Venous thromboembolism: a clinical review

Emergency medicine residents' learning curve in diagnosing deep vein thrombosis with 3-point venous point-of-care ultrasound

BACKGROUND

Many cases of deep vein thrombosis (DVT) are diagnosed in the emergency department, and abbreviated lower extremity venous point-of-care ultrasound (POCUS) has already shown an accuracy comparable to that of specialists. This study aimed to identify the learning curve necessary for emergency medicine (EM) residents to achieve expertise-level accuracy in diagnosing DVT through a 3-point lower extremity venous POCUS.

METHODS

This prospective study was conducted at an emergency department between May 2021 and October 2022. Four EM residents underwent a one-hour POCUS training session and performed DVT assessments in participants with DVT symptoms or confirmed pulmonary embolism. POCUS was performed at three proximal lower extremity sites to evaluate the thrombi presence and vein compressibility, with results validated by specialized radiology ultrasound. Cumulative sum (CUSUM) and the Bush and Mosteller models were used to analyze the learning curve, while generalized estimating equations were used to identify factors affecting diagnostic accuracy.

RESULTS

91 POCUS scans were conducted in 49 patients, resulting in 22% DVT confirmed by specialized venous ultrasound. In the CUSUM analysis, all four EM residents attained a 90% success rate at the common femoral vein, whereas only half achieved this rate when all three sites were considered. According to Bush and Mosteller models, 13-18 cases are required to attain 90-95% diagnostic accuracy. After 10-16 cases, the examination time for each resident decreased, and a 20% increase in examiner confidence was linked to a 2.506-fold increase in the DVT diagnosis accuracy.

CONCLUSION

EM residents generally required 13-18 cases for 90-95% DVT diagnostic accuracy, but proficiency varied among individuals, particularly requiring more cases for regions outside the common femoral vein.

Synthesis of pyrrolo[3,2-d]pyrimidineone derivatives as novel FXa inhibitors

A series of pyrrolo[3,2-d]pyrimidineone compounds have been designed and synthesized as novel FXa inhibitors. Bioassay of the tested compounds showed moderate to excellent anticoagulant potency in vitro. Further FXa inhibitory and bioactivity evaluation in rats, the FeCl₃-induced venous thrombosis model, showed that the compound 17a has good FXa inhibitory activity (IC₅₀ = 1.57 nM) and in vivo antithrombotic potency. The anticoagulant effects of compound 17a were dose dependent whether in vitro or in vivo. The results further confirmed our hypothesis that the large conjugated structure is an ideal skeleton binding FXa.

HD, Sarma P, Srikanth L, V. SK. Thrombophilic risk factors and ABO blood group profile for arteriovenous access failure in end stage kidney disease patients: a single-center experience

INTRODUCTION

Thrombosis of fistula occurs most frequently in end-stage kidney disease (ESKD) patients receiving hemodialysis. However, the role of thrombophilia in arteriovenous fistula (AVF) failure has not been well established. Hence, this study was aimed at assessing the roles of hereditary and acquired thrombophilic factors in association with AVF failure among patients with ESKD undergoing hemodialysis.

METHODS

A cross-sectional study was conducted on 100 ESKD patients, of whom 50 patients with well-functioning AVFs with no fistula failures earlier were enrolled as Group 1, and 50 patients who have had AVF failure were enrolled as Group 2. The hereditary factors as factor V Leiden, factor XIII, prothrombin, and methylene tetrahydrofolate reductase and the acquired factors as lipoprotein (a), fibrinogen, homocysteine, and anticardiolipin antibodies IgG and IgM were studied.

RESULTS

Among the hereditary factors, no statistically significant difference was observed in relation to factor V Leiden and Prothrombin (p > 0.05). However, for factor XIII and methylene tetrahydrofolate reductase, a statistically significant difference was observed between patients with well-functioning AVFs and patients who have had AVF failure (p < 0.05). We found a statistically significant increase in all the acquired factors in patients who have had AVF failure in comparison with patients with well-functioning AVFs (p < 0.001). Association between ABO blood groups and thrombophilic factors showed significant association between factor V Leiden, anticardiolipin antibody IgG and IgM and ABO blood groups (p < 0.05), whereas none of the other thrombophilic factors showed significant association (p > 0.05).

CONCLUSION

Thus, our study suggests significant role of acquired factors in causing AVF failure.

