrin, activate through glycoprotein VI, express phosphatidylserine, and subsequently promote thrombus growth beyond the valve sinus and into the bulk flow.

Venous Thromboembolism-Related Readmission in Emergency General Surgery Patients: A Role for Prophylaxis on Discharge?

BACKGROUND

Patients undergoing emergency general surgery (EGS) operations experience high rates of venous thromboembolism (VTE). The rates at which thrombus formation occurs after discharge, and whether VTE prophylaxis at discharge might be warranted to prevent readmission, are unknown. This analysis aimed to determine risk factors associated with VTE formation after discharge for EGS operations.

STUDY DESIGN

An analysis of the American College of Surgeons NSQIP database from 2013 and 2014 of patients undergoing 10 common EGS operations in an emergent fashion. Multivariable logistic regression modeling was used to determine factors that predicted VTE after discharge.

RESULTS

A total of 130,036 patients were included. The 30-day VTE rate was 1.30%, with 35% of all VTEs occurring after discharge. Of those who had VTE develop after discharge, 69.4% required readmission. Predictive factors for post-discharge VTE included prolonged length of stay (odds ratio [OR] 5.25; p < 0.001), presence of metastatic cancer (OR 2.23; p < 0.001), urinary tract infection (OR 1.91; p < 0.001), and postoperative sepsis (OR 1.55; p < 0.001). Identified high-risk groups had a rate of readmission with thrombus 6 times greater than that of average-risk EGS patients.

CONCLUSIONS

More than 30% of VTEs in the EGS population occur after discharge; of these, a vast majority require readmission. Select high-risk EGS subgroups might benefit from prophylactic anticoagulation at discharge.

Venous Thromboembolism Events After Hip Arthroscopy: A Systematic Review

PURPOSE

The purpose of this systematic literature review focused on hip arthroscopy was to (1) report the venous thromboembolism (VTE) event incidence in patients who receive VTE prophylaxis and those who do not, (2) report how VTE prophylaxis is currently being administered, and (3) report operative and patient-related risk factors for VTE identified in the literature.

METHODS

The electronic databases MEDLINE, Embase, and PubMed were searched from database inception to October 10, 2016, and screened in duplicate for relevant studies. Data were collected regarding VTE prophylaxis, traction use, surgical time, VTE incidence, patient and operative factors, and postoperative weight bearing and rehabilitation. Study quality was assessed in duplicate with the Methodological Index for Non-Randomized Studies criteria.

RESULTS

Outcome analyses included 14 studies that involved 2,850 patients (2,985 hips). The weighted mean follow-up period was 19 ± 8 months, ranging from 7 days to 103 months. The weighted mean age was 40.7 ± 7 years, ranging from 6 to 82 years, and 39.6% of patients were male patients. The overall weighted proportion of VTE events after hip arthroscopy found in 14 included studies was 2.0% (95% confidence interval, 0.01%-4.1%), with 25 VTE events. Several studies reported patient risk factors, which included increased age, increased body mass index, prolonged traction time, and use of oral contraceptives.

CONCLUSIONS

The use and efficacy of VTE prophylaxis are highly under-reported within hip arthroscopy. The low incidence of VTE events found in this review (2.0%) suggests that prophylaxis may not be necessary in low-risk patients undergoing hip arthroscopy; however, the true rate may be under-reported. Current literature suggests that prophylaxis is typically not prescribed. Early mobility and postoperative rehabilitation may also help to further mitigate the risk of VTE events, but use of these strategies needs further prospective evaluation.

LEVEL OF EVIDENCE

Level IV, systematic review of Level II through IV studies.

Genetics in thrombophilia

Venous thromboembolism (VTE) poses a worldwide health burden affecting millions of people each year. The annual incidence of symptomatic VTE, the collective term used here for deep venous thrombosis, pulmonary embolism or both, is 2–3 per thousand inhabitants. The one-year mortality is 20% after a first VTE. Of the surviving patients 15–25% will experience a recurrent episode of VTE in the three years after the first event. Primary and secondary prevention is key to reducing death and disability from VTE. How to make use of our current knowledge of inherited risk of VTE for primary and secondary disease prevention is not straightforward. This despite the fact that in the past two or three decades we have made major strides in enlarging our understanding of inherited VTE risk, and that new inherited risk factors continue to be identified.

For primary prevention of VTE genetic testing is not likely to play a role in the future. Genetic variations also determine recurrence risk, albeit that the effect sizes for individual genetic variations are invariably lower than those for first VTE events. Multilocus genetic risk scores improve risk classification, and it is now possible to stratify patients who have had a first venous thrombosis, into subgroups with a high and low risk of recurrence. Whether this approach can be used to tailor intensity and duration of treatment remains to be established.

Platelets in cancer and thrombosis

Platelets are the smallest circulating blood cells and their major function is the maintenance of haemostasis. They do not have a nucleus, but instead a multitude of granules that contain molecules important for several physiological processes. These granules can be released after platelet activation and thereby platelets take part in haemostasis, wound repair or immunological processes. Furthermore, platelets are also involved in the pathophysiology of several diseases, including cancer. Platelets can support various steps of cancer development and progression by promoting tumour growth, angiogenesis and metastasis. Moreover, platelets contribute to the hypercoagulable state frequently observed in cancer patients, leading to an increased risk of venous thromboembolism (VTE). In previous studies a high platelet count was repeatedly found to be associated with an elevated risk of VTE and a worse prognosis in patients with cancer.

