Prothrombotic conditions in an unselected cohort of children with venous thromboembolic disease

Coagulation Profile in Neonates with Congenital Heart Disease: A Pilot Study

Background and Objectives: congenital heart disease (CHD), cyanotic and, to a lesser degree, acyanotic, often are accompanied by coagulation abnormalities, impacting substantially morbidity and mortality. Until now, no consistent hemostatic patterns have been demonstrated in neonates and children with CHD because they represent a variable and heterogenous population. The aim of the present study is to investigate the hemostatic profile, as well as the role of ADAMTS-13 (a disintegrin and metalloprotease with thrombospondin type-1 motives), the cleaving protein of von Willebrand factor (VWF) in neonates with CHD and compare them to healthy age-matched controls. Materials and Methods: twenty neonates with a mean gestational age of 37.1 ± 2.5 weeks were included in the CHD group, and 18 healthy neonates with a mean gestational age of 38.2 ± 1.5 weeks were in the control group. Results: prothrombin time was significantly prolonged, and accordingly, factor VII (FVII) levels were significantly decreased in the CHD group in comparison to controls. Factor VIII (FVIII), VWF, and ristocetin cofactor activity (Rcof) levels were significantly higher in the study vs. control group. Concentrations of ADAMTS-13 were decreased in the CHD vs. control group, but the difference was not statistically significant. Our results, in combination, indicate a balanced hemostatic mechanism, although with greater variability in neonates with CHD, while developmental aspects of coagulation are evident in the specific patient population. Conclusions: the coagulation profile is moderately impaired early in the course of CHD, though increased thrombogenicity is already present and should not be ignored.

Budd-Chiari syndrome in children: Challenges and outcome

Budd-Chiari syndrome (BCS) is an uncommon disease of the liver, characterised by obstruction of the hepatic venous outflow tract. The etiological spectrum of BCS as well as venous obstruction pattern show wide geographical and demographic variations across the globe. Compared to adults with BCS, children have primary BCS as the predominant etiology, earlier clinical presentation, and hence better treatment outcome. Underlying prothrombotic conditions play a key role in the etiopathogenesis of BCS, though work-up for the same is often unyielding in children. Use of next-generation sequencing in addition to conventional tests for thrombophilia leads to better diagnostic yield. In recent years, advances in radiological endovascular intervention techniques have revolutionized the treatment and outcome of BCS. Various non-invasive markers of fibrosis like liver and splenic stiffness measurement are being increasingly used to assess treatment response. Elastography techniques provide a novel non-invasive tool for measuring liver and splenic stiffness. This article reviews the diagnostic and therapeutic advances and challenges in children with BCS.

Post-viral idiopathic purpura fulminans is associated with inherited thrombophilia and anti-cardiolipin antibodies

Introduction

Idiopathic purpura fulminans (IPF) is a rare and severe coagulation disorder, associated with transient anti-protein S (anti-PS) antibodies in the context of post-viral infection such as varicella. Anti-protein S antibodies are frequently found in the context of varicella, in contrast with the rarity of IPF. Other factors such as anti-phospholipid antibodies (APL) and inherited thrombophilia may be associated with severe vascular complication.

Method

This is an ancillary study of a French multicenter retrospective series and systematic review of literature. We analyzed patients who were tested for inherited thrombophilia, namely antithrombin, protein C, protein S deficiency; prothrombin gene G20210A polymorphism (FII:G20210A),Factor V R506Q polymorphism (FV:R506Q); and/or for APL (lupus anticoagulant (LA), anti-cardiolipin antibodies (ACL), or anti-beta 2-GPI antibodies (Aβ2GP1).

Results

Among the 25 patients tested for inherited thrombophilia, 7 (28%) had positive results. Three had FV R506Q, two FII:G20210A, one compound heterozygote FV:R506Q associated to FII:G20210A, and one protein C deficiency. APL testing was performed in 32 patients. It was positive in 19 patients (59%): 17 ACL (53%), 5 LA (16%), 4 Aβ2GP1 (13%). The risk of severe complications was not associated with presence of inherited thrombophilia or APL presence, with RR: 0.8 [95% CI: 0.37-1.71], p = 1 and RR: 0.7 [95% CI: 0.33-1.51], p = 0.39, respectively. We found a high prevalence of inherited thrombophilia or APL in a population of patients with IPF. However, we do not find an association with the occurrence of severe vascular complications or venous thromboembolism.

Modern Aspects of Anticoagulation System Disorders Diagnosis in Children with Different Polymorphisms in Coagulation Genes. Initial Results

Background. Hemostatic system pathology is topical and poorly studied issue in pediatrics. One of the main causes of coagulation pathway disorders associated with thrombotic events is abnormality in various parts of the hemostatic system. Vascular accidents are commonly caused by anticoagulation system factors deficiency. Conventionally, thrombosis is a common event in adult patients, and there is no adequate attention to disorders of primary physiological anticoagulants system in children. More often acquired anticoagulant proteins deficiency develops in presence of various pathological conditions, especially after the past infectious diseases. All these diseases (thrombophilia, trombotic events, cardiovascular pathology, nervous system diseases, genetic diseases) can occur separately and in association with each other, plus clinical picture of coagulation events may be similar. Objective. The aim of the study is to evaluate changes in the physiological anticoagulants system in children with different pathologies who have polymorphic variants in coagulation genes and who had new coronavirus infection. Methods. The study included 33 children who had severe coronavirus infection in family clusters and had severe chronic pathology potentially associated with disorders of the coagulation system (nervous system damage, hypertrophic cardiomyopathy, hereditary monogenic syndromes, hemato-mesenchymal dysplasia syndrome). All children underwent complete examination including clinical examination, laboratory, and instrumental diagnostics. Results. Preliminary study results indicate significant incidence of polymorphic variants in coagulation genes (one third of children with various diseases from the study). Some children had decreased activity of anticoagulation system glycoproteins (from 6% to 36%) that confirmed the topicality of the examination of anticoagulation system factors deficiency and the need for further dynamic follow-up, as well as revealing of trombophilia predictors in children in selected target groups. Study on revealing anticoagulation system disorders and mutations in coagulation genes will predict the risk of thrombotic disorders. Conclusion. The obtained results have confirmed the significant role of the ongoing study for comprehensive assessment of hemostatic system disorders in children. That will allow us to optimize the approach to diagnosis and personalize the management strategy for patients with different chronic pathologies and disorders of the natural anticoagulants system. The study is currently ongoing.

Lipoprotein(a): Pathophysiology, measurement, indication and treatment in cardiovascular disease. A consensus statement from the Nouvelle Société Francophone d'Athérosclérose (NSFA)

Lipoprotein(a) is an apolipoprotein B100-containing low-density lipoprotein-like particle that is rich in cholesterol, and is associated with a second major protein, apolipoprotein(a). Apolipoprotein(a) possesses structural similarity to plasminogen but lacks fibrinolytic activity. As a consequence of its composite structure, lipoprotein(a) may: (1) elicit a prothrombotic/antifibrinolytic action favouring clot stability; and (2) enhance atherosclerosis progression via its propensity for retention in the arterial intima, with deposition of its cholesterol load at sites of plaque formation. Equally, lipoprotein(a) may induce inflammation and calcification in the aortic leaflet valve interstitium, leading to calcific aortic valve stenosis. Experimental, epidemiological and genetic evidence support the contention that elevated concentrations of lipoprotein(a) are causally related to atherothrombotic risk and equally to calcific aortic valve stenosis. The plasma concentration of lipoprotein(a) is principally determined by genetic factors, is not influenced by dietary habits, remains essentially constant over the lifetime of a given individual and is the most powerful variable for prediction of lipoprotein(a)-associated cardiovascular risk. However, major interindividual variations (up to 1000-fold) are characteristic of lipoprotein(a) concentrations. In this context, lipoprotein(a) assays, although currently insufficiently standardized, are of considerable interest, not only in stratifying cardiovascular risk, but equally in the clinical follow-up of patients treated with novel lipid-lowering therapies targeted at lipoprotein(a) (e.g. antiapolipoprotein(a) antisense oligonucleotides and small interfering ribonucleic acids) that markedly reduce circulating lipoprotein(a) concentrations. We recommend that lipoprotein(a) be measured once in subjects at high cardiovascular risk with premature coronary heart disease, in familial hypercholesterolaemia, in those with a family history of coronary heart disease and in those with recurrent coronary heart disease despite lipid-lowering treatment. Because of its clinical relevance, the cost of lipoprotein(a) testing should be covered by social security and health authorities.

The Incidence and Characteristics of Venous Thromboembolisms in Paediatric-Onset Inflammatory Bowel Disease: A Prospective International Cohort Study Based on the PIBD-SETQuality Safety Registry

BACKGROUND AND AIMS

Guidelines regarding thromboprophylaxis for venous thromboembolisms [VTEs] in children with inflammatory bowel disease [IBD] are based on limited paediatric evidence. We aimed to prospectively assess the incidence of VTEs in paediatric-onset IBD [PIBD], characterize PIBD patients with a VTE and identify potential IBD-related risk factors.

METHODS

From October 2016 to September 2020, paediatric gastroenterologists prospectively replied to the international Safety Registry, monthly indicating whether they had observed a VTE case in a patient <19 years with IBD. IBD details [type, Paris classification, clinical and biochemical disease activity, treatment] and VTE details [type, location, treatment, outcome] were collected. To estimate VTE incidence, participants annually reported the number of PIBD patients, data source and catchment area of their centre. A systematic literature review and meta-analysis was performed to calculate the VTE incidence in the general paediatric population.

RESULTS

Participation of 129 PIBD centres resulted in coverage of 24 802 PIBD patients. Twenty cases of VTE were identified [30% Crohn's disease]. The incidence of VTEs was 3.72 (95% confidence interval [CI] 2.27-5.74) per 10 000 person-years, 14-fold higher than in the general paediatric population (0.27 [95% CI 0.18-0.38], p < 0.001). Cerebral sinus venous thrombosis was most frequently reported [50%]. All but one patient had active IBD, 45% were using steroids and 45% were hospitalized. No patient received thromboprophylaxis, whereas according to current PIBD guidelines, this was recommended in 4/20 patients.

CONCLUSION

There is an increased risk of VTEs in the PIBD population compared to the general paediatric population. Awareness of VTE occurrence and prevention should be extended to all PIBD patients with active disease, especially those hospitalized.

Preoperative Considerations for Teenagers Undergoing Orthopaedic Surgery: VTE Prevention, Mental Health Assessment, Vaping, and Drug Addiction

INTRODUCTION

Adolescents undergoing pediatric orthopaedic surgery typically experience an uncomplicated postoperative course. However, adolescence represents a unique transition period from pediatric to adult physiology. As a result, the astute pediatric orthopaedic surgeon will be aware of unique medical and social scenarios which are relevant to adolescents during the perioperative course including the risk of venous thromboembolism (VTE), prevalence of mental health conditions, and rising use of electronic cigarettes or "vaping" to consume nicotine and cannibas.

DISCUSSION

Adolescents are at a greater risk of VTE after pediatric orthopaedic surgery. In particular, adolescent females with a family history of blood clotting disorders and those with a change in mobility after surgery should be considered for prophylaxis. The prevalence of adolescent mental health conditions including anxiety, depression, and behavioral issues is increasing in the United States. Higher levels of preoperative anxiety and the presence of mental health pathology are associated with slower recovery, higher levels of postoperative pain, and the increased likelihood for chronic pain. Several quick screening instruments are available to assess adolescents for preoperative anxiety risk, including the Visual Analogue Scale for Anxiety or the Amsterdam Perioperative Anxiety Information Scale. Unfortunately, electronic cigarettes have become increasingly popular for the consumption of nicotine and cannabis among adolescents. Preoperative use of combustive cigarettes (nicotine/cannabis) represents perioperative risks for induction/anesthesia, postoperative pain, and analgesia requirements and issues with delayed wound and fracture healing.

CONCLUSIONS

VTE, underlying mental health conditions, and usage of nicotine and cannabis are clear detriments to the recovery and healing of adolescent patients following orthopaedic surgery. Therefore, standardized screening for adolescents before orthopaedic surgery is indicated to identify perioperative risk factors which have negative impacts on functional outcomes.

Pediatric Venous Thromboembolism: Different Rates of Incidence, Anatomic Locations, and Risk Factors Between Orthopaedic and Nonorthopaedic Related Patients

BACKGROUND

The prevalence of venous thromboembolism (VTE) may be increasing in children; however, scarce literature exists comparing incidence rates between pediatric orthopaedic patients and other pediatric patients. The purpose of this study was to compare the incidence, anatomic locations, and risk factors of VTEs between orthopaedic and nonorthopaedic pediatric related patients to determine if important differences exist.

METHODS

Computed tomography and ultrasound data were reviewed for children (below 19 y old) with a diagnosed VTE between January 1, 2009 and December 31, 2016. Demographic and clinical data, including VTE anatomic location and risk factors, were recorded. Two major cohorts were identified: orthopaedic-related (ORTH) and nonorthopaedic-related (NORTH) VTEs. Incidence rates were estimated and risk factors were compared using χ2 testing.

RESULTS

There were 373 children diagnosed with a VTE (average age 10.3 y) of a total of 810,097 treated as in-patients for an incidence rate of 4.60 per 10,000 cases (95% confidence interval=4.15 to 5.10 per 10,000 cases). The rate of ORTH VTEs (28 of 188,669 orthopaedic patients, 1.48 per 10,000 cases) was significantly lower than that of NORTH VTEs (345 of 621,428 nonorthopaedic patients, 5.55 per 10,000 cases; P<0.001). For the ORTH cohort, there was a significant difference in the proportion of deep vein thrombosis in the lower extremity (91%) compared with the upper extremity (9%) (P<0.001), while a more even distribution of NORTH deep vein thrombosis in the upper (50%) and lower (41%) extremities was appreciated. The primary risk factors for ORTH VTEs included surgery (93%; P<0.001), change in ambulatory status (61%; P<0.001), and trauma (18%; P<0.001), while the primary risk factors for NORTH VTEs included intravenous peripheral inserted central catheter/central line (61%; P<0.001) and cancer (27%; P=0.001).

CONCLUSIONS

Pediatric ORTH VTEs have a significantly lower incidence rate and different primary risk factors than those of NORTH VTEs. This information is useful for health care providers when making decisions regarding risk and prophylaxis in pediatric patients with orthopaedic and nonorthopaedic conditions.

LEVEL OF EVIDENCE

Level III.

[Thrombosis of the inferior vena cava and right atrium in a neonate with thrombophilia: diagnosis, treatment, result]

Hereditary thrombophilia is rare pathology giving rise to a ninefold increase in the risk for the development of thromboembolism in infants. The problem is multifactorial and characterized by high mortality, especially in neonates. Infants who develop thrombosis, particularly those with no family history, are often subjected to testing for hereditary thrombophilia. However, genetic testing for thrombophilia does not change the plan of treatment but makes it possible to perform prevention of thrombosis within the risk periods for the patient. Poor awareness of paediatricians, the complexity of carrying out genetic testing, the absence of approaches supported by evidence-based medicine due to shortage of high-quality clinical trials and no guidelines on prevention of thromboembolism in infants, as well as the frequent occurrence of diversified causes and diseases in different age groups make the problem significant for modern medicine. Further studies are needed to address many unanswered as yet questions.

Management of Venous Thromboembolism in Children: Current Recommendations and Therapeutic Options

Venous thromboembolism has an increasing significance in the pediatric patient population. Due to the lack of well-designed pediatric clinical trials, recommendations for the treatment of venous thromboembolic events in children have low evidence and are mainly extrapolated from adult guidelines. This review summarizes and compares recommendations for the treatment of several venous thromboembolic events in children from CHEST, ASH, and the UK guidelines.

Venous Thromboembolism in Children: From Diagnosis to Management

Venous thromboembolism (VTE) in children is a rare occurrence, although in recent decades we have seen an increase due to several factors, such as the rise in survival of subjects with chronic conditions, the use of catheters, and the increased sensitivity of diagnostic tools. Besides inherited thrombophilia, acquired conditions such as cardiovascular diseases, infections, chronic disorders, obesity and malignancy are also common risk factors for paediatric VTE. The treatment of paediatric VTE consists of the use of heparins and/or vitamin K antagonists to prevent dissemination, embolization, and secondary VTE. Randomized clinical trials of direct oral anticoagulants in paediatric VTE are ongoing, with the aim to improve the compliance and the care of patients. We reviewed the physiological and pathological mechanisms underlying paediatric thrombosis and updated the current diagnosis and treatment options.

