Thrombophilia in children with venous thromboembolic disease

Inferior vena cava atresia predisposing to acute lower extremity deep vein thrombosis in children: A descriptive dual-center study

PURPOSE

Thrombosis in the healthy pediatric population is a rare occurrence. Little is known about the optimal treatment or outcomes of children with unprovoked acute lower extremity (LE) deep vein thrombosis (DVT) associated with atresia of the inferior vena cava (IVC).

METHODS

We retrospectively analyzed the records of patients with acute LE DVT subsequently found to have IVC atresia who presented to two tertiary pediatric institutions between 2008 and 2016. Data were reviewed for thrombophilia risk factors, treatment, and outcomes.

RESULTS

Eighteen patients, aged 13-18 years (median: 16 years), presenting with acute LE DVT were found to have IVC atresia. Three patients also presented with pulmonary embolism. Fourteen patients underwent site-directed thrombolysis in addition to anticoagulation. Five patients (28%) had confirmed or suspected recurrent thrombosis. Thirteen patients (72%) had no identified provocation for DVT. Ten patients (56%) had post-thrombotic syndrome, and 17 of 18 patients remain on indefinite anticoagulation.

CONCLUSION

This study suggests that IVC atresia is a risk factor for LE DVT and pulmonary embolism in otherwise healthy children and highlights the importance of dedicated imaging of the IVC in young patients with unprovoked LE DVT. Indefinite anticoagulation may be considered in pediatric patients presenting with unprovoked thrombosis secondary to an atretic IVC.

Thrombophilia testing in children: a 7 year experience

BACKGROUND

Incidence of venous thromboembolism (VTE) in children is reported to be increasing. We examined thrombophilia testing results in children with VTE that presented in inpatient and outpatient settings to explore patterns of thrombophilia testing.

PATIENTS/METHODS

Children, ages 0-20 years with VTE seen at our institution from Jan 2005 to Apr 2012 were studied retrospectively. All patients with VTE confirmed by imaging were eligible and the presence of significant risk factors was evaluated. Thrombophilia was diagnosed if >1 tests confirmed: persistently low protein C (PC), protein S (PS), and antithrombin (AT) following VTE resolution, persistent antiphospholipid antibodies (APA) positivity >12 weeks from first test, factor V Leiden (FVL) and prothrombin mutation (PTm) hetero- or homozygosity, elevated plasminogen activator inhibitor (PAI-1) levels with 4G/5G or 4G/4G polymorphisms, methylene tetrahydrofolate reductase (MTHFR) polymorphisms with elevated fasting homocysteine levels.

RESULTS

Three hundred ninety-two patients met inclusion criteria. At least one test was ordered in 157/239 inpatients. All 153 outpatients had >1 test ordered. Thrombophilia rate differences between inpatients and outpatients did not reach statistical significance except for PC deficiency, which was significantly higher in outpatients. Of inpatients, central venous line (CVL) was significantly associated with not having tests done (P < 0.0022).

CONCLUSIONS

This study of pediatric VTE demonstrated a low thrombophilia rate in both inpatient and outpatient populations. The role of testing in other pediatric patients should be further explored.

Bleeding and Thrombotic Emergencies in Pediatric Cardiac Intensive Care

Children in the cardiac intensive care unit (CICU) with congenital or acquired heart disease are at risk for hematologic complications, both hemorrhage and thrombosis. The overall incidence of hematologic complications in the CICU is unknown, but risk factors and target groups have been identified where the essential physiologic balance between bleeding and clotting has been disrupted. Although the best management of life-threatening bleeding and clotting is prevention, the cardiac intensivist is often faced with managing life-threatening hematologic events involving patients from within the unit or those who present from outside. Part I of this review deals with the propensity of children with congenital and acquired heart disease to complications of both bleeding and clotting, and includes discussions of perioperative bleeding, thromboses in single-ventricle patients, clotting of Blalock-Taussig shunts and thrombotic complications of mechanical valves. Part II deals with the subject of stroke in children with heart disease. Part III reviews monitoring the effectiveness of anticoagulation and thrombolysis in the CICU. Currently available diagnostics modalities, medications and management strategies are reviewed and future directions discussed.

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.

Diagnosis and management of central-line-associated thrombosis in newborns and infants

Although the use of central lines has many valuable applications in neonates and infants, they may cause serious mechanical, infectious and thrombotic complications. In fact, the use of central lines is the main cause for thrombosis in this age group. The frequency of central-line-related thrombosis in neonates and infants is reported to be as low as 1% when including only symptomatic cases, around 44% when systematically screened for thrombosis, and as high as 65% in autopsy studies. The risk factors for line-related thrombosis in neonates and infants include those associated with the underlying medical conditions, the duration of the line in situ, the placement of the umbilical artery catheter and the therapy used through the line. The contribution of inherited and acquired thrombophilia to central-line-related thrombosis is controversial, and the data are not sufficiently consistent to make a firm recommendation for thrombophilia screening for neonates and infants with central-line-related thrombosis. Most experts will recommend pursuing a thrombophilia work-up in the setting of a significant thrombosis event and will recommend avoiding thrombophilia work-up in subclinical and asymptomatic central-line-related thrombosis. The management of line-related thrombosis is based on expert opinion guidelines and is largely dependent on the type of the catheter and the further requirement of the catheter. Continuous heparin infusion through the central lines prevents catheter occlusion, but has no effect on occurrence of thrombosis. Currently no definitive recommendations exist for thromboprophylaxis in children, infants and neonates with central lines.

Successful pulmonary embolectomy in a 4-year-old girl with antithrombin III deficiency

We report the case of a 4-year-old girl, successfully treated by surgical pulmonary embolectomy for acute massive pulmonary embolism. She was known to have a congenital antithrombin III deficiency diagnosed after a familial history of thromboembolic events. Surgical embolectomy may be considered as a treatment option in selected patient with anatomically extensive pulmonary embolism.

Aspects of anticoagulation in children

The number of children receiving anticoagulation is increasing. Thromboembolic events are associated with significant risk of morbidity and mortality although the optimal management of asymptomatic events remains unclear. Specific challenges in paediatrics include the diagnosis of thrombosis, delivery and monitoring of anticoagulation in a wide range of ages from neonates through to adolescents. The development of the haemostatic system as children age results in changing pathophysiology of thrombosis and response to anticoagulation agents. Although registry and observational studies have provided vital information, specific paediatric, prospective anticoagulation studies have been few and limited in design. The result is that much of current practice is extrapolated from adult studies. Traditional anticoagulants have significant limitations. Both heparin and warfarin are in widespread use but many fundamental questions regarding dose, therapeutic range, efficacy and optimum duration have not been fully answered. Alternative agents, such as direct thrombin inhibitors and the selective anti-factor Xa inhibitor fondaparinux, may have advantages for children. Clinical trials in adults and preliminary data in children are promising but caution should be applied until specific paediatric studies have demonstrated safety and efficacy.

Thrombosis in the pediatric population

Whereas thrombotic events in critically ill children do not occur as commonly as in adults, they are being recognized with increasing frequency in the pediatric intensive care unit. The reasons for this are not clear but likely include an increased awareness of the problem and the ability to make a diagnosis using relatively noninvasive tests. In this section, I attempt to define the extent of the problem, summarize and discuss the relevant literature (pointing out where published experience in the pediatric population differs from that in adult patients), and suggest some guidelines regarding thrombophilia treatment and the management of thrombotic events.

Thrombophilic conditions in the adolescent: the gynecologic impact

As Virchow's triad suggests, a fine balance exists between the vascular wall, intravascular contents, and dynamic blood flow, such that a shift in this balance predisposes to thrombosis. Although thromboembolic events (TEs) are relatively infrequent in adolescents, the morbidity and mortality associated with TEs can be significant. Over the past 15 years, TEs and inherited and acquired thrombophilic conditions underlying them have become increasingly recognized in teens at risk, with combined hormonal contraception constituting one of the most significant of these risk factors. Therefore, managing gynecologic problems in teens who have thrombophilic conditions can be challenging. It is important to have a clear understanding about safe options available to help address adolescent gynecologic concerns in this setting and to manage situations collaboratively with a hematologist.

Testing children for inherited thrombophilia: more questions than answers

Thrombotic events in children have become an increasingly common problem, particularly in paediatric tertiary care hospitals. The prevalence of inherited thrombophilia in children who develop thrombosis varies substantially depending on the population. Children who develop thrombosis, as well as those who have not but have a positive family history, are frequently tested for inherited thrombophilia. The clinical utility of performing such tests has been questioned, in both adults and children. This review will examine the practise of testing for inherited thrombophilia in children, focusing on the rationale for testing and highlighting areas in which more evidence is needed prior to making strong recommendations. Future studies, many of which are currently being performed or proposed, are necessary to address many of the unanswered questions.

Pylephlebitis due to perforated appendicitis in a teenager

Pylephlebitis, a septic thrombophlebitis of the portal vein, is a life-threatening complication of intraabdominal infections, commonly associated with acute appendicitis in children, and diverticulitis in adults. A 13-year-old boy was admitted for high fever and jaundice. On the fifth day of hospitalization, ultrasound Doppler flow and Computer Tomography scan studies showed thrombosis of the portal vein and acute appendicitis. The patient was treated with antibiotics, anticoagulation and laparotomy with appendectomy. No thrombophilic risk factors were diagnosed. Our aim is to improve physicians' awareness of this complication and emphasize the importance of early diagnosis and appropriate therapy in children in order to reduce serious complications and long-term sequels.

Current practice perspectives on the management of thrombosis in children with renal insufficiency: the results of a survey of pediatric hematologists in North America

BACKGROUND

No guidelines exist for the management of venous thromboembolic events (VTE) in children with renal insufficiency (RI).

OBJECTIVE

To define current practice patterns of VTE management in children with RI.

METHODS

An online multiple choice survey encompassing general questions/clinical scenarios related to thrombosis in RI.

STUDY PARTICIPANTS

Pediatric hematologists who were members of Hemophilia and Thrombosis Research Society (HTRS) of North America.

RESULTS

Response rate was 54% (39/75). VTE was perceived as the major hemostatic problem in children with RI by half (20/39) of respondents. All respondents used anticoagulation for treatment of VTE while 56% used it for prophylaxis of VTE in this population. Management practices varied with respect to choice of anticoagulants employed, consideration of prophylactic anticoagulation, and evaluation for hereditary thrombophilia. Low molecular weight heparin was perceived as a safe anticoagulation for VTE treatment by 77% of respondents given that anti-factor Xa monitoring was performed to assess bioaccumulation in RI. Thromboprophylaxis was considered for preventing thrombosis at central venous catheter, renal allo-graft and arterio-venous fistula in the context of previous history of thrombosis and congenital/acquired thrombophilia. The majority (>70%) would treat life-threatening emergencies such as superior vena cava syndrome with fibrinolytics despite RI.

CONCLUSIONS

This pediatric study documents that substantial variability existed among pediatric hemologists with respect to VTE management in children with RI. Larger studies are required to better define the epidemiology and management of VTE in children with RI including the value of screening for underlying hereditary thrombophilia.

Thrombophilia in Children: Who to Test, How, When, and Why?

Thrombosis and thrombotic risk factors in children are receiving increased attention, and pediatric hematologists frequently are asked to evaluate children with symptomatic thrombosis, or asymptomatic children who have relatives affected with either thrombosis or thrombophilia. The clinical utility of thrombophilia testing has become increasingly debated, both in adults and children. Children with thrombosis are a heterogeneous group, and it is unlikely that a single approach to testing or treatment is optimal or desirable. A causative role of inherited prothrombotic defects in many pediatric thrombotic events, particularly catheter-related thrombosis, has not been established. Pediatric patients most likely to benefit from thrombophilia testing include adolescents with spontaneous thrombosis and teenage females with a known positive family history who are making choices about contraception. Recent data suggest that some inherited thrombophilic defects are associated with a higher risk of recurrent venous thromboembolism in children, though optimal management of these patients has yet to be determined. The decision to perform thrombophilia testing in asymptomatic patients with a family history should be made on an individual basis after discussion with the family. Given that the field of pediatric thrombosis continues to evolve, and the settings in which many of these events occur are unique to childhood, prospective longitudinal analyses of such patients to determine outcome and response to treatment as well as the impact of known thrombophilic states on these outcomes are clearly needed.

Thrombophilia screening in asymptomatic children

Children with a family history of thrombophilia and/or thrombosis are often referred to pediatric thrombosis centers for evaluation. This article reviews the risks and benefits of thrombophilia testing in this unique population. The article also reviews an approach to testing including a step-wise evaluation and involvement of a genetic counselor.

Evaluation of the Coagulation System in Children with Two-Ventricle Congenital Heart Disease

BACKGROUND

Multiple coagulation factor abnormalities involving both procoagulant and anticoagulant proteins have been described in children with single-ventricle physiology. This study used age-matched controls to evaluate coagulation factors in children with two-ventricle congenital heart disease (CHD).

METHODS

Coagulation factors were assayed in 120 patients with CHD, divided into four age groups: group 1, 0 to 3 months; group 2, 3 to 12 months; group 3, 12 to 48 months; and group 4, older than 48 months. Healthy children without CHD were assayed as controls. Concentration of factors II, V, VII, VIII, IX, and X; protein C and S, plasminogen, and antithrombin III, were measured by standard assays. Normal ranges were determined by the empirical 95% confidence intervals.

RESULTS

Significant reductions were found in mean levels of both procoagulant and anticoagulant factors in patients in groups 1, 2, and 3 compared with controls, but no differences were found in group 4. In group 1, all variables had significantly lower concentrations except fibrinogen and protein S; in group 2, all variables had significantly lower concentrations except for fibrinogen, factors VIII and IX, and plasminogen and protein S; and in group 3, all variables had significantly lower concentrations except fibrinogen, factors VIII and IX, and antithrombin III, plasminogen, and protein S.

CONCLUSIONS

Neonates and infants with two-ventricle CHD have lower levels of procoagulant and anticoagulant factors compared with aged-matched controls approaching normal levels in children aged older than 4 years. These coagulation factor abnormalities are similar to those described in patients with single-ventricle physiology.