The aim of this review is to give an overview of the most important alterations of platelet physiology in cancer patients and how these alterations may influence cancer disease and contribute to cancer-associated VTE.

Optimization of quantitative proteomic analysis of clots generated from plasma of patients with venous thromboembolism

Background

It is well known that fibrin network binds a large variety of proteins, including inhibitors and activators of fibrinolysis, which may affect clot properties, such as stability and susceptibility to fibrinolysis. Specific plasma clot composition differs between individuals and may change in disease states. However, the plasma clot proteome has not yet been in-depth analyzed, mainly due to technical difficulty related to the presence of a highly abundant protein—fibrinogen and fibrin that forms a plasma clot.

Methods

The aim of our study was to optimize quantitative proteomic analysis of fibrin clots prepared ex vivo from citrated plasma of the peripheral blood drawn from patients with prior venous thromboembolism (VTE). We used a multiple enzyme digestion filter aided sample preparation, a multienzyme digestion (MED) FASP method combined with LC–MS/MS analysis performed on a Proxeon Easy-nLC System coupled to the Q Exactive HF mass spectrometer. We also evaluated the impact of peptide fractionation with pipet-tip strong anion exchange (SAX) method on the obtained results.

Results

Our proteomic approach revealed 476 proteins repeatedly identified in the plasma fibrin clots from patients with VTE including extracellular vesicle-derived proteins, lipoproteins, fibrinolysis inhibitors, and proteins involved in immune responses. The MED FASP method using three different enzymes: LysC, trypsin and chymotrypsin increased the number of identified peptides and proteins and their sequence coverage as compared to a single step digestion. Peptide fractionation with a pipet-tip strong anion exchange (SAX) protocol increased the depth of proteomic analyses, but also extended the time needed for sample analysis with LC–MS/MS.

Conclusions

The MED FASP method combined with a label-free quantification is an excellent proteomic approach for the analysis of fibrin clots prepared ex vivo from citrated plasma of patients with prior VTE.

Electronic supplementary material

The online version of this article (10.1186/s12014-017-9173-x) contains supplementary material, which is available to authorized users.

Economy class syndrome: what is it and who are the individuals at risk?

The term ‘economy class syndrome’ refers to the occurrence of thrombotic events during long-haul flights that mainly occur in passengers in the economy class of the aircraft. This syndrome results from several factors related to the aircraft cabin (immobilization, hypobaric hypoxia and low humidity) and the passenger (body mass index, thrombophilia, oral contraceptives or hormone replacement therapy, cancer), acting together to predispose to excessive blood coagulation, which can result in venous thromboembolism. Several risk factors, both genetic and acquired, are associated with venous thromboembolism. The most important genetic risk factors are natural anticoagulant deficiencies (antithrombin, protein C and protein S), factor V Leiden, prothrombin and fibrinogen gene mutations and non-O blood group individuals. Acquired risk factors include age, pregnancy, surgery, obesity, cancer, hormonal contraceptives and hormone replacement therapy, antiphospholipid syndrome, infections, immobilization and smoking. People who have these risk factors are predisposed to hypercoagulability and are more susceptible to suffer venous thromboembolism during air travel. For these individuals, a suitable outfit for the trip, frequent walks, calf muscle exercises, elastic compression stockings and hydration are important preventive measures. Hence, it is essential to inform about economic class syndrome in an attempt to encourage Brazilian health and transport authorities to adopt measures, in partnership with the pharmaceutical industry, to prevent venous thromboembolism.

Epidemiology and pathophysiology of venous thromboembolism: similarities with atherothrombosis and the role of inflammation

Venous thromboembolism (VTE) is a multifactorial disease. Major provoking factors (e. g. surgery, cancer, major trauma, and immobilisation) are identified in 50–60 % of patients, while the remaining cases are classified as unprovoked. However, minor predisposing conditions may be detectable in these patients, possibly concurring to the pathophysiology of the disease, especially when co-existing. In recent years, the role of chronic inflammatory disorders, infectious diseases and traditional cardiovascular risk factors has been extensively investigated. Inflammation, with its underlying prothrombotic state, could be the potential link between these risk factors, as well as the explanation for the reported association between arterial and venous thromboembolic events.

Whole exome sequencing in thrombophilic pedigrees to identify genetic risk factors for venous thromboembolism

BACKGROUND

Family studies have shown a strong heritability component for venous thromboembolism (VTE), but established genetic risk factors are present in only half of VTE patients.

AIM

To identify genetic risk factors in two large families with unexplained hereditary VTE.

METHODS

We performed whole exome sequencing in 10 affected relatives of two unrelated families with an unexplained tendency for VTE. We prioritized variants shared by all affected relatives from both families, and evaluated these in the remaining affected and unaffected individuals. We prioritized variants based on 3 different filter strategies: variants within candidate genes, rare variants across the exome, and SNPs present in patients with familial VTE and with low frequency in the general population. We used whole exome sequencing data available from 96 unrelated VTE cases with a positive family history of VTE from an affected sib study (the GIFT study) to identify additional carriers and compared the risk-allele frequencies with the general population. Variants found in only one individual were also retained for further analysis. Finally, we assessed the association of these variants with VTE in a population-based case-control study (the MEGA study) with 4,291 cases and 4,866 controls.

