Management of patients with hereditary hypercoagulable disorders

The natural anticoagulant protein S; hemostatic functions and deficiency

Protein S (PS) is a vital endogenous anticoagulant. It plays a crucial role in regulating coagulation by acting as a cofactor for the activated protein C (APC) and tissue factor pathway inhibitor (TFPI) pathways. Additionally, it possesses direct anticoagulant properties by impeding the intrinsic tenase and prothrombinase complexes. Protein S oversees the coagulation process in both the initiation and propagation stages through these roles. The significance of protein S in regulating blood clotting can be inferred from the significant correlation between deficits in protein S and an elevated susceptibility to venous thrombosis. This is likely because activated protein C and tissue factor pathway inhibitor exhibit low efficacy as anticoagulants when no cofactors exist. The precise biochemical mechanisms underlying the roles of protein S cofactors have yet to be fully elucidated. Nevertheless, recent scientific breakthroughs have significantly enhanced comprehension findings for these functions. The diagnosis of protein S deficiency, both from a technical and genetic standpoint, is still a subject of debate due to the complex structural characteristics of the condition. This paper will provide an in-depth review of the molecular structure of protein S and its hemostatic effects. Furthermore, we shall address the insufficiency of protein S and its methods of diagnosis and treatment.

Impact of thrombophilia on venous thromboembolism management

Hypercoagulable states, also called thrombophilia, can either be congenital or acquired. Congenital thrombophilia, associated mainly with venous thrombosis, is either secondary to coagulation-inhibitor deficiencies, i.e., antithrombin, protein C and Protein S, or gain of function mutations, i.e., factor V Leiden and prothrombin G20210A mutations. Despite the relative frequency of these two mutations, they have not been associated with venous thrombosis recurrence. Most prevalent thrombophilia have a limited impact and usually does not change indications for duration of antithrombotic treatment or prophylaxis compared to decisions based on clinical factors. However, rare inherited thrombophilia such as antithrombin deficiency could justify a long-term anticoagulation. The main acquired thrombophilia, the Antiphospholipid syndrome (APS), is associated with both arterial and venous thrombosis. Its impact on patient management is significant: choice of the anticoagulant (DOAC vs. warfarin), duration of anticoagulation, screening of any organ involvement and systemic autoimmune disease, introduction of immunosuppressive therapy.

Antithrombin diagnostics by mass spectrometry: Development and analytical validation of a next-generation test

Background

Antithrombin deficiency is a rare but severe disorder leading to high risk of thrombosis. The current clinical care pathway relies on activity tests, which only provide overall functional information on the in vitro activity of antithrombin. However, antithrombin exists in many different forms, also known as proteoforms, with varying clinical phenotypes. Precision diagnostics, facilitated by mass spectrometry, provides a strategy to improve patient diagnostics by molecular characterization.

Objectives

To develop and analytically validate a mass spectrometry-based test for molecular characterization of antithrombin.

Methods

The test was analytically validated based on predefined analytical performance specifications. The validation covered imprecision, carryover, linearity, stability, analytical specificity, a provisional reference interval, and an explorative method comparison.

Results

The test passed the predefined analytical performance specifications with a mean within-laboratory imprecision of 5.9%, linearity between 0.08 and 2.58 μmol/L, and a provisional reference interval of 1.07 to 1.49 μmol/L. When measuring samples with a suspected quantitative deficiency, the test showed a good correlation with a commercial activity test (Pearson r = 0.88).

Conclusion

The test passed the validation, and we now envision the use of the test for exploration of the clinical relevance of specific antithrombin proteoforms. Puzzling cases of antithrombin deficiency, for instance, due to ambiguous activity results or an atypical clinical presentation, can be investigated by the LC-MRM mass spectrometry test serving as an add-on to the activity test and providing a molecular diagnosis. Clinical studies are planned to investigate the potential of the test to improve antithrombin diagnostics. Furthermore, the molecular information gained using the test may aid in establishing better risk stratification and a basis for personalized medicine.

Venous Thromboembolic Events are Exceedingly Rare in Spinal Fusion for Adolescent Idiopathic Scoliosis

STUDY DESIGN

Review of health care record database and determination of population statistics.

OBJECTIVE

The purpose of this study was to quantify the incidence of clinically significant venous thromboembolic (VTE) events in patients undergoing spinal fusion surgery for adolescent idiopathic scoliosis (AIS) and to identify risk factors for VTE.

SUMMARY OF BACKGROUND DATA

VTE is a serious complication that can cause disability and even death following surgery. Incidence of VTE following AIS surgery has not been well studied; the use of a national database allows the assessment of rare, yet important complications.

MATERIALS AND METHODS

The PearlDiver Database was used to identify AIS patients who underwent primary instrumented spinal fusion between 2010 and 2020. Patient records were cross-referenced for documented VTEs within 30 and 90 postoperative days. Patients with nonidiopathic scoliosis were excluded. Logistic regression was used to evaluate risk factors for correlation with VTE events.

RESULTS

Thirty-eight of 11,775 (0.323%) patients undergoing surgery for AIS developed a VTE complication within 90 postoperative days. Hypercoagulability [odds ratio (OR)=13.50, P <0.0001], spinal fusion involving 13+ vertebral levels (OR=2.61, P <0.0001), obesity (OR=1.30, P <0.005), and older (15-18 y) compared with younger adolescence (10-14 y) (OR=2.12, P <0.0001) were associated with VTE. Seven of 38 (18.4%) patients with a diagnosed thrombophilia experienced VTE.

CONCLUSIONS

The incidence of clinically significant VTEs in pediatric patients following spinal fusion surgery for AIS is low with an incidence of 0.323%. Postoperative chemoprophylaxis in the general pediatric population is not indicated. Patients with obesity, those undergoing spinal fusion of 13 or more vertebrae, and adolescents 15-18 years old were found to have higher but still small risk of VTE following surgery. Further prospective studies are needed to validate the risk profile of patients with hypercoagulability and establish clinical guidelines for use of postoperative chemoprophylaxis in this cohort.

LEVEL OF EVIDENCE

Level III.

Investigations on 2-(4-Cyanophenylamino) acetic acid by FT-IR,FT-Raman, NMR and UV-Vis spectroscopy, DFT (NBO, HOMO-LUMO, MEP and Fukui function) and molecular docking studies

Extensive quantum chemical calculation have been carried out to investigate the Fourier Transform Infrared(FT-IR), Fourier Transform Raman(FT-RAMAN) and Nuclear magnetic resonance(NMR), and Ultra Violet-Visible(UV-vis) spectra of 2-(4-Cyanophenylamino) acetic acid. The molecular structure, fundamental vibrational frequencies and intensities of the vibrational bands were interpreted with the aid of optimizations and normal coordinate force field calculations based on density functional theory (DFT) and ab initio HF methods with 6–311++G(d,p) basis set. The theoretical vibrational wavenumbers are compared with the experimental values. The calculated HOMO-LUMO energies were found to be-6.2056 eV and -1.2901 eV which indicates the charge transfer within the molecule. Natural bond orbital analysis has been carried out to explain the charge transfer (or) delocalization of charge due to the intra molecular interactions. Molecular Electrostatic Potential (MEP), First order hyperpolarizability, and Fukui functions calculation were also performed. The thermodynamic properties of the title compound were studied for different temperatures. Molecular docking studies were made on the title compound to study the hydrogen bond interactions and the minimum binding energy was calculated.

Management of antithrombin deficiency: an update for clinicians

Introduction. Antithrombin is a serpin that inhibits multiple procoagulant serine proteases and acts as an endogenous anticoagulant. Thus, congenital antithrombin deficiency constitutes a major thrombophilic state, the most severe so far. Areas covered. In the present work, we globally review the biology, genetics, diagnosis, and management of congenital antithrombin deficiency, and also discuss puzzling questions and future perspectives regarding this severe inherited thrombophilia. Expert opinion. Although this disorder exerts high clinical heterogeneity, many carriers will need careful and long-term anticoagulation and/or thromboprophylaxis, especially in high-risk situations, such as surgery and pregnancy. Notably, antithrombin concentrates constitute a considerable arsenal for both treatment and prevention of acute venous thrombosis in subjects with antithrombin deficiency. Current evidences are based almost exclusively on retrospective case series, so an integrated functional, biochemical and molecular characterization will be of clinical relevance and guide hematologists' personalized decisions.

Hypercoagulable States: A Review

Vascular surgeons are often asked to evaluate patients with recurrent thromboses or thromboses in unusual locations either arterial or venous. There may be obvious inciting factors, but in many of these patients the possibility of a previously undiagnosed hypercoagulable state must be considered. Hypercoagulable states can be acquired (smoking, medication, change in physiologic status as occurs with pregnancy) or congenital. Congenital hypercoagulable disorders are more prevalent in families or patients with a history of thromboembolic events early in life or multiple miscarriages and include conditions such as protein C or S deficiencies, factor V Leiden mutation, and prothrombin gene variant. This article reviews the hypercoagulable states that are encountered in clinical practice as well as guidelines for testing and goals of therapy.

Issues in the Diagnosis and Management of Hereditary Antithrombin Deficiency

Objective: To review insights gained in the past several years about hereditary antithrombin (AT) deficiency and to outline approaches to the management of patients with AT deficiency in the acute and chronic settings. Data Sources: An extensive literature search of Scopus (January 2008-April 2016) was performed for the terms congenital antithrombin deficiency, inherited antithrombin deficiency, or hereditary antithrombin deficiency. Additional references were identified by reviewing literature citations. Study Selection: All relevant English-language case reports, reviews, clinical studies, meeting abstracts, and book chapters assessing hereditary AT deficiency were included. Data Synthesis: AT deficiency significantly increases the risk of venous thromboembolism (VTE). The risk of VTE is particularly high during pregnancy, the postpartum period, and following major surgery. Effective clinical management includes determination of the appropriate type and duration of antithrombotic therapy (ie, AT replacement for acute situations) while minimizing the risk of bleeding. For persons newly diagnosed with AT deficiency, age, lifestyle, concurrent medical conditions, family history, and personal treatment preferences can be used to individualize patient management. Patients should be informed of the risks associated with hormonal therapy, pregnancy, surgical procedures, and immobility, which further increase the risk of VTE in patients with AT deficiency. Conclusion: AT deficiency poses the highest risk for VTE among the hereditary thrombophilias, often requiring long-term anticoagulation. Undertaking an evaluation for hereditary thrombophilia is controversial; however, a diagnosis of VTE in association with AT deficiency can have management implications. An important treatment option for patients with this disorder in high-risk situations is AT concentrate.

Vena Caval Filters: A Review for Intensive Care Specialists

Venous thromboembolism (VTE) is a common complication among patients in the intensive care unit. While anticoagulation remains standard therapy, vena caval filters are an important alternative when anticoagulation is contraindicated. To determine the safety and efficacy of vena caval filters in the treatment of VTE, a comprehensive review of the English-language medical literature was performed. Except for one randomized controlled trial, the literature supporting the use of vena caval filters consists almost exclusively of case series, which in many instances are limited by incomplete and short follow-up. While case series suggest that filters function effectively in the prevention of pulmonary embolism (2%-4% symptomatic pulmonary embolism [PE], fatal PE < 2%), recent higher quality studies indicate that filters may not provide significant additional protection to that provided by anticoagulation alone. Furthermore, filters are associated with a 2- fold increase in the incidence of recurrent DVT. Until randomized comparative studies are available, the safety and efficacy of all the available devices should be considered to be roughly equivalent. Since filters do not inhibit continued clot formation, all filter patients should receive anticoagulation for durations appropriate for their thrombotic disorder. Although extended anticoagulation may prevent thrombotic complications associated with filter placement, this strategy has yet to be experimentally tested. While many additional indications for vena caval filter use have been proposed (VTE in cancer patients, PE prophylaxis in trauma patients, etc), well-designed clinical trials demonstrating their efficacy in these situations are lacking. Further development of temporary/retrievable filters, which offer the potential to avoid the long-term complications of permanent filters, should be a research priority. Until additional data are available, vena caval filters should generally be restricted to patients with VTE who cannot receive anticoagulation.

