Cause Of Venous Thromboembolism Research Articles

Venous anomalies: an underrecognized but important cause of venous thromboembolism

AbstractAnatomical variants, such as May-Thurner syndrome (MTS) and inferior vena cava (IVC) variants, are underrecognized causes of deep venous thrombosis (DVT), despite affecting management. We aimed to identify the proportion of anatomical variants in proximal lower limb DVT. A retrospective cohort study was performed with cases of acute proximal DVT from 2014 to 2021 identified from ICD-10 codes. We identified 4731 DVTs and included 1268 proximal DVTs. Thirty-six (2.84%) had an anatomical variant (25 MTS and 11 IVC variants), with a rate of 14.39% in females <50 years old. Compared with nonvariant DVTs, they were more likely to be unprovoked (81% vs 23%), younger (median age, 37 vs 63 years), female (67% vs 37%), and have postthrombotic syndrome (22% vs 9%). Variants frequently received thrombolysis (58% vs 1%) or angioplasty (47% vs 0%) and indefinite anticoagulation (83% vs 40%). Further investigation for variants should be considered for high-risk patients, as variants affect management.

Bioinformatics and Machine Learning-Based Identification of Critical Biomarkers and Immune Infiltration in Venous Thromboembolism.

Objective: This study aims to use bioinformatics and machine learning algorithms to screen and analyze the key genes involved in venous thromboembolism (VTE) and explore the relationship between these biomarkers and immune cell infiltration. Methods: The gene expression profile with the identifier GSE19151 was downloaded from the GEO database. Differential expression analysis using the limma package was conducted to identify genes that were differentially expressed between VTE and normal samples. Biological activities of these genes were then investigated through GO analysis utilizing the R language package. KEGG and GSEA were also performed to identify key signaling pathways. Furthermore, machine learning techniques were employed to determine hub gene signatures related to VTE, and ROC curves were used to validate the findings. To compare the immune infiltration of healthy and VTE samples, single sample gene set enrichment analysis (ssGSEA) was applied. Lastly, the Spearman correlation coefficient was used to assess the relationship between the expression of hub genes and immune cell infiltration. Results: A total of 628 differentially expressed genes (DEGs) were discovered between the VTE samples and normal samples. GO analysis identified protein polyubiquitination, lysosomal lumen acidification, organellar ribosome, mitochondrial ribosome, ammonium transmembrane transporter activity, and immunoglobulin binding as the processes with the highest abundance of DEGs. KEGG pathway analysis revealed that DEGs were enriched in ribosome, COVID-19, viral infection, oxidative phosphorylation, Parkinson's disease, nonalcoholic fatty liver disease, apoptosis, and cancer. The most prominent KEGG pathways associated with VTE were ribosome, Parkinson's disease, oxidative phosphorylation, Alzheimer's disease, and Huntington's disease according to GSEA findings. DLST and LSP1 were identified as hub gene signatures in VTE by machine learning integrative analysis, and ROC curves confirmed their diagnostic value. Results from ssGSEA indicated a significant difference in the degree of immune cell infiltration between VTE and normal samples, with the expression of DLST and LSP1 positively correlated with the content of some immune cells. The R package, code, and analysis results used in this paper are available on https://github.com/doctorlaby/my-project. Conclusion: Our research is the first to utilize machine learning techniques in identifying DLST and LSP1 as significant biomarkers of VTE. With our findings, we have uncovered new insights into the underlying causes of VTE and potential treatments for affected patients.

Episodic Cocaine Use as a Cause of Venous Thromboembolism and Acute Liver Injury.

BACKGROUND Pulmonary embolism secondary to deep vein thrombosis (DVT) with cor pulmonale is commonly associated with risk factors including surgery, cancer, and prolonged immobility. Cocaine is known to cause vasoconstriction and has a prothrombotic effect. Prolonged and heavy use of cocaine can also cause inflammation and liver damage. However, data on its potential role in causing pulmonary embolism and direct hepatotoxicity in cases of episodic use are scarce. CASE REPORT A 34-year-old man with no significant medical history except for episodic cocaine use presented in respiratory distress. Workup revealed submassive pulmonary embolism with pulmonary infarctions complicated by pneumonia, hypoxemic respiratory failure, and anemia. He was treated with anticoagulation and intensive care. On day 5 of hospitalization, the patient had an acute hepatic injury. His alanine aminotransferase level peaked at over 2000 IU/L on day 7, until finally tapering. Liver failure was found to be secondary to cocaine use. Liver enzyme levels improved with supportive care. He was discharged with apixaban and continued liver enzyme monitoring. CONCLUSIONS When investigating the cause of venous thromboembolism and transaminitis, evaluating cocaine use via patient history or laboratory analysis of cocaine and its metabolites should be considered. Cocaine is known to cause vasoconstriction and has a prothrombotic effect, although data on its potential role in causing pulmonary embolism and direct hepatotoxicity in cases of episodic use are scarce. Further investigation, such as cohort studies, could help strengthen our understanding of the relationship between cocaine use, acute hepatic injury, and pulmonary embolism.

Antithrombin, Protein C, and Protein S: Genome and Transcriptome-Wide Association Studies Identify 7 Novel Loci Regulating Plasma Levels.

Antithrombin, PC (protein C), and PS (protein S) are circulating natural anticoagulant proteins that regulate hemostasis and of which partial deficiencies are causes of venous thromboembolism. Previous genetic association studies involving antithrombin, PC, and PS were limited by modest sample sizes or by being restricted to candidate genes. In the setting of the Cohorts for Heart and Aging Research in Genomic Epidemiology consortium, we meta-analyzed across ancestries the results from 10 genome-wide association studies of plasma levels of antithrombin, PC, PS free, and PS total. Study participants were of European and African ancestries, and genotype data were imputed to TOPMed, a dense multiancestry reference panel. Each of the 10 studies conducted a genome-wide association studies for each phenotype and summary results were meta-analyzed, stratified by ancestry. Analysis of antithrombin included 25 243 European ancestry and 2688 African ancestry participants, PC analysis included 16 597 European ancestry and 2688 African ancestry participants, PSF and PST analysis included 4113 and 6409 European ancestry participants. We also conducted transcriptome-wide association analyses and multiphenotype analysis to discover additional associations. Novel genome-wide association studies and transcriptome-wide association analyses findings were validated by in vitro functional experiments. Mendelian randomization was performed to assess the causal relationship between these proteins and cardiovascular outcomes. Genome-wide association studies meta-analyses identified 4 newly associated loci: 3 with antithrombin levels (GCKR, BAZ1B, and HP-TXNL4B) and 1 with PS levels (ORM1-ORM2). transcriptome-wide association analyses identified 3 newly associated genes: 1 with antithrombin level (FCGRT), 1 with PC (GOLM2), and 1 with PS (MYL7). In addition, we replicated 7 independent loci reported in previous studies. Functional experiments provided evidence for the involvement of GCKR, SNX17, and HP genes in antithrombin regulation. The use of larger sample sizes, diverse populations, and a denser imputation reference panel allowed the detection of 7 novel genomic loci associated with plasma antithrombin, PC, and PS levels.

Venous Thromboembolism in a Patient with Interrupted Inferior Vena Cava and Compressed Azygos Continuation: A Case Report and Review of Literature.

We report an unusual case of a 40-year-old male patient who experienced painful swelling of the left lower limb that persisted for 1week. Imaging modalities not only confirmed the diagnosis of acute iliofemoral venous thrombosis and pulmonary embolism (PE), but also an incidental finding of interrupted inferior vena cava (IVC). This congenital anomaly is uncommon but rarely associated with venous thromboembolism (VTE). The azygos continuation was compressed by the descending aorta against the 11th thoracic vertebrae, which was identified as the cause of VTE. He was treated successfully with anticoagulation and compression therapy. The patient was discharged with lifelong oral Rivaroxaban and remained asymptomatic. In the literature, only 9 cases of interrupted IVC-associated PE were identified but none was due to significant venous compression.

Characteristics and Outcomes of Cancer Patients With Venous Thromboembolic Events After Treatment With Immune Checkpoint Inhibitors.

This study aimed to describe the clinical characteristics and outcomes of patients with venous thromboembolism (VTE) after Immune checkpoint inhibitors (ICI), focusing on patients with gastrointestinal (GI) immune-related adverse events (irAE). In this retrospective, single-center study, we report the clinical outcomes of adult cancer patients who developed a VTE within 2 years of ICI initiation. Patients were excluded if alternate causes of VTE were present apart from malignancy and cancer therapy. The cohort was classified into those with GI-irAE, non-GI-irAE, and no irAE. A control group with ICI exposure without irAE and VTE was selected for comparative analysis. Of all ICI-treated patients, 1891 (17.2%) were diagnosed with VTE. In all, 501 (4.6%) had no etiology for VTE aside from malignancy and cancer therapy. Of these, 137 patients were included and classified as: 44 GI-irAE, 42 non-GI-irAE, and 51 no irAE. Chemotherapy within 6 months of ICI therapy was associated with increased VTE risk. There was no difference in the clinical course between those exposed to chemotherapy versus ICI therapy alone, time from ICI initiation to VTE, and VTE type, recurrence, or related hospitalization. While there was no difference in VTE-related mortality, the GI-irAE group was associated with lower all-cause mortality and superior overall survival. Combined ICI and chemotherapy use increased VTE risk. There is a similar disease course of VTE after ICI exposure, regardless of other irAEs. Co-existing GI-irAE with VTE is associated with superior overall survival. Prospective studies are needed to evaluate the relationship between ICI therapy and VTE and irAE impact on VTE outcomes.

Measurement of the awareness of venous thromboembolism in the Saudi population.

Venous thromboembolism (VTE) causes significant morbidity and mortality. International studies have suggested poor public awareness of VTE, with a few data from Saudi Arabia. The aim of this study was to investigate the knowledge and awareness of VTE in the Saudi population. Awareness of other important diseases was also investigated to allow contextualization. A cross-sectional survey study was conducted throughout Saudi Arabia from April to June 2021. A nonprobability, purposive, social media-driven, snowballing sampling technique was used to distribute a validated online questionnaire to Saudi adults (aged over 18 years) from the general population. Of 1226 respondents, 214 were excluded as they were health-care professionals. The majority of the participants were unaware and unconcerned about VTE. They were more aware of other medical conditions such as hypertension. Immobility and old age were frequently recognized as risk factors for VTE. While less than half of the participants were aware that thrombosis is the cause of VTE, most participants correctly identified leg pain and tenderness as symptoms of deep venous thrombosis. The majority of the participants identified chest pain and breathlessness as symptoms of pulmonary embolism. However, leg paralysis and slow, shallow breathing were frequently identified as symptoms of VTE. The majority of subjects disagreed with the statement, "having a blood clot is not considered a medical emergency." Awareness of VTE varied significantly with age. In Saudi Arabia, the public awareness of VTE is poor. To improve outcomes, public health initiatives must increase awareness, introduce preventive measures, encourage early diagnosis, and ensure compliance with treatment.

The risk of venous thromboembolism after minor surgical procedures: A population-based case-control study

BackgroundSurgery is a well-known risk factor for venous thromboembolism (VTE). However, for several minor surgical procedures, thromboprophylaxis is not advised. ObjectivesThese “low-risk” procedures include a wide variation of interventions for which we estimated the VTE risk to verify their “low-risk” status. Patients/MethodsWe used data from a large population–based case-control study (Multiple Environment and Genetic Assessment study) into causes of VTE, and linked these to the Dutch Hospital Data Registry to identify exposure to surgical procedures. Logistic regression was used to calculate odds ratios for the 90-day and 1-year relative risks of VTE following these procedures, which were adjusted for body mass index (BMI), sex, age, comorbidities, and infection/inflammation. ResultsWe included 4247 patients with VTE and 5538 control subjects. Median age and BMI were 48.5 years and 25.5 m2/kg, respectively. Nine unique procedures or groups of procedures were analyzed. One hundred twenty-three participants—90 cases and 33 controls—had undergone a minor procedure within 90 days of the index date, resulting in a 3.5-fold (OR, 3.5; 95% CI, 2.3-5.3) overall increased VTE risk. Furthermore, venous stripping (OR, 7.2; 95% CI, 2.4-21.2), open abdominal/inguinal hernia repair (OR, 3.7; 95% CI, 1.2-11.6), and laparoscopic cholecystectomy (OR, 3.2; 95% CI, 1.0-10.6) were associated with an increased risk. Other minor procedures were less strongly or not associated with an increased risk. In the 1-year period before the index date, all odds ratios were lower. ConclusionOf the “low-risk” procedures, we found that venous stripping, open abdominal/inguinal hernia repair, and laparoscopic cholecystectomy were associated with a clearly increased risk of VTE within 90 postoperative days.