Chitosan/Alginate Nanoparticles for the Enhanced Oral Antithrombotic Activity of Clam Heparinoid from the Clam Coelomactra antiquata

Chitosan/alginate nanoparticles (DG1-NPs and DG1/Cur-NPs) aiming to enhance the oral antithrombotic activity of clam heparinoid DG1 were prepared by ionotropic pre-gelation. The influence of parameters, such as the concentration of sodium alginate (SA), chitosan (CTS), CaCl2, clam heparinoid DG1, and curcumin (Cur), on the characteristics of the nanoparticles, were investigated. Results indicate that chitosan and alginate can be used as polymer matrices to encapsulate DG1, and nanoparticle characteristics depend on the preparation parameters. Nano-particles should be prepared using 0.6 mg/mL SA, 0.33 mg/mL CaCl2, 0.6 mg/mL CTS, 7.2 mg/mL DG1, and 0.24 mg/mL Cur under vigorous stirring to produce DG1-NPS and DG1/Cur-NPS with small size, high encapsulation efficiency, high loading capacity, and negative zeta potential from approximately −20 to 30 mV. Data from scanning electron microscopy, Fourier-transform infrared spectrometry, and differential scanning calorimetry analyses showed no chemical reaction between DG1, Cur, and the polymers; only physical mixing. Moreover, the drug was loaded in the amorphous phase within the nanoparticle matrix. In the acute pulmonary embolism murine model, DG1-NPs enhanced the oral antithrombotic activity of DG1, but DG1/Cur-NPs did not exhibit higher antithrombotic activity than DG1-NPs. Therefore, the chitosan/alginate nanoparticles enhanced the oral antithrombotic activity of DG1, but curcumin did not further enhance this effect.

Clinical characteristics and outcomes of patients with isolated pulmonary embolism

The clinical relevance of concomitant deep vein thrombosis (DVT) in patients with pulmonary embolism remains controversial. The aim of the present study was to assess clinical characteristics of patients with isolated pulmonary embolism, thereby investigating isolated pulmonary embolism related clinical factors. Patients hospitalized for pulmonary embolism who underwent DVT workup within 3 days of pulmonary embolism diagnosis were retrospectively classified into two groups: patients with isolated pulmonary embolism and patients with DVT-associated pulmonary embolism (DVT-PE). The clinical, laboratorial and radiological parameters were compared between the two groups. Of 1012 patients, 322 (31.8%) presented with isolated pulmonary embolism, and 690 (68.2%) presented with DVT-PE. In a multivariate analysis, female sex was an independent factor for predicting isolated pulmonary embolism [odds ratio (OR) 1.69, 95% confidence interval (CI) 1.26-2.26, P < 0.001], whereas cancer (OR 0.64, 95% CI 0.43-0.96, P = 0.031), leg pain or swelling (OR 0.08, 95% CI 0.04-0.18, P < 0.001), and central pulmonary embolism (OR 0.44, 95% CI 0.32-0.59, P < 0.001) were negatively associated with isolated pulmonary embolism. There were no significant differences between the two groups with regard to risk stratification and short-term prognosis of pulmonary embolism, including adverse outcomes and pulmonary embolism related in-hospital mortality. Of pulmonary embolism patients who underwent imaging tests for DVT, approximately 32% presented with isolated pulmonary embolism. Isolated pulmonary embolism was positively associated with female sex, whereas it was negatively associated with cancer, leg pain or swelling, and central pulmonary embolism. The presence or absence of concomitant DVT did not influence the severity and short-term prognosis of pulmonary embolism.

A Brief Review of Cardiovascular Diseases, Associated Risk Factors and Current Treatment Regimes

