Factor V Leiden, protein C, and lipoprotein (a) in catheter-related thrombosis in childhood: a prospective study

Prenatal and Neonatal Pulmonary Thrombosis as a Potential Complication of SARS-CoV-2 Infection in Late Pregnancy

Neonatal venous thrombosis is a rare condition that can be iatrogenic or occur due to viral infections or genetic mutations. Thromboembolic complications are also commonly observed as a result of SARS-CoV-2 infections. They can affect pediatric patients, especially the ones suffering from multisystem inflammatory syndrome in children (MIS-C) or multisystem inflammatory syndrome in neonates (MIS-N). The question remains whether the maternal SARS-CoV-2 infection during pregnancy can lead to thromboembolic complications in fetuses and neonates. We report on a patient born with an embolism in the arterial duct, left pulmonary artery, and pulmonary trunk, who presented several characteristic features of MIS-N, suspecting that the cause might have been the maternal SARS-CoV2 infection in late pregnancy. Multiple genetic and laboratory tests were performed. The neonate presented only with a positive result of IgG antibodies against SARS-CoV-2. He was treated with low molecular weight heparin. Subsequent echocardiographic tests showed that the embolism dissolved. More research is necessary to evaluate the possible neonatal complications of maternal SARS-CoV-2 infection.

Neonatal thrombosis

Neonatal thromboembolism in pediatric patients is a rare but life-threatening condition mainly caused by combinations of at least 2 prothrombotic triggering risk factors such as the central venous lines, septic condition, and prematurity. Other risk factors include asphyxia, dehydration, liver dysfunction, inflammation, and maternal condition. Neonatal hemostatic system is different from one of the older children and adults. Coagulation proteins do not cross the placenta but are synthesized in the fetus from an early stage. In the term neonate, concentrations of several procoagulant proteins, particularly the vitamin K dependent and contact factors are reduced when compared with adults. Conversely, levels of antithrombin, heparin cofactor II and protein C and S are low at birth and fibrinolysis system is characterized by the decreased level of plasminogen and alpha-1-antiplasmin, increased tissue plasminogen activator. These features all tend to be gestational dependent and are more present in the preterm infant. Primarily in this context neonates appear to be at a higher risk of thrombosis than older children. Thrombotic complications reach their peak in the group of children born at 22-27 weeks. The role of inherited thrombophilic risk factors in neonatal VTE development is poorly defined. The presence of inherited and acquired thrombophilia in mother and newborn is also responsible for the development of thrombosis in neonates and should be considered. Thrombophilia in the mother can lead to increased coagulation potential and prethrombotic conditions during pregnancy, causing thrombotic vasculopathy at the placental level. The benefit of identifying thrombophilia in the sick preterm newborns who are in the group of risk for development of thrombotic complications may facilitate the thromboprophylaxis. Further research regarding assessment of risk factors, diagnostics and treatment strategy is required.

Management of Extremity Venous Thrombosis in Neonates and Infants: An Experience From a Resource Challenged Setting

We aimed to evaluate the outcome of different treatment modalities for extremity venous thrombosis (VT) in neonates and infants, highlighting the current debate on their best tool of management. This retrospective study took place over a 9-year period from January 2009 to December 2017. All treated patients were referred to the vascular and pediatric surgery departments from the neonatal intensive care unit. All patients underwent a thorough history-taking as well as general clinical and local examination of the affected limb. Patients were divided into 2 groups: group I included those who underwent a conservative treated with the sole administration of unfractionated heparin (UFH), whereas group II included those who were treated with UFH plus warfarin. Sixty-three patients were included in this study. They were 36 males and 27 females. Their age ranged from 3 to 302 days. Forty-one (65%) patients had VT in the upper limb, whereas the remaining 22 (35%) had lower extremity VT. The success rate of the nonsurgical treatment was accomplished in 81% of patients. The remaining 19% underwent limb severing, due to established gangrene. The Kaplan-Meier survival method revealed a highly significant increase in both mean and median survival times in those groups treated with heparin and warfarin compared to heparin-only group ( P < .001). Nonoperative treatment with anticoagulation or observation (ie, wait-and-see policy) alone may be an easily applicable, effective, and a safe modality for management of VT in neonates and infants, especially in developing countries with poor or highly challenged resource settings.

Inferior Petrosal Sinus Thrombosis in a Child due to Malposition of Central Venous Catheter: A Case Report

OBJECTIVE

To report a case of inferior petrosal sinus thrombosis associated with malposition of central venous catheterization (CVC).

CLINICAL PRESENTATION AND INTERVENTION

A 5-month-old boy was admitted to Şifa University Hospital because of pneumonia. When exophthalmos occurred in the right eye, he was referred to Ege University Hospital. Cranial magnetic resonance imaging and magnetic resonance venography confirmed that the catheter in the right inferior petrosal sinus caused the thrombosis. The catheter was extracted and anticoagulant treatment was started.

CONCLUSION

In this case report, malpositioning of the CVC was the cause of the thrombosis. To minimize such complications, catheterization should be done with the supervision of an expert and postprocedure radiography should also be performed.

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.

Association of thrombophilia and catheter-associated thrombosis in children: a systematic review and meta-analysis

Essentials It is unclear if thrombophilia increases the risk of catheter-associated thrombosis in children. We conducted a meta-analysis on thrombophilia and pediatric catheter-associated thrombosis. Presence of ≥1 trait confers additional risk of venous thrombosis in children with catheters. Limitations of included studies preclude us from recommending routine thrombophilia testing.