Thrombosis in Chronic Kidney Disease in Children.

Venous thromboembolism (VTE) in children is a rare condition. An increased incidence has been observed in the last few years due to several factors, such as increased survival in chronic conditions, especially chronic kidney disease (CKD), use of catheters, and increased sensitivity of diagnostic tools. VTE includes deep vein thrombosis (DVT) and pulmonary embolism (PE). VTE in children is associated with a two to six times higher mortality risk and a 5-10% prevalence of post-thrombotic syndrome. Overall, 5% of VTE episodes in children are associated with chronic kidney disease. The etiology of VTE in chronic kidney disease covers a wide range of pathologies. Various types of thrombotic complications may occur during long-term use of a chronic dialysis catheter. VTE occurs in 3% of children with nephrotic syndrome (NS). The risks for VTE and arterial thromboembolism (ATE) were particularly high in the first 6 months after the onset of NS. Other causes of VTE are graft rejection due to thrombosis of vascular anastomoses after kidney transplantation (3%) and autoimmune diseases (lupus nephritis, antiphospholipid syndrome). In this state-of-the-art overview, we have reviewed the physiologic and pathologic mechanisms underlying pediatric thrombosis and updated current diagnostic and treatment options, emphasizing personal experience as well.

Identification of outcomes in clinical studies of interventions for venous thromboembolism in non‐pregnant adults

Identification of outcomes in clinical studies of interventions for venous thromboembolism in non‐pregnant adults

Prostate Cancer History and Total Hip Arthroplasty: A Matched Cohort Analysis Investigating Venous Thromboembolism and Anticoagulation

BackgroundProstate cancer (PCa) is a common cancer among men in the United States. While malignancy is a known cause of venous thromboembolism (VTE), little is known about the effect of PCa history on postoperative complications after elective total hip arthroplasty (THA). This study aimed to evaluate the risk of hematologic complications in patients with a history of PCa taking common postoperative anticoagulants. MethodsTHA patients were identified through the PearlDiver Mariner database. Patients with a history of PCa were placed in one of the following cohorts based on postoperative anticoagulant prescription: aspirin, warfarin, low-molecular-weight heparin, direct Xa inhibitor, or any anticoagulant. PCa cohorts were matched 1:3 to patients without a history of PCa with the same anticoagulant prescription based on age, gender, and Charlson Comorbidity Index. Postoperative complications were evaluated using multivariable logistic regression. ResultsA total of 74,744 patients that underwent THA were included. PCa patients taking any anticoagulant were found to have increased risk of postoperative deep vein thrombosis (DVT) (odds ratio: 1.25, lower 99% confidence interval: 1.09, upper 99% confidence interval: 1.43, P value <.001). PCa patients taking warfarin, low-molecular-weight heparin, and direct Xa inhibitors additionally showed increased risk of postoperative DVT. Patients taking aspirin did not have an increased risk of postoperative DVT. ConclusionsOur results suggest postoperative aspirin prophylaxis may not increase VTE complication risk when compared to other anticoagulants. Surgeons should be aware that PCa history may be an independent risk factor for VTE, and these patients may benefit from medical optimization.

Microparticles and D-dimers improve prediction of chemotherapy-associated thrombosis in cancer patients

Background: The cancer is associated with a state of hypercoagulability, which may be the cause of venous thromboembolism (VTE), representing an undeniable cause of morbidity and mortality. Our study aimed to investigate the role of hypercoagulability markers (D-dimers, microparticles, and V Leiden mutation) in predicting cancer-associated VTE. Methods: A prospective cohort study was conducted among cancer patients who will receive chemotherapy in the Medical Oncology and Hematology departments of the EHU of Oran, Algeria from February 2013 to May 2015, followed by an observation period of two years. First, we evaluated the risk of cancer-related VTE by hypercoagulability parameters (D-dimers, microparticles, V Leiden mutation). In the second step, we tested the predictive value of the Khorana risk score (KRS) of cancer-related VTE. Then, we developed and tested the predictive value of an expanded score based on the addition of predictive biomarkers to the KRS parameters. Results: A total of 165 patients were included in our study whose median age was 62 years. More than half were males (52.7%). After an observation period of 2 years, ten patients (6.0%) developed a VTE. Among the criteria studied, only the D-dimers and the microparticles were predictive of VTE in cancer. The positive predictive value (PPV) of the KRS was 13.6%, and the negative predictive value (NPV) was 97.9%. After adding two predictive biomarkers (D-dimers and microparticles), the expanded score had a better predictive value with a PPV of 23.5% and a VPN of 98.6%. Conclusion: The addition of hypercoagulability biomarkers (microparticles and D-dimers) to the routine clinical and biological parameters of the KRS enhances the predictive potential of VTE risk in cancer.

