Venous thromboembolism in neonates and children

Thromboembolism in Children

OBJECTIVE

To study pediatric patients who were diagnosed with thrombosis between January 2009 and March 2020.

METHODS

Patients were evaluated with respect to thrombophilic risk factors, localization of the thrombus, response to treatment, and recurrence rates during the last 11 y.

RESULTS

Among 84 patients, 59 (70%) had venous thrombosis and 20 (24%) had arterial thrombosis. The number of documented thrombosis amongst hospitalized children in authors' hospital has increased over the years. It has been observed that the annual incidence of thromboembolism has increased after 2014. Thirteen patients were recorded between 2009 and 2014 and 71 patients between 2015 and 2020 (until March 2020). Exact thrombosis localization could not be detected in 5 patients. The median age of patients was 8 ± 5.95 (range 0-18). Fourteen children (16.9%) had a history of familial thrombosis. Genetic and/or acquired risk factors were detected in 81 (96.4%) of the patients. Overall, 64 patients (76.1%) had acquired risk factors such as infection (20.2%), catheterization (13.1%), liver disease (11.9%), mastoiditis (8.3%), liver transplantation (6%), hypoxic-ischemic encephalopathy (4.8%), dehydration (3.6%), trauma (3.6%) and cancer (2.4%). As genetic risk factors, the most common genetic mutations were PAI-1 4G>5G, MTHFR C677T, and MTHFR A1298C mutations. Twenty-eight (41.2%) patients had at least one genetic thrombophilic mutation. At least one homozygous mutation in 37 patients (44%) and at least one heterozygous mutation in 55 patients (65.4%) were detected.

CONCLUSIONS

The annual incidence of thrombosis has increased over the years. Genetic predisposition and acquired risk factors play an important role in etiology, treatment, and follow-up in children with thromboembolism. Especially, genetic predisposition is common. Thrombophilic risk factors should be investigated and optimal therapeutic and prophylactic measures should be promptly taken in children with thrombosis.

Systemic Catheter-Related Venous Thromboembolism in Children: Data From the Italian Registry of Pediatric Thrombosis

BACKGROUND

Central venous catheters (CVCs) represent one of the main risk factors for venous thrombotic events (VTEs) in children.

METHODS

We studied the Italian Registry of Pediatric Thrombosis (RITI) with regard to systemic radiologically confirmed CVC-related VTEs (CVC-VTEs) occurred during 6.5 years in children aged 29 days to 18 years.

RESULTS

A total of 78 CVC-VTEs were included, which occurred in 76 patients (40/76, 53% males). CVC-VTEs comprised 67 non-cardiac VTEs (86%) and 11 intracardiac thrombotic events (ICTEs) (14%); the median age at onset was 19 and 17 months, respectively. The most frequent reason for CVC insertion was supportive therapy. The catheters were placed percutaneously in 85% of cases (56/66) and surgically in the remaining 15% (10/66). Peripherally inserted central catheters (PICCs) were used in 47% (31/66) cases, partially implanted catheters in 42% (28/66), non-implantable catheters in 7% (5/66), and totally implanted catheters (Port) in 2% (1/66). CVC-VTEs were symptomatic in 77% of cases (60/78), while in the remaining 23%, they were incidentally detected on the imaging performed for the underlying condition. The median time between CVC insertion and the onset of symptoms was 10 days in non-cardiac VTEs and 39 days in ICTEs. Doppler ultrasound was the diagnostic technique most frequently used. The venous compartment most frequently affected was the veins of the lower extremities (52%, 43/73). Anti-thrombotic treatment was administered in 96% of CVC-VTEs (75/78). About 2.6% (2/76) of patients experienced a second thrombotic event. At discharge, post-thrombotic syndrome was reported in 13.5% (5/37) events with available data, CVC replacement in 10.8% (4/47), and ischemic necrosis with toe finger amputation in 2.7% (1/37). Three patients died due to an underlying condition; no CVC-VTE-related deaths were reported.