SUMMARY

Background The association between thrombophilia and deep vein thrombosis (DVT) associated with central venous catheter (CVC) use, the most important pediatric risk factor for thrombosis, is unclear in children. Pediatric studies with small sample sizes have reported conflicting results. We sought to evaluate whether, among children with CVCs, thrombophilia increases the risk of CVC-associated DVT (CADVT). Materials and methods We systematically searched MEDLINE, EMBASE, the Web of Science, the Cochrane Central Register for Controlled Trials, PubMed and reference lists for controlled studies published from the inception of the database until September 2015. Included were studies of children aged <21 years with CVCs who were systematically tested for thrombophilic traits that are commonly screened for in clinical practice. Pooled prevalence rates and pooled odds ratios (pORs) of CADVT with thrombophilia were estimated by use of a random effects model. Results We analyzed 16 cohort studies with 1279 children, 277 of whom had CADVT, and with 12 traits tested. There was significant heterogeneity in the included studies. The presence of one or more traits was associated with CADVT (pOR 3.20; 95% confidence interval [CI] 1.56-6.54). Although the prevalence of most traits was < 0.10, children with protein C deficiency, elevated factor VIII levels and the FV Leiden mutation had an increased prevalence of CADVT. The association with thrombophilia seemed to be stronger for symptomatic CADVT (pOR 6.71; 95% CI 1.93-23.37) than for asymptomatic CADVT (pOR 2.14; 95% CI 1.10-4.18). Conclusions On the basis of the low prevalence of specific traits, the relatively weak association with CADVT, and the limitations of the included studies, we cannot recommend routine testing of thrombophilias in children with CADVT.

Clinical Data of Neonatal Systemic Thrombosis

OBJECTIVE

To evaluate clinical data and associated risk conditions of noncerebral systemic venous thromboembolism (VT), arterial thromboembolism (AT), and intracardiac thromboembolism (ICT) in neonates.

STUDY DESIGN

Data analysis of first systemic thromboembolism occurring in 75 live neonates (0-28 days), enrolled in the Italian Registry of Pediatric Thrombosis from neonatology centers between January 2007 and July 2013.

RESULTS

Among 75 events, 41 (55%) were VT, 22 (29%) AT, and 12 (16%) ICT; males represented 65%, and 71% were preterm. In 19 (25%), thromboembolism was diagnosed on the first day of life. In this "early onset" group, prenatal-associated risk conditions (maternal/placental disease) were reported in 70% and inherited thrombophilia in 33%. Postnatal risk factors were present in 73%; infections and central vascular catheters in 56% and 54% VT, respectively, and in 67% ICT vs 27% AT (<.05). Overall mortality rate was 15% and significant thromboembolism-related sequelae were reported in 16% of discharged patients.

CONCLUSIONS

This report from the Registro Italiano Trombosi Infantili, although limited by representing an uncontrolled case series, can be used to develop future clinical trials on appropriate management and prevention of neonatal thrombosis, focusing on obstetrical surveillance and monitoring of critically ill neonates with vascular access. A thrombosis risk prediction rule specific for the neonatal population should be developed through prospective controlled studies.

Thrombosis in the Neonatal Intensive Care Unit

Neonates have the highest risk for pathologic thrombosis among pediatric patients. A combination of genetic and acquired risk factors significantly contributes to this risk, with the most important risk factor being the use of central venous catheters. Proper imaging is critical for confirming the diagnosis. Despite a significant number of these events being life- and limb-threatening, there is limited evidence on what the appropriate management strategy should be. Evaluation and treatment of any neonate with a clinically significant thrombosis should occur at a tertiary referral center that has proper support.

Prevalence of post-thrombotic syndrome after cardiac catheterization

BACKGROUND

As the survival of children with cardiac disease increases, chronic complications of deep venous thrombosis from cardiac catheterization, particularly post-thrombotic syndrome, may be important to monitor for and treat, if needed. We aimed to determine the prevalence of this syndrome in children who underwent cardiac catheterization.

PROCEDURE

We conducted a cross-sectional study of children <18 years old at least 1 year from first catheterization through the femoral vein. We used the Manco-Johnson instrument, the only tool validated in children, to diagnose post-thrombotic syndrome. We defined the syndrome as a score ≥ 1. It was considered physically and functionally significant if the score was ≥ 1 in both physical and functional domains of the instrument. We also conducted ultrasonography to assess for thrombosis and valvular insufficiency.

RESULTS

We enrolled 62 children with a median age of 4 months during catheterization and a median of 5.4 years since catheterization. A total of 40 children had post-thrombotic syndrome (prevalence: 64.5%; 95% confidence interval: 51.3-76.3%), the majority of which were mild. Presence of cyanotic congenital heart disease, total number of catheterizations, use of antithrombotic agents at any time after the first catheterization, age at first catheterization, or time since first catheterization was not associated with the syndrome. A total of seven children (prevalence: 11.3%; 95% confidence interval: 3.2-19.4%) had physically and functionally significant syndrome. None of the children had abnormalities on ultrasonography at the time of enrollment.

CONCLUSIONS

Post-thrombotic syndrome is a common complication after cardiac catheterization. Manifestations are usually mild and unlikely to require treatment.

Central venous catheter-related thrombosis and thromboprophylaxis in children: a systematic review and meta-analysis

OBJECTIVES

In preparation for a pediatric randomized controlled trial on thromboprophylaxis, we determined the frequency of catheter-related thrombosis in children. We also systematically reviewed the pediatric trials on thromboprophylaxis to evaluate its efficacy and to identify possible pitfalls in the conduct of these trials.

PATIENTS/METHODS

We searched MEDLINE, EMBASE, Web of Science and the Cochrane Central Register for Controlled Trials for articles published until December 2013. We included cohort studies and trials on patients aged 0-18 years with central venous catheters who underwent active surveillance for thrombosis with radiologic imaging. We estimated the pooled frequency of thrombosis and the pooled risk ratio (RR) with thromboprophylaxis by using a random effects model.

RESULTS

From 2651 articles identified, we analyzed 37 articles with 3128 patients. The pooled frequency of thrombosis was 0.20 (95% confidence interval [CI] 0.16-0.24). In 10 trials, we did not find evidence that heparin-bonded catheters (RR 0.34; 95%CI 0.01-7.68), unfractionated heparin (RR 0.93; 95% CI 0.57-1.51), low molecular weight heparin (RR 1.13; 95% CI 0.51-2.50), warfarin (RR 0.85; 95%CI 0.34-2.17), antithrombin concentrate (RR 0.76; 95% CI 0.38-1.55) or nitroglycerin (RR 1.53; 95%CI 0.57-4.10) reduced the risk of thrombosis. Most of the trials were either not powered for thrombosis or were powered to detect large, probably unachievable, reductions in thrombosis. Missing data on thrombosis also limited these trials.

CONCLUSIONS

Catheter-related thrombosis is common in children. An adequately powered multicenter trial that can detect a modest, clinically significant reduction in thrombosis is critically needed. Missing outcome data should be minimized in this trial.

Internal jugular vein thrombosis: an uncommon presentation

Internal jugular vein (IJV) thrombosis is a rare entity. It is usually secondary to various etiologies such as ovarian hyperstimulation, deep vein thrombosis of upper limbs, venous catheter, malignancy, trauma, infection, and neck surgery and hypercoagulable status. We report an unusual case of internal jugular vein thrombosis with cerebral sinus thrombosis, postpartum in a 22-year-old female patient who presented with a painful swelling on the left side of her neck. Diagnosis was established by color Doppler ultrasonography and magnetic resonance venography. Thorough evaluation of the patient revealed no etiological factor leading to thrombosis. Patient was treated with low-molecular-weight heparin.

Epidemiology and prevention of catheter-related thrombosis in patients with cancer

Central venous catheters are extensively used in patients with cancer to secure delivery of chemotherapy and facilitate phlebotomy. Unfortunately, considerable morbidity can result from early complications or late sequelae, ranging from arterial puncture, pneumothorax and bloodstream infections to catheter-related thrombosis (CRT). Contemporary studies have shown that the incidence of symptomatic CRT is ∼5%, whereas the incidence of asymptomatic CRT is higher, at 14-18%. The significance and mechanisms of catheter design, material, insertion location and technique, position of the catheter tip and other risk factors in contributing to the development of CRT are not well understood. Efforts to reduce thrombotic complications, involving flushing the catheter with heparinized solutions, the use of heparin-bonded catheters, and systemic anticoagulant prophylaxis, have been largely ineffective. More studies are needed to understand the pathophysiology of thrombotic complications, to help identify effective interventions to reduce this adverse outcome.

Management of neonatal thrombosis

Neonates have one of the highest risks for thromboembolism among pediatric patients. This risk is attributable to a combination of multiple genetic and acquired risk factors. Despite a significant number of these events being either life threatening or limb threatening, there is limited evidence on appropriate management strategy. Most of what is recommended is based on uncontrolled studies, case series, or expert opinion. This review begins with a discussion of the neonatal hemostatic system, focusing on the common sites and imaging modalities for the detection of neonatal thrombosis. Perinatal and postnatal risk factors are presented and management options discussed.

Anticoagulation in neonates and children: Pitfalls and dilemmas

Anticoagulation in children is problematic for many reasons, related to the patient population as well as the anticoagulant drugs themselves. This paper describes the multitude of reasons why providing anticoagulation therapy in children is different from anticoagulation therapy in adults, and hence why dedicated paediatric anticoagulant services are the ideal structure to provide this service. The paper then describes the three most common anticoagulants used in children, and details specifically what is and is not known about them in the paediatric population. Finally the paper addresses the issue of how best to introduce newer anticoagulant drugs into the paediatric population. There remains much research to be done in this field, in the meantime clinicians need to carefully consider the evidence available to them and manage each individual patient accordingly.

Epidemiology and classification of perinatal stroke

Stroke is an important cause of mortality and chronic morbidity in infants and children. Case definitions for perinatal stroke have varied among studies by clinical and laboratory criteria. A recent US National Institutes of Health workshop on perinatal stroke provided consensus recommendations on the definition and classification of perinatal stroke. The incidence of perinatal stroke has been estimated at 1 in 1600 to 5000 births. The clinical presentation of perinatal stroke depends on the time of diagnosis, acute or delayed, but most will present with seizures. Risk factors for perinatal stroke have not been well studied. Several maternal and neonatal disorders have been reported in infants with perinatal stroke. Children who suffer perinatal stroke typically develop long-term disabilities including motor deficits, cognitive and behavioral disorders, and epilepsy. More than half will develop long-term motor or cognitive problems and the recurrence rate after perinatal stroke is very low.

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.

The evaluation and management of postnatal thromboses

In the pediatric population, neonates have the highest risk for thromboembolism (TE), most likely due to the frequent use of intravascular catheters. This increased risk is attributed to multiple risk factors. Randomized clinical trials dealing with management of postnatal thromboses do not exist, thus, opinions differ regarding optimal diagnostic and therapeutic interventions. This review begins with an actual case study illustrating the complexity and severity of these types of cases, and then evaluates the neonatal hemostatic system with discussion of the common sites of postnatal thrombosis, perinatal and prothrombotic risk factors, and potential treatment options. A proposed step-wise evaluation of neonates with symptomatic postnatal thromboses will be suggested, as well as future research and registry directions. Owing to the complexity of ischemic perinatal stroke, this topic will not be reviewed.

The evaluation and management of neonatal coagulation disorders

Neonatal hemostatic abnormalities can present diagnostic and therapeutic challenges to the physician. Developmental deficiencies and/or increases of certain coagulation proteins, coupled with acquired or genetic risk factors, can result in a hemorrhagic or thromboembolic emergency. The timely diagnosis of a congenital hemorrhagic or thrombotic disorder can avoid significant long-term sequelae. However, due to the lack of randomized clinical trials addressing the management of neonatal coagulation disorders, treatment strategies are usually empiric and not evidence-based. In this chapter, we will review the neonatal hemostatic system and will discuss the most common types of hemorrhagic and thrombotic disorders. Congenital and acquired risk factors for hemorrhagic and thromboembolic disorders will be presented, as well as current treatment options. Finally, suggested evaluations for neonates with either hemorrhagic or thromboembolic problems will be reviewed.

Incidence of and risk factors for childhood thrombosis: a single-center experience in Ankara, Turkey

This study was conducted to analyze the incidence of and risk for thrombosis in thrombotic children monitored in the Department of Pediatric Hematology of our hospital at the time of diagnosis, in addition to the clinical characteristics of those patients. The clinical and laboratory findings of 122 patients diagnosed with thrombosis from 1997 to 2006 were retrospectively analyzed. The incidence of thrombosis was 88.6/10,000 hospital admissions. The authors found that 31.1% of the patients studied had a thrombosis in more than 1 region. The incidence of thrombosis by anatomic site was as follows: 42 thromboses in the peripheral arterial system, 39 in an intracardiac region, 38 in the abdominal venous system, 36 in the deep peripheral venous system, and 28 in the cerebral vascular system. The mean age of the patients at the time of diagnosis was 4.9 years. Of the patients studied, 10.7% were neonates, 35.3% were infants younger than 1 year, and 48.4% were younger than 2 years. Most of the patients had a congenital cardiac disease and spontaneous thrombosis, and 66.1% had at least 1 acquired risk factor, the most common of which were having undergone surgery (42%) or wearing a central venous catheter (39%). A hereditary factor for the development of thrombosis was present in 54% of the patients. The most frequently observed hereditary risk factor was the MTHFR 677C-T mutation, and the second most common was the factor V Leiden mutation. Thrombosis should be considered a systemic disorder, and thrombotic patients should be evaluated with appropriate methods. Acquired and hereditary risk factors should be analyzed systematically in thrombotic patients.

Risk factors for umbilical venous catheter-associated thrombosis in very low birth weight infants

BACKGROUND

Thrombosis in neonates is a rare but serious occurrence, usually associated with central catheterization. The objective of this study was to investigate the risk factors associated with catheter related thrombosis in very low birth weight (VLBW) infants.

PROCEDURE

The present retrospective study was performed using data from a randomized trial of duration of umbilical venous catheters (UVC) placement among infants <1,250 g birth weight. Twenty-two cases of UVC-associated thrombosis were identified in this sample. The remaining study sample (n = 188) served as the comparison group. Data on thrombosis, platelets, gestational age, birth weight, hematocrit, serum sodium, maternal preeclampsia, blood group, infant of diabetic mother (IDM) and demographic factors were collected using database and record review.

RESULTS

Among the total subjects (n = 210), 112 (53%) were males and 126 (60%) were Caucasians, with mean gestational age of 27.7 +/- 2.1 weeks (standard deviation) and mean birth weight of 923 +/- 195 g. Bivariate analysis revealed significant association of thrombosis with hematocrit >55% in the first week (odds ratio [OR] 5.4; 95% confidence interval [CI] 2.0-14.6; P = 0.0003), being small for gestational age (SGA) (OR, 2.9; 95% CI, 1.2-7.4; P = 0.02) and maternal preeclampsia (OR, 3.97; 95% CI, 1.6-9.84; P = 0.0017). In multivariate logistic regression analysis, only hematocrit >55% was independently associated with thrombus (OR, 3.7; 95% CI 1.1-11.8; P = 0.03).

CONCLUSIONS

This study demonstrates a significant, independent association between elevated hematocrit and development of UVC-associated thrombosis. Careful monitoring for catheter-associated thrombosis may be indicated in VLBW infants who have hematocrit >55% in the first week of life.

Impact of Inherited Thrombophilia on Venous Thromboembolism in Children

Background— The aim of the present study was to estimate the impact of inherited thrombophilia (IT) on the risk of venous thromboembolism (VTE) onset and recurrence in children by a meta-analysis of published observational studies.

Methods and Results— A systematic search of electronic databases (Medline, EMBASE, OVID, Web of Science, The Cochrane Library) for studies published from 1970 to 2007 was conducted using key words in combination as both MeSH terms and text words. Citations were independently screened by 2 authors, and those meeting the inclusion criteria defined a priori were retained. Data on year of publication, study design, country of origin, number of patients/controls, ethnicity, VTE type, and frequency of recurrence were abstracted. Heterogeneity across studies was evaluated, and summary odds ratios and 95% CIs were calculated with both fixed-effects and random-effects models. Thirty-five of 50 studies met inclusion criteria. No significant heterogeneity was discerned across studies. Although >70% of patients had at least 1 clinical risk factor for VTE, a statistically significant association with VTE onset was demonstrated for each IT trait evaluated (and for combined IT traits), with summary odds ratios ranging from 2.63 (95% CI, 1.61 to 4.29) for the factor II variant to 9.44 (95% CI, 3.34 to 26.66) for antithrombin deficiency. Furthermore, a significant association with recurrent VTE was found for all IT traits except the factor V variant and elevated lipoprotein(a).

Conclusions— The present meta-analysis indicates that detection of IT is clinically meaningful in children with, or at risk for, VTE and underscores the importance of pediatric thrombophilia screening programs.

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.

Genetic prothrombotic mutations are common in neonates but are not associated with umbilical catheter-associated thrombosis

OBJECTIVE

To evaluate the prevalence of hereditary prothrombotic mutations, and their effect on the incidence and severity of umbilical arterial or venous catheter (UAC or UVC)-associated thrombosis.

STUDY DESIGN

All neonates with a UAC or UVC were studied prospectively for the presence, severity and timing of thrombosis with duplex Doppler ultrasound scan. Genetic testing for factor V Leiden (FVL), prothrombin mutation (PTm) and methylene-tetrahydrofolate reductase (MTHFR) mutations was performed using PCR and restriction fragment length polymorphism assays.

RESULT

Umbilical catheter (UC)-associated thrombosis developed in 16/53 (31%) neonates; 23% of UACs and 22% of UVCs were associated with thrombosis. The prevalence of a significant prothrombotic mutation was present in 10/51 (20%) of infants: FVL (8%), MTHFR667 homozygosity (10%), MTHFR1298 homozygosity (2%) and PTm (0%). There was no increase in the risk of UC-associated thrombus in patients carrying these prothrombotic mutations; our study had the power to detect a 2.5-fold increased risk of thrombosis for any of these significant mutations. In addition, MTHFR667 heterozygosity was found in 41% of infants and MTHFR1298 heterozygosity in 52% and also were not associated with increased risk of UC-associated thrombus. The risk of MTHFR double heterozygosity (db het) was 14%, the risk of a significant or db het was 17/51 (33%) and the risk of any mutation was 90%.

CONCLUSION

Prothrombotic genetic mutations are common in our Neonatal Intensive Care Unit population but do not appear to increase the risk of UC-associated thrombosis.

La greffe intestinale

Even though surgical techniques for isolated intestine, liver-intestine, and multivisceral transplantations were developed in the 1960's, very few patients were transplanted before 1990 because initial immunosuppression regimens were insufficient, making intestine transplantation impossible. Intestine transplantation resulted in death in most patients within days or months. The discouraging results of the first clinical trials were due to technical complications, sepsis, and the failure of conventional immunosuppression to control rejection. By 1990 the development of tacrolimus-based immunosuppression and improved surgical techniques, the increased array of potent immunosuppressive medications, infection prophylaxis, and suitable patient selection helped improve actuarial graft and patient survival rates for all types of intestine transplantation. The aims of this review are to describe the current status of intestine transplantation including the underlying diseases and conditions that may be indications for intestine transplantation, to identify patient populations for this indication, to provide key steps for patient evaluation, to summarize current recommendations for immunosuppression, to list the most common postoperative complications, and to discuss the international experience of small bowel transplantation compiled and analyzed by the International Intestine Transplant Registry since 1985.

Congenital prothrombotic disorders in children with peripheral venous and arterial thromboses

AIMS

To evaluate the prevalence of congenital prothrombotic disorders in children with peripheral venous and arterial thromboses.

METHODS

Deficiencies in antithrombin (AT), proteins C (PC) and S (PS), and increased lipoprotein (a), and the presence of factor V (FV) G1691A, prothrombin G20210A and methylenetetrahydrofolate reductase (MTHFR) mutations were investigated.

RESULTS

Forty-eight patients (mean age, 3.4 years) were investigated. Of these patients, 23 had venous thrombosis, 22 had arterial thrombosis, and 3 had both. No patients had AT, PC or PS deficiency. FV G1691A mutation was present in 2 (7.6%) and 3 (12%) patients with venous and arterial thromboses, respectively. The prothrombin G20210A mutation was present in 1 (4%) patient with arterial thrombosis. Homozygous MTHFR C677T mutation was detected in 4 (18%) and 2 (9%) patients with venous and arterial thromboses, respectively. Increased lipoprotein (a) was present in 2 (10%) and 1 (4.5%) patients with venous and arterial thromboses, respectively. Regarding acquired risk factors, 79% of all thrombotic events were related to catheter usage. An underlying disease was present in 96% of the patients.

CONCLUSIONS

Compared to acquired risk factors, congenital prothrombotic disorders are rarely present in children with peripheral venous and arterial thromboses. These results do not support general screening of children with venous and arterial thromboses for congenital prothrombotic disorders.

Profil épidémiologique et complications des voies veineuses centrales en oncologie pédiatrique : à propos de 125 cas

OBJECTIVE

To report the indications and early and late catheter-related complications in a Tunisian unit of paediatric oncology.

PATIENTS AND METHODS

This prospective study has been performed in a paediatric oncology unit of the Salah Azaïz Institute between 1989 and 2005. It concerns 58 girls and 57 boys with a median age of 7.9 years(4 months to 18 years) treated for cancer disease predominantly lymphoma (22%), sarcoma (23.2%) or leukaemia (8.5%) proposed for insertion of a central venous catheter (CVC).

RESULTS

Excluding 2 insertion failures (1.6%), we placed 123 CVC (double for 10 patients), 43 (35%) exteriorised (EC) and 80 (65%) connected to an implantable site (IS). Catheters were placed in the subclavian vein in 59.2% of cases vs 32% for internal jugular vein and 8.8% for femoral vein. Early complications included 15 cases of multiple punctures (12%), 4 cases of pneumothorax (3.2%) and 6 of arterial punctures (4.8%) originating a cervical subcutaneous haematoma in 1 patient (0.8%). Late complications were represented by infection in 7 cases (5.7%). We observed 2 cases of intracardiac catheter migration due to catheter disconnection from the IS (1.6%) and 2 cases of thrombosis (1.8%). The mean life of CVC was longer for IS (305.2 days) than for EC (64.4 days).

CONCLUSION

Implantable sites are effective progress for venous access in children with cancer. They improved the quality of care in pediatric oncology.