Cardiovascular diseases (CVDs) are the leading cause of premature death and disability in humans and their incidence is on the rise globally. Given their substantial contribution towards the escalating costs of health care, CVDs also generate a high socio-economic burden in the general population. The underlying pathogenesis and progression associated with nearly all CVDs are predominantly of atherosclerotic origin that leads to the development of coronary artery disease, cerebrovascular disease, venous thromboembolism and, peripheral vascular disease, subsequently causing myocardial infarction, cardiac arrhythmias or stroke. The aetiological risk factors leading to the onset of CVDs are well recognized and include hyperlipidaemia, hypertension, diabetes, obesity, smoking and, lack of physical activity. They collectively represent more than 90% of the CVD risks in all epidemiological studies. Despite high fatality rate of CVDs, the identification and careful prevention of the underlying risk factors can significantly reduce the global epidemic of CVDs. Beside making favorable lifestyle modifications, primary regimes for the prevention and treatment of CVDs include lipid-lowering drugs, antihypertensives, antiplatelet and anticoagulation therapies. Despite their effectiveness, significant gaps in the treatment of CVDs remain. In this review, we discuss the epidemiology and pathology of the major CVDs that are prevalent globally. We also determine the contribution of well-recognized risk factors towards the development of CVDs and the prevention strategies. In the end, therapies for the control and treatment of CVDs are discussed.

Thrombophilic risk factors in hemodialysis: Association with early vascular access occlusion and patient survival in long-term follow-up

Objective

Thrombophilic risk factors (TRFs) occur rather frequently in hemodialysis (HD) patients. However, little is known about their significance in HD patients, besides their potential impact on arteriovenous (AV) access failure, with varying results. We examined the effects of a wide variety of TRFs on both early AV fistula occlusion and survival among HD patients in long-term follow-up.

Methods

In this single-center, observational study, 70 consecutive HD patients from our dialysis center were examined with respect to shunt occlusion within the first 2 years after fistula creation and patient survival in a long-term follow-up (at least 16 years). We examined the presence of factor V, prothrombin, and MTHFR mutations using real-time fluorescence polymerase chain reaction. Furthermore, antithrombin (AT), protein C, protein S, and antiphospholipid antibodies (APL-Abs) were assessed.

Results

Among the 70 patients, 32 had MTHFR mutations, 10 had heterozygous factor V Leiden mutations, 4 had prothrombin mutations, 4 had protein S deficiency, 2 had protein C deficiency, 9 had AT deficiency, and 14 had APL-Abs. 40 patients had shunt occlusion. TRFs were associated with a significantly increased risk for shunt thrombosis (P<0.02). Kaplan–Meier analysis with a log-rank test revealed significantly shorter survival in HD patients with TRFs (P<0.02). Cox regression analysis showed that the presence of TRFs (P<0.05; hazard ratio, 1.94; 95% CI: 1.07–3.56), but not early shunt occlusion, was associated with short patient survival.

Conclusions

TRFs in hemodialysis patients have a strong impact on patient survival and early AV fistula failure; however, patient survival is not significantly affected by early shunt occlusion.

Comparison of the Accuracy of Emergency Department-Performed Point-of-Care-Ultrasound (POCUS) in the Diagnosis of Lower-Extremity Deep Vein Thrombosis

BACKGROUND

Compression ultrasonography is the most effective diagnostic tool in the emergency department (ED) for the diagnosis of deep vein thrombosis (DVT). It has been demonstrated to be highly accurate and cost-effective.

OBJECTIVE

The objective of this study was to determine the accuracy of emergency physicians who performed three-point compression ultrasound (US) for suspected above-knee DVT within the context of using Wells score and D-dimer.

METHOD

This was a prospective diagnostic test assessment of three-point ultrasound conducted in a district general hospital of patients who presented to the ED with suspected DVT of the lower limb. The accuracy of three-point ultrasound carried out by the emergency physicians was assessed by comparison of the Doppler ultrasound carried out by the Radiology Department as reference standard. The study incorporated ultrasound alongside the Wells score and D-dimer.

RESULTS

A total of 109 patients (66.1%) had a three-point compression point-of-care ultrasound in the ED and a second ultrasound performed by the Radiology Department. Bedside three-point compression ultrasound of the lower extremity performed by physicians in the ED had a sensitivity of 93.2% (95% confidence interval [CI] 83.8-97.3%) and a specificity of 90.0% (95% CI 78.6-95.7%), with an accuracy of 91.7% (95% CI 85-95.6%).

CONCLUSIONS

Emergency physicians can obtain a level of competence equivalent to that of radiologists, but it requires substantial training and practice to achieve and maintain this performance. Providers should be aware of their limitations and maintain regular training with ultrasound applications.