Venous thromboembolism in childhood: where is Brazil after 20 years?

Due to the longer survival of critically ill children, venous thromboembolism is a problem which is becoming increasingly recognized in pediatric practice. In the last decades, several international studies have been published, shedding a light upon the epidemiology of this disease during childhood. These data show peculiarities in the clinical presentation and the significant morbidity and mortality. The new "epidemic of thrombosis" in pediatric hospitals points toward the urgent need for specific treatment and prevention protocols targeting this population. In Brazil, knowledge regarding this disease remains scarce. The lack of epidemiological data impacts both the clinical care and the design of specific public policies in the field. Thus, a national registry of pediatric venous thromboembolism is relevant to the proposal of an appropriate plan of action to create a qualified net of assistance. The improvement in educational initiatives related to the field of Pediatric Hemostasis is also very important. In this review, we have updated the epidemiological, clinical and therapeutic aspects of the disease, as well as the prevention strategies.

Salvage pulmonary thromboembolectomy for massive pulmonary embolism in a child presented with syncope and subsequent cardiac arrest

Pulmonary embolism is frequently under-recognised in children and, therefore, a high index of suspicion should be exerted on patients with exertional dyspnoea, presyncope/syncope and unexplained cardiopulmonary arrest. We discuss a 10-year-old previously healthy girl who presented with syncope and subsequent cardiac arrest related to massive pulmonary embolism and was salvaged successfully by emergent pulmonary embolectomy.

Thrombosis in children: Which test to whom, when and how much necessary?

Pediatric thrombosis is multifactorial, and usually risk factors either congenital or acquired are present. After 2000, systematic reviews and meta-analysis on pediatric venous thromboembolic disease and inherited thrombophilia revealed elevated thrombotic risks in these children. In this review, we discuss thrombosis and new literature in various pediatric patient groups and the usefulness of thrombophilia testing.

Six Weeks Versus 3 Months of Anticoagulant Treatment for Pediatric Central Venous Catheter-related Venous Thromboembolism

OBJECTIVE

Central venous catheters (CVCs) are the single most important predisposing factor for the development of pediatric venous thromboembolism (VTE). Treatment recommendations suggest anticoagulation for the duration of 6 weeks to 3 months. This project investigated clinical outcomes associated with 6 weeks compared with 3 months of enoxaparin therapy following diagnosis of a CVC-related VTE.

METHODS

This retrospective cohort study enrolled patients aged 18 years and below treated with enoxaparin with/without unfractionated heparin for a radiologically confirmed CVC-related VTE. Patients were identified using the pharmacy database, radiologic imaging, and medical records. Patients were divided into 2 groups based on the duration of anticoagulation (6+1 or 12±2 wk) and data were analyzed using descriptive statistics.

RESULTS

Seventy-four patients were included. Higher rates of complete thrombosis resolution were observed in children treated for 6 weeks at treatment cessation (39.4%) and long-term follow-up (61.5%), compared with 3 months (11.8% and 9.0%, respectively).

CONCLUSIONS

Six weeks of treatment for CVC-related VTE may provide noninferior clinical outcomes compared with 3 months of anticoagulation. An international randomized-controlled trial (Kids-DOTT) is underway to explore the optimal duration of anticoagulation for acute-provoked VTE in children. This manuscript highlights that data from such studies is urgently needed.

Cohort Study: Central Venous Catheter-Related Complications in Children with Hematologic Diseases at a Single Center

Objective:

This study aims to document and analyze the central venous catheter (CVC)-related complications in children with hematological diseases who were treated within a single institution.

Materials and Methods:

A retrospective investigation was conducted in 106 pediatric patients in whom 203 CVCs were inserted. A total of 175 catheter-related complications occurred in 5 years.

Results:

The rates of clinical catheter infections, local catheter infections, venous thromboembolism, bleeding, and mechanical complications were 2.6, 1.1, 0.2, 0.2, and 0.2 per 1000 catheter days. Methicillin-resistant Staphylococcus epidermidis was the predominant infectious organism in blood and catheter cultures. The children with leukemia had a significantly higher frequency of clinical catheter infections (p=0.046). The children who underwent bone marrow transplantation had a significantly lower frequency of clinical catheter infections (p=0.043) and higher frequency of local catheter infections (p=0.003). The children with implanted catheters had a significantly lower frequency of clinical catheter infections (p=0.048). The children with thrombocytopenia had significantly fewer local catheter infections and significantly more clinical catheter infections and catheter-related bleeding (respectively p=0.001, p=0.042, and p=0.024).

Conclusion:

Leukemia, bone marrow transplantation, and thrombocytopenia are risk factors for CVC-associated complications. The relatively higher number of interventions performed via permanent catheters may be responsible for the significantly increased incidence of systemic infections and mechanical injury.

Inherited Thrombophilia in Pediatric Venous Thromboembolic Disease: Why and Who to Test

Venous thromboembolic disease in childhood is a multifactorial disease. Risk factors include acquired clinical risk factors such as a central venous catheter and underlying disease and inherited thrombophilia. Inherited thrombophilia is defined as a genetically determined tendency to develop venous thromboembolism. In contrast to adults, acquired clinical risk factors play a larger role than inherited thrombophilia in the development of thrombotic disease in children. The contributing role of inherited thrombophilia is not clear in many pediatric thrombotic events, especially catheter-related thrombosis. Furthermore, identification of inherited thrombophilia will not often influence acute management of the thrombotic event as well as the duration of anticoagulation. In some patients, however, detection of inherited thrombophilia may lead to identification of other family members who can be counseled for their thrombotic risk. This article discusses the potential arguments for testing of inherited thrombophilia, including factor V Leiden mutation, prothrombin mutation, and deficiencies of antithrombin, protein C, or protein S and suggests some patient groups in childhood, which may be tested.

Neonatal Venous Thromboembolism

Neonates are the pediatric population at highest risk for development of venous thromboembolism (VTE), and the incidence of VTE in the neonatal population is increasing. This is especially true in the critically ill population. Several large studies indicate that the incidence of neonatal VTE is up almost threefold in the last two decades. Central lines, fluid fluctuations, sepsis, liver dysfunction, and inflammation contribute to the risk profile for VTE development in ill neonates. In addition, the neonatal hemostatic system is different from that of older children and adults. Platelet function, pro- and anticoagulant proteins concentrations, and fibrinolytic pathway protein concentrations are developmentally regulated and generate a hemostatic homeostasis that is unique to the neonatal time period. The clinical picture of a critically ill neonate combined with the physiologically distinct neonatal hemostatic system easily fulfills the criteria for Virchow's triad with venous stasis, hypercoagulability, and endothelial injury and puts the neonatal patient at risk for VTE development. The presentation of a VTE in a neonate is similar to that of older children or adults and is dependent upon location of the VTE. Ultrasound is the most common diagnostic tool employed in identifying neonatal VTE, but relatively small vessels of the neonate as well as frequent low pulse pressure can make ultrasound less reliable. The diagnosis of a thrombophilic disorder in the neonatal population is unlikely to change management or outcome, and the role of thrombophilia testing in this population requires further study. Treatment of neonatal VTE is aimed at reducing VTE-associated morbidity and mortality. Recommendations for treating, though, cannot be extrapolated from guidelines for older children or adults. Neonates are at risk for bleeding complications, particularly younger neonates with more fragile intracranial vessels. Developmental alterations in the coagulation proteins as well as unique pharmacokinetics must also be taken into consideration when recommending VTE treatment. In this review, epidemiology of neonatal VTE, pathophysiology of neonatal VTE with particular attention to the developmental hemostatic system, diagnostic evaluations of neonatal VTE, and treatment guidelines for neonatal VTE will be reviewed.

Lipoprotein (a) as a cause of cardiovascular disease: insights from epidemiology, genetics, and biology

Human epidemiologic and genetic evidence using the Mendelian randomization approach in large-scale studies now strongly supports that elevated lipoprotein (a) [Lp(a)] is a causal risk factor for cardiovascular disease, that is, for myocardial infarction, atherosclerotic stenosis, and aortic valve stenosis. The Mendelian randomization approach used to infer causality is generally not affected by confounding and reverse causation, the major problems of observational epidemiology. This approach is particularly valuable to study causality of Lp(a), as single genetic variants exist that explain 27-28% of all variation in plasma Lp(a). The most important genetic variant likely is the kringle IV type 2 (KIV-2) copy number variant, as the apo(a) product of this variant influences fibrinolysis and thereby thrombosis, as opposed to the Lp(a) particle per se. We speculate that the physiological role of KIV-2 in Lp(a) could be through wound healing during childbirth, infections, and injury, a role that, in addition, could lead to more blood clots promoting stenosis of arteries and the aortic valve, and myocardial infarction. Randomized placebo-controlled trials of Lp(a) reduction in individuals with very high concentrations to reduce cardiovascular disease are awaited. Recent genetic evidence documents elevated Lp(a) as a cause of myocardial infarction, atherosclerotic stenosis, and aortic valve stenosis.

Incidence Trends and Mortality from Childhood Venous Thromboembolism: A Population-Based Cohort Study

OBJECTIVE

To determine the incidence, incidence trend, and mortality of venous thromboembolism (VTE) in a general pediatric population during an 11-year period.

STUDY DESIGN

The administrative health care databases of the province of Québec, Canada were used to identify all children (ages 1-17 years inclusive) diagnosed with incident VTE between January 1, 1994 and December 31, 2004. The incidence rate and trend over the 11-year study period were then analyzed.

RESULTS

In total, 487 incident cases of pediatric VTE were documented. The age-standardized incidence rate was 0.29 VTE per 10 000 person-years (95% CI 0.26-0.31). Girls had a statistically significant higher incidence rate (per 10 000 person-years) than boys, 0.37 and 0.21 per 10 000 person-years, respectively, with an incidence rate ratio comparing females with males, adjusted for age group of 1.75 (95% CI 1.46-2.10). Trend analysis illustrated no statistically significant change in the age-standardized incidence rates. Overall all-cause mortality was 11.4 per 1000 children-years (95% CI 8.1-16.1).

CONCLUSIONS

Pediatric VTE is frequent, although its incidence is stable over time and all-cause mortality is lower than previously reported. Future studies that address possible sex and age group differences in the incidence of pediatric VTE are needed to help determine effective primary thromboprophylaxis strategies in children at high risk for VTE.

Pediatric antiphospholipid syndrome

Antiphospholipid syndrome (APS) is a multisystem autoimmune condition characterized by vascular thromboses associated with persistently positive antiphospholipid antibodies. There is currently a paucity of data (incidence, prevalence, thrombosis risk, and effective treatment) in pediatric APS. The purpose of this report is to review the current literature on APS in children and neonates, identify the gaps in current knowledge, and suggest avenues for studies to fill those gaps.