Regulation of thrombosis and vascular function by protein methionine oxidation

Redox biology is fundamental to both normal cellular homeostasis and pathological states associated with excessive oxidative stress. Reactive oxygen species function not only as signaling molecules but also as redox regulators of protein function. In the vascular system, redox reactions help regulate key physiologic responses such as cell adhesion, vasoconstriction, platelet aggregation, angiogenesis, inflammatory gene expression, and apoptosis. During pathologic states, altered redox balance can cause vascular cell dysfunction and affect the equilibrium between procoagulant and anticoagulant systems, contributing to thrombotic vascular disease. This review focuses on the emerging role of a specific reversible redox reaction, protein methionine oxidation, in vascular disease and thrombosis. A growing number of cardiovascular and hemostatic proteins are recognized to undergo reversible methionine oxidation, in which methionine residues are posttranslationally oxidized to methionine sulfoxide. Protein methionine oxidation can be reversed by the action of stereospecific enzymes known as methionine sulfoxide reductases. Calcium/calmodulin-dependent protein kinase II is a prototypical methionine redox sensor that responds to changes in the intracellular redox state via reversible oxidation of tandem methionine residues in its regulatory domain. Several other proteins with oxidation-sensitive methionine residues, including apolipoprotein A-I, thrombomodulin, and von Willebrand factor, may contribute to vascular disease and thrombosis.

The hypercoagulable states in anaesthesia and critical care

Hypercoagulable disorders are now diagnosed more frequently than before. These patients are, usually, managed with multiple anticoagulant and antiplatelet medications. Left unmonitored and unevaluated, there can be disastrous haemorrhagic or thrombotic complications. Appropriate perioperative and anaesthetic management of these patients will invite an aetiological diagnosis, severity analysis and the on-going treatment review. Different assays, thromboelastography and molecular cytogenetics have helped to diagnose these conditions precisely and thus guide the long-term management. Besides this, there are varieties of clinical conditions that will predispose to the hypercoagulability. These need to be defined and classified in order to offer a suitable therapeutic option. Pregnancy is one such important condition and can have more than one responsible factor favouring hypercoagulability. With such diverse kinds of disorders, it would be essential to note the anaesthetic implications, to avoid adverse perioperative outcomes. Available evidence based guidelines will help to make the therapeutic approach more precise. Selection of the appropriate technique of anaesthesia, offering the appropriate anticoagulation bridging as necessary and defining an appropriate interval and time for the intervention will help to minimise the complications.

Pharmacokinetics of recombinant human antithrombin in delivery and surgery patients with hereditary antithrombin deficiency

Population pharmacokinetic (PK) analyses were conducted to refine dosing recommendations for recombinant human anti-thrombin therapy in surgery and delivery patients with hereditary antithrombin deficiency (HD). Single-dose PK data from patients with HD and nonlinear mixed-effects modeling were used to devise a dosing regimen to target antithrombin (AT) activity levels between 80% and 120% of normal. External validation with data from a phase 3 trial confirmed the correctness of a covariate-free model for surgery patients, but dosing adjustment was necessary for delivery patients. After different covariates were tested, the model was updated to incorporate the influential covariate, delivery. Simulations were used to develop a therapeutic drug-monitoring scenario that results in steady state AT activity levels within the target range as quickly as practically feasible. Data from a second clinical trial provided additional external validation and confirmed the accuracy of the dosing model for both groups of patients.

Current knowledge on the genetics of incident venous thrombosis

The genetic burden underlying venous thrombosis (VT) is characterized by a sibling relative risk of 2.5 and a strong heritability whose estimates varied from 35% to 60% according to different studies. However, the genetic factors identified so far only explain about 5% of VT heritability and just 16 genes have been robustly associated with the susceptibility to VT, most of them affecting the coagulation cascade. Eight of these have been identified during the last 5 years, thanks to the development of high-throughput micro-array genotyping technologies, which have radically changed the research landscape in human genetics. The present work is aimed at providing a historical review of the known genetic factors contributing to VT risk, as well as discussing future research strategies to follow to disentangle the whole spectrum of genetic variants associated with VT.

[The optimal duration of anticoagulant treatment following pulmonary embolism]

The optimal course of oral anticoagulant therapy is determined according to the risk of recurrent venous thromboembolism after stopping therapy and the risk of anticoagulant-related bleeding. Clinical risk factors appear to be important in predicting the risk of recurrence whereas the influence of biochemical and morphological tests is uncertain. The risk of recurrent venous thromboembolism is low when the initial episode was provoked by a reversible major risk factor (surgery): 3 months of anticoagulation is sufficient. Conversely, the risk is high when venous thromboembolism was unprovoked or associated with persistent risk factor (cancer): 6 months or more prolonged anticoagulation is necessary. After this first estimation, the duration of anticoagulation may be modulated according to the presence or absence of certain additional risk factors (major thrombophilia, chronic pulmonary hypertension, massive pulmonary embolism): 6 months if pulmonary embolism was provoked and 12 to 24 months if pulmonary embolism was unprovoked. If the risk of anticoagulant-related bleeding is high, the duration of anticoagulation should be shortened (3 months if pulmonary embolism was provoked and 3 to 6 months if it was unprovoked). Lastly, if pulmonary embolism occurred in association with cancer, anticoagulation should be conducted for 6 months or more if the cancer is active or treatment is on going. Despite an increasing knowledge of the risk factors for recurrent venous thromboembolism, a number of issues remain unresolved. Randomised trials comparing different durations of anticoagulation are needed.

