Diagnosis and treatment of antiphospholipid syndrome in childhood: A review.

The antiphospholipid syndrome (APS) is a multisystem autoimmune disease characterized by recurrent fetal loss and thromboembolic events associated with the presence of elevated titres of antiphospholipid antibodies (aPL). The purpose of this review is to summarize what is currently known about the diagnosis and treatment of pediatric APS, to highlight key differences between APS presenting in adults versus children throughout, and to identify areas where future research is needed.

Coagulopathy in Children With Liver Disease.

It was thought that a high international normalized ratio predicted bleeding in patients with chronic liver disease (CLD) and patients were "autoanticoagulated." Contrary to this belief, while patients with CLD experienced bleeding, they also developed thromboses. In the last decade, the prevailing literature challenged the idea that an elevated international normalized ratio increased bleeding risk. The global assays of coagulation such as thromboelastography (TEG)/rotational thromboelastometry and thrombin generation assays provide additional insight into coagulation processes. It has become apparent that a parallel reduction of procoagulant and anticoagulant factors leave patients in a new "balanced" state, albeit a fragile one, where the balance can be easily disrupted. The inherent differences in coagulation between children and adults such as differences in levels of procoagulant and anticoagulant factors, underlying liver disease, and the paucity of studies in children make extrapolation of these findings to the pediatric population problematic. Ultimately, this is an area that requires further investigation to avoid inappropriate use of blood products and medication.

Immunizations in Children Requiring Warfarin Therapy.

Children with conditions requiring chronic warfarin therapy have increased. The importance of receiving immunizations in this population is magnified due to potential weakness in their immune response. There is concern about immunizing on therapeutic anticoagulation due to risk of hematomas and the influence of vaccine on warfarin metabolism. This study evaluated the influence of vaccines on warfarin effect as measured by the International Normalized Ratio and the clinically relevant hematomas or bruising postimmunization. There were no clinically relevant negative outcomes postimmunizations. This study demonstrates that immunizations may be safely administered to children receiving therapeutic warfarin therapy.

Impact of persistent antiphospholipid antibodies on risk of incident symptomatic thromboembolism in children: a systematic review and meta-analysis.

The aim of this study was to estimate the impact of antiphospholipid (aPL) antibodies on the risk of incident thromboembolism (TE; arterial and venous) in children via meta-analysis of published observational studies. A systematic search of electronic databases (Medline, EMBASE, OVID, Web of Science, The Cochrane Library) for studies published from 1966 to 2010 was conducted using keywords in combination both as MeSH terms and text words. Two authors independently screened citations and those meeting the a priori defined inclusion criteria were retained. Data on year of publication, study design, country of origin, number of patients/controls, ethnicity, TE type, and frequency of recurrence were abstracted. Heterogeneity across studies was evaluated, and summary odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using either fixed-effects or random-effects models. Of 504, 16 pediatric studies met the inclusion criteria. In total 1403 patients and 1667 population-based controls ≤18 years were enrolled. No significant heterogeneity was discerned across studies, and no publication bias was detected. Thus, data from arterial and venous TE were analyzed together. In addition, meta-regression analysis did not reveal statistically significant differences between site of TE, age at first TE, country, or publication year. A statistically significant association with a first TE was demonstrated for persistent aPL antibodies, with an overall summary ORs/CI of 5.9/3.6-9.7 (arterial 6.6/3.5-12.4; deep vein thrombosis 4.9/2.2-10.9). The present meta-analysis indicates that detection of persistent aPL is clinically meaningful in children with, or at risk for, TE and underscores the importance of pediatric thrombophilia screening programs.

The Impact of Central Venous Catheters on Pediatric Venous Thromboembolism.