RESULTS

Six variants remained as putative disease-risk candidates. These variants are located in 6 genes spread among 3 different loci: 2p21 (PLEKHH2 NM_172069:c.3105T>C, LRPPRC rs372371276, SRBD1 rs34959371), 5q35.2 (UNC5A NM_133369.2:c.1869+23C>A), and 17q25.1 (GPRC5C rs142232982, RAB37 rs556450784). In GIFT, additional carriers were identified only for the variants located in the 2p21 locus. In MEGA, additional carriers for several of these variants were identified in both cases and controls, without a difference in prevalence; no carrier of the UNC5A variant was present.

CONCLUSION

Despite sequencing of several individuals from two thrombophilic families resulting in 6 candidate variants, we were unable to confirm their relevance as novel thrombophilic defects.

Modelling and simulation of flow and agglomeration in deep veins valves using discrete multi physics

The hemodynamics in flexible deep veins valves is modelled by means of discrete multi-physics and an agglomeration algorithm is implemented to account for blood accrual in the flow. Computer simulations of a number of valves typologies are carried out. The results show that the rigidity and the length of the valve leaflets play a crucial role on both mechanical stress and stagnation in the flow. Rigid and short membranes may be inefficient in preventing blood reflux, but reduce the volume of stagnant blood potentially lowering the chances of thrombosis. Additionally, we also show that in venous valves, cell agglomeration is driven by stagnation rather than mechanical stress.

Mast Cells Granular Contents Are Crucial for Deep Vein Thrombosis in Mice

RATIONALE

Deep vein thrombosis (DVT) and its complication pulmonary embolism have high morbidity reducing quality of life and leading to death. Cellular mechanisms of DVT initiation remain poorly understood.

OBJECTIVE

We sought to determine the role of mast cells (MCs) in DVT initiation and validate MCs as a potential target for DVT prevention.

METHODS AND RESULTS

In a mouse model, DVT was induced by partial ligation (stenosis) of the inferior vena cava. We demonstrated that 2 strains of mice deficient for MCs were completely protected from DVT. Adoptive transfer of in vitro differentiated MCs restored thrombosis. MCs were present in the venous wall, and the number of granule-containing MCs decreased with thrombosis. Pharmacological depletion of MCs granules or prevention of MC degranulation also reduced DVT. Basal plasma levels of von Willebrand factor and recruitment of platelets to the inferior vena cava wall after DVT induction were reduced in MC-deficient mice. Stenosis application increased plasma levels of soluble P-selectin in wild-type but not in MC-deficient mice. MC releasate elevated ICAM-1 (intercellular adhesion molecule-1) expression on HUVEC (human umbilical vein endothelial cells) in vitro. Topical application of compound 48/80, an MC secretagogue, or histamine, a Weibel-Palade body secretagogue from MCs, potentiated DVT in wild-type mice, and histamine restored thrombosis in MC-deficient animals.

CONCLUSIONS

MCs exacerbate DVT likely through endothelial activation and Weibel-Palade body release, which is, at least in part, mediated by histamine. Because MCs do not directly contribute to normal hemostasis, they can be considered potential targets for prevention of DVT in humans.

Antisense molecules: A new class of drugs

An improved understanding of disease pathogenesis leads to identification of novel therapeutic targets. From a pharmacologic point of view, these can be addressed by small chemical compounds, so-called biologicals (eg, mAbs and recombinant proteins), or by a rather new class of molecule based on the antisense concept. Recently, a new wave of clinical studies exploring antisense strategies is evolving. In addition to cancer, they include predominantly trials on infectious and noninfectious diseases, such as chronic inflammatory and metabolic conditions. This article, based on a systematic PubMed literature search, highlights recent developments in this emerging field.

The efficacy of forceful ankle and toe exercises to increase venous return: A comprehensive Doppler ultrasound study

Objective Venous stasis is a risk factor for venous thromboembolism. We aimed to determine the efficacy of forceful foot exercises for actuation of the calf muscle pump to counteract stasis. Methods We examined 20 seated healthy subjects. The peak systolic velocity at the level of the popliteal vein was assessed by Doppler ultrasound. Results The mean peak systolic velocity measurements (in cm/s) were as follows: baseline = 5.6; ankle plantar flexion with toe flexion = 91.0; toe touch heel lift = 107.4; ankle dorsiflexion with toe extension = 193.6; isolated flexion of all toes = 118.8; ankle plantarflexion with 100 and 250 Newton forefoot force = 89.9 and 154.5, respectively. Conclusion All exercises achieved significant increases in peak systolic velocity compared to baseline. Ranking showed that forceful ankle dorsiflexion, plantarflexion with 250 Newtons and forceful flexion of all toes yielded the highest mean peak systolic velocity values (193.6, 154.5, and 118.8 cm/s, respectively).

Recent Progress in Research on the Pathogenesis of Pulmonary Thromboembolism: An Old Story with New Perspectives

Pulmonary thromboembolism (PTE) is part of a larger clinicopathological entity, venous thromboembolism. It is also a complex, multifactorial disorder divided into four major disease processes including venous thrombosis, thrombus in transit, acute pulmonary embolism, and pulmonary circulation reconstruction. Even when treated, some patients develop chronic thromboembolic pulmonary hypertension. PTE is also a common fatal type of pulmonary vascular disease worldwide, but earlier studies primarily focused on the pathological changes in the blood component of the disease. With contemporary advances in molecular and cellular biology, people are becoming increasingly aware of coagulation pathways, the function of vascular smooth muscle cells, microparticles, and the inflammatory pathways that play key roles in PTE. Combined hypoxia and immune research has revealed that PTE should be regarded as a class of complex diseases caused by multiple factors involving the vascular microenvironment and vascular cell dysfunction.

The ENTPD1 promoter polymorphism -860 A > G (rs3814159) is associated with increased gene transcription, protein expression, CD39/NTPDase1 enzymatic activity, and thromboembolism risk

Ectonucleoside triphosphate diphosphohydrolase 1 (NTPDase1) degrades the purines ATP and ADP that are key regulators of inflammation and clotting. We hypothesized that NTPDase1 polymorphisms exist and that they regulate this pathway. We sequenced the ENTPD1 gene (encoding NTPDase1) in 216 subjects then assessed genotypes in 2 cohorts comprising 2213 humans to identify ENTPD1 polymorphisms associated with venous thromboembolism (VTE). The G allele of the intron 1 polymorphism rs3176891 was more common in VTE vs. controls (odds ratio 1.26-1.9); it did not affect RNA splicing, but it was in strong linkage disequilibrium with the G allele of the promoter polymorphism rs3814159, which increased transcriptional activity by 8-fold. Oligonucleotides containing the G allele of this promoter region bound nuclear extracts more avidly. Carriers of rs3176891 G had endothelial cells with increased NTPDase1 activity and protein expression, and had platelets with enhanced aggregation. Thus, the G allele of rs3176891 marks a haplotype associated with increased clotting and platelet aggregation attributable to a promoter variant associated with increased transcription, expression, and activity of NTPDase1. We term this gain-of-function phenotype observed with rs3814159 G "CD39 Denver."-Maloney, J. P., Branchford, B. R., Brodsky, G. L., Cosmic, M. S., Calabrese, D. W., Aquilante, C. L., Maloney, K. W., Gonzalez, J. R., Zhang, W., Moreau, K. L., Wiggins, K. L., Smith, N. L., Broeckel, U., Di Paola, J. The ENTPD1 promoter polymorphism -860 A > G (rs3814159) is associated with increased gene transcription, protein expression, CD39/NTPDase1 enzymatic activity, and thromboembolism risk.

A porous sodium polyacrylate-grafted chitosan xerogel for severe hemorrhage control synthesized from one-pot reaction

In this study, we fabricated a SPA-co-CTS sponge and demonstrated a fast and powerful hemostatic effect bothin vitroandin vivo, which was a promising first-aid device for severe hemorrhage control.

Pharmacology of Heparin and Related Drugs

Heparin has been recognized as a valuable anticoagulant and antithrombotic for several decades and is still widely used in clinical practice for a variety of indications. The anticoagulant activity of heparin is mainly attributable to the action of a specific pentasaccharide sequence that acts in concert with antithrombin, a plasma coagulation factor inhibitor. This observation has led to the development of synthetic heparin mimetics for clinical use. However, it is increasingly recognized that heparin has many other pharmacological properties, including but not limited to antiviral, anti-inflammatory, and antimetastatic actions. Many of these activities are independent of its anticoagulant activity, although the mechanisms of these other activities are currently less well defined. Nonetheless, heparin is being exploited for clinical uses beyond anticoagulation and developed for a wide range of clinical disorders. This article provides a "state of the art" review of our current understanding of the pharmacology of heparin and related drugs and an overview of the status of development of such drugs.

Elevated risk of venous thromboembolic events in patients with inflammatory myopathies

Venous thromboembolism (VTE) is a multifactorial disease manifesting as either deep vein thrombosis or pulmonary embolism. Its prevalence makes VTE a significant issue for both the individual – as a negative factor influencing the quality of life and prognosis – and the society due to economic burden. VTE is the third most common vascular disorder in Western countries, after myocardial infarction and stroke, making it a major cause of in-hospital mortality, responsible for 5%–10% of hospital deaths. Despite many studies conducted, only 50%–60% provoking factors have been identified, while the remaining 40%–50% have been classified as idiopathic or unprovoked. Chronic inflammatory disorders, with their underlying prothrombotic state, reveal an increased risk of VTE (six to eight times) compared with the general population. Among the inflammatory disorders, we can identify inflammatory myopathies – a group of rare, chronic diseases featuring weakness and inflammation of muscles with periods of exacerbation and remission; their main classes are polymyositis and dermatomyositis. The objective of this review is to emphasize the need of VTE prophylaxis in individuals with inflammatory myopathies in order to reduce morbidity and mortality rates among those patients and improve their quality of life and prognosis.