CONCLUSIONS

We have carried out a registry-based study on CVC-VTEs in the children in Italy, providing the data that may help improve the detection and management of this CVC-related complication.

Clinical Impact of Heritable Thrombophilia on Neonatal-Onset Thromboembolism: A Nationwide Study in Japan

OBJECTIVE

To clarify the incidence and genetic risk of neonatal-thromboembolism, we conducted a nationwide study exploring the impact of thrombophilia on neonatal-thromboembolism in Japan.

STUDY DESIGN

A questionnaire survey was conducted for perinatal centers in Japan, focusing on the clinical expression, genotype, treatment, and outcome of patients who developed thromboembolism within 28 days of birth from 2014 to 2018.

RESULTS

The estimated incidence of neonatal-thromboembolism was 0.39 cases per 10 000 live births. Intracranial lesions and purpura fulminans occurred in 66 and 5 of 77 patients, respectively. Fifty-eight (75.3%) infants presented within 3 days after birth. Four (5.2%) died, and 14 (18.2%) survived with disability. At the diagnosis, <20% plasma activity of protein C was noted in 16 infants, protein S (in 2), and antithrombin (in 1). Thirteen genetic tests identified 4 biallelic and 5 monoallelic protein C-variants but no protein S- or antithrombin-variants. Protein C-variants had purpura fulminans (P < .01), ocular bleeding (P < .01), positive-family history (P = .01), and death or disability (P = .03) more frequently than others. Protein C-variants were independently associated with disability (OR 5.74, 95% CI 1.16-28.4, P = .03) but not death. Four biallelic variants had serious thrombotic complications of neurologic disability, blindness, and/or amputation. Three monoallelic variants survived without complications. The only protein C-variant death was an extremely preterm heterozygote infant.

CONCLUSIONS

Monoallelic protein C-variants had a higher incidence of neonatal-thromboembolism than biallelic variants. Thrombophilia genetic testing should be performed in the setting of neonatal-thromboembolism and low protein C to identify the underlying genetic defect.

Neonatal thrombosis: risk factors and principles of prophylaxis

Data analysis on the pathogenesis and risk factors of neonatal thrombosis was carried out. The main risk factor of any neonatal thrombosis is central catheter installment, but other maternal, fetal and neonatal factors should be taken into consideration. We discuss the epidemiology of neonatal thrombosis and the main features of the hemostasis system in newborns, the most significant risk factors, including genetic and acquired thrombophilia. We consider the von Willebrand factor activity and ADAMTS-13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) level in the development of neonatal thrombotic microangiopathy. Finally, we discuss the basic principles of prevented neonatal thrombosis by using low molecular weight heparins.

Budd-Chiari syndrome: consensus guidance of the Asian Pacific Association for the study of the liver (APASL)

Budd Chiari syndrome (BCS) is a diverse disease with regard to the site of obstruction, the predisposing thrombophilic disorders and clinical presentation across the Asia-Pacific region. The hepatic vein ostial stenosis and short segment thrombosis are common in some parts of Asia-Pacific region, while membranous obstruction of the vena cava is common in some and complete thrombosis of hepatic veins in others. Prevalence of myeloproliferative neoplasms and other thrombophilic disorders in BCS varies from region to region and with different sites of obstruction. This heterogeneity also raises several issues and dilemmas in evaluation and approach to management of a patient with BCS. The opportunity to recanalize hepatic vein in patients with hepatic vein ostial stenosis or inferior vena cava stenting or pasty among those membranous obstruction of the vena cava is a unique opportunity in the Asia-Pacific region to restore hepatic outflow closely mimicking physiology. In order to address these issues arising out of the diversity as well as the unique features in the region, the Asia Pacific Association for Study of Liver has formulated these guidelines for clinicians.

Thrombophilia screening revisited: an issue of personalized medicine

Clinical thrombophilia is the consequence of multiple gene and/or environment interactions. Thrombophilia screening requires a targeted patient with specific indication, in which a finding would have implications. Carrying out a thrombophilia examination in the physician's practice is often a cause of uncertainty and concern. The concerns begin in choosing the right patient to be examined, are associated with the time of investigation, with the choice of analysis, the test-material and with the correct interpretation of the results. Difficulties, which can influence the results, can occur with both organization and blood sampling. As common for any analysis, pre-analytical, analytical and post-analytical factors should be considered, as well as the possibility of false positive or false negative results. Finally, recommendation of correct therapeutic and prophylactic measures for the patient and his relatives is an additional focus. In this article we want to provide-on the basis of the evidence and personal experience-the theory of thrombophilia-investigation, the indications for testing, as well as practical recommendations for treatment options.

"APS pregnancy - The offspring"

BACKGROUND

Antiphospholipid antibody syndrome (APS) is an autoimmune disease that affects women in childbearing age. In recent years, great improvements were achieved in the management of pregnancies in these women. Prematurity could be an issue in these pregnancies, mainly due to the direct pathogenic effect of antiphospholipid antibodies (aPL) on the placental surface. Maternal IgG aPL can cross the placenta and theoretically interact with the growing fetus; it could reach the fetal brain because of the incompleteness of the fetal blood-brain barrier: whether this can have an effect on brain development is still debated. Neonatal thrombosis episodes have been described in children positive for aPL, not always associated with maternal antibody positivity, suggesting the hypothesis of a possible aPL de novo synthesis in fetus and neonates.

METHODS

A keyword-based literature search was conducted. We also described a case of neonatal catastrophic antiphospholipid syndrome (CAPS).

RESULTS

Offspring of patients with APS are generally healthy but the occurrence of neonatal thrombosis or minor neurological disorders were reported.

CONCLUSIONS

The limited number of the available data on this sensitive issue supports the need for further studies. Clinical follow-up of children of mothers with APS seems to be important to exclude, in the neonatal period, the occurrence of aPL associated pathological events such as thrombosis, and in the long-term, impairment in learning skills or behavioral problems.

Inferior vena cava syndrome in neonates: An evidence-based systematic review of the literature

Neonatal inferior vena cava syndrome (IVCS), though uncommon, is associated with significant morbidity and mortality. Information on risk factors, diagnosis, treatment, and outcomes is limited. This review comprised 61 neonates across 33 reports. Thrombosis occurred in 98% and 42% involved a central venous catheter. Diagnosis was mainly established by ultrasound in 82%. Therapeutically, heparin was employed in 36% and thrombolysis in 18% of the cases. The overall mortality was 23%. An algorithm of clinical signs, investigation, and management is presented. Well-designed prospective studies are needed to establish a concrete investigational approach to neonatal IVCS and institute safe, evidence-based treatment.

Advances in predicting venous thromboembolism risk in children

Paediatric venous thromboembolism (VTE) is a rare disorder but a rising incidence has been observed in recent years, due to improved VTE diagnosis and increased use of central venous catheters in the treatment of severe diseases. Risk assessment strategies are well established for adult patients, however, similar guidelines for paediatric patients are largely lacking. Several risk prediction tools have been reported in recent literature, which make use of established risk factors to assess VTE risk in paediatric subgroups, such as hospitalised children, cancer-diagnosed children and paediatric trauma patients. Although these models suffer several limitations regarding their study size and heterogeneous selection of predictor variables, they offer potential for improving the thromboprophylaxis management in these children. Here, we give an overview on recently reported risk prediction models for paediatric VTE.

[Neonatal arterial ischemic stroke: Which thrombotic biological risk factors to investigate and which practical consequences?]