The use of central venous catheters (CVCs) in children is escalating, which is likely linked to the increased incidence of pediatric venous thromboembolism (VTE). In order to better understand the specific risk factors associated with CVC-VTE in children, as well as available prevention methods, a literature review was performed. The overall incidence of CVC-VTE was found to range from 0 to 74%, depending on the patient population, CVC type, imaging modality, and study design. Throughout the available literature, there was not a consistent determination regarding whether a particular type of central line (tunneled vs. non-tunneled vs. peripherally inserted vs. implanted), catheter material, insertion technique, or insertion location lead to an increased VTE risk. The patient populations who were found to be most at risk for CVC-VTE were those with cancer, congenital heart disease, gastrointestinal failure, systemic infection, intensive care unit admission, or involved in a trauma. Both mechanical and pharmacological prophylactic techniques have been shown to be successful in preventing VTE in adult patients, but studies in children have yet to be performed or are underpowered. In order to better determine true CVC-VTE risk factors and best preventative techniques, an increase in large, prospective pediatric trials needs to be performed.

Dose-finding and pharmacokinetics of therapeutic doses of tinzaparin in pediatric patients with thromboembolic events.

In children, there is an increasing off-label use of low molecular weight heparin (LMWH). However, there is an absence of information on dosing and pharmacokinetics of LMWH over all age groups. The objectives of the current study were to determine i) the once daily dose required to achieve anti-Xa levels of 0.5-1.0 IU/mL, ii) the pharmacokinetics and iii) preliminary safety data using tinzaparin. The study took the form of a single centre open-label Phase II study performed in 35 children requiring anticoagulation for treatment of thromboembolism. Age groups studied were: 0- < 2 months; 2 months- < 1 year; 1- < 5 years; 5- < 10 years; 10-16 years. Both population pharmacokinetic analysis using nonlinear mixed-effect modeling techniques and model-independent pharmacokinetic methods were employed. Results showed a relationship of age and dose requirements, clearance, time to peak anti-Xa level and volume of distribution. Younger children required an increased dose, cleared tinzaparin more rapidly, had anti-Xa levels peak earlier and had an increased volume of distribution. Younger children were more likely to be below target range than older children,with up to 75% of children < 1 year being below the target anti-Xa level. Four recurrences and one major bleed occurred. In conclusion, there is an inverse relationship of age on dose requirements related to volume of distribution, clearance and time to peak anti-Xa. Children < 5 years likely require dose adjustment samples to be drawn 2-3 hours post injection. Infants require anti-Xa levels to be monitored at least twice monthly.

Clinically important venous thromboembolism in pediatric critical care: a Canadian survey.

PURPOSE: Pediatric venous thromboembolism (VTE) is becoming an increasingly recognized morbidity associated with critical illness. The objective of this survey is to identify the patient factors and radiological features that pediatric intensivists consider more or less likely to make a venous thrombosis (VTE) clinically important in their patients. MATERIALS AND METHODS: Our definition of clinically important VTE was a VTE likely to result in short- or long-term morbidity or mortality if left untreated. We asked respondents to rate the likelihood that patient factors and radiological features make a venous thrombosis clinically important using a 5-point scale (1 = much less likely to 5 = much more likely). RESULTS: The 38 (58.5%) of 65 pediatric intensivists responding rated 4 patient factors as most likely to make a VTE clinically important: clinical suspicion of pulmonary embolism (mean score, 4.8), symptoms (mean, 4.5), detection by physical exam (mean, 4.4), and the presence of an acute or chronic cardiopulmonary comorbidity that might limit a patient's ability to tolerate pulmonary embolism (mean, 4.3). Of the radiological features, the 2 considered most important were VTE involving the vena cava extending into the right atrium (mean, 5) and central veins (mean, 4.5). CONCLUSIONS: When labeling a VTE as clinically important, pediatric intensivists rely on several specific patient factors and thrombus characteristics.

A case series of 72 neonates with renal vein thrombosis. Data from the 1-800-NO-CLOTS Registry.