Caprini Scores, Risk Stratification, and Rivaroxaban in Plastic Surgery: Time to Reconsider Our Strategy

Limited data are available regarding the pathophysiology of venous thromboembolism in plastic surgery patients. In an effort to identify patients at greater risk, some investigators promote individual risk assessment using Caprini scores. However, these scores do not correlate with relative risk values. Affected patients cannot be reliably predicted (97% false positive rate). Caprini scores make many body contouring patients candidates for chemoprophylaxis, an intervention that introduces risks related to anticoagulation. Caprini has financial conflicts with several companies that manufacture products such as enoxaparin, commonly used for chemoprophylaxis. Rivaroxaban, taken orally, has been used by some plastic surgeons as an alternative to enoxaparin injections. However, this medication is not United States Food and Drug Administration approved for venous thromboembolism prophylaxis in plastic surgery patients, and a reversal agent is unavailable. This article challenges the prevailing wisdom regarding individual risk stratification and chemoprophylaxis. Alternative methods to reduce risk for all patients include safer anesthesia methods and Doppler ultrasound surveillance. Clinical findings alone are unreliable in diagnosing deep venous thromboses. Only by using a reliable diagnostic tool such as Doppler ultrasound are we able to learn more about the natural history of this problem in our patients. Such knowledge is likely to better inform our treatment recommendations.

Association between micro particle-tissue factor activity, factor VIII activity and recurrent VTE in patients with acute pulmonary embolism

Studies on the association between microparticle expressing tissue factor (MP-TF) activity, FVIII activity (FVIII:C) and recurrent VTE yielded inconclusive results. We studied these associations in patients diagnosed with acute pulmonary embolism. Plasma levels of MP-TF and FVIII activity were measured in 277 patients with a first and 72 patients with a recurrent VTE. All patients were categorized based on the quintiles of MP-TF and FVIII activity in those with a single VTE. For both markers, odds ratios (ORs) for recurrent VTE were computed using patients in the lowest quintile as a reference group. No association was observed between MP-TF activity and recurrent VTE, with an OR of 1.4 (95 % CI 0.7–2.9) in the highest quintile of MP-TF activity. Compared with the reference group, patients in the highest quintile of FVIII:C were at increased risk of recurrent VTE, OR 4.2 (95 % CI 1.4–12.2). MP-TF activity was not associated with recurrent VTE whereas high FVIII:C levels were associated with a 4-fold increased risk of VTE recurrence. Future prospective studies are necessary to explore the potential of FVIII:C as a tool for risk stratification, either by itself or in combination with other pro-thrombotic markers.

Pulmonary Embolism Following Outpatient Vasectomy

Venous thromboembolic events have several known major risk factors such as prolonged immobilization or major surgery. Pulmonary embolism has rarely been reported after an outpatient vasectomy was completed. We present the rare case of a healthy 32-year-old Caucasian male with no known risk factors who presented with pleuritic chest pain 26 days after his outpatient vasectomy was performed. Subsequently, he was found to have a pulmonary embolism as per radiological imaging. We explore the association between outpatient vasectomies and venous thromboembolic events. A review of the literature is also included.

Factor XIII A-Subunit V34L Variant Affects Thrombus Cross-Linking in a Murine Model of Thrombosis

OBJECTIVE

Factor XIII (FXIII) cross-links fibrin upon activation by thrombin. Activation involves cleavage at residue 37 by thrombin, releasing an activation peptide. A common polymorphism (valine to leucine variant at residue 34, V34L), located in the activation peptide, has been associated with increased activation rates and paradoxically a protective effect in cardiovascular disease. There is, currently, no data available on the effects of V34L from in vivo models of thrombosis. We examined the effect of FXIII V34L on clot formation and cross-linking in vivo.

APPROACH AND RESULTS

We generated a panel of full-length recombinant human FXIII-A2 variants with amino acid substitutions in the activation peptide to investigate the effect of these variants on activation rate, and we used wild-type, V34L, and alanine to glycine variant at residue 33 variants to study the effects of varying FXIII activation rate on thrombus formation in a murine model of FeCl3 injury. FXIII activation assay showed that residues 29, 30, 33, and 34 play a critical role in thrombin interaction. Full-length recombinant human FXIII-A2 V34L has significant effects on clot formation, structure, and lysis in vitro, using turbidity assay. This variant influenced fibrin cross-linking but not size of the thrombus in vivo.

CONCLUSIONS

Mutations in the activation peptide of full-length recombinant FXIII regulate activation rates by thrombin, and V34L influences in vivo thrombus formation by increased cross-linking of the clot.

Comorbid risks of deep vein thrombosis and pulmonary thromboembolism in patients with chronic pancreatitis: a nationwide cohort study

ESSENTIALS: Risks of deep vein thrombosis (DVT) and pulmonary embolism (PE) in chronic pancreatitis (CP) are unclear. We conducted a nationwide cohort study to evaluate the risks of DVT and PE in CP patients. 17 778 patients with CP and 71 106 without CP were followed for 86 740 and 429 116 person-years, respectively. Patients with CP had a 2.95-fold increased rate of DVT and a 4.51-fold increased rate of PE.

BACKGROUND

Studies on the association between chronic pancreatitis (CP) and cardiovascular diseases are scarce. We conducted a nationwide cohort study to evaluate the risks of deep vein thrombosis (DVT) and pulmonary embolism (PE) in CP patients.