FV Leiden Mutation and Deep Venous Thrombosis in Vojvodina: A Case-Control Study

Between September 2007 and February 2010, the occurrence of symptomatic deep venous thrombosis (DVT) was investigated in a cohort of 79 consecutive patients. A case-control study inclu ded 71 healthy controls matched with cases for sex and age. The prevalence of factor V G1691A mutation genotype was analyzed. Eighteen cases (22.79%; 95% confidence interval (CI) 13.53% to 32.03%) and four controls (5.63%; 95% CI 0.27% to 10.99%) were heterozygous carriers of FV Leiden (p= 0.025). The odds ratio for DVT was 4.94 (95% CI 1.58 to 15.42) and the relative risk 4.04 (95% CI 1.44-11.38) compared with FV 1691G carriers. Four cases were homozygous carriers of FV Leiden, giving a prevalence of 5.06% (95% CI 0.23 to 9.89%) and no controls, therefore OR and RR calculation was based on the prevalence of homozygotes in the general Caucasian population. The OR for DVT was 47.28 (95% CI 0.04 - 52167.3) and the RR 45.57 (95% CI 0.04 to 49540.77; p=0.025) compared with FV 1691 G carriers. Our study confirms that factor V Leiden carriers in Vojvodina, as in similar studies previously carried out in other populations, have an increased risk of developing DVT. The evaluated risk of DVT in heterozygous carriers of the mutation is four- to five-fold higher, whereas for homozygous carriers it is 45- to 48-fold higher than in non-carriers. These results confirm that patients with DVT and their relatives should undergo screening for FV Leiden mutation.

Predictors of thrombosis in relatives of patients with venous thromboembolism

PURPOSE OF REVIEW

Hereditary and acquired risk factors contribute to the development of venous thromboembolism (VTE). Relatives of patients who have a hereditary predisposition to thrombosis ('hereditary thrombophilia') will have a heightened risk of VTE if they share the same thrombophilic abnormality. However, if patients do not have a currently recognized thrombophilia it cannot be assumed that their relatives have a normal risk of thrombosis; the patient and their relatives may have a yet to be discovered hereditary abnormality.

RECENT FINDINGS

A recent study by our group suggests that the relatives of patients with unprovoked VTE at a young age (e.g. <45 years) have a substantially higher risk [odds ratio (OR) 3.3; 95% confidence interval (CI) 1.7-6.4] of developing VTE than the relatives of older patients with unprovoked VTE (e.g. >71 years). This effect occurred independently of whether patients had a currently recognized hereditary thrombophilia.

SUMMARY

Relatives of patients with unprovoked VTE have an increased risk of VTE. Testing for thrombophilia in the patients, and in the relatives of the patients who have a thrombophilia, allows the risk of thrombosis in the relatives to be estimated. Thrombosis at a young age appears to be an additional independent risk factor for a heightened risk of thrombosis in patients' relatives.

Normal levels of protein C and protein S tested in the acute phase of a venous thromboembolic event are not falsely elevated

Background

Protein C (PC) and protein S (PS) determination is part of the thrombophilia investigation in patients with idiopathic venous thromboembolism (VTE). Based on scarce evidence it is a common notion that PC and PS levels decrease during the acute phase of VTE, necessitating delay of testing and temporary transition from warfarin to low molecular weight heparin. We have previously demonstrated that an abnormal PC or PS result determined within 24 hours of VTE diagnosis and before the initiation of warfarin needs to be repeated for confirmation ≥3 months after starting treatment and ≥14 days after stopping anticoagulation therapy. In the current study, we sought to show that normal PC and PS values determined during the acute phase of VTE are not false negatives.

Methods

99 patients with acute idiopathic VTE who had normal PC and PS determination within the first 24 hours of presentation and who subsequently had their oral anticoagulation discontinued after six months of therapy. PC and PS determinations were repeated ≥6 months after starting treatment and ≥ 14 days after stopping warfarin. Proportions of patients who tested abnormal on the second test were calculated and 95% confidence intervals obtained using the Wilson's score method. Data from a previously published study on patients with abnormal initial tests was included for comparison.

Results

None of the 99 patients who had normal PC and PS initially had an abnormal result on repeated testing (0%; 95% CI 0 - 3.7%). Data from the previous study showed that, among patients who initially had abnormal results, 40% (95%CI 35.4-84.8%) were confirmed to have low PC and 63.6% (95%CI 16.8-68.7%) low PS on repeated testing. The difference between proportions was statistically significant (χ² p-value < 0.001).

Conclusion

Our results suggest that PC and PS can be determined during the acute phase of VTE and whereas abnormal results need to be confirmed with repeat testing at a later date, a normal result effectively rules out deficiency with only one test.

Rapid multiplexed genotyping for hereditary thrombophilia by SELDI-TOF mass spectrometry

Approximately 50% of patients with venous thromboembolism also present with hereditary predisposition. The most common genetic factors are single nucleotide polymorphisms (SNPs) of factor V Leiden, prothrombin G20210A, and methylenetetrahydrofolate reductase C677T. Genotyping these SNPs helps clinicians to correctly diagnose the disease and properly manage patients. In this study, we report a novel method using surface-enhanced laser desorption and ionization time of flight mass spectrometry to rapidly genotype, in a multiplex fashion, 3 SNPs that predispose patients to thrombosis. First, patient DNA samples were subjected to polymerase chain reaction to amplify and extend the DNA products with masses corresponding to specific genotypes. Polymerase chain reaction products were then applied to Q10 anionic protein chips, undergoing on-chip sample enrichment and clean-up. Finally, the genotypes of the SNPs were determined by surface-enhanced laser desorption and ionization time of flight mass spectrometry. This method offers a rapid turnaround time of less than 5 hours from sample collection to result reporting. The analytical accuracy of each SNP genotyping result has been confirmed by DNA sequencing. In addition, the genotype results produced by this method were validated by comparing them with results obtained by the approved method in the clinical reference laboratory. This novel method is fast, accurate, and reproducible, and thus provides an excellent platform to promote personalized medicine in the management of clotting disorders.

Influence of thrombophilia on risk of recurrent venous thromboembolism while on warfarin: results from a randomized trial

We sought to determine whether thrombophilic defects increase recurrent venous thromboembolism (VTE) during warfarin therapy. Six hundred sixty-one patients with unprovoked VTE who were randomized to extended low-intensity (international normalized ratio [INR], 1.5-1.9) or conventional-intensity (INR, 2.0-3.0) anticoagulant therapy were tested for thrombophilia and followed for a mean of 2.3 years. One or more thrombophilic defects were present in 42% of patients. The overall rate of recurrent VTE was 0.9% per patient-year. Recurrent VTE was not increased in the presence of factor V Leiden (hazard ratio [HR], 0.7; 95% CI, 0.2-2.6); the 20210G>A prothrombin gene mutation (HR, 0); antithrombin deficiency (HR, 0); elevated factor VIII (HR, 0.7; 95% CI, 0.1-5.4); elevated factor XI (HR, 0.7; 95% CI, 0.1-5.0), or elevated homocysteine (HR, 0.7; 95% CI, 0.1-5.3), but showed a trend to an increase with an antiphospholipid antibody (HR, 2.9; 95% CI, 0.8-10.5). Compared with patients with no thrombophilic defects, the rate of recurrence was not increased in the presence of one (HR, 0.7; 95% CI, 0.2-2.3) or more than one (HR, 0.7; 95% CI, 0.2-3.4) defect. We conclude that single or multiple thrombophilic defects are not associated with a higher risk of recurrent VTE during warfarin therapy.

[Optimum duration of anticoagulant treatment after an episode of venous thromboembolism]

Vitamin K antagonists are the mainstay for the treatment for venous thromboembolism. The optimum (VTE) course of oral anticoagulant therapy is determined according to the risk of recurrent VTE after stopping anticoagulant therapy and the risk of anticoagulant-related bleeding while on antivitamin K. The risk of recurrent VTE is low when the initial episode is provoked by a reversible major-risk factor (surgery), whereas this risk is high when VTE is not provoked or associated with a persistent-risk factor (cancer). Conversely, the influence of biochemical and morphological tests is uncertain. The optimum balance of the benefits and the risks of oral anticoagulant therapy is based on the frequency as well as the consequences of the risk of recurrent VTE and anticoagulant-related bleeding. After VTE provoked by a major reversible-risk factor, three months of anticoagulation is optimal, whereas after unprovoked VTE, anticoagulation should be extended. However, given the number of unresolved issues, a randomised trial comparing different durations of anticoagulation is needed.

Manifestações cutâneas das trombofilias

O escopo deste artigo é revisar os estados de hipercoagulabilidade sangüínea (trombofilias) mais provavelmente encontrados por dermatologista. Seus sinais cutâneos incluem o livedo reticular, necrose cutânea, ulcerações e isquemia digital, púrpura retiforme, além de úlceras nas pernas. Revisamos seu tratamento adequado, bem como ressaltamos as manifestações cutâneas que impõem pesquisa laboratorial de trombofilias e os exames indicados nessas situações.

Stuttering priapism complicating warfarin therapy in a patient with protein C deficiency

Priapism is a rare disorder defined as a persistent penile erection that continues hours beyond, or is unrelated to, sexual stimulation. There are two types of priapism; ischemic low-flow type or non-ischemic high flow, with differing etiologies. Priapism associated with thrombophilia is a well-recognized entity. However, the pathogenesis of this association is not fully understood. We report a rare case of recurrent (stuttering) priapism in a patient with protein C deficiency while maintained on Warfarin therapy. This therapy was also complicated by Warfarin-induced skin necrosis.

Chronic superior mesenteric venous thrombosis revealed by diabetic ketonuria and bacteremia

We report a patient with superior mesenteric venous thrombosis presenting as diabetic ketonuria and bacteremia. The patient was a 65-year-old man with a history of diabetes mellitus, and was admitted to our hospital due to high fever. Tests revealed diabetic ketonuria and Bacteroides fragilis bacteremia. Abdominal computed tomographic scan and Doppler sonography revealed an old thrombus in the superior mesenteric vein with good flow through collateral vessels, causing the patient to have an absence of abdominal symptoms. There was no evidence of hereditary thrombophilia. The thrombus was secondary to a combination of comorbidities, including dehydration, hyperosmolarity, and diabetes mellitus.

Coagulation Defects

The present understanding of the coagulation process emphasizes the final common pathway and the proteolytic systems that result in the degradation of formed clots and the prevention of unwanted clot formations, as well as a variety of defense systems that include tissue repair, autoimmune processes, arteriosclerosis, tumor growth, the spread of metastases, and defense systems against micro-organisms. This article discusses diagnosis and management of some of the most common bleeding disorders. The goals are to provide a simple guide on how best to manage patients afflicted with congenital or acquired clotting abnormalities during the perioperative period, present a brief overview of the methods of testing and monitoring the coagulation defects, and discuss the appropriate pharmacologic or blood component therapies for each disease.

The treatment of venous thromboembolism in special populations

Anticoagulant therapy for the typical venous thromboembolism patient is straightforward with predictably favorable outcomes. However, for certain patients with venous thromboembolism, there remains uncertainty and controversy about optimal treatment. These controversial areas include venous thromboembolism patients with: heparin resistance, renal insufficiency, morbid obesity, cancer, antiphospholipid antibody syndrome, recurrent thrombosis despite appropriate anticoagulation, and patients with unprovoked VTE who may or may not benefit from thrombophilia testing. This review summarizes the current data for these special patient populations with venous thromboembolism and provides our recommendations for management.

Hypercoagulability: interaction between inflammation and coagulation in familial Mediterranean fever

Familial Mediterranean fever (FMF) patients in clinical remission are reported to have increased baseline inflammation. Normal function of the natural anticoagulant pathways is particularly needed in diminishing inflammatory responses. In the presence of subclinical inflammation, natural anticoagulant response may be exaggerated. We aimed to observe the anticoagulant-procoagulant status in attack-free FMF patients. Twenty-seven FMF patients diagnosed in accordance with Tel-Hashomer criteria, and 26 healthy controls were included. All patients were attack-free under regular colchicine treatment. Amyloidosis, autoimmunity, accompanying liver and renal disease, and vasculitis were excluded. Predisposing factors for thrombosis were not present. Acute phase reactants (APRs), anticardiolipin antibody positivity, prothrombin time (PT), activated prothrombin time, thrombin time (TT) and d-dimer, protein C activity, activated protein C resistance, free protein S, antithrombin, lupus anticoagulant, human prothrombin fragment F 1 + 2, and human thrombin/antithrombin III complex were analyzed for all subjects. APRs were comparable with controls. Autoimmune markers were negative in all. Anti-streptolysin titers were significantly different than the control group. PT, TT, protein C activity, and F 1 + 2 levels were significantly different from those of healthy controls. Shortened PT and TT, decreased protein C activity vs increased levels of F 1 + 2 suggested a hypercoagulable state in our patients. The hypercoagulable state detected in FMF patients suggests that screening with abnormal coagulation tests may be beneficial for tracing the future consequences of subclinical inflammation in these patients. Studies covering larger groups of patients are needed to verify the currently observed hypercoagulable status in FMF.

The Leiden mutation and activated protein C resistance as risk factors for disseminated intravascular coagulation in acutely poisoned patients

The aim of this work was to assess the prevalence of a genetic predisposition to disseminated intravascular coagulation (DIC) among acutely poisoned patients. Activated protein C resistence (APCR) is a genetically determined cause of thrombophilia and DIC development. One hundred seventy-six subjects were divided into three groups: one consisted of 83 acutely poisoned patients with DIC; a second consisted of 57 acutely poisoned patients without DIC; the third group consisted of 91 healthy controls. Abnormal results of APCR testing were found in 24.1% of the poisoned DIC group, 5.3% of the poisoned nonDIC group, and 3.3% of the control group. Genetic tests were performed in 37 selected patients. Factor V Leiden mutation (G/A genotype) was determined to be present in people whose R index value was below 1.9. These results raise the possibility that outcomes of acute poisonings may be influenced by genetic predisposition.

Protein C and protein S levels can be accurately determined within 24 hours of diagnosis of acute venous thromboembolism

In the 50% of cases of acute idiopathic venous thromboembolism, laboratory testing for inherited causes is often performed. Most physicians are under the impression that assays for protein C and protein S should not be measured at the time of diagnosis because of a high false positive rate. We performed a prospective cohort study from two outpatient thromboembolism clinics on consecutive patients with an objectively confirmed diagnosis of first acute idiopathic venous thromboembolism. Assays for protein C and protein S were performed prior to the initiation of oral anticoagulation therapy and within 24 h of diagnosis of venous thromboembolism. Abnormal results were repeated when patients discontinued oral anticoagulant therapy. Of 253 patients tested for both protein C and protein S, 229 (91%; 95% confidence interval 87-94%) were negative and 484 of 508 (95%) tests were normal. Of the 24 initial abnormal results, 21 were repeated and 10 (48%; 95% confidence interval 26-70%) were still abnormal. Overall, 97.8% of initial protein C and protein S results were accurate. If protein C and protein S are measured at the time of diagnosis of acute venous thromboembolism, the majority of the results will be normal and false positives are uncommon.

Anticoagulant Treatment of Deep Vein Thrombosis and Pulmonary Embolism

Venous thrombosis is a common disease. As the mean age of the population increases, so does the incidence of venous thromboembolism. Anticoagulant therapy is equally effective in young and older patients, and can reduce substantially the associated morbidity and mortality. When considering long-term oral anticoagulant therapy in older patients, however, careful ongoing evaluation is imperative to ensure that the risk of bleeding does not outweigh the antithrombotic benefits.

Thrombophilia in children with venous thromboembolic disease

Venous thromboembolic events (VTEs) in children are usually associated with underlying clinical conditions such as central venous line, cancer and cardiac diseases. The objective of this review is to present the importance of thrombophilia to the occurrence of childhood VTE. The reported prevalence of thrombophilia in children with VTE varies extremely between 10% and 78% in different registries. The variation in the reported prevalence most probably reflects differences in the clinical characteristics of the children studied and differences in study designs. The initial management of children with thrombophilia and VTE is similar to those individuals who do not have a specific inherited thrombophilic risk factor, except in the rare events of homozygous deficiencies of prothrombotic coagulation proteins. The impact of thrombophilic markers on long-term therapy and outcome of children with VTE has not been completely clarified. According to the current guidelines for thrombophilia, all children with VTE should be tested for a full panel of genetic and acquired prothrombotic traits. However, re-evaluation of co-morbid risk factors other than thrombophilic markers and careful consideration of the prognostic value of thrombophilic markers might help to change future attitude from the rigidity of current guidelines to more rational schemes.

Antithrombotic Therapy for Stroke in Young Adults

Stroke in young adults is a markedly heterogeneous disease, and remains an understudied phenomenon. While advances are being made in our understanding of the pathophysiology of its underlying conditions, treatment concerns are controversial, and clinical trials are sorely lacking. This review presents an overview of some of the relevant management issues in hypercoagulable states, migraine, patent foramen ovale, vascular dissection and venous sinus thrombosis.

Hormone replacement therapy and risk for venous thromboembolism: what's new and how do these findings influence clinical practice?

PURPOSE OF REVIEW

Although an association between hormone replacement therapy and venous thromboembolism has been established, several unanswered questions remain. This review will address additional questions relating to hormone replacement therapy and venous thromboembolism. Does the risk for venous thromboembolism differ according to the type of hormone replacement therapy? Does the presence of thrombophilia influence the risk for venous thromboembolism in hormone replacement therapy users? Should hormone replacement therapy be temporarily interrupted around the time of surgery?

RECENT FINDINGS

The risk for venous thromboembolism seems to be less in users of estrogen-only hormone replacement therapy (odds ratio = 1.2; 95% confidence interval: 0.6-2.6) than in users of estrogen-progestin hormone replacement therapy (odds ratio = 2.7; 95% confidence interval: 1.4-5.1), and there may be no increased risk for venous thromboembolism with transdermal hormone replacement therapy (odds ratio = 1.0; 95% confidence interval: 0.3-3.3). The presence of a prothrombotic blood abnormality, such as the factor V Leiden mutation, seems to further increase the risk for venous thromboembolism in hormone replacement therapy users (odds ratio = 17.1; 95% confidence interval: 3.7-78). Continued use of hormone replacement therapy in the perioperative period does not seem to have an impact on the overall risk for postoperative venous thromboembolism (odds ratio = 0.66; 95% confidence interval: 0.35-1.18).

SUMMARY

Recent studies have extended our understanding regarding the association between hormone replacement therapy and venous thromboembolism. The implications of these findings on clinical practice are discussed.

Management of thrombophilia: who to screen?

Testing for laboratory evidence of heritable thrombophilia is now common. This practice undoubtedly arose in response to association studies, which revealed the influence of heritable thrombophilic defects on the development of VTE. Now that high quality clinical outcome studies are being reported it is becoming apparent that despite association, testing has limited predictive value for the majority of unselected symptomatic patients. Clearly, there is a difference between the ability of a test to explain why one individual is more likely to suffer a thrombosis than another and the ability of the same test to predict which patients who have already had thrombosis are likely to suffer a recurrence. In the absence of grade A recommendations, it is inevitable that practice will vary. Decisions will be influenced by local resources, competing demands for clinical and laboratory services and not least the professional interest of the haematologist. If thrombophilia testing is performed there is a strong case for selecting patients for testing as in most cases decisions regarding intensity and duration of anticoagulant therapy can be made purely in relation to clinical criteria.

Ethnic Differences in Cerebral Venous Thrombosis

BACKGROUND

Cerebral venous thromboses (CVT) with distinct clinical presentations have been shown worldwide. However, there is little information regarding race-ethnic differences in this disease.

METHODS

We prospectively studied 50 CVT patients from Brazil, comparing clinical and laboratory data among white (W) and African-Brazilian (AB) patients.

RESULTS

Seventy percent of the patients were female, 26 W and 23 AB, mean age 34.7 years. Multiple sinus CVT, deep CVT and worse outcome were significantly more frequent in AB than in W patients. There was a trend towards a higher frequency of factor V Leiden and prothrombin mutation in W than in AB, and of protein C deficiency in AB.

CONCLUSIONS

CVT was more severe in AB patients than in W patients. Race-ethnic differences may account for the heterogeneous distribution of inherited thrombophilia in this series.

Anticoagulation in Hypercoagulable Conditions: Special Considerations in the Treatment and Prevention of Venous Thromboembolism

Patients with hypercoagulable conditions, including malignancy, are at increased risk of recurrent venous thromboembolic events (VTE). The general approach to treatment and prevention of VTE in patients with thrombophilia is similar to that of patients who present with VTE associated with transient risk factors, including immobility, trauma, and surgery. However, several important issues must be considered in the initial management of acute VTE, in the long-term prevention of VTE following an initial event, and in VTE prophylaxis in patients with hypercoagulable conditions. Patients with antithrombin deficiency are prone to heparin resistance and may require concurrent antithrombin concentrates or anticoagulation with direct thrombin inhibitors for adequate treatment of acute VTE. In patients with malignancy, low-molecular-weight heparins have been found to be more effective than unfractionated heparin for the initial treatment of VTE. Long-term prevention is preferred for most patients with hypercoagulable conditions, and the latest trials show that low-intensity warfarin is not as effective as typical moderate-intensity therapy for chronic therapy. Primary prophylaxis of asymptomatic carriers is not warranted unless they are exposed to additional risk factors, including surgery, trauma, immobilization, and pregnancy. Prolonged prophylaxis may be appropriate in patients with malignancy who undergo surgical procedures.

Long-Term Management of Patients After Venous Thromboembolism

Long-term treatment of venous thromboembolism (VTE) focuses mainly on the duration of anticoagulant therapy, usually with vitamin K (VK) antagonists. The duration of therapy should be individualized based on the risk of recurrent VTE if treatment were stopped and the risk of bleeding if treatment were continued. The risk of recurrence is low if thrombosis was provoked by a major reversible risk factor such as surgery; 3 months of treatment is usually adequate for such patients. The risk of recurrence is high if thrombosis was unprovoked (“idiopathic”) or associated with an irreversible risk factor such as cancer; anticoagulant treatment for at least 6 months, and often indefinitely, is indicated for such patients. Risk of recurrence is intermediate if thrombosis was associated with a minor transient risk factor; such patients can be treated for 3 to 6 months. Within each of these categories, presentation as pulmonary embolism, >1 previous VTE, an underlying malignancy, an antiphospholipid antibody, or selected hereditary thrombophilic states favor more prolonged therapy, whereas isolated distal deep vein thrombosis, high risk of bleeding, and patient preference favor shorter treatment. The optimal intensity of anticoagulant therapy with VK antagonists corresponds to a target international normalized ratio of 2.5 (range, 2.0 to 3.0). Long-term treatment with low-molecular-weight heparin is an alternative to VK-antagonist therapy and is usually preferable in patients with active cancer. Oral direct thrombin inhibitors also appear suitable for long-term prevention of recurrent VTE but await regulatory approval and comparison with VK antagonists.

Gold nanoparticle-based detection of genomic DNA targets on microarrays using a novel optical detection system

The development of a nanoparticle-based detection methodology for sensitive and specific DNA-based diagnostic applications is described. The technology utilizes gold nanoparticles derivatized with thiol modified oligonucleotides that are designed to bind complementary DNA targets. A glass surface with arrays of immobilized oligonucleotide capture sequences is used to capture DNA targets, which are then detected via hybridization to the gold nanoparticle probes. Amplification with silver allows for detection and quantitation by measuring evanescent wave induced light scatter with low-cost optical detection systems. Compared to Cy3-based fluorescence, silver amplified gold nanoparticle probes provide for a approximately 1000-fold increase in sensitivity. Furthermore, direct detection of non-amplified genomic DNA from infectious agents is afforded through increased specificity and even identification of single nucleotide polymorphisms (SNP) in human genomic DNA appears feasible.