Phlegmasia cerulea dolens in a teenage boy found to have Factor V Leiden

A 16-year-old boy with morbid obesity and asthma presented with 1 week of progressive right leg pain, swelling and discolouration that started 1 week after a minor fall. Ultrasound and then CT with contrast revealed a large occlusive deep venous thrombosis (DVT) extending from the calf through the inferior vena cava bifurcation. Heparin was initiated and catheter-directed thrombolysis with tissue plasminogen activator and balloon angioplasty were performed with good flow postprocedure, however, the clot reaccumulated after several days and the procedure had to be repeated. After this occurred twice more, finally a right common iliac and femoral vein stent was placed to prevent clot reaccumulation and vein stenosis. Hypercoagability testing revealed activated protein C resistance and genetic testing confirmed homozygous Factor V Leiden (FVL). Family history was significant for maternal lower extremity DVT at age 21 and possible DVT in the patient's maternal grandmother.

Manifestations and clinical impact of pediatric inherited thrombophilia

The etiology of pediatric venous thromboembolic disease (VTE) is multifactorial, and in most children, 1 or more clinical risk factors are present. In addition, inherited thrombophilic disorders contribute to the development of pediatric VTE. In this review, the role of inherited thrombophilic disorders in the development of pediatric VTE, as well as the benefits and limitations of thrombophilia testing, will be discussed.

No impact of endogenous prothrombotic conditions on the risk of central venous line-related thrombotic events in children: results of the KIDCAT study (KIDs with Catheter Associated Thrombosis)

BACKGROUND AND OBJECTIVE

Central venous lines (CVLs) are the major exogenous risk factor for deep venous thrombosis (DVT) in children. The study objective was to assess whether endogenous prothrombotic conditions contribute to the risk of CVL-related DVT in children.

METHODS

This was a cohort study of consecutive children with heart disease requiring CVLs for perioperative care. CVLs were inserted percutaneously in the upper venous system and patients received prophylaxis with continuous unfractionated heparin (50 u kg(-1)  d(-1) ). Blood samples to test for prothrombotic conditions were collected prospectively and assayed in a blinded fashion. Outcome assessment was by screening for DVT by venography, venous ultrasound and echocardiography.

RESULTS

The study population consisted of 90 children, median age 2.7 years (0 months-18 years). Prevalence rates of antithrombin deficiency, protein C deficiency, protein S deficiency, heterozygous factor V Leiden, prothrombin G20210A mutation, methylentetrahydrofolate C677TT genotype, hyperhomocysteinemia, lupus anticoagulant, anticardiolipin antibodies and increased levels of lipoprotein (a) were within the range reported for the general population. At least one prothrombotic condition was present in 38% of children and combined abnormalities in 8%. The incidence of DVT was 28% (25/90), and most DVTs were asymptomatic. None of the prothrombotic conditions showed a significant association with DVT. The population attributable risk (i.e. the risk of DVT in the overall population attributable to a specific condition) did not exceed 2.2%.

CONCLUSION

Prothrombotic conditions did not have an important impact on the risk of DVT in children with short-term CVLs. The results of the study suggest that screening for prothrombotic conditions is not justified in this setting.

Postthrombotic syndrome following upper extremity deep vein thrombosis in children

Upper limb PTS in children depends on DVT pathogenesis (primary vs secondary) and on the age of the patient (neonates vs non-neonates). DVT pathogenesis and thrombus resolution are independent predictors of upper limb PTS in children.

Effort thrombosis (Paget-Schroetter syndrome) in a 16-year-old male

Patient: Male, 16

Final Diagnosis: Effort thrombosis (Paget-Schroetter Sydnrome)

Symptoms: Swollen arms

Medication: —

Clinical Procedure: —

Specialty: Metabolic Disorders and Diabetics

Assessment of the outcomes associated with periprocedural anticoagulation management in children with acute lymphoblastic leukemia

OBJECTIVE

To report the outcomes of an institutional protocol for periprocedural anticoagulant (AC) management in children with acute lymphoblastic leukemia (ALL).

STUDY DESIGN

Children being treated for ALL who received full-dose (therapeutic) anticoagulation before undergoing at least 1 lumbar puncture (LP) were included in this retrospective cohort study. The main outcome was the risk of traumatic LP; exploratory analysis included the risks of symptomatic spinal hematoma and progression/recurrence of the thrombotic event. Analyses were conducted using logistic regression analysis with a generalized estimating equation approach.

RESULTS

Twenty-two children with ALL receiving an AC underwent a total of 396 LPs. Although traumatic LP was associated with full-dose AC therapy in univariable analysis, a multiple logistic regression model controlling for other risk factors for traumatic LP showed that AC therapy was not significantly associated with the risk of traumatic LP when the ACs were held as per the institutional protocol. No patient developed symptomatic spinal hematoma. Exploratory analysis revealed that AC dose, a likely marker of thrombus burden, was significantly associated with progression/recurrence of the thrombotic event in univariable analysis.

CONCLUSION

In our cohort, recent AC therapy was not statistically associated with an increased risk of bleeding after LP when following a specific protocol for periprocedural AC management. The risk associated with the progression/recurrence of thromboembolic events requires further evaluation.