Neonatal renal vein thrombosis (RVT) is a well-recognized clinical entity which is associated with serious morbidity. However, current information regarding RVT has been restricted to case reports and small case series. In this study, it was our objective to describe patient demographics, clinical presentation, location and risk factors of RVT. For our study design, we looked at a case series of 72 neonates with RVT referred to the 1-800-NO-CLOTS consultation service between 9/1996 and 8/2001. Data on age, gender, associated conditions, prothrombotic disorders, family history, location of the thrombosis, diagnostic techniques, and treatment were prospectively recorded using a standardized form. Our results show that RVT affected males (65%, CI 52-76%) significantly more often than females (35%, CI 24-48%). Median age at presentation was 2 days (0-21 days). RVT was unilateral in 72% (left side: 67%,CI 49-81%; right side: 33%, CI 19-51%), and bilateral in 28%. The majority (83%) had at least one associated condition: Prematurity (54%), central venous lines (17%), a diabetic mother (13%), asphyxia (6%), infections (6%). Prothrombotic testing was performed in 21 neonates. Activated protein C resistance was found in 8 children (38%), other defects in three. This is the largest case series of neonatal RVT to date. Data from the study show that i) male infants are affected twice as often as females and ii) there appears to be a left-sided predominance of neonatal RVT. Neonatal RVT is only infrequently associated with the presence of a catheter as compared to thrombosis at other sites. The majority of infants have associated conditions with prematurity being most frequent. A small subset of neonates were screened for prothrombotic abnormalities and 50% of the children screened were positive.

Antithrombotic therapy in children: the Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy.

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).

Thrombotic complications of neonates and children with congenital nephrotic syndrome.

Congenital nephrotic syndrome (CNS) refers to a disease presenting with massive proteinuria in association with hypoalbuminemia, hyperlipidemia, and edema at birth or within the first three months of life. In the past, most children with CNS had extremely poor prognosis and succumbed to various complications, usually within the first 6 months. Recent advancements in protein supplementation and nutritional support, renal replacement therapy and renal transplantation in infancy, render these patients to have much better outcomes. However, there are still many hurdles in the management of this disease. Thromboembolism is an uncommon, yet important complication which the healthcare givers must be aware of. This article reviews the challenges in the management of the thrombotic complications with special emphasis on the unique characteristics of the newborn hemostasis system and anti-thrombin (AT) depletion in nephrotic syndrome. Due to the relatively low incidence of CNS in children and scarce information in the literature on the optimal management of the thromboembolic complications, most of the recommendations are based on the authors' experience.

Novel paediatric anticoagulants: a review of the current literature.

There are many limitations with respect to anticoagulants currently used in standard paediatric practice for prophylaxis and treatment of thrombosis: heparin, low molecular-weight heparin, and warfarin. Factors such as pharmacokinetic and dosing variability are further exacerbated by properties of the immature haemostatic system of children. These shortcomings necessitate exploring alternative anticoagulants in the paediatric population. In this review, we discuss several promising direct thrombin inhibitors and factor Xa inhibitors, and synthesize relevant drug information and clinical experience from the limited available case reports, case series, and nonrandomized dose-finding trials published to date.

Decompressive hemicraniectomy in children with severe ischemic stroke and life-threatening cerebral edema.

Decompressive hemicraniectomy has been discussed as a treatment option that increases survival in adults with malignant stroke. This approach has not been studied extensively in children. From a prospective cohort, we identified 4 children who underwent decompressive hemicraniectomy for malignant infarctions with life-threatening cerebral edema within 72 hours of their stroke. All 4 children had different causes for their stroke and experienced severe cerebral edema with increasing intracranial pressure and an impending fatal outcome. Despite massive cerebral infarction, all patients were ambulant and able to speak at the time of follow-up. Although a limited experience, decompressive hemicraniectomy is a life-saving approach for malignant stroke in children.

Management of a pediatric patient on the Berlin Heart Excor ventricular assist device with argatroban after heparin-induced thrombocytopenia.

We report a 15-year-old male patient who developed type II heparin-induced thrombocytopenia (HIT) after 6 weeks of heparin administration and placement of a Berlin Heart Excor left ventricular assist device (LVAD).