METHODS

Using the data from the Taiwan National Health Insurance Research Database, we randomly selected a non-CP cohort from insurants without a history of CP, and frequency-matched them at a ratio of 4 : 1 according to age, sex and index year with each patient newly diagnosed with CP between 2000 and 2010. The follow-up period ranged from the index date of new CP diagnosis to the diagnosis of DVT or PE, censoring, or the end of 2011. We used univariable and multivariable Cox proportional hazard regression models to determine the risks of DVT and PE.

RESULTS

In total, 17 778 patients in the CP cohort (82.6% men; mean age of 48.6 years) and 71 106 persons in the non-CP cohort were observed for 86 740 and 429 116 person-years, respectively. The CP cohort showed a 2.95-fold greater adjusted hazard ratio (aHR) for DVT (95% confidence interval [CI] 2.06-4.22) and a 4.51-fold greater aHR for PE (95% CI 2.86-7.11) than the non-CP cohort. Substantial risks of DVT and PE were evident in patients with CP aged < 55 years. The CP cohort with comorbidities showed increased risks of DVT and PE as compared with the non-CP cohort with no comorbidities.

CONCLUSIONS

The risks of DVT and PE are significantly higher in CP patients than in the general population.

Multiple sclerosis increases the risk of venous thromboembolism: a nationwide cohort analysis

OBJECTIVES

The purpose of this study was to evaluate the effects of multiple sclerosis (MS) on the risk of venous thromboembolism (VTE) development.

METHODS

We identified patients diagnosed with MS in Taiwan between 1998 and 2010 using the National Health Insurance Research Database and the Catastrophic Illness Patient Database (RCIPD). Each MS patient was frequency matched to 4 controls according to age, sex and the year of MS registration to the RCIPD. Patients with a history of VTE and incomplete information of age and sex were excluded. All patients were followed up from the index year until VTE diagnosis, loss to follow-up or the end of 2010. We calculated the hazard ratios (HRs) and 95% confidence intervals (CIs) of VTE in the MS and comparison cohorts using Cox proportional hazards regression models.

RESULTS

We followed up 1238 MS patients and 4952 comparison patients for approximately 6437 and 27 595 person-years, respectively. After adjusting for age, sex and comorbidities, the MS patients exhibited a 6·87-fold increased risk of VTE compared with the control patients. Women with MS were associated with an 11·1-fold increased risk of VTE development compared with the non-MS women (95% CI: 2·70-45·5). The MS patients aged < 50 years exhibited a 14·8-fold increased risk of developing VTE compared with age-matched patients in the comparison cohort (95% CI: 2·99-73·4). The risk of VTE development increased with the duration of hospitalization stay.

CONCLUSION

MS patients are associated with significantly greater risk of developing VTE compared with non-MS patients.

Prothrombotic genetic risk factors are associated with an increased risk of liver fibrosis in the general population: The Rotterdam Study

BACKGROUND & AIMS

The coagulation system is known to be involved in fibrogenesis in patients with liver disease. We investigated whether common genetic prothrombotic risk factors are associated with an increased risk of fibrosis in the general population.

METHODS

This investigation was part of the Rotterdam Study, an ongoing, population-based cohort study. Liver stiffness (LS) was measured using transient elastography (Fibroscan) and associated with single nucleotide polymorphisms determining blood group type and presence of the Factor V Leiden (FVL) mutation or prothrombin G20210A gene variant.

RESULTS

Reliable LS measurements and genetic data were obtained from 1055 Caucasian participants. LS ⩾8.0 kPa, suggestive of clinically relevant fibrosis, was observed in 101 subjects (9.6%). Presence of FVL or prothrombin G20210A was independently associated with an increased risk of LS ⩾8.0 kPa (OR 2.09, 95%CI 1.07-4.07, p=0.03). Combination of blood group type non-O and the FVL mutation or prothrombin G20210A variant resulted in an even higher risk of LS ⩾8.0 kPa (OR 3.36, 95%CI 1.50-7.56, p=0.003). Presence of the FVL mutation or prothrombin G20210A variant in participants with blood group non-O was associated with a predicted probability of 14.3% (7.7-23.8) of LS ⩾8.0 kPa.

CONCLUSIONS

Participants carrying the FVL mutation or prothrombin G20210A variant have an increased risk of clinically relevant liver fibrosis, which is even higher in blood group type non-O carriers. The fact that genetic prothrombotic risk factors are associated with an increased risk of liver fibrosis suggests that coagulation plays an important role in fibrogenesis in the general population.

Splenectomy is associated with a higher risk for venous thromboembolism: A prospective cohort study

BACKGROUND

Thrombocytosis following splenectomy is a common occurrence. Whether this thrombocytosis leads to a higher risk for venous thromboembolism (VTE) remains unclear. This investigation aimed to determine if splenectomy increases the risk for VTE.

METHODS

This was a prospective study conducted in the SICU between 1/2011 and 11/2013 investigating the VTE risk in patients undergoing a splenectomy compared with those undergoing any other abdominal procedure.

RESULTS

In total 2503 patients were admitted to the SICU: 37 (2%) after a splenectomy and 638 (26%) after any other abdominal surgery. Splenectomy patients had a higher incidence of VTE compared to patients undergoing any other abdominal procedure (29.7% vs. 12.1%, p < 0.01). After adjustment, splenectomy was associated with a higher adjusted risk for VTE compared to the no-splenectomy group (AOR [95% CI]: 2.6 [1.2, 5.9], p = 0.02). Reactive thrombocytosis did not predict the development of VTE.

CONCLUSION

Splenectomy increases the risk for VTE, however reactive thrombocytosis is not associated with this higher incidence. Further investigations are required to characterize the pathophysiologic mechanisms of VTE development following splenectomy.

Introduction to the analysis of next generation sequencing data and its application to venous thromboembolism

Despite knowledge of various inherited risk factors associated with venous thromboembolism (VTE), no definite cause can be found in about 50% of patients. The application of data-driven searches such as GWAS has not been able to identify genetic variants with implications for clinical care, and unexplained heritability remains. In the past years, the development of several so-called next generation sequencing (NGS) platforms is offering the possibility of generating fast, inexpensive and accurate genomic information. However, so far their application to VTE has been very limited. Here we review basic concepts of NGS data analysis and explore the application of NGS technology to VTE. We provide both computational and biological viewpoints to discuss potentials and challenges of NGS-based studies.

The simultaneous occurrence of both hypercoagulability and hypofibrinolysis in blood and serum during systemic inflammation, and the roles of iron and fibrin(ogen)

Although the two phenomena are usually studied separately, we summarise a considerable body of literature to the effect that a great many diseases involve (or are accompanied by) both an increased tendency for blood to clot (hypercoagulability) and the resistance of the clots so formed (hypofibrinolysis) to the typical, 'healthy' or physiological lysis. We concentrate here on the terminal stages of fibrin formation from fibrinogen, as catalysed by thrombin. Hypercoagulability goes hand in hand with inflammation, and is strongly influenced by the fibrinogen concentration (and vice versa); this can be mediated via interleukin-6. Poorly liganded iron is a significant feature of inflammatory diseases, and hypofibrinolysis may change as a result of changes in the structure and morphology of the clot, which may be mimicked in vitro, and may be caused in vivo, by the presence of unliganded iron interacting with fibrin(ogen) during clot formation. Many of these phenomena are probably caused by electrostatic changes in the iron-fibrinogen system, though hydroxyl radical (OH˙) formation can also contribute under both acute and (more especially) chronic conditions. Many substances are known to affect the nature of fibrin polymerised from fibrinogen, such that this might be seen as a kind of bellwether for human or plasma health. Overall, our analysis demonstrates the commonalities underpinning a variety of pathologies as seen in both hypercoagulability and hypofibrinolysis, and offers opportunities for both diagnostics and therapies.

Preoperative thrombocytosis and poor prognostic factors in endometrial cancer

This study aimed to evaluate the prevalence of preoperative thrombocytosis and its prognostic significance in Thai patients with endometrial cancer. We retrospectively reviewed the medical records of 238 cases who had undergone surgical staging procedures between January 2005 and December 2008. Associations between clinicopathological variables and preoperative platelet counts were analyzed using Pearson's chi square or two- tailed Fisher's exact tests. Survival analysis was performed with Kaplan-Meier estimates. Univariate and Cox- regression models were used to evaluate the prognostic impact of various factors including platelet count in terms of disease-free survival and overall survival. The mean preoperative platelet count was 315,437/μL (SD 100,167/ μL). Patients who had advanced stage, adnexal involvement, lymph node metastasis, and positive peritoneal cytology had significantly higher mean preoperative platelet counts when compared with those who had not. We found thrombocytosis (platelet count greater than 400,000/μL) in 18.1% of our patients with endometrial cancer. These had significant higher rates of advanced stage, cervical involvement, adnexal involvement, positive peritoneal cytology, and lymph node involvement than patients with a normal pretreatment platelet count. The 5-year disease-free survival and overall survival were significantly lower in patients who had thrombocytosis compared with those who had not (67.4% vs. 85.1%, p=0.001 and 86.0% vs. 94.9%, p=0.034, respectively). Thrombocytosis was shown to be a prognostic factor in the univariate but not the multivariate analysis. In conclusion, presence of thrombocytosis is not uncommon in endometrial cancer and may reflect unfavorable prognostic factors but its prognostic impact on survival needs to be clarified in further studies.

Diabetes increases the risk of deep-vein thrombosis and pulmonary embolism. A population-based cohort study

We evaluated the effects of diabetes on the risks of developing deep-vein thrombosis (DVT) and pulmonary embolism (PE) in a nationwide, population-based cohort study in Taiwan. The patients with newly diagnosed type 2 diabetes mellitus (T2DM) were identified, and DM-free controls were randomly selected from the general population and frequency-matched according to age, sex, and index year by using the records of the Longitudinal Health Insurance Database between 2000 and 2011. Both cohorts were followed up until the end of 2011 to measure the incidence of DVT and PE. We analysed the risks of DVT and PE using Cox proportional-hazards regression models. The overall incidence of VTE was higher in the T2DM patients than in the controls (12.0 vs 7.51 per 10,000 person-years). The T2DM patients exhibited a 1.44-fold adjusted hazard ratio (aHR) of VTE development compared with the controls (95% confidence interval [CI] = 1.27-1.63). The risks of DVT (aHR = 1.43, 95% CI = 1.23-1.65) and PE (aHR = 1.52, 95% CI = 1.22-1.90) were greater in the T2DM than those in the controls. The T2DM patients had a substantially higher risk of DVT (aHR = 5.10, 95% CI = 3.12-8.32) and PE (aHR = 7.50, 95% CI = 3.29-17.1) development than the controls did in adults aged 49 years and younger. In conclusion, the longitudinal nationwide cohort study indicated that T2DM patients carried greater risks of developing VTE than did the general population.