Pediatric thrombophilia

Pediatric thrombosis and thrombophilia are increasingly recognized and studied. In this article, both the inherited and acquired factors for the development of thrombosis in neonates and children are categorized using the elements of Virchow's triad: stasis, hypercoagulable state, and vascular injury. The indications and rationale for performing thrombophilia testing are described. Also included are discussions on who, how, when, and why to test. Finally, recommendations for the use of contraceptives for adolescent females with a family history of thrombosis are outlined.

Catheter-related thrombosis in cancer patients

Central venous catheters are commonly used in haematology departments for the administration of chemotherapy, blood products and parenteral nutrition in patients with haematological malignancy. Thrombosis is a recognized complication of such devices especially in oncology patients. Catheter-related thrombi (CRT) may lead to pulmonary embolism and infection, as well as catheter failure and potential delays in treatment. The vast majority of CRT are asymptomatic, thus a high index of suspicion is required in making the diagnosis. Doppler ultrasound or venography may be employed to identify CRT. Once confirmed, the initiation of treatment is a balance between the risks of anticoagulation against potential complications of CRT. A number of risk factors for CRT are discussed along with an overview of catheter types, their appropriate choice and intravascular positioning.

The impact of quality and duration of enoxaparin therapy on recurrent venous thrombosis in children

BACKGROUND

Venous thromboembolism (VTE) and recurrent venous thromboembolism (rVTE) are rare, but significant problems in pediatrics. Current recommendations for anticoagulant therapy arise from adult literature, and there is little data on clinical outcomes following therapeutic low-molecular-weight heparin in children.

METHOD

All patients <19 years of age that were diagnosed with a VTE or right atrial thrombus via standard imaging methods at St. Jude Children's Research Hospital were retrospectively identified from January 2004 through August 2008. Demographic characteristics, coexisting clinic conditions, description of anticoagulant therapy, and record of rVTE were chronicled following a comprehensive chart review. Descriptive statistics of clinical characteristics and anticoagulation are presented.

RESULTS

Venous thrombosis was identified in 149 children with 21% (31/149) developing a rVTE. Coexisting clinical conditions were identified in 93% of children at initial diagnosis with 48% (71/149) of patients having a coexisting malignancy. Seventy-seven percent (114/149) of children received anticoagulant therapy with UFH (10/114) or enoxaparin (104/114). Neither duration of enoxaparin therapy (>6, 3-6, <3 months) (P = 0.61), nor quality of therapy (≥75% of time on anticoagulation spent with an anti-FXa of 0.5-1.0 U/ml) (P = 1.0) were found to be protective against rVTE.

CONCLUSION

Anticoagulation with enoxaparin based on adult literature may be suboptimal in preventing rVTE in pediatric populations. Future prospective randomized controlled trials in pediatrics using clinical outcomes with anticoagulant therapy are urgently needed.

Thrombosis risk factor assessment and implications for prevention in critically ill children

OBJECTIVES

To describe nursing compliance with a computer-based pediatric thrombosis risk assessment tool; to generate an estimate of risk factors present in our population; and to explore relationships between risk factors and confirmed thrombotic events.

DESIGN

Institutional review board-approved prospective, observational cohort study.

SETTING

Pediatric intensive care unit within a tertiary care children's hospital.

PATIENTS

All infants and children admitted to the pediatric intensive care unit during a 6-month study period (January 1, 2010-June 30, 2010).

MEASUREMENTS AND MAIN RESULTS

Eight hundred admissions were enrolled, representing 742 patients. Thrombosis risk assessment scores were recorded for 707 admissions (88% of total). Mean age = 6.95 ± 6 yrs, mean weight = 28 ± 23 kg, 45% female. A total of 32 thrombi (14 prehospital and 18 in-hospital) were present in the study group. This translated to an overall occurrence rate of 4.3% (1.9% for prehospital and 2.4% for in-hospital). Logistic regression identified that for every 1-point increase in total thrombosis score, the risk of developing a symptomatic thrombus increased by 1.57-fold (95% confidence interval 0.192-5.5) to 2.12-fold (95% confidence interval 0.175-18.34), for prehospital and in-hospital thrombi, respectively (p < .05). The most important risk factors identified for development of any thrombus were thrombophilia (acquired or inherited) (p < .001), presence of a central catheter (p = .01), and age <1 or >14 yrs (p = .052).

CONCLUSIONS

Incorporation of a scoring system into the bedside nursing assessment flow sheet was successful and identified children at risk for in-hospital thrombosis. The overall score appears to be most indicative of thrombus risk. These data may serve as a platform for future development of routine screening and possible interventional trials in critically ill children.

Hematology and Oncology in Critical Illness

This chapter will focus on a variety of hematologic issues pertinent to the care of critically ill children. This is an area of intense research with the pathophysiology underlying these clinical conditions becoming progressively better understood. This improved understanding has resulted in new therapeutic strategies that are being assessed in multicenter clinical trials. The chapter will begin by describing the incidence and pathophysiologic significance of anemia in the pediatric intensive care unit (PICU) providing a differential diagnosis of the many conditions that may present with anemia in this setting. The chapter will next consider disseminated intravascular coagulation (DIC) focusing on the pathophysiology of a condition that has been associated with much morbidity and mortality. The underlying conditions predisposing to DIC will be detailed as well as a number of treatment options that have been implemented in clinical trials. In addition to DIC, thrombocytopenia may be caused by a number of other clinical conditions important to the pediatric critical care provider. The clinical and prognostic significance of thrombocytopenia will be addressed and a focused differential diagnosis will be provided. Thrombotic disorders are becoming increasingly recognized in children and are a particular concern for the pediatric intensivist. The epidemiology of thromboembolism in children will be reviewed focusing on the conditions most commonly associated with these thromboses. Finally, a chapter on hematologic issues in the critically ill child would not be complete without a discussion of sickle cell disease. Acute chest syndrome, one of the most frequent complications of sickle cell disease resulting in the need for intensive care services, will be discussed in detail.

