Antithrombotic Therapy in Children*

Postoperative chylothorax development is associated with increased incidence and risk profile for central venous thromboses

This study tested the hypothesis that pediatric patients who develop chylothorax (CTX) after surgery for congenital heart disease (CHD) have an elevated incidence and risk profile for central venous thrombosis (CVT). We evaluated 30 patients who developed CTX after surgery for CHD. All but one CTX patient were surgery-, anatomy-, and age-matched with two controls (NON-CTX) to compare their relative risk and incidence of CVT. Using conditional logistic regression analyses, CTX development was associated with significantly longer ventilator dependence (14.8 +/- 10.9 vs. 6.1 +/- 5.9 days, p = 0.003) and a non-significant trend towards more days of central venous catheters (CVC) (19.1 +/- 16.6 vs. 12.2 +/- 10.0 days; p = 0.16) when comparing the period prior to CTX development with the entire hospitalization in NON-CTX patients. CTX development was associated with a significantly elevated mortality risk (Odds Ratio 6.2, 95% CI 1.3-30.9). Minimum and mean daily central venous pressures were significantly higher in the CTX group. Post operative need for extracorporeal membrane oxygenation conferred an increased risk of CTX development in this sample of patients (Odds Ratio 9.9, 95% CI 2.2-44.8). Incidence of documented CVT was 26.7% in the CTX group versus 5.1% in the NON-CTX group. Prospective screening for CVT risk and formation, combined with early removal of CVC may help reduce the incidence of CTX.

Venous thrombosis in children

The advances in pediatric tertiary care have resulted in a decrease in the mortality of children with serious underlying conditions. Consequently, there has been an increase in previously rare complications of therapy in children, including venous thrombosis. Although there is a paucity of properly designed trials in the field of pediatric thrombosis, many advances have been made over the past 15 years. Venous thrombosis in children has been the subject of many reviews. This review is an update of the available evidence in the management of venous thrombosis in children, excluding thrombosis of the CNS.

Post-thrombotic syndrome in children: a single center experience

BACKGROUND

Development of post-thrombotic syndrome (PTS) is increasingly being recognized as a complication of deep venous thrombosis (DVT) in children.

OBJECTIVE

To determine the prevalence, clinical characteristics, and predictors of moderate to severe PTS in children.

METHODS

A retrospective chart review was performed on those children who were followed in the coagulation clinic for objectively confirmed DVTs from December 2004 to December 2006. The scoring system used by Kuhle et al was used to grade the severity of PTS as: mild, moderate, and severe.

RESULTS

PTS developed in 20% (11/55; 95% confidence interval 9.4-30.1) of children, in which 8/11 were moderate and 3/11 were severe. Median interval between diagnosis of PTS and DVT was 90 days (range, 46 d to 3 y). The majority (72.7%) of patients in the non-PTS group received treatment intervention within 48 hours of diagnosis of DVT. Delay in treatment initiation (>48 h) and recurrence of DVT were associated with the development of PTS (P<0.05). Variables including occlusive thrombus, location and number of vessels involved with DVT, age at diagnosis, underlying thrombophilia, intensity of anticoagulation, and body mass index were not associated with the development of PTS. Other debilitating consequences of DVT requiring intervention included portal hypertension (n=2), chylothorax (n=1), and reflux sympathetic dystrophy (n=1). The small sample size and limited follow up restricted the statistical analysis.

CONCLUSIONS

PTS is a significant problem in children with symptomatic DVTs. Early treatment intervention within the first 48 hours of diagnosis of DVT and prevention of thrombosis recurrence may prevent development of PTS. Although PTS refers to consequences of intravenous hypertension owing to extremity DVTs, sequlae of nonextremity DVTs require special consideration in pediatric PTS classification.

Pediatric arterial ischemic stroke

Arterial ischemic stroke (AIS) is a rare disorder in children. Research suggests that risk factors, outcomes, and presentation are different from those of adult stroke. In particular, prothrombotic abnormalities and large vessel arteriopathies that are nonatherosclerotic seem to play a large role in the pathogenesis of childhood AIS. This review examines the epidemiology and etiologies of neonatal and childhood AIS and provides a detailed discussion of approaches to the clinical characterization, diagnostic evaluation, and management. Long-term outcomes of recurrent AIS and neuromotor, speech, cognitive, and behavioral deficits are considered. Emphasis is on evidence underlying current knowledge and key questions for further investigation.

Venous thromboembolism in children

With improved pediatric survival from serious underlying illnesses, greater use of invasive vascular procedures and devices, and a growing awareness that vascular events occur among the young, venous thromboembolism (VTE) increasingly is recognized as a critical pediatric concern. This review provides background on etiology and epidemiology in this disorder, followed by an in-depth discussion of approaches to the clinical characterization, diagnostic evaluation, and management of pediatric VTE. Prognostic indicators and long-term outcomes are considered, with emphasis on available evidence underlying current knowledge and key questions for further investigation.

Prevalence of post-thrombotic syndrome following asymptomatic thrombosis in survivors of acute lymphoblastic leukemia

BACKGROUND

Deep vein thrombosis (DVT) is a complication of treatment of acute lymphoblastic leukemia (ALL) in children but little is known about the long-term outcomes of these DVT.

OBJECTIVE

To determine the incidence of post-thrombotic syndrome (PTS) in (i) children with ALL diagnosed with asymptomatic DVT using radiographic testing and (ii) an unselected group of ALL survivors.

METHODS

Cross-sectional study in two populations. Group I comprised children in the Prophylactic Antithrombin Replacement in Kids with ALL treated with L-Asparaginase (PARKAA) study diagnosed with DVT by radiographic tests. Group II consisted of non-selected childhood ALL survivors <21 years. PTS was assessed using a standardized scoring sheet.

RESULTS

Group I: 13 PARKAA patients (median age 12 years) were assessed, and 7 had PTS (54%; 95% CI, 25-81). All patients had collaterals, three also had increased arm circumference. Group II: 41 patients (median age 13 years) with a history of ALL were enrolled, and 10 had PTS (24%; 95% CI, 11-38). All patients had collaterals; five also had increased arm circumference.

CONCLUSION

There is a high incidence of PTS in survivors of childhood ALL with radiographically diagnosed asymptomatic DVT. A significant proportion of ALL survivors develop PTS, indicating previously undiagnosed DVT.

Anti-Xa Stability of Diluted Dalteparin for Pediatric Use

BACKGROUND:

The low-molecular-weight heparin (LMWH) dalteparin is approved by the Food and Drug Administration for prophylaxis of venous thromboembolism (VTE) in adults and has recently received an indication for acute VTE therapy in adults with cancer. Published reports of experience with dalteparin use in European children suggest that this LMWH agent is safe and effective in the prophylaxis and treatment of VTE in the pediatric population. However, dalteparin is commonly available in the US in a concentrated form that requires dilution for accurate administration in infants and young children.

OBJECTIVE:

To investigate the in vitro stability of diluted dalteparin for pediatric use, as measured by serial anti-Xa activity assays over the course of 4 weeks.

METHODS:

At 2 clinical research pharmacies, dalteparin multidose vials (anti-Xa concentration 25,000 U/mL) of the 2 distinct lots presently available for clinical use were diluted 1:10 with preservative-free NaCl 0.9% and maintained in tuberculin syringes at 4 °C. Syringes were then sampled for anti-Xa activity by chromogenic assay at baseline and weekly over the course of 4 weeks.

RESULTS:

For each lot of dalteparin, there was strong agreement in anti-Xa activity between corresponding diluted syringes prepared at the 2 pharmacy sites. No statistically significant difference in anti-Xa activity was detected from baseline to any time point, nor was a trend of change detected in anti-Xa activity with time for either lot of dalteparin.

CONCLUSIONS:

These data indicate that the anti-Xa activity of diluted dalteparin for pediatric use is stable over the course of 4 weeks.

Oral anticoagulation with warfarin is significantly influenced by steroids and CYP2C9 polymorphisms in children with cancer

Clinical management of warfarin therapy is complex, and dosing algorithms do not include genetic factors or interactions with other drugs for warfarin dose determinations. We evaluated the interaction of warfarin and CYP2C9 polymorphisms and concomitant corticosteroids in 29 children with cancer. Children with heterozygous polymorphisms of CYP2C9 achieved target INR sooner and more frequently had INR above the target level, compared to children without mutations. Children on concomitant steroids had significantly lower warfarin requirements. Thus, awareness of CYP2C9 genotype and steroid-induced responsiveness to warfarin may be important when administrating oral anticoagulation in children.

Complications of vascular catheters in the neonatal intensive care unit

Insertion of an intravascular catheter is the most common invasive procedure in the neonatal ICU. With every passing decade, technological innovations in catheter materials and sizes have allowed vascular access in infants who are smaller and sicker for purposes of blood pressure monitoring, blood sampling, and infusion of intravenous fluids and medications. There is, however, growing recognition of potential risks to life and limb associated with the use of intravascular catheters. This article reviews complications of venous and arterial catheters in the neonatal ICU and discusses treatment approaches and methods to prevent such complications, based on current evidence.

Patent foramen ovale and unexplained ischemic cerebrovascular events in children

OBJECTIVES

To consider the role of patent foramen ovale (PFO) in ischemic cerebrovascular event of unknown cause in children.

BACKGROUND

Data regarding the possibility of paradoxical embolism in unexplained ischemic cerebrovascular event in children are lacking.

METHODS

Between January 2005 and March 2007, all consecutive children evaluated due to ischemic cerebrovascular event were included in the retrospective study. In addition to the standard diagnostic protocol, a contrast transcranial Doppler (TCD) with Valsalva maneuver (VM) was performed in patients with unexplained events. Percutaneous PFO closure was offered to all patients with ischemic cerebrovascular event of unknown cause and presumed paradoxical embolism.

RESULTS

Eighteen patients aged between 2 and 17 years (median 11.5 years) were included in the study: 12 patients suffered ischemic stroke and six with transient ischemic attack (TIA). In six patients, ischemic stroke was of unknown cause and contrast TCD with VM was positive in four of them. In addition, TCD study was positive in five patients evaluated because of TIA. Nine patients with presumed paradoxical embolism underwent an attempt at the percutaneous PFO closure.

CONCLUSIONS

It appears that the role of PFO in ischemic cerebrovascular event of unknown cause in children may be underestimated. Contrast TCD with VM is a sensitive, noninvasive method for PFO detection, proved in our experience particularly suitable for children. In children with unexplained ischemic cerebrovascular event and presumed paradoxical embolism, percutaneous PFO closure should be considered.

Outcome of cardiac thrombi in infants

Use of central lines in the neonatal intensive care unit (NICU) has led to the formation of intracardiac thrombi. A paucity of data exists on the management of neonatal cardiac thrombi, with the few reported cases focusing on outcomes following thrombolytic therapy. This study was undertaken to evaluate the outcome of cardiac thrombi in neonates who do not receive thrombolytic therapy. Nineteen patients younger than 3 months of age diagnosed with cardiac thrombi were included. All 19 patients had a central line. Management consisted of a combination of antibiotics and low-molecular-weight heparin (n = 16) or surgical removal (n = 2). In one case, no treatment was instituted. One patient was lost to follow-up after partial resolution of the thrombus. Complete thrombus resolution occurred in 18 patients, 9 with negative blood cultures and 9 with positive blood cultures. It took longer for resolution of thrombi associated with positive blood cultures than for sterile thrombi. No patient had evidence of thrombus embolization. From these data we concluded that the natural history of cardiac thrombi is resolution. Infected thrombi require more prolonged therapy. Surgery is seldom required and thrombolytics are not usually necessary for clot resolution.

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.

Management of a child with renal artery stenosis and homozygous factor V Leiden mutation

Presence of factor V Leiden mutation is a known risk factor for thrombosis. It contributes for premature occlusion of vascular anastomosis. This report describes the intraoperative and postoperative anticoagulation management of a girl with homozygous factor V Leiden mutation and renal artery stenosis after her renovascular reconstruction surgery. This report suggests that postoperative anticoagulation may be helpful for the successful maturation of vascular anastomoses in children with underlying acquired or hereditary risk factors for thrombosis including factor V Leiden mutation.

Inflammatory bowel disease and cerebrovascular arterial and venous thromboembolic events in 4 pediatric patients: a case series and review of the literature

Inflammatory bowel disease has been linked to cerebrovascular lesions, but the mechanisms of these vascular complications and their frequency among children with inflammatory bowel disease are unclear. We present 4 children with inflammatory bowel disease who developed ischemic or hemorrhagic stroke or cerebral sinovenous thrombosis. All 4 patients were female; 3 had Crohn's disease and 1 had indeterminate colitis. All of the patients had additional risk factors for thrombosis including thrombocytosis, severe dehydration attributable to an inflammatory bowel disease exacerbation, and, in 2 instances, genetically mediated coagulation defects. It is believed that the occurrence of thrombotic complications in individuals with inflammatory bowel disease is attributable to multifactorial causes. The current literature on cerebrovascular complications and treatment in the setting of pediatric inflammatory bowel disease is reviewed.

Case of adolescent with Paget-Schroetter syndrome and underlying thrombophilia due to an elevated lipoprotein (A)

Upper extremity deep vein thrombosis (UEDVT) is a rare disorder in children and is most often associated with a central venous catheter (CVC), cancer, or an underlying thrombophilia. In adults, repetitive or strenuous upper extremity activity has been linked to mechanical compression of the thoracic outlet resulting in subclavian vein thrombosis, also known as Paget-Schroetter Syndrome (PSS). We present the case of a 14 year old female who was found to have an UEDVT consistent with PSS. On subsequent thrombophila screening, she was noted to have a significantly elevated lipoprotein (a) level of 83 (normal: <30 mg/dL). She underwent 3 months of anticoagulation therapy prior to her first rib resection and in follow-up was noted to have complete patency of her subclavian vein. This case illustrates the necessity for thrombophilia screening in the pediatric patient with UEDVT despite evidence of anatomic abnormality or mechanical venous compression.

Arterial ischemic stroke in children

Stroke in children is relatively rare. Advances in the clinical recognition and radiographic diagnosis of ischemic stroke have increased the frequency of the diagnosis in infants and children and have raised the need for immediate therapy. A vast amount of data has recently become available through basic research and neuroimaging techniques shedding new light on the chain of events that occur in ischemic stroke in animal models and in the adult population. Whether this new information can also be applied to the pediatric population remains to be seen, but it is likely that the active management of children with acute ischemic stroke in the near future will include brain protection, brain reperfusion, and prevention measures.

Unusual left atrial appendage thrombus in a neonate with normal heart after sustained supraventricular tachycardia

Left atrial appendage thrombi in neonates are uncommon. We describe a neonate with a large thrombus in the left atrial appendage detected by echocardiography after a paroxystic sustained supraventricular tachycardia associated with intermittent Wolff-Parkinson-White syndrome. Mechanisms and therapy of atrial thrombosis in neonates are briefly discussed.

Pharmacokinetics, efficacy, and safety of LMWHs in venous thrombosis and stroke in neonates, infants and children

Since the early nineties it has been shown that low molecular weight heparin (LMWH) has significant advantages over unfractionated heparin and oral anticoagulants for both the treatment and the prevention of thrombosis, not only in adults, but also in children. The present review was based on an 'EMBASE', 'Medline' and 'PubMed' search including literature published in any language since 1980 on LMWH in neonates, infants and children. It included paediatric pharmacokinetic studies, the use of LMWH in children with venous thrombosis, LMWH administration in paediatric patients with ischaemic stroke, and its use in order to prevent symptomatic thromboembolism in children at risk. An increasing rate of off-label use of LMWH in children has been reported, showing that LMWHs offer important benefits to children with symptomatic thromboembolic events and poor venous access. Two well-conducted pharmacokinetic studies in this age group showed that neonates and younger infants require higher LMWH doses than older children to achieve the targeted anti-Xa levels, due to an increased extra vascular clearance. Recurrent symptomatic thromboses under LMWH occur in approximately 4% of children treated for venous thrombosis, and in 7% of children treated for stroke; major bleed was documented in 3% of children with therapeutic target LMWH anti-Xa levels, whereas minor bleeding was reported in approximately 23% of children receiving either therapeutic or prophylactic doses, respectively. Further randomized controlled trials are recommended to evaluate the optimum duration and application for different LMWH indications in children.

Enoxaparin Use in the Neonatal Intensive Care Unit: Experience Over 8 Years

STUDY OBJECTIVE

To evaluate the effectiveness and safety of enoxaparin therapy in a neonatal intensive care unit (NICU).

DESIGN

Retrospective chart review.

SETTING

Level III NICU in a Canadian academic center.

PATIENTS

All neonates treated with enoxaparin while in the NICU between January 1, 1998, and June 1, 2006.

MEASUREMENTS AND MAIN RESULTS

Data abstracted included patient demographics, diagnosis of thrombosis and its progression, enoxaparin dosages with corresponding antifactor Xa levels, and adverse events. Sixteen neonates (four term, 12 preterm) were treated with enoxaparin at a mean +/- SD initial subcutaneous dose of 1.41 +/- 0.15 mg/kg every 12 hours. The target therapeutic range (antifactor Xa level 0.5-1.0 U/ml) was achieved by 12 infants at a mean +/- SD dose of 1.92 +/- 0.43 mg/kg every 12 hours, after a mean of 5.6 days (range 1-15 days). Preterm infants required a higher dose (per kilogram) compared with term infants to maintain therapeutic antifactor Xa levels (mean +/- SD 1.94 +/- 0.39 vs 1.65 +/- 0.14 mg/kg every 12 hrs, p<0.001). Enoxaparin doses were more strongly correlated to antifactor Xa levels in term infants (r(2)=0.51, p<0.001) compared with preterm infants (r(2)=0.20, p<0.001). Ten (71%) of 14 thromboembolic events resolved, either partially or completely, at a mean of 39 days (range 8-61 days) of enoxaparin therapy. Nine infants (56%) experienced minor local adverse effects at the site of the indwelling subcutaneous catheter (induration, bruises, hematomas, or leakage). Systemic adverse events that were possibly related to enoxaparin therapy included osteopenia (one infant), scleral hemorrhage (one), and minor gastrointestinal tract bleeding (three) found in gastric feeding tubes. No adverse effects were associated with antifactor Xa levels greater than 1.0 U/ml.

CONCLUSION

Enoxaparin may be effective in the treatment of neonatal thrombosis. An initial dosage of 1.5 mg/kg every 12 hours is likely inadequate to obtain therapeutic antifactor Xa levels rapidly and differs for term and preterm neonates. Therapeutic levels in preterm infants may be more variable, and the pharmacokinetics of this drug in preterm infants requires further evaluation. Future studies in neonates should prospectively evaluate a higher starting dose of enoxaparin to document effectiveness, acceptance, compliance with treatment guidelines, and adverse effects.

Risk factors for recurrent venous thromboembolism in the European collaborative paediatric database on cerebral venous thrombosis: a multicentre cohort study

Background

The relative importance of previous diagnosis and hereditary prothrombotic risk factors for cerebral venous thrombosis (CVT) in children in determining risk of a second cerebral or systemic venous thrombosis (VT), compared with other clinical, neuroimaging, and treatment variables, is unknown.

Methods

We followed up the survivors of 396 consecutively enrolled patients with CVT, aged newborn to 18 years (median 5·2 years) for a median of 36 months (maximum 85 months). In accordance with international treatment guidelines, 250 children (65%) received acute anticoagulation with unfractionated heparin or low-molecular weight heparin, followed by secondary anticoagulation prophylaxis with low-molecular weight heparin or warfarin in 165 (43%).

Results

Of 396 children enrolled, 12 died immediately and 22 (6%) had recurrent VT (13 cerebral; 3%) at a median of 6 months (range 0·1–85). Repeat venous imaging was available in 266 children. Recurrent VT only occurred in children whose first CVT was diagnosed after age 2 years; the underlying medical condition had no effect. In Cox regression analyses, non-administration of anticoagulant before relapse (hazard ratio [HR] 11·2 95% CI 3·4–37·0; p<0·0001), persistent occlusion on repeat venous imaging (4·1, 1·1–14·8; p=0·032), and heterozygosity for the G20210A mutation in factor II (4·3, 1·1–16·2; p=0·034) were independently associated with recurrent VT. Among patients who had recurrent VT, 70% (15) occurred within the 6 months after onset.

Conclusion

Age at CVT onset, non-administration of anticoagulation, persistent venous occlusion, and presence of G20210A mutation in factor II predict recurrent VT in children. Secondary prophylactic anticoagulation should be given on a patient-to-patient basis in children with newly identified CVT and at high risk of recurrent VT. Factors that affect recanalisation need further research.

Venous thromboembolism in the neonatal period

Thromboembolism occurs more frequently in newborns than in older infants or children. The developing hemostasis system of neonates has decreased concentrations of procoagulant proteins and the naturally occurring anticoagulants and hemostatic control proteins. Overall, neonatal hemostasis provides protection from excessive bleeding at the expense of an increased risk for thromboembolism. Intensive medical care for premature and ill infants often requires central vascular assess, and the most frequent risk factor for thromboembolism is the presence of an indwelling vascular catheter. Management of venous thromboembolism in the newborn period varies depending on the location and extent of the thrombus as well as the risk for acute embolic complications and later vascular compromise. Therapeutic decisions are guided by practitioners' past experience, published case reports and case series, several large registries, and extrapolation from results of clinical trials in adults with thromboembolic disease. Valuable consensus guidelines have been compiled by the AACP Conference on Antithrombotic and Thrombolytic Therapy. Heparin, either unfractionated or a low molecular weight preparation, is the most commonly utilized anticoagulant to treat thromboembolism in newborn infants. Thrombolytic therapy may be considered if the thrombus is life or limb threatening and there is no hemorrhagic contraindication. Multicenter, prospective, controlled clinical trials in this important patient population are needed to provide evidence-based data to better inform optimal management.