Thromboembolism in paediatric lupus patients

Paediatric patients with systemic lupus erythematosus (SLE) and antiphospholipid antibodies (aPL), specifically lupus anticoagulants (LAC) are at high risk of developing thromboembolic events (TE). Our objectives were to determine the prevalence of TE in paediatric SLE patients with LAC and to determine if anticoagulation was effective to decrease morbidity, and prevent recurrent TE. We reviewed data on 149 paediatric SLE patients treated over 10 years. In all, 24 patients (16%) were LAC positive, and 21 TE occurred in 13 of these LAC positive patients (54% incidence of TE in LAC positive patients). The events were cerebral venous thrombosis (9), arterial stroke (3), deep venous thrombosis (4), pulmonary embolism (2), other venous event (1) and other arterial events (2). The median duration between SLE diagnosis and first TE was 15.2 months (range 0-62), and the median age at first TE was 15.1 years (range 11.4-18.4). Long-term anticoagulation was prescribed, and eight patients (62%) were transferred to adult care on lifelong oral warfarin; four (31%) remain under our care on lifelong warfarin, and one patient died of causes unrelated to her TE. No patient has been identified with deficiencies of protein C, protein S or antithrombin III. One patient is heterozygous for Factor V Leiden, and one is heterozygous for both the Prothrombin 20210A mutation and the MTHFR (methylene tetrahydrofolate reductase) mutation. Four patients had recurrent TE (31%), and three were not anticoagulated at the time of their second event. One patient had two recurrences on therapeutic anticoagulation. Thromboembolic events are prevalent in the LAC positive paediatric SLE population, and consideration for lifelong anticoagulation must occur after an initial TE.

Coagulation, inflammation, and apoptosis: different roles for protein S and the protein S-C4b binding protein complex

Protein S (PS) has an established role as an important cofactor to activated protein C (APC) in the degradation of coagulation cofactors Va and VIIIa. This anticoagulant role is evident from the consequences of its deficiency, when there is an increased risk of venous thromboembolism. In human plasma, PS circulates approximately 40% as free PS (FPS) and 60% in complex with C4b-binding protein (C4BP). Formation of this complex results in loss of PS cofactor function, and C4BP can then modulate the anticoagulant activity of APC. It had long been predicted that the complex could act as a bridge between coagulation and inflammation due to the involvement of C4BP in regulating complement activation. This prediction was recently supported by the demonstration of binding of the PS-C4BP complex to apoptotic cells. This review aims to summarize recent findings on the structure and functions of PS, the basis and importance of its deficiency, its interaction with C4BP, and the possible physiologic and pathologic importance of the PS-C4BP interaction.

Hypercoagulable state testing and malignancy screening following venous thromboembolic events

Mounting interest in hypercoagulability, increased availability of hypercoagulable state test 'panels' and enhanced ability to identify abnormalities in tested patients have prompted widespread testing. Testing for acquired and inherited hypercoagulable states uncovers an abnormality in over 50% of patients presenting with an initial venous thromboembolic event (VTE) but may have minimal actual impact on management in most of these patients. Such laboratory screening should be reserved for patients in whom the results of individual tests will significantly impact the choice of anticoagulant agent, intensity of anticoagulant therapy, therapeutic monitoring, family screening, family planning, prognosis determination, and most of all duration of therapy. Testing 'just to know' is neither cost-effective nor clinically appropriate. The most important testing in patients following acute VTE may be age- and gender-specific cancer screening. Cancer screening following VTE seems most prudent in older individuals and in those with idiopathic VTE and no laboratory evidence for an inherited hypercoagulable state. Cancer screening should focus on identification of treatable cancers and those where diagnosis in an early stage favorably impacts patient survival. Extensive searches for occult malignancy employing whole-body computed tomography and serum tumor markers may identify more cancers but without affecting patient outcome. We advocate that physicians should focus their attention more on VTE prophylaxis and proper treatment and less on costly and, at times, invasive testing of questionable value.

Patients with inferior vena caval filters should receive chronic thromboprophylaxis

A 32-year-old man with testicular carcinoma is diagnosed with an acute left leg deep venous thrombosis (DVT) during his fourth cycle of combination chemotherapy. Because of anticipated moderate to severe thrombocytopenia, anticoagulation is initially avoided and an inferior vena cava (IVC) filter is placed to prevent pulmonary embolism (PE). After completion of all chemotherapy he is deemed to be in remission and anticoagulation is begun. The optimal duration of anticoagulation in this patient is pondered.

Cerebrovascular Disease in Pregnancy

Stroke during pregnancy is a special category of stroke in young women. Although the absolute risk is small, there are diverse causes, including those inherent to the pregnant state, that may have a significant impact on maternal and fetal outcome. Severe pre-eclampsia and eclampsia are commonly associated with ischemic and hemorrhagic stroke, but must not be presumed the sole cause of stroke in pregnant women. Magnesium sulfate is the treatment of choice to prevent eclampsia. Randomized clinical trials in pregnant women are not available to provide guidance for the treatment of ischemic and hemorrhagic stroke in pregnant women. Various antithrombotic agents may be safely used during specific stages of pregnancy for treatment and prevention of ischemic stroke, with low-dose aspirin, unfractionated heparin, and low molecular weight heparin the preferred agents. Low molecular weight heparin may be safer than unfractionated heparin. Treatment of parenchymatous intracerebral hemorrhage and subarachnoid hemorrhage during pregnancy and the puerperium must be individualized. Aneurysms may be treated with neurosurgical clipping or endovascular coiling, depending on neurosurgical considerations. Cesarean or vaginal delivery may be used depending on the timing of delivery, adequacy of aneurysm occlusion, and risk to mother and fetus. Arteriovenous malformations are best treated in a multimodal fashion at a specialized treatment center.