All biological risk factors that have been previously identified to increase the risk of thrombosis in adults, have also been studied in neonates with arterial Ischemic Stroke (NAIS), but most studies were retrospective and included relatively low numbers of affected children. We therefore could not suggest recommendations with a strong level of evidence and only expert proposals potentially useful for clinical practice will be presented in this text. Despite these limitations, the extensive analysis of published data supported that factor V Leiden (FVL) and increased levels of Lp(a) could be significant risk factors for NAIS. Importantly, these 2 risk factors cannot be considered as having provoked NAIS, and moreover, they do not influence the prognosis and the immediate treatment. However, since the FVL may have an impact for the prescription of a thromboprophylaxis when the neonate will become adult, to look for its presence in affected patients may be justified. For clinical practice, the following propositions can be applied: 1. Routine testing for thrombophilia (AT, PC PS deficiency, FV Leiden or FII20210A) or for detecting other biological risk factors such as antiphospholipid antibodies, high FVIII, homocystein or Lp(a) levels, MTHFR thermolabile variant, should not be considered in neonates with NAIS. 2. Testing for FV Leiden can be performed in case of documented family history of venous thromboembolic disease. 3. Testing neonates for the presence of antiphospholipid antibodies (APA) is mandatory in case of clinical events suggesting antiphospholipid syndrome in the mother (vascular thrombosis, and/or pregnancy morbidity). 4. Routine testing for thrombophilia is not proposed in both parents in case of early death of the neonate, apart from APA in the mother.

Paediatric venous thromboembolism: a report from the Italian Registry of Thrombosis in Children (RITI)

BACKGROUND

The Italian Registry of Thrombosis in Children (RITI) was established by a multidisciplinary team with the aims of improving knowledge about neonatal and paediatric thrombotic events in Italy and providing a preliminary source of data for the future development of specific clinical trials and diagnostic-therapeutic protocols.

MATERIALS AND METHODS

We analysed the subset of RITI data concerning paediatric systemic venous thromboembolic events that occurred between January 2007 and June 2013.

RESULTS

Eighty-five deep venous thromboses and seven pulmonary emboli were registered in the RITI. A prevalence peak was observed in children aged 10 to 18 years and, unexpectedly, in children aged 1 to 5 years. A central venous line was the main risk factor (55% of venous thromboembolic events); surgery (not cardiac) (25%), concomitant infections (23%) and malignancy (22%) were the clinical conditions most often associated with the onset of venous thromboembolism. There was a diagnostic delay of more than 24 hours in 37% of the venous thromboembolic events. Doppler ultrasound was the most widely used test for the objective diagnosis of deep venous thrombosis (87%). Antithrombotic therapy was administered in 96% of venous thromboembolic events, mainly low molecular weight heparin (60%). In 2% of cases recurrences occurred, while post-thrombotic syndrome developed in 8.5% of cases.

DISCUSSION

Although the data from the RITI are largely in agreement with published data, peaks of prevalence of thrombosis, risk factors and objective tests used for the diagnosis showed some peculiarities which may deserve attention.

Risk Factors for Intracardiac Thrombosis in the Right Atrium and Superior Vena Cava in Critically Ill Neonates who Required the Installation of a Central Venous Catheter

BACKGROUND

Central venous catheter (CVC) installation is essential for the treatment of critically ill neonates; however, it is associated with the development of neonatal intracardiac thrombosis, which is a complication that is associated with a poor prognosis. We aimed to identify specific risk factors for the development of intracardiac thrombosis in the right atrium (RA) and superior vena cava (SVC) related to the use of CVC in critically ill neonates.

METHODS

A case-control study was conducted at the tertiary referral neonatal intensive care unit of the Pediatric Hospital Siglo XXI in Mexico City, Mexico from 2008 to 2013. The included cases (n = 43) were de novo patients with intracardiac thrombosis in the RA and SVC diagnosed by echocardiography. The controls (n = 43) were neonates without intracardiac thrombosis or thrombosis at other sites. A logistic regression analysis was conducted, and odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated.

RESULTS

The independent risk factors for intracardiac thrombosis in the RA and SVC were the surgical cut-down insertion technique (OR = 2.98; 95% CI: 1.18-9.10), a maternal history of gestational diabetes/diabetes mellitus (OR = 10.64; 95% CI: 1.13-121.41), Staphylococcus epidermidis infection (OR = 7.09; 95% CI: 1.09-45.92), and CVC placement in the SVC (OR = 5.77; 95% CI: 1.10-30.18).