Synthesis of 3,4-diaminobenzoyl derivatives as factor Xa inhibitors

The coagulation factor Xa (FXa) plays a central role in the blood coagulation cascade. Recent studies have shown that FXa is a particularly attractive target for the development of oral antithrombotic agents. In view of the excellent pharmaceutical properties of 1,2-phenylenediamine-based FXa inhibitors and the reported structure-activity relationship (SAR) analysis of FXa inhibitors, we designed and synthesized a series of 3,4-diaminobenzoyl-based FXa inhibitors. Intensive SAR studies on this new series led to the discovery of 3,4-dimethoxyl substituted compound 7b. 7b is a highly potent, selective, direct FXa inhibitor with excellent in vivo antithrombotic activity.

Primary Nephrotic Syndrome in Adults as a Risk Factor for Pulmonary Embolism: An Up-to-Date Review of the Literature

Patients with nephrotic syndrome are at an increased risk for thrombotic events; deep venous thrombosis, renal vein thrombosis, and pulmonary embolism are quite common in patients with nephrotic syndrome. It is important to note that nephrotic syndrome secondary to membranous nephropathy may impose a greater thrombotic risk for unclear reasons. Increased platelet activation, enhanced red blood cell aggregation, and an imbalance between procoagulant and anticoagulant factors are thought to underlie the excessive thrombotic risk in patients with nephrotic syndrome. The current scientific literature suggests that patients with low serum albumin levels and membranous nephropathy may benefit from primary prophylactic anticoagulation. A thorough approach which includes accounting for all additional thrombotic risk factors is, therefore, essential. Patient counseling regarding the pros and cons of anticoagulation is of paramount importance. Future prospective randomized studies should address the question regarding the utility of primary thromboprophylaxis in patients with nephrotic syndrome.

The effects of obesity on venous thromboembolism: A review

Obesity has emerged as a global health issue that is associated with wide spectrum of disorders, including coronary artery disease, diabetes mellitus, hypertension, stroke, and venous thromboembolism (VTE). VTE is one of the most common vascular disorders in the United States and Europe and is associated with significant mortality. Although the association between obesity and VTE appears to be moderate, obesity can interact with other environmental or genetic factors and pose a significantly greater risk of VTE among individuals who are obese and who are exposed simultaneously to several other risk factors for VTE. Therefore, identification of potential interactions between obesity and certain VTE risk factors might offer some critical points for VTE interventions and thus minimize VTE morbidity and mortality among patients who are obese. However, current obesity measurements have limitations and can introduce contradictory results in the outcome of obesity. To overcome these limitations, this review proposes several future directions and suggests some avenues for prevention of VTE associated with obesity as well.

Intracardiac thrombi in extracardiac disorders: an autopsy study

INTRODUCTION

Intracardiac thrombi (ICT), more commonly encountered at autopsy, are well documented with underlying cardiovascular disease. Occurrence of ICT in systemic diseases without an intrinsic cardiac disorder is rare. The aim of this autopsy study was to highlight such an occurrence.

METHODS

From 1996 to 2010, cases with ICT unrelated to primary cardiac disorders were selected at autopsy and analyzed. Clinical and investigational data were obtained from the medical records. The location, morphology, size, and histological appearance of the thrombi were noted. The thrombi were then classified on the basis of their location, nature, and histology (fresh and/or organized); this was correlated with the clinical setting.

RESULTS

Among a total of 11,724 autopsies performed in 15 years, 276 patients (2.4%) had ICT. Of these, 45 patients (0.4%) had ICT that were unrelated to primary cardiac diseases. There were 25 men and 20 women with a mean age of 46.1 years. Antemortem diagnosis was not made in any of these patients. Eight patients each (35.6%) showed isolated left-sided and multichambered involvement, while the rest of the hearts (64.4%) had thrombi in the right-sided chamber(s). The recognizable risk factors were underlying cancers (24.4%), prolonged immobilization (20%), systemic lupus erythematosus (6.7%), pregnancy (4.4%), nephropathy (4.4%), primary antiphospholipid antibody syndrome (2.2%), and ulcerative colitis (2.2%). However, 16 patients (35.7%) had no obvious predisposing factor, although investigations for prothrombotic markers had not been done. Diabetes mellitus, chronic alcoholism, and deep vein thrombosis of the lower limbs had been clinically documented in some of them. The cause of death in most patients (73.3%) had been related to pulmonary and/or systemic thromboembolism.