The influence of risk factors in promoting thrombosis during childhood: the role of acquired factors

Thrombo-embolism in childhood is a multifactorial disorder. The present study is a case-control study that investigated the role of genetic and acquired risk factors in 60 children with thrombosis and compared the results with the controls. Acquired and inherited risk factors precipitating thrombosis were present in 75 and 40% of the thrombotic children, respectively. The most frequent acquired risk factor was infection (58%). Of the genetic factors, factor V G20210A was the most common (38%). The comparison of the genetic and acquired risk factors in thrombotic versus nonthrombotic settings identified that acquired factors played a more significant role in causing thrombosis (OR:14.44; 95% CI: 7.05-29.94, p < .001). This study has clearly suggested that the prevention of acquired risk factors, particularly infection, could decrease the risk of thrombosis in pediatric cases.

Iliofemoral Deep Vein Thrombosis in Childhood; Developing a Management Protocol

OBJECTIVE

To develop an evidence-based protocol for the management of iliofemoral deep vein thrombosis (IDVT) in childhood.

METHODS

A search of the literature was undertaken. All publications pertaining to IDVT in childhood were analysed and then categorised according to their level of evidence. Recommendations were then made on the basis of this.

RESULTS

The commonest presenting symptoms were pain and swelling in the affected limb (evidence level II). Predisposing risk factors of special significance in children included the recent use of a venous access device, malignancy, prothrombotic disorders, infection, surgery and congenital venous anomalies (evidence level II). The most frequently described imaging modalities were B-mode ultrasonography, duplex, venography, and helical CT (evidence level III). The mainstay of treatment was anticoagulation with LMWH alone or followed by warfarin (evidence level I). Early clot removal through catheter-directed thrombolysis or surgical thrombectomy has been shown to be beneficial (evidence level II/III). There is little evidence for the benefit of early mobilisation and compression therapy in childhood.

CONCLUSION

Level I evidence relating to IDVT in childhood is sparse. The possibility of IDVT should be considered when examining a child with a swollen and painful limb. Imaging should be with duplex ultrasound, followed by spiral CT to include assessment of the IVC. A thrombophilia screen should be taken prior to anticoagulation with LMWH (and warfarin). Thrombolysis should be considered in cases of extensive IDVT.

Central venous line-related thrombosis in children

Central venous lines are used in critically ill children and in children with chronic conditions for the administration of intravenous therapy, such as fluids, medications, total parenteral nutrition and blood products. Although the use of central venous lines has greatly improved the quality of care in these children, these catheters may cause serious mechanical, infectious and thrombotic complications. The reported frequency of catheter thrombosis in children is low as 5% in studies including only symptomatic cases and high as 50% in studies where patients are systematically screened for catheter-related thrombosis. The risk factors for catheter-related thrombosis in children are associated with the methods used for catheter insertion and with individual patient characteristics, underlying diagnosis and treatment. The management of catheter-related thrombosis is largely dependent on the requirement of the catheter. If no longer required or nonfunctioning the catheter should be removed. If access is still required and the catheter is functioning, treatment with anticoagulation is recommended in the absence of contraindications. The management of radiographically detected asymptomatic thrombosis in children is less clear. Clinical studies of prophylaxis for catheter-related thrombosis are inconclusive and no definitive recommendations for prophylaxis in adults or in children with central venous thrombosis can be made. Properly designed studies are needed to assess the role of prophylactic anticoagulation for preventing catheter-related thrombosis.

Thromboembolic complications in children with cancer

Thrombosis is a significant problem in patients with cancer. The impact of thromboembolism in association with childhood cancer is not clearly defined. Similarly the information of prevention and management of thromboembolic events in children receiving cancer-therapy is limited. This review aims to examine current knowledge regarding the epidemiology, pathophysiology and management of thrombosis in association with cancer in children.

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.

Central venous catheter use in the pediatric patient: mechanical and infectious complications

OBJECTIVE

Following the introduction and widespread use of central venous catheters (CVCs) in adults, these devices are being used with increasing frequency in the pediatric population. This review will focus on differences between adults and children regarding CVC use and its potential complications. Both mechanical and infectious complications will be discussed.

DATA SOURCES

Systematic review of the literature.

CONCLUSIONS

CVC-related complications in pediatric patients are closely linked to age, body size, and age-related immune status. In older children, many complications are similar to those encountered in adult patients. Because of ongoing growth and body changes, a cutoff point beyond which children can be regarded as "young adults" is difficult to define; many of our recommendations are therefore age-related. More frequently than in adults, an implanted port may be the first choice in pediatric patients when long indwelling times are expected. The optimal site of insertion also depends on factors such as the patients' age as well as the need for sedation and analgesia during the insertion procedure. In contrast to guidelines in adult patients, we recommend that a radiograph always be made following CVC insertion to check the position of the catheter. Regarding prevention of infectious complications, we recommend full sterile barrier precautions during CVC insertion and strict protocols for catheter care. CVCs should be removed as soon as possible when they are no longer needed, but there is no place for elective CVC replacement on a routine basis. New developments such as the use of impregnated catheters might help reduce infection rates; however, additional research will be required to provide more evidence of benefit in the pediatric population.

Factor V Leiden and its effect on children with cardiac pathology

Factor V Leiden thrombophilia, formed by a genetic mutation, slows the body's anticoagulation response to clot formation. First described in 1994, factor V Leiden mutation has been identified as a contributing risk factor for venous thromboembolism. Although venous thromboembolism is considered rare in the pediatric population, Factor V Leiden has implications for certain at-risk pediatric patients.

Prevalence of Factor V Leiden and other thrombophilic traits among Cretan children with malignancy

BACKGROUND

The prevalence of thrombophilic traits, which might further enhance the risk of thrombotic complications in children treated for cancer, varies significantly among different populations.