CONCLUSION

This study allowed us to identify several contributing factors to the development of intracardiac thrombosis in the RA and SVC related to the installation of a CVC in a subgroup of critically ill neonates. Multicenter and well-designed studies with a larger number of patients could help validate our findings and/or identify other risk factors that were not identified in the present study.

Ultrasound Assisted Endovascular Thrombolysis in Adolescents: 2 Case Reports

Descending iliofemoral thrombosis in children is a rare event. Anticoagulation therapy with low-molecular-weight-heparin is standard of care. However, patency cannot be achieved in all cases, increasing the risk for rethrombosis and postthrombotic syndrome. To reduce the risk of venous valve failure in adults, local catheter-directed thrombolysis is used to reopen vessels. Two adolescent girls (17 and 15 years old) presented with acute descending iliofemoral thrombosis of the left common iliac, external, and common femoral veins. Anticoagulation with enoxaparin was started until insertion of an EkoSonic Mach 4e catheter for ultrasound-assisted local thrombolysis with recombinant tissue plasminogen activator and administration of unfractionated heparin. Success was monitored by increases in D-dimer levels and ultrasound findings. After 24 hours respectively 48 hours, complete recanalization was obtained. No complication occurred except minimal local bleeding. Screening for hereditary thrombophilia revealed a heterozygous antithrombin mutation in 1 girl (ie, the 15-year-old). May-Thurner syndrome was identified in both girls, necessitating stenting of the left common iliac veins and continuation of anticoagulation therapy with enoxaparin and acetylsalicylic acid. No rethrombosis or complications occurred during the follow-up period. Ultrasound-assisted catheter-directed local thrombolysis with the EkoSonic Mach 4e system was effective in achieving immediate recanalization of the occluded veins and should be considered in children experiencing descending iliofemoral thrombosis. The fast recanalization might reduce the incidence of postthrombotic syndrome. May-Thurner syndrome is regularly found in these patients, and if present, requires stenting of the common iliac vein to avoid early reocclusion. However, long-term patency of iliac vein stenting in children remains to be examined.

Evaluation of Factor V Leiden, Prothrombin G20210A, MTHFR C677T and MTHFR A1298C gene polymorphisms in retinopathy of prematurity in a Turkish cohort

BACKGROUND

To assess Factor V Leiden (FVL) (rs6025), Prothrombin G20210A (rs1799963), MTHFR C677T (rs1801133), and MTHFR A1298C (rs1801131) gene mutations as risk factors in the development of retinopathy of prematurity (ROP).

MATERIALS AND METHODS

A total of 105 children were included in this cross-sectional study. Patients were divided into two groups. The study group consisted of 55 infants with a history of ROP and the control group comprised 50 healthy infants with term birth. All subjects were screened for the presence of certain mutations (FVL, Prothrombin G20210A, MTHFR C677T and MTHFR A1298C) by Real-Time PCR at 1 year of age.

RESULTS

The mean gestational age (GA) and birth weight (BW) of the study group were, 28.65 ± 2.85 weeks and 1171 ± 385.74 g, respectively. There were no significant differences of genotype and allele frequency of Prothrombin G20210A, MTHFR A1298C and MTHFR C677T between the study and control groups (p > 0.05). Eight children (14.5 %) had heterozygous and one child (1.8%) had homozygous FVL mutation in the study group. One child (2%) in the control group had heterozygous FVL mutation. There was statistically significant differences of FVL allele and genotype frequencies between the groups (p < 0.05).

CONCLUSIONS

The prevalence of FVL polymorphism (16.3 %) was higher in ROP patients than control subjects in this Turkish cohort. We suggest a possible association of FVL mutation with ROP at the end of the study.

Venous Thromboembolism in Patients With Thrombocytopenia: Risk Factors, Treatment, and Outcome

Background:

Venous thromboembolism (VTE) is a frequent and potentially lethal condition. Venous thrombi are mainly constituted of fibrin and red blood cells, but platelets also play an important role in VTE formation. Information about VTE in patients with thrombocytopenia is, however, missing.