CONCLUSIONS

This autopsy study emphasizes the great need for a higher index of suspicion of in situ thrombosis in the heart in hypercoagulable states so as to curtail the morbidity and mortality of the primary disease process.

Emergency Physician Performed Ultrasound for DVT Evaluation

Deep vein thrombosis is a common condition that is often difficult to diagnose and may be lethal when allowed to progress. However, early implementation of treatment substantially improves the disease prognosis. Therefore, care must be taken to both acquire an accurate differential diagnosis for patients with symptoms as well as to screen at-risk asymptomatic individuals. Many diagnostic tools exist to evaluate deep vein thrombosis. Compression ultrasonography is currently the most effective diagnostic tool in the emergency department, shown to be highly accurate at minimal expense. However, limited availability of ultrasound technicians may result in delayed imaging or in a decision not to image low-risk cases. Many studies support emergency physiciansas capable of accurately diagnosing deep vein thrombosis using bedside ultrasound. Further integration of ultrasound into the training of emergency physicians for use in evaluating deep vein thrombosis will improve patient care and cost-effective treatment.

Markers of thrombogenesis are activated in unmedicated patients with acute psychosis: a matched case control study

BACKGROUND

Antipsychotic treatment has been repeatedly found to be associated with an increased risk for venous thromboembolism in schizophrenia. The extent to which the propensity for venous thromboembolism is linked to antipsychotic medication alone or psychosis itself is unclear. The objective of this study was to determine whether markers of thrombogenesis are increased in psychotic patients who have not yet been treated with antipsychotic medication.

METHODS

We investigated the plasma levels of markers indicating activation of coagulation (D-dimers and Factor VIII) and platelets (soluble P-selectin, sP-selectin) in an antipsychotic-naive group of fourteen men and eleven women with acute psychosis (age 29.1 ± 8.3 years, body mass index 23.6 ± 4.7), and twenty-five healthy volunteers were matched for age, gender and body mass index.

RESULTS

D-dimers (median 0.38 versus 0.19 mg/l, mean 1.12 ± 2.38 versus 0.28 ± 0.3 mg/l; P = 0.003) and sP-selectin (median 204.1 versus 112.4 ng/ml, mean 209.9 ± 124 versus 124.1 ± 32; P = 0.0005) plasma levels were significantly increased in the group of patients with acute psychosis as compared with healthy volunteers. We found a trend (median 148% versus 110%, mean 160 ± 72.5 versus 123 ± 62.5; P = 0.062) of increased plasma levels of factor VIII in psychotic patients as compared with healthy volunteers.

CONCLUSIONS

The results suggest that at least a part of venous thromboembolic events in patients with acute psychosis may be induced by pathogenic mechanisms related to psychosis rather than by antipsychotic treatment. Finding an exact cause for venous thromboembolism in psychotic patients is necessary for its effective treatment and prevention.

The dental patient on oral anticoagulant medication: a literature review

Specific diseases and medications may considerably influence the delivery of oral care and the course of dental therapy. The purpose of this literature review is to examine the relationship between oral anticoagulant medication and dental treatment. Electronic and manual searches were conducted for clinical studies in the English literature for the years 1988-2010. The review process provided a total of 110 pertinent literature references, out of which 38 studies dealt with oral anticoagulants and dental treatment. Different treatment strategies relative to dental periprocedural anticoagulation regimens have been identified, and their accompanying thromboembolic and bleeding risks are being presented and discussed. Regarding to what extent a safe and successful dental treatment in patients on anticoagulant medication is feasible, the level of evidence is lacking. Until high-level data are provided, an individualised treatment approach after consultation with the physician of the patient is highly recommended.

Recurrent deep vein thrombosis despite warfarin therapy in a patient with Crohn's disease

Patients with inflammatory bowel disease (IBD) are known to have an increased propensity for thromboembolic events. Like any patient with a high risk of event recurrence, most of these patients can be managed successfully with long-term warfarin therapy. We present the case of a 66-year-old woman with Crohn's disease who, despite careful attention to the management of her international normalized ratio, developed a new deep vein thrombosis and required inferior vena cava filter placement in addition to ongoing warfarin therapy to prevent recurrent pulmonary emboli. This report serves as a reminder to physicians to have a low threshold for diagnosing thromboembolic events in patients with IBD, even if they are presumed to be adequately anticoagulated. Known and theoretical contributing factors to this increased clotting tendency are also reviewed.