OBJECTIVE

To evaluate the prevalence of common thrombophilic traits of the East Mediterranean Region, among native Cretan children treated for malignancy.

METHODS

Blood samples were consecutively collected from 31 native Cretan children treated for acute lymphoblastic leukaemia (n = 19) or other malignancies (n = 12) over 3 years. A molecular diagnosis based on the presence of Factor V Leiden (FVL), as well as on PT G20210A and MTHFR C677T mutation (in 14 patients) using PCR was applied. Patients who had central venous catheters (n = 29) were treated with an intensified thromboprophylaxis protocol that had been previously established in our institution.

RESULTS

The prevalence of the FVL mutation was 19.4% (95% CI = 5-32). The allele frequency is estimated at 11.3% (95% CI: 3.5-19.1) which is higher than that reported for the population of the mainland of Greece. The prevalence of the PT G20210A and MTHFR C677T mutation was 14.3 and 71.4%, respectively (corresponding allele frequencies 7.1 and 50%, respectively). Only one patient developed thrombosis, having although no thrombophilic trait.

CONCLUSIONS

Thrombophilic traits were relatively common in this group of native Cretan children treated for malignancy. Thromboprophylaxis should be considered in Cretan children in the presence of known acquired risk factors for thrombosis, but a larger prospective to study is first needed.

Evaluation of thrombotic children with malignancy

The purpose of this study was to evaluate inherited and acquired prothrombotic risk factors among children with malignancies who have thrombosis and emphasize the importance of inherited prothrombotic risk factors. Thirty-seven consecutive children with thrombosis and malignancy were included in this study. The patients were evaluated separately for time of development of thrombosis, insertion of a central venous line (CVL), history of L: -asparaginase usage, and recent infections. Prothrombotic risk factors such as factor V G1691A and prothrombin G20210A mutation, protein C, protein S, antithrombin III deficiencies, factor VIII and lipoprotein(a) elevation, and antiphospholipid antibodies were analyzed for all patients. Of 387 children with thrombosis, 37 (9.5%) had a malignancy. Thrombosis was detected in 9 patients at the time of diagnosis, during maintenance therapy in 25 patients, and after the discontinuation of treatment in 3 patients. One or two additional prothrombotic risk factors other than L: -asparaginase therapy and insertion of central venous lines were present in 20 of these patients (54%). It was found that eight patients had the factor V G1691A mutation in the heterozygote state. One of them had the factor V G1691A mutation associated with a history of infection and one patient had the factor V G1691A mutation associated with factor VIII elevation. One had the the prothrombin G20210A mutation in the heterozygote state, four had lipoprotein(a) elevation, two had factor VIII elevation, one had a decreased protein S level, one had a decreased protein C level, one had antiphospholipid positivity, and two had histories of infection. Malignancy is an important risk factor for the development of childhood thrombosis. However, the risk of thrombosis increases when accompanied by additional prothrombotic risk factors. For this reason, especially children with malignancy and at high risk for the development of thrombosis, such as those who have received L: -asparaginase or a replaced CVL during their therapy, might be screened for additional prothrombotic risk factors and appropriate measures might be taken to prevent the development of thrombosis.

Thromboembolic Diseases in Neonates and Children

Acquired and inherited prothrombotic risk factors increase the risk of thrombosis in neonates, infants and children. After suffering thrombosis white paediatric patients should be screened for common gene mutations, i.e. the factor V G1691A, factor II G20210A and MTHFR C677T genotypes, rare inherited prothromboticrisk factors, i.e. deficiencies of protein C,protein S, and antithrombin, plasminogen, probably inherited risk factors, i.e. fibrinogen, factor VIIIC, factor XII, new candidates, i.e. elevation of lipoprotein (a),and fasting homocysteine concentrations (3-6 months after thrombotic onset). Data interpretation is based on age-dependent reference ranges or the identification of causative gene mutations/polymorphisms with respect to individual ethnic backgrounds.

Thrombosis during infancy and childhood: what we know and what we do not know

Despite underlying illnesses, children have a greater chance to survive and are expected to live 6 to 8 decades following an episode of venous or arterial thrombosis. The disproportionate benefits of preventing thrombosis and its sequelae in pediatric patients are evident. Therefore, it is necessary to develop appropriate strategies for diagnosis and management of thromboembolic events in children and to understand their acute and long-term effects. There still are many unanswered questions and clinical trials are being designed to help study these important issues.

Fetal thrombotic vasculopathy in the placenta: a thrombophilic connection between pregnancy complications and neonatal thrombosis?

OBJECTIVE

Fetal thrombotic vasculopathy (FTV) has been related to pregnancy complications and neonatal thrombosis separately. We assessed whether a relationship existed in our population of women with neonates who were admitted to our Neonatal Intensive Care Unit (NICU). In addition, the presence of thrombophilic factors in children and parents was investigated.

METHODS

Two groups were detected by a search of the departmental databases. Group A was a cohort of 5000 neonates admitted to our NICU (1992-2002). Infants who developed thrombotic complications were selected. Group B was a cohort of placentae from our institution (2000, n = 141). Those with a diagnosis of FTV were selected. Case-notes and laboratory results were obtained through the hospital information system.

RESULTS

Of Group A, thrombosis was reported in 55 children. Of these, 20 matching placentae were available. Eight placentae showed FTV (40 per cent). Of the eight corresponding pregnancies, seven were complicated by pre-eclampsia and/or intra uterine growth restriction (IUGR). Of the 12 placentae without FTV, five of the pregnancies had pre-eclampsia and/or IUGR (odds ratio for relation FTV-Complications: 9.8, 95 per cent CI = 0.9-107). In Group B, nine placentae showed FTV (6.4 per cent). Of these nine, six of the pregnancies were complicated by pre-eclampsia and/or IUGR. None of the neonates developed thrombosis.