Pilot dose-finding and safety study of bivalirudin in infants <6 months of age with thrombosis

BACKGROUND

Thrombosis is not uncommon in children with serious medical conditions. Unfractionated heparin, the most commonly used anticoagulant in the acute management of thrombosis, has significant pharmacologic limitations, especially in infants. Newer anticoagulants have improved properties relative to heparin, and this may enhance the outcome in children.

OBJECTIVE

To determine dosing, and to assess the safety and efficacy of bivairudin for infants with thrombosis.

METHODS

Infants <6 months old were chosen for this pilot study as they may most benefit from a direct thrombin inhibitor because of their physiologically low antithrombin levels. This was an open label, dose-finding and safety study. Patients received one of three bolus doses and one of two initial infusion doses with subsequent dosing adjusted utilizing the activated partial thromboplastin time. Safety was assessed by specific bleeding endpoints. Efficacy was determined by reassessing the initial imaging study at 48-72 h and by measurement of molecular markers of thrombin generation.

RESULTS

Sixteen patients completed the study. All three bolus doses resulted in therapeutic anticoagulation, as did both initial infusion doses. A dose-response effect was noted for the continuous infusion but not the bolus dosing. Two patients met the study criteria for major bleeding, both with gross hematuria, which resolved with a reduction in the bivalirudin infusion rate. In terms of efficacy, 37.5% of patients had complete or partial resolution of their thrombosis by 48-72 h. There was a significant decrease in all three molecular markers of thrombin generation.

CONCLUSION

This study demonstrates the potential utility of bivalirudin in the pediatric population.

Cranial MR venography findings of severe hypernatremic dehydration in association with cerebral venous thrombosis in the neonatal period

Severe neonatal hypernatremia is an important electrolyte disorder that has serious effects on the central nervous system, including brain edema, intracranial hemorrhage, hemorrhagic infarct, and thrombosis. Cerebral venous thrombosis is relatively rare in severe neonatal hypernatremic dehydration. The English literature contains only a few reports of the cranial radiological findings in severe neonatal hypernatremia. The authors report cranial MR venography findings of a newborn infant with severe hypernatremic dehydration. To the best of their knowledge, this is the first such report in the English literature.

Thrombosis and acute lymphoblastic leukaemia

Venous thrombosis is more frequent in patients treated for acute lymphoblastic leukaemia (ALL) than other malignancies and has distinctive causes, clinical features and remedies. The reported incidence varies from 1% to 36%, depending on the chemotherapy protocol and whether the reported cases are symptomatic or detected on screening radiography. The risk is thought to arise from increased thrombin generation at diagnosis combined with reduced thrombin inhibitory capacity due to depletion of circulating anti-thrombin (AT) by asparaginase. A number of patient and treatment variables have been reported to influence the risk of thrombosis including hereditary thrombophilia, early insertion of central venous catheters and exposure to a combination of steroids and asparaginase during induction. Erwinia asparaginase is associated with a lower risk of thrombosis compared with Escherichia coli asparaginase. The majority of symptomatic thromboses are related to central venous catheters and involve the upper venous system. Central nervous system thrombosis involving the cerebral venous sinuses is a unique feature of asparaginase-related thrombosis and is reported to occur in 1-3% of patients. Conclusive evidence to support the use of anti-coagulant treatment or AT concentrates for primary prevention is lacking, as is evidence for the efficacy of AT concentrates in the management of established thrombosis. Preventative strategies are hampered by conflicting data on factors that would enable identification of those at highest risk of thrombosis.

Enoxaparin therapy for arterial thrombosis in infants with congenital heart disease

OBJECTIVE

To investigate efficacy and safety of enoxaparin for catheter-related arterial thrombosis in infants with congenital heart disease.

DESIGN

Prospective observational study.

SETTING

Pediatric Intensive Care and Cardiology Unit at the University Children's Hospital of Zurich.