Integrated Bioinformatics Analysis Identifies microRNA-200a-5p as a New Plasma Marker in Patients with Venous Thromboembolism

Venous thromboembolism (VTE) is a major global health problem with high incidence and mortality. Vein endothelial cell (VEC) dysfunction is the primary cause of VTE. MicroRNAs (miRNAs) assist in the regulation of VEC functional pathways. Our objective was to identify potential miRNA target genes associated with VTE. To explore the association between mRNAs and miRNAs in VTE, we performed an mRNA or miRNA microarray analysis and experiments invitro. In addition, five online bioinformatics tools identified the target genes of differentially expressed miRNAs, and a miRNA-gene network was constructed. As a result, hub miRNA and mRNA were confirmed. Finally, wound healing assay and transwell migration assay were performed to elucidate the effect of hub miRNA in VEC. Luciferase reporter assay and real-time quantitative polymerase chain reaction (RT-qPCR) were performed to decide the role of miRNA in the expression of hub mRNA. Screening identified eight overlapping dysregulated genes in patients with VTE, three of which demonstrated a significantly decreased expression of miR-200a-5p. Low expression miR-200a-5p in VTE patients is confirmed by a receiver operating characteristic analysis (AUC=0.800, P=0.023) and binary logistic regression (OR=0.359, 95% confidence interval: 0.605-0.995). RT-qPCR results showed that the miR-200a-5p level was decreased in hypoxia VEC (P=0.038). MiR-200a-5p significantly promoted the migration ability of VEC. The result of Dual-luciferase reporter assay showed that cytochrome coxidase Ⅶc (COX7C) directly inhibit the miR-200a-5p expression by binding 5'UTR of miR-200a-5p (P=0.011). We anticipate that the miR-200a-5p-COX7C pair might be involved in the progression of VTE. Moreover, miR-200a-5p might be a therapeutic target for VTE.

A Survey of the Clinical Management of Pediatric Patients with Asymptomatic Central Venous Catheter-Associated Venous Thromboembolism in Saudi Arabia

BACKGROUND: Central venous catheters (CVCs) are the main cause of venous thromboembolism (VTE) in critically ill children. The optimal first-line treatment for children with asymptomatic CVC-related VTE is unknown. Due to a paucity of clinical trials, clinical practice guidelines can offer only weak recommendations for the management of asymptomatic CVC-related VTE. METHODS: This case-based survey was designed to assess the current trends in local management strategies for pediatric patients with an asymptomatic CVC-related thrombosis. The survey focused on the use of the thrombophilia testing, management approach, duration of anticoagulation, and the use of secondary prophylaxis. We hypothesize that there will be significant variation in these four management areas, in the large part due to the aforementioned paucity of available data. REDCap® questions were sent to the members of the Saudi Arabian Pediatric Hematology/Oncology Society clinical forum/email database. We used a hypothetical case scenario to assess management strategies for asymptomatic CVC-related VTE and secondary prophylaxis. RESULTS: Seventy-one (30%) physicians responded to the survey. The majority of the respondents (83.3%) did not use thrombophilia testing. The far majority (95%) treated with anticoagulation. In contrast, the survey respondents varied widely in the duration of anticoagulation and the use of secondary prophylaxis. CONCLUSIONS: Asymptomatic CVC-related VTE is a common clinical entity with limited data guiding management. In Saudi Arabia, there remains considerable variability in the clinical management. These findings will help identify crucial knowledge gaps in the management of asymptomatic CVC-related VTE and facilitate clinical trials that will help establish evidence-based treatment guidelines.

Состояние гемостаза у женщин с ожирением и метаболическим синдромом

To date, obesity is a global epidemic that resulted in increased morbidity and mortality, including those associated with thrombotic conditions. Metabolic syndrome (MS) is characterized by abdominal obesity, glucose metabolism disorders, hypertension, and dyslipidemia. Patients with MS have higher risks of thrombosis and cardiovascular events. Hemostatic disorders in women with obesity and MS are an important clinical issue. Hemostatic abnormalities in these patients (hypercoagulation, hypofibrinolysis, platelet dysfunctions) increase the risk of cardiovascular morbidity and mortality and venous thromboembolism (VTE). Combined oral contraceptives (COCs) increase VTE risk in women with obesity. During pregnancy and postnatal period, obesity is one of the most common causes of VTE. In postmenopause, obesity and MS, and COCs prescribed as menopausal hormone therapy require close attention in controlling hemostatic parameters. This paper reviews significant hemostatic abnormalities in obesity and MS and discusses the role of these conditions in developing hemostatic disorders and VTE in women of reproductive age and postmenopause. KEYWORDS: obesity, metabolic syndrome, hemostasis, combined oral contraceptives, pregnancy, postmenopause, venous thromboembolism. FOR CITATION: Kuzina I.A., Goncharova E.V., Martirosyan N.S. et al. Hemostasis in women with obesity and metabolic syndrome. Russian Medical Inquiry. 2021;5(9):598–604 (in Russ.). DOI: 10.32364/2587-6821-2021-5-9-598-604.

The Current Practice of Management of Asymptomatic Central Venous Catheters Associated Venous Thromboembolism in Children: A Result of Saudi Arabian Pediatric Hematology/Oncology Society Survey

Introduction:Central venous catheters (CVCs) are the main cause of venous thromboembolism (VTE) in critically ill children. The optimal first-line treatment for children with asymptomatic CVC-related VTE is unknown. Due to a paucity of clinical trials, clinical practice guidelines can offer only weak recommendations for the management of asymptomatic CVC- related VTE. This case-based survey was designed to assess current trends in local management strategies for pediatric patients with an asymptomatic CVC- related thrombosis. The survey focused on the use of the thrombophilia testing, management approach, duration of anticoagulation, and the use of secondary prophylaxis. We hypothesize that there will be significant variation in these four management areas, in large part due to the aforementioned paucity of available data. Method:After Institutional Review Board approval, REDCap® questions were sent to members of the Saudi Arabian Pediatric Hematology/Oncology Society (SAPHOS) clinical forum/email database. We used a hypothetical case to assess management strategies for asymptomatic CVC-related VTE and secondary prophylaxis. Result:Seventy-one (30%) physicians responded to the survey. The majority of the respondents (83.3%) did not use thrombophilia testing. 95% treated with anticoagulation, of which 20% treated only if clot propagation was identified on follow-up and 3.3% treated only if a thrombophilia was identified. In contrast, the survey respondents varied widely in the duration of anticoagulation (19% for 6 weeks, 41.4% for 12 weeks, 29.3% until CVC removal). Secondary prophylaxis was used by 20% of the respondents, whereas 21.4% did so, only if there was a previously identified thrombophilia. Conclusion:Asymptomatic CVC-related VTE is a common clinical entity with limited data guiding management. In Saudi Arabia there remains considerable variability in clinical management; particularly, in the duration of treatment and use of secondary prophylaxis. These findings will help identify crucial knowledge gaps in the management of asymptomatic CVC-related VTE and facilitate clinical trials that will help establish evidence-based treatment guidelines. Disclosures No relevant conflicts of interest to declare.

Anticoagulation for Patients with Venous Thromboembolism: When is Extended Treatment Required?

The need for extended venous thromboembolism (VTE) treatment beyond 3 to 6 months is usually determined by balancing the risk of recurrence if treatment is stopped against the risk of bleeding from continuing treatment. The risk of recurrence, and in turn the decision to extend, can be determined through the nature of the index event. Patients with VTE provoked by surgery or trauma (major transient risk factors) are recommended to receive 3 months of anticoagulation therapy because their risk of recurrence is low, whereas patients with VTE provoked by a major persistent risk factor, such as cancer, or those considered to have “unprovoked” VTE, are recommended to receive an extended duration of therapy based on an established high risk of recurrence. Nonetheless, recent evidence and new guidance identify that this approach fails to consider patients with risk factors classed as minor transient (e.g., impaired mobility and pregnancy) or minor persistent (e.g., inflammatory bowel disease and congestive heart disease). Indeed, the risk of recurrence with respect to VTE provoked by minor persistent risk factors has been demonstrated to be not dissimilar to that of VTE without identifiable risk factors. This review provides an overview of the available data on the risk of recurrence according to the underlying cause of VTE, a critical evaluation of evidence from clinical studies on the available anticoagulants for extended VTE treatment, models of risk prediction for recurrent VTE and bleeding, and guidance on how to apply the evidence in practice.