Objectives:

To identify VTE risk factors and describe treatment and outcome (bleeding episodes and mortality) in patients with thrombocytopenia.

Patients/Methods:

Patients with thrombocytopenia (platelet count <100 × 109/L) admitted to Odense University Hospital, Denmark, between April 2000 and April 2012 were included. Fifty cases had experienced VTE. Controls without VTE were matched 3:1 with cases on sex and hospital department. Medical records were examined, and data were analyzed using conditional logistic regression.

Results:

In multivariate analysis, platelet count <50 × 109/L (odds ratio [OR] 0.22, P < .05) and chronic liver disease (OR 0.05, 95% confidence interval [CI] 0.01-0.58) reduced the risk of VTE. Surgery (OR 6.44, 95% CI 1.37-30.20) and previous thromboembolism (OR 6.16, 95% CI 1.21-31.41) were associated with an increased VTE risk. Ninety-two percent of cases were treated with anticoagulants. There was no difference in bleeding incidence between cases and controls.

Conclusions:

Several known VTE risk factors also seems to apply in patients with thrombocytopenia. Also, patients with thrombocytopenia may be VTE risk stratified based on platelet count and comorbidities. Finally, patients having thrombocytopenia with VTE seem to be safely treated with anticoagulants without increased occurrence of bleeding.

Clinical risk factors for central line-associated venous thrombosis in children

BACKGROUND

Identifying risk factors related to central venous line (CVL) placement could potentially minimize central line-associated venous thrombosis (CLAVT). We sought to identify the clinical factors associated with CLAVT in children.

METHODS

Over a 3-year period, 3733 CVLs were placed at a tertiary-care children's hospital. Data were extracted from the electronic medical records of patients with clinical signs and symptoms of venous thromboembolism, diagnosed using Doppler ultrasonography and/or echocardiography. Statistical analyses examined differences in CLAVT occurrence between groups based on patient and CVL characteristics (type, brand, placement site, and hospital unit).

RESULTS

Femoral CVL placement was associated with greater risk for developing CLAVT (OR 11.1, 95% CI 3.9-31.6, p < 0.0001). CVLs placed in the NICU were also associated with increased CLAVT occurrence (OR 5.3, 95% CI 2.1-13.2, p = 0.0003). CVL brand was also significantly associated with risk of CLAVT events.

CONCLUSION

Retrospective analyses identified femoral CVL placement and catheter type as independent risk factors for CLAVT, suggesting increased risks due to mechanical reasons. Placement of CVLs in the NICU also led to an increased risk of CLAVT, suggesting that small infants are at increased risk of thrombotic events. Alternative strategies for CVL placement, thromboprophylaxis, and earlier diagnosis may be important for reducing CLAVT events.

Venous thromboembolism at uncommon sites in neonates and children

We retrospectively analyzed the data of 24 children (whereof 11 neonates), with non-central venous line-related and nonmalignancy-related venous thromboembolism (VTE) at uncommon sites, referred to our Unit from January 1999 to January 2012. Thirty patients who also suffered deep vein thrombosis, but in upper/low extremities, were not included in the analysis. The location of rare site VTE was: portal (n=7), mesenteric (n=2) and left facial vein (n=1), spleen (n=3), lung (n=3), whereas 10 neonates developed renal venous thrombosis. The majority of patients (91.7%) had at least 1 risk factor for thrombosis. Identified thrombophilic factors were: antiphospholipid antibodies (n=2), FV Leiden heterozygosity (n=6), MTHFR C677T homozygosity (n=4), protein S deficiency (n=2), whereas all neonates had age-related low levels of protein C and protein S. All but 6 patients received low-molecular-weight heparin, followed by warfarin in 55% of cases, for 3 to 6 months. Prolonged anticoagulation was applied in selected cases. During a median follow-up period of 6 years, the clinical outcome was: full recovery in 15 patients, evolution to both chronic portal hypertension and esophageal varices in 2 children, and progression to renal failure in 7 of 10 neonates. Neonates are greatly vulnerable to complications after VTE at uncommon sites, particularly renal. Future multicentre long-term studies on neonatal and pediatric VTE at unusual sites are considered worthwhile.