Ethnic diversity in the genetics of venous thromboembolism

Genetic susceptibility is considered as a crucial factor for the development of venous thromboembolism (VTE). Epidemiologic and genetic studies have revealed clear disparities in the incidence of VTE and the distribution of genetic factors for VTE in populations stratified by ethnicity worldwide. While gain-of-function polymorphisms in the procoagulant genes are common inherited factors in European-origin populations, the most prevalent molecular basis for venous thrombosis in Asians is confirmed to be dysfunctional variants in the anticoagulant genes. With the breakthrough of genomic technologies, a set of novel common alleles and rare mutations associated with VTE have also been identified, in different ethnic groups. Several putative pathways contributing to the pathogenesis of thrombophilia in populations of African-ancestry are largely unknown, as current knowledge of hereditary and acquired risk factors do not fully explain the highest risk of VTE in Black groups. In-depth studies across diverse ethnic populations are needed to unravel the whole genetics of VTE, which will help developing individual risk prediction models and strategies to minimise VTE in all populations.

Study on relationships among deep vein thrombosis, homocysteine & related B group vitamins

Objectives:

Hyperhomocysteinemia has been considered as a potential risk factor for deep venous thrombosis (DVT) but it is still controversy. We aimed to evaluate the prevalence of hyperhomocysteinemia in patients with DVT. Our second objective was to document the prevalence of folate, Vitamin B6, and Vitamin B12 level in this patient population.

Methods:

Sixty patients with DVT aged from 23 to 84 years, were assessed regarding demographic characteristics, serum levels of homocysteine, folate, vitamin B12, and vitamin B6. The diagnosis of DVT was based upon Wells scoring system and serum D-dimer level and confirmed by deep venous Doppler ultrasonography of the lower limbs.

Results:

Mean serum homocysteine levels were found significantly higher in patients over the age of 40 years (10.81±4.26 µmol/L vs 9.13±3.23 µmol/L). Of all the patients, 9 patients had homocysteine level above the 15µmol/L, 26 had folic acid level below 3 ng/ml, one had vitamin B12 level below 150 pmol/L, and two had vitamin B6 level below 30 nmol/L. In the hyperhomocysteinemic group, five patients had low folic acid level, one had low vitamin B12 level, and two had low vitamin B6 level.

Conclusions:

Hyperhomocysteinemia, in women older than 40 years, may be a risk factor for DVT. Folic acid deficiency may also influence serum homocysteine concentrations. Folate therapy may be offered to the patients with DVT. However further studies are required to clarify the underlying molecular mechanisms.

Critical appraisal of dabigatran in the treatment of deep vein thrombosis and pulmonary embolism

OBJECTIVE

To compare the safety and efficacy of dabigatran to warfarin for the treatment of deep vein thrombosis and pulmonary embolism.

BACKGROUND

Venous thromboembolism (VTE) is a disease comprised of two conditions: deep vein thrombosis and pulmonary embolism. VTE is a major cause of morbidity and mortality worldwide with an annual incidence estimated at 1-3 cases per 1,000 individuals. This incidence increases with age from 0.1 per 1,000 in adolescence to eight per 1,000 in those 80 years of age and older. As the proportion of patients 65 years of age and older expands, the number of patients presenting with VTE will also increase. Anticoagulation remains the cornerstone of VTE treatment. Traditionally, vitamin K antagonists have been used to minimize the risk of thrombus extension and for secondary prevention. Unpredictable pharmacokinetics and pharmacodynamics, routine monitoring, drug-food and drug-drug interactions, and potentially severe adverse events have all been cited as barriers to optimal care. Dabigatran has been proposed as a suitable alternative to warfarin therapy in the treatment of VTE. Therefore, a critical appraisal of dabigatran's safety and efficacy is necessary to determine its role in therapy.

CONCLUSION

Dabigatran remains an alternative to warfarin therapy for the treatment of VTE. However, dabigatran also has distinct disadvantages that warrant consideration. Clinicians must ensure that drug characteristics align with patient characteristics to optimize patient outcomes.

Extracellular DNA and histones: double-edged swords in immunothrombosis

The existence of extracellular DNA in human plasma, also known as cell-free DNA (cfDNA), was first described in the 1940s. In recent years, there has been a resurgence of interest in the functional significance of cfDNA, particularly in the context of neutrophil extracellular traps (NETs). cfDNA and histones are key components of NETs that aid in the host response to infection and inflammation. However, cfDNA and histones may also exert harmful effects by triggering coagulation, inflammation, and cell death and by impairing fibrinolysis. In this article, we will review the pathologic nature of cfDNA and histones in macrovascular and microvascular thrombosis, including venous thromboembolism, cancer, sepsis, and trauma. We will also discuss the prognostic value of cfDNA and histones in these disease states. Understanding the molecular and cellular pathways regulated by cfDNA and histones may provide novel insights to prevent pathological thrombus formation and vascular occlusion.