Case of Deep Venous Thrombosis Secondary to May-Thurner Syndrome

May-Thurner syndrome (MTS) remains an underdiagnosed cause of venous thromboembolism (VTE) because most individuals with MTS anatomy are asymptomatic. The most common variant of MTS is due to compression of the left iliac vein between the overlying right common iliac artery and the fifth lumbar vertebrae. Clinical features include chronic venous hypertension that usually presents as lower extremity pain and swelling. Acute VTE almost exclusively affects the left lower extremity. In cases of acute VTE of an unknown etiology, MTS should be considered when other more common pathologies have been ruled out. A 65-year-old African American gentleman with past medical history of hypertension and coronary artery disease presented with left lower extremity pain and swelling of the leg for five days. He had no history of leg trauma, recent surgery, bed rest, travel, malignancy, previous clotting episodes or family history of hypercoagulable disorders. Patient regularly ambulates. He is a lifetime non-smoker and does not take any medication. His left lower extremity was swollen from the calf down to the ankle and foot, tense, erythematous and tender to palpation. Dorsalis pedis and posterior tibial pulses were weakly palpable. Homan’s sign was appreciated while the rest of the physical exam was unremarkable. Duplex ultrasound of the left lower extremity showed thrombi in the left popliteal, posterior tibial and peroneal veins. CT abdomen and pelvis with IV contrast demonstrated significant compression of the left common iliac vein as it crosses posterior to the left internal iliac artery, consistent with MTS. Spiral chest CT was significant for subsegmental emboli in the bilateral lobe pulmonary arteries. Patient was started on anticoagulation, then he was referred to an advanced vascular center to consider the need for angioplasty and stenting and for possible thrombolysis. MTS was first described in 1908 by Virchow, who observed that iliofemoral vein thrombosis was five times more likely to occur in the left leg than in the right leg. May and Thurner discovered an anatomical variant where the right iliac artery compressed the left iliac vein against the fifth lumbar vertebra. Clinicians should have a high index of suspicion for MTS in the presence of unprovoked DVT in the left lower extremity, and/or signs of chronic venous hypertension. Angioplasty and stenting of the affected lesion is the definitive treatment for MTS, while anticoagulation management is similar to patients with provoked VTE. Therefore, it can be argued that in patients with an unexplained cause of VTE, investigation for MTS if clinically suspected can impact management decisions.

Thrombosis in pediatric malignancy: a review and future perspectives with focus on management.

: Venous thromboembolism (VTE) result in significant morbidity and mortality in children with cancer. The cause of VTE in children with cancer is multifactorial and includes genetic predisposition (thrombophilia), disease-related factors, and treatment-related factors including use of central venous catheter (CVC), surgery, and chemotherapy. This review aims to examine current knowledge regarding the incidence, risk factors, clinical manifestation, evaluation, prevention, and management of thromboembolic events in children with cancer.

Occurrence of Venous Thromboembolism in Patients with Lung Cancer and Its Anticoagulant Therapy

目前，肺癌的发病率和死亡率在全世界范围内居首位。静脉血栓栓塞症（venous thromboembolism, VTE）是一种公认的肺癌并发症，也是肺癌患者的主要死因之一。癌症自身因素、患者自身因素以及治疗相关因素都是导致肺癌患者发生VTE的主要原因。肿瘤细胞可产生组织因子（tissue factor, TF）、癌性促凝物质（cancer procoagulant, CP）、炎症因子和细胞因子，从而直接激活凝血；其中TF过度表达是肿瘤患者血栓形成的主要机制之一。2016年美国胸外科医师协会（American College of Chest Physicians, ACCP）发布的第10版肿瘤患者VTE防治指南（AT-10）指出，抗凝治疗是肺癌患者合并VTE的基本治疗措施；其中低分子肝素（low molecular-weight-heparin, LWMH）被认为是首选的抗凝药物，但要注意出血风险。