Natural history of deep vein thrombosis in children

OBJECTIVE

To determine the natural history of deep vein thrombosis in children presented with a first episode in the lower extremity veins.

METHODS

Children with objective diagnosis of acute deep vein thrombosis were followed up with ultrasound and clinical examination. Risk factors and clinical presentation were prospectively collected. The prevalence of recurrent deep vein thrombosis and the development of signs and symptoms of chronic venous disease were recorded.

RESULTS

There were 27 children, 15 males and 12 females, with acute deep vein thrombosis, with a mean age of 4 years, range 0.1-16 years. The median follow-up was 23 months, range 8-62 months. The location of thrombosis involved the iliac and common femoral vein in 18 patients and the femoral and popliteal veins in 9. Only one vein was affected in 7 children, two veins in 14 and more than two veins in 6. Recurrent deep vein thrombosis occurred in two patients, while no patient had a clinically significant pulmonary embolism. Signs and symptoms of chronic venous disease were present at last follow-up in 11 patients. There were nine patients with vein collaterals, but no patient developed varicose veins. Reflux was found in 18 veins of 11 patients. Failure of recanalization was seen in 7 patients and partial recanalization in 11. Iliofemoral thrombosis (p = 0.012) and failure to recanalize (p = 0.036) increased significantly the risk for developing signs and symptoms.

CONCLUSIONS

Children with acute proximal deep vein thrombosis develop mild chronic venous disease signs and symptoms at mid-term follow-up and are closely related with iliofemoral thrombosis and failure to recanalization.

A novel mutation in protein C gene (PROC) causing severe phenotype in neonatal period

Homozygous protein C deficiency is among rare causes of thrombophilia. Herein, we present a neonate with purpura fulminans, disseminated intravascular coagulation and severe intracranial hemorrhage who was found to have plasma protein C level of 4%. The molecular work-up revealed a novel homozygous mutation of T903C (amino acid position Leu 270 Pro) located in a catalytic domain region of PROC gene. Asymptomatic course in patients with low but measurable levels of protein C levels has been reported, which is different than observed in our patient who had a very severe course despite plasma protein C level of 4%.

Dosing and monitoring of enoxaparin therapy in children: experience in a tertiary care hospital

Pediatric deep vein thrombosis (DVT) is an emerging problem in tertiary care hospitals, recent reviews shows a rate of 40.2/10,000 admissions. Experts affirm that enoxaparin has become in the drug of choice for DVT therapy. Despite this, there is a little information regarding the optimal dose schedule for enoxaparin therapy in children and the therapeutic guidelines for enoxaparin use in children are extrapolated from adult guidelines. Monitoring by antifactor Xa (anti-Xa) measurement and target concentrations between 0.5-1 U/ml at 4-6 h postdose are recommended. This study was designed to analyse our experience in paediatric-specific dosage requirements for enoxaparin therapy. A retrospective study was performed with patients less than 16 years old, who were treated with enoxaparin for DVT and monitored by anti-Xa concentration, between January 2005 and March 2012. Demographic and clinical characteristics and outcomes were obtained. Fourteen patients were analyzed: boy/girl ratio, 8/4; median age, 3.5 months. Cerebral venous sinus thrombosis was the most common indication for therapy. All patients presented thrombosis risks factors. Dose increases were necessary only in patients less than 6 years old. Target anti-Xa concentrations were achieved in 12 (85%) patients. Children younger than 1 year required a higher dose of enoxaparin/kg (1.5-2.7 mg/kg per 12 h). Complete resolutions of DVT were registered in all cases. The mean number of dose increases was three and a median of 11 days to achieve target anti-Xa concentration. This study indicates that an initial higher enoxaparin dose may be necessary in neonates and infants, but other factors must be considered to improve management.