Thrombophilia testing in neonates and infants with thrombosis

In neonates and infants with idiopathic venous thrombosis (VTE) and in pediatric populations in which thromboses were associated with medical diseases, inherited thrombophilia (IT) have been described as risk factors. Follow-up data for VTE recurrence in neonates suggest a recurrence rate between 3% in provoked and 21% in idiopathic VTE. Apart from underlying medical conditions, recently reported systematic reviews on pediatric VTE have shown significant associations between factor V G1691A, factor II G20210A, and deficiencies of protein C, protein S and antithrombin, even more pronounced when combined IT were involved. Independent from the age at first VTE onset, the pooled odds ratios (OR: single IT) for VTE ranged from 2.4 for the factor II G20210A mutation to 9.4 in neonates and infants with antithrombin deficiency. The pooled OR for persistent antiphospholipid antibodies/lupus anticoagulants was 4.9 for pediatric patients with venous VTE. The factor II G20210A mutation (OR: 2.1), and deficiencies of protein C (OR: 2.4), S (OR: 3.1) and antithrombin (OR: 3.0) also played a significant role at recurrence. Based on these data, screening and treatment algorithms must be discussed.

Neonatal portal vein thrombosis: diagnosis and management

Neonatal portal vein thrombosis (PVT) is an increasingly recognized event. Patients are generally asymptomatic in the neonatal period. The diagnosis is made with Doppler ultrasound. Umbilical catheterization, exchange transfusion and sepsis are risk factors for neonatal PVT. Thrombophilia is possibly a contributing risk factor. Although there are potential serious acute complications such as hepatic necrosis, the outcome is good in the majority of cases, followed up to 8 years of age. Thrombus resolution occurs in 30-70% in days to months. Liver lobe atrophy may occur following PVT, and does not appear to be associated with any impairment of liver function. Non-occlusive thrombosis is more likely to resolve than non-occlusive thrombosis. A subset of patients without resolution is at risk for developing portal hypertension over the next decade of life. There are no current defining features present during the neonatal period to enable identification of neonates at risk for portal hypertension. There is no evidence that anticoagulation therapy improves time to resolution or decreases the likelihood of portal hypertension. Anticoagulation therapy may be considered. A management algorithm is proposed.

Sonography of renal venous thrombosis in neonates and infants: can we predict outcome?

BACKGROUND

The relationship between sonographic features of renal venous thrombosis (RVT) and outcome has not been described in a large series of patients.

OBJECTIVE

To analyze sonographic findings of RVT and their evolution in a large series of patients and to attempt to identify features that might predict outcome.

MATERIALS AND METHODS

Retrospective analysis of sonograms and medical records of neonates and infants diagnosed with RVT during the period 1998-2007.

RESULTS

Of 22 children (mean age: 3 days; age range: 0-107 days), RVT was bilateral in 12. Of 34 affected kidneys, thrombus in the main renal vein was seen in 17 and typical RVT sonographic findings without main renal vein thrombus were seen in the remaining 17. All children had US follow-up (range: 0.6-97.2 months). Three children with bilateral RVT died. Nine kidneys atrophied. Imaging findings associated with subsequent kidney atrophy included markedly reduced perfusion at diagnosis, subcapsular collections, patchy cortical echotexture and profoundly hypoechoic and irregular renal pyramids. Six patients (eight kidneys) presented with renal calcifications on initial sonogram before 7 days of life, suggesting antenatal RVT.

CONCLUSION

Sonography is useful in neonatal and early infant RVT and might help predict renal atrophy. Antenatal RVT appears to be relatively common.

Risk factors for central venous catheter thrombotic complications in children and adolescents with cancer

BACKGROUND

The use of central venous catheters (CVCs) has greatly improved the quality of care in children with cancer, yet these catheters may cause serious infectious and thrombotic complications. The aim of this prospective registry study was to assess the host and CVC-related risk factors for CVC-created thrombotic complications.

METHODS

Patients undergoing CVC insertion for chemotherapy were followed prospectively for CVC complications. At the time of enrollment, demographic, clinical, and CVC-related data, and family history of thrombosis were collected. Survival and Cox regression analyses were performed.

RESULTS

A total of 423 CVCs were inserted into 262 patients for a total of 76,540 catheter days. The incidence of CVC-related deep-vein thrombosis (DVT) was 0.13 per 1000 catheter-days (95% confidence interval [CI], 0.06-0.24). Insertion of peripherally inserted central catheters (PICCs) and insertion in an angiography suite significantly increased the risk of symptomatic CVC-related DVT. The incidence of CVC occlusion was 1.35 per 1000 catheter-days (95% CI, 1.1-1.63). Positive family history of thrombosis significantly increased the risk of CVC occlusion (hazard ratio [HR], 2.16; 95% CI, 1.2-3.8). The CVC-related risk factors were insertion of Hickman catheters, insertion in angiography suite, and proximal-tip location. Patients developing at least 1 episode of both CVC occlusion and infection had an increased risk for developing symptomatic CVC-related DVT (HR, 4.15; 95% CI, 1.2-14.4).

CONCLUSIONS

Both patient-related and CVC-related factors are associated with higher risk of symptomatic thrombotic complications. These risk factors could be used in the clinical setting and in developing future studies for CVC thromboprophylaxis.