PATIENTS

A cohort of 32[Symbol: see text]infants aged 0-12[Symbol: see text]months treated with enoxaparin for catheter-related arterial thrombosis from 2002 to 2005.

MEASUREMENTS

Dose requirements of enoxaparin, resolution of thrombosis by Doppler ultrasound, and bleeding complications.

RESULTS

Catheter-related arterial thrombosis was located in the iliac/femoral arteries in 31 (97%) infants and aorta in 1 infant, and was related to indwelling catheters and cardiac catheterization in 17 (53%) and 15 (47%) cases, respectively. Newborns required increased doses of enoxaparin to achieve therapeutic anti-FXa levels (mean 1.62[Symbol: see text]mg/kg per dose) compared with infants aged 2-12 months (mean 1.12 mg/kg per dose; p=0.0002). Complete resolution of arterial thrombosis occurred in 29 (91%) infants at a mean of 23 days after initiation of enoxaparin therapy. Partial or no resolution was observed in 1 (3%) and 2 (6%) infants, respectively, at a mean follow-up time of 4.3 months. Bleeding complications occurred in 1 (3%) infant.

CONCLUSION

Enoxaparin is efficient and safe for infants with congenital heart disease and catheter-related arterial thrombosis, possibly representing a valid alternative to the currently recommended unfractionated heparin.

Tissue plasminogen activator for a left atrial thrombus after Senning repair

OBJECTIVE

To avoid the surgical removal of an obstructive thrombus in a Senning baffle by the administration of recombinant tissue-type plasminogen activator.

SETTING

A pediatric intensive care unit in a children's university hospital.

PATIENTS

A 3-yr-old male was diagnosed with a large left atrial thrombus 2 wks after Senning repair for D-transposition of the great arteries. The child presented with massive chylous pleural, pericardial effusions, and cardiac tamponade, secondary to partial obstruction of the pulmonary venous channel.

INTERVENTION

Thrombolysis with recombinant tissue-type plasminogen activator was instituted.

RESULTS

We observed a resolution of the thrombus in <48 hrs. Minor local bleeding was the only noted side effect. No signs of systemic thromboembolization were detected.

CONCLUSION

Early thrombolysis with recombinant tissue-type plasminogen activator could be considered a possible alternative to surgical thrombectomy in selected postoperative pediatric cases, although there may be a potential risk of serious bleeding.

Cerebral sinovenous thrombosis in children

Cerebral sinovenous thrombosis (CSVT) is a rare but increasingly recognized disease process in children. In the pediatric population, the etiologies of CSVT are multiple and the outcomes are variable. The current therapies for CSVT include anticoagulation, thrombolysis, hydration, surgery, and supportive care. Adult studies, pediatric case studies, and expert opinion form the basis for these treatment strategies. International cooperative efforts are currently being undertaken to collect data on pediatric stroke patients, including CSVT. These multicenter collaborations are needed to increase our understanding of the incidence, risk factors, treatment modalities, and outcomes of CSVT in pediatric populations.

Assessing the outcome of systemic tissue plasminogen activator for the management of venous and arterial thrombosis in pediatrics

This study sought to ascertain the outcomes of systemic thrombolytic therapy used in a cohort of infants and children. Complete thrombus resolution was achieved in 81% of patients with arterial thromboses (n=16) compared to 0% of children with venous thromboses (n=10). A major bleeding rate of 11.5% occurred across the entire cohort (n=3, all arterial). In our cohort, no patient with venous thromboembolism achieved complete resolution of their thrombosis after thrombolytic therapy. More cohort studies reporting the outcome of uniform protocols of thrombolytic therapy in children are required.

A thrombolytic regimen for high-risk deep venous thrombosis may substantially reduce the risk of postthrombotic syndrome in children

Important predictors of adverse outcomes of thrombosis in children, including postthrombotic syndrome (PTS), have recently been identified. Given this knowledge and the encouraging preliminary pediatric experience with systemic thrombolysis, we sought to retrospectively analyze our institutional experience with a thrombolytic regimen versus standard anticoagulation for acute, occlusive deep venous thrombosis (DVT) of the proximal lower extremities in children in whom plasma factor VIII activity and/or D-dimer concentration were elevated at diagnosis, from within a longitudinal pediatric cohort. Nine children who underwent the thrombolytic regimen and 13 who received standard anticoagulation alone were followed from time of diagnosis with serial clinical evaluation and standardized PTS outcome assessments conducted in uniform fashion. The thrombolytic regimen was associated with a markedly decreased odds of PTS at 18 to 24 months compared with standard anticoagulation alone, which persisted after adjustment for significant covariates of age and lag time to therapy (odds ratio [OR] = 0.018, 95% confidence interval [CI] = < 0.001-0.483; P = .02). Major bleeding developed in 1 child, clinically judged as not directly related to thrombolysis for DVT. These findings suggest that the use of a thrombolysis regimen may safely and substantially reduce the risk of PTS in children with occlusive lower-extremity acute DVT, providing the basis for a future clinical trial.

Risk of recurrent childhood arterial ischemic stroke in a population-based cohort: the importance of cerebrovascular imaging

OBJECTIVE

Few data exist regarding rates and predictors of recurrence after childhood arterial ischemic stroke. We sought to establish such rates within a large, multiethnic population and determine whether clinical vascular imaging predicts recurrence.

PATIENTS AND METHODS

In a population-based cohort study, we collected data on all documented cases of arterial ischemic stroke among 2.3 million children (<20 years old) enrolled in a northern Californian managed care plan from January 1993 to December 2004. Perinatal strokes were those that occurred by 28 days of life. Data on cerebrovascular imaging (conventional or magnetic resonance angiography), including presence of vascular abnormalities, were abstracted from official radiology reports. We used Kaplan-Meier survival-analysis techniques to determine rates and predictors of recurrent stroke.

RESULTS

Among 181 incident childhood stroke cases (84 perinatal; 97 later childhood), there were 16 recurrent strokes (1 after a perinatal stroke) at a median of 2.7 months. The 5-year cumulative recurrence rates were 1.2% after perinatal stroke and 19% after later childhood stroke. Of the 97 children with later childhood strokes, 52 received cerebrovascular imaging, predominantly magnetic resonance angiography (n = 36) and conventional angiography (n = 26). Although there were no recurrences among children with normal vascular imaging, children with a vascular abnormality had a 5-year cumulative recurrence rate of 66%.

CONCLUSIONS

Strokes recur in one fifth of cases of later childhood arterial ischemic stroke but are rare after perinatal stroke. Among the later childhood cases, cerebrovascular imaging identifies those at highest risk for recurrence.

Ischemic stroke complicating pediatric cardiovascular disease

BACKGROUND

After a year of unsuccessful treatment for hypertension, a young boy underwent a stenting procedure for aortic hypoplasia and awoke with hemiparesis and language deficits.

INVESTIGATIONS

Neuroimaging, echocardiography, craniocervical vascular imaging and prothrombotic testing.

DIAGNOSIS

Procedure-related acute arterial ischemic stroke and malignant cerebral edema with herniation.

MANAGEMENT

Anticoagulation with heparin, seizure prophylaxis and neuroprotective care, including external cooling for hyperthermia. Medical management of increased intracranial pressure and hemicraniectomy at 48 h for malignant cerebral edema. Treatment of deep vein thrombosis with inferior vena cava filter was also required. Long term treatments included extensive rehabilitation, aspirin, antiepileptics, antidyskinetics, antidepressants, antihypertensives and cosmetic skull reconstruction.

Isolated intracranial hypertension as a late manifestation of sinus venous compression secondary to a depressed skull fracture

Cerebral venous sinus compression can mimic idiopathic intracranial hypertension. The authors report the case of a 12-year-old girl who presented with diplopia and papilledema 3 weeks after a head injury. Lumbar puncture confirmed raised intracranial pressure, and neuroimaging subsequently identified a skull fracture compressing the right transverse sinus. Papilledema and diplopia resolved following surgical elevation of the bone fragment. Computer tomography or magnetic resonance venography are indicated in children presenting with isolated intracranial hypertension following head injury to exclude cerebral venous sinus compression secondary to skull fracture.

AE. Hemorrhagic stroke in children

Hemorrhagic stroke accounts for approximately half of stroke in childhood. Unlike arterial ischemic stroke, there are no consensus guidelines to assist in the evaluation and treatment of these children. This article reviews the literature on the evaluation, treatment, etiology, and neurologic outcome of hemorrhagic stroke in children. Important differences between pediatric and adult hemorrhage are highlighted, as treatment guidelines for adults may not be applicable in all cases. Required future research and potential therapies are also discussed.