CONCLUSION

Pre-eclampsia and/or IUGR as well as neonatal thrombosis are both associated with fetal thrombotic vasculopathy in the placenta. However, in our selected-tertiary centre-population, FTV did not predict neonatal thrombosis. The thrombophilic investigations of parents and children were incomplete. A standard approach for evaluating parents at risk for FTV and evaluating neonates at risk for thrombosis should be developed.

Antithrombotic Therapy in Children*

This article about antithrombotic therapy in children is part of the 7th American College of Chest Physicians Conference on Antithrombotic and Thrombolytic Therapy: Evidence-Based Guidelines. Grade 1 recommendations are strong and indicate that the benefits do, or do not, outweigh the risks, burden, and costs. Grade 2 suggests that individual patients' values may lead to different choices (for a full understanding of the grading see Guyatt et al, CHEST 2004; 126:179S-187S). Among the key recommendations in this article are the following. In neonates with venous thromboembolism (VTE), we suggest treatment with either unfractionated heparin or low-molecular-weight heparin (LMWH), or radiographic monitoring and anticoagulation therapy if extension occurs (Grade 2C). We suggest that clinicians not use thrombolytic therapy for treating VTE in neonates, unless there is major vessel occlusion that is causing the critical compromise of organs or limbs (Grade 2C). For children (ie, > 2 months of age) with an initial VTE, we recommend treatment with i.v. heparin or LMWH (Grade 1C+). We suggest continuing anticoagulant therapy for idiopathic thromboembolic events (TEs) for at least 6 months using vitamin K antagonists (target international normalized ratio [INR], 2.5; INR range, 2.0 to 3.0) or alternatively LMWH (Grade 2C). We suggest that clinicians not use thrombolytic therapy routinely for VTE in children (Grade 2C). For neonates and children requiring cardiac catheterization (CC) via an artery, we recommend i.v. heparin prophylaxis (Grade 1A). We suggest the use of heparin doses of 100 to 150 U/kg as a bolus and that further doses may be required in prolonged procedures (both Grade 2 B). For prophylaxis for CC, we recommend against aspirin therapy (Grade 1B). For neonates and children with peripheral arterial catheters in situ, we recommend the administration of low-dose heparin through a catheter, preferably by continuous infusion to prolong the catheter patency (Grade 1A). For children with a peripheral arterial catheter-related TE, we suggest the immediate removal of the catheter (Grade 2C). For prevention of aortic thrombosis secondary to the use of umbilical artery catheters in neonates, we suggest low-dose heparin infusion (1 to 5 U/h) (Grade 2A). In children with Kawasaki disease, we recommend therapy with aspirin in high doses initially (80 to 100 mg/kg/d during the acute phase, for up to 14 days) and then in lower doses (3 to 5 mg/kg/d for > or = 7 weeks) [Grade 1C+], as well as therapy with i.v. gammaglobulin within 10 days of the onset of symptoms (Grade 1A).

Central venous line thrombosis in children and young adults with thalassemia major

High doses of intravenous deferoxamine via central venous line (CVL) has recently been shown to improve survival in patients with noncompliant thalassemia major (TM). The aim of this retrospective study was to evaluate the extent of CVL-related thrombosis and to determine the presence of prothrombotic factors in children and young patients with TM on such a regimen. Twenty-three patients (median age 13, range 5-25 years) with TM in whom a tunneled CVL was inserted for intensification of iron chelation were evaluated for signs and symptoms of thrombosis and for inherited and acquired risk factors of thrombosis. Mean duration of CVL placement was 37 +/- 31 months (range 6-98 months). Eight patients (35%) had CVL-related thrombosis diagnosed clinically or by echocardiography. Nine patients (39%) had prothrombotic factors, but the thrombosis subgroup did not differ from the other group in age, platelet counts, duration of CVL placement, or the presence of predisposing prothrombotic factors. Based on the high rate of CVL-related thrombosis, routine monitoring is suggested for CVL thrombosis in this population.

Stroke in newborn infants

The few days before and after birth are a time of special risk for stroke in both mother and infant, probably related to activation of coagulation mechanisms in this critical period. Arterial ischaemic stroke around the time of birth is recognised in about one in 4000 full-term infants, and may present with neurological and systemic signs in the newborn. Neonatal seizures are most commonly the clinical finding that triggers assessment. In other children, perinatal stroke is recognised only retrospectively, with emerging hemiparesis or seizures after the early months of life. Risk factors for perinatal stroke include hereditary or acquired thrombophilias and environmental factors. Perinatal stroke underlies an important share of congenital hemiplegic cerebral palsy, and probably some spastic quadriplegic cerebral palsy and seizure disorders. There is much to be learned about the natural history of perinatal stroke, and there are as yet no evidence-based strategies for prevention or treatment.

Thrombotic complications of central venous catheters in children

Use of central venous catheters has become standard in the treatment of many chronic conditions during childhood and for the acute treatment of critically ill infants and children. However, these catheters can be associated with numerous complications, including thrombosis at the tip or in the lumen causing difficulty with its overall function. Even more concerning is the occlusion of large veins into which the catheter is placed, which could predispose patients to pulmonary embolism or postthrombotic syndrome. Recent research has focused on identifying risk factors for catheter-related thrombosis in children and determining methods for diagnosing deep venous thrombosis associated with a catheter in the upper extremities. Evidence now exists that as many as 50% of children with catheters develop deep venous thrombosis; however, most events are clinically silent. Few clinical trials have studied prevention of catheter-related thrombosis in pediatric patients. Data regarding incidence, treatment, and long-term outcome of catheter-related thrombosis in children are limited. Although central venous catheters are extremely important in the supportive care of sick children, concerns remain about their immediate and long-term safety.