Arterial thromboembolic complications in critically ill children

Patient Characteristics and Treatment Outcomes of Symptomatic Catheter-Related Arterial Thrombosis in Infants: A Retrospective Cohort Study

OBJECTIVE

To describe the clinical characteristics, outcomes, and adverse events of treatment for symptomatic infant catheter-related arterial thrombosis.

STUDY DESIGN

Single-center retrospective medical record review of 99 infants (age <365 days) with catheter-related arterial thrombosis, either following indwelling arterial catheter placement or cardiac catheterization, who were treated with anticoagulation over an 8-year span at a pediatric tertiary care center. Outcomes measured include thrombosis progression, bleeding events, and thrombus resolution following the treatment period.

RESULTS

Thromboses were secondary to indwelling arterial catheter placement in 51 (51.5%) and cardiac catheterization in 48 (48.5%). The median age at diagnosis of catheter-related arterial thrombosis was 52 days. All patients received therapeutic anticoagulation with either unfractionated heparin or low molecular weight heparin for a maximum of 28 days. Progression of catheter-related arterial thrombosis occurred in 8 (8.1%) patients. One (1%) major and 3 (3%) minor bleeding events occurred within the cohort. Complete thrombus resolution was observed in 60 (60.6%), partial resolution in 33 (33.3%), and no resolution in 6 (6.1%) following the treatment period. Factors associated with complete thrombus resolution included time from intervention to catheter-related arterial thrombosis diagnosis (median of 1 day vs 5 days in those who experienced thrombus resolution vs those who did not, P = .035), and iliac and/or femoral artery involvement (P = .015).

CONCLUSIONS

Our treatment approach to infant catheter-related arterial thrombosis is safe and effective. Limitations of the study are its retrospective nature with a limited number of patients from a single institution. Additional prospective studies are needed to determine the optimal treatment approach to catheter-related arterial thrombosis in infants.

Different unfractionated heparin doses for preventing arterial thrombosis in children undergoing cardiac catheterization

BACKGROUND

The role of cardiac catheterization in pediatrics has progressed significantly over the last two decades, evolving from a primary diagnostic tool to a primary treatment modality in children with congenital heart disease. Vascular complications, particularly arterial thrombosis, are among the most common unwanted post-cardiac catheterization events. In 1974, unfractionated heparin proved to be superior to placebo in decreasing the incidence of arterial thrombosis in pediatric patients. However, the optimal dose of unfractionated heparin to be utilized in this setting remains a matter of controversy. This is an update of the review first published in 2014.

OBJECTIVES

To evaluate the use of low-dose (< 100 units/kg) versus high-dose (≥ 100 units/kg) unfractionated heparin administered as an intravenous bolus at the time of initiation of cardiac catheterization (that is, immediately after arterial puncture), with or without subsequent heparin maintenance doses, for the prevention of post-procedural arterial thrombosis in children.

SEARCH METHODS

The Cochrane Vascular Information Specialist searched the Cochrane Vascular Specialised Register, CENTRAL, MEDLINE, Embase and CINAHL databases and World Health Organization International Clinical Trials Registry Platform and ClinicalTrials.gov trials registers to 15 October 2019. We planned to undertake reference checking of identified trials to identify additional studies. No language restrictions were applied.

SELECTION CRITERIA

We included randomized or quasi-randomized trials that compared low dose to high dose unfractionated heparin administered prior to cardiac catheterization. We selected studies conducted in children aged 0 to 18 years.

DATA COLLECTION AND ANALYSIS

The first screening of potentially eligible studies was conducted by one of the authors (MLA). The second screening, risk of bias assessment and data extraction were independently conducted by two authors (MLA, LRB). Outcomes (thrombotic events, bleeding complications, other complications) were treated as dichotomous variables. The effect measures used were risk ratio (RR), risk difference (RD) and number needed to treat (NNT), with 95% confidence intervals (CI). We assessed the certainty of evidence for each outcome using the GRADE approach.

MAIN RESULTS

We identified no new studies for inclusion in this review. In total, two studies with a total of 492 participants were included. We had concerns about risk of bias for one of the two studies. The certainty of the evidence for our key outcomes was downgraded to moderate due to risk of bias concerns and imprecision. The confidence interval for the risk of arterial thrombotic events was compatible with benefits of either high or low unfractionated heparin dose regimens (RR low-dose versus high-dose 1.06, 95% CI 0.58 to 1.92). Only one of the studies reported the frequency of bleeding events and found no clear difference in the incidence of major or minor bleeding events between arms (RR low-dose versus high-dose 2.96, 95% CI 0.12 to 71.34 for major bleeding events; RR low-dose versus high-dose 1.38, 95% CI 0.46 to 4.13 for minor bleeding). This study also reported on the incidence of deep vein thrombosis when comparing the high versus low dose of heparin and reported a non-significant difference (RR low-dose versus high-dose 0.34, 95% CI 0.01 to 8.28). The other study lacked information about bleeding. Additional side effects of heparin other than bleeding events were not reported in either of the studies.

AUTHORS' CONCLUSIONS

Due to the limitations of the current evidence, small number of included studies, and lack of details reported in one study, we are unable to determine the effects of different dosing regimens of unfractionated heparin for the prevention of vascular thrombosis during cardiac catheterization in children. Further adequately powered, randomized clinical trials are needed.

Extremity Arterial Thromboses in Hospitalized Children: A National Database Analysis of Prevalence and Therapeutic Interventions

OBJECTIVES

The purpose of this study was to evaluate the prevalence, demographics, predisposing conditions, therapeutic interventions, and outcomes of extremity arterial thrombosis in hospitalized children.

DESIGN

Retrospective cohort study.

PATIENTS

National discharge database analysis.

MEASUREMENTS AND MAIN RESULTS

Cases of extremity arterial thrombosis in children and neonates were extracted from the Kids' Inpatient Database 2012. These were analyzed and compared with other discharges for prevalence, demographics, treatments, outcomes, and further analyzed by age group and select predisposing conditions. A total of 961 children with extremity arterial thrombosis (prevalence of 2.35/10,000 discharges) were included in our analysis. The median age of extremity arterial thrombosis patients was significantly lower when compared with other pediatric discharges (1 yr [interquartile range, 0-15 yr) vs 3 yr [interquartile range, 0-16 yr]; p < 0.0001). The proportion of females with extremity arterial thrombosis was lower (41.4% vs 53.3%; odds ratio, 0.62; 95% CI, 0.55-0.70) with no racial/ethnic variation in the prevalence of extremity arterial thrombosis. An upper extremity was involved in 18.1% and a lower extremity in 83.3%. Arterial cannulation and cardiac catheterization were much more common in the younger age groups. External trauma was documented in 13.2% of all patients with extremity arterial thrombosis and was more frequent in older age groups. A systemic thrombolytic medication was administered to 5.7% of the patients, thromboembolectomy was performed in 11.8% of the cases, and 3.1% of the patients required amputation. There was a significant variation in the use of thrombolysis, thrombectomy/embolectomy, or requirement for amputation limb based on age groups and underlying predisposing condition.

CONCLUSIONS

The study describes the national prevalence of extremity arterial thrombosis in hospitalized children. The management strategies of extremity arterial thrombosis vary with age and underlying predisposing factors.

Incidence of arterial catheter complications: a retrospective study of 35 cats (2010-2014)

OBJECTIVES

The aim of this study was to investigate the incidence of complications associated with arterial catheterization in cats in a veterinary hospital, and to document which factors may increase the incidence of complications.

METHODS

Medical records at a referral veterinary hospital were retrospectively reviewed to identify cats that had an arterial catheter placed between January 2010 and October 2014.

RESULTS

Thirty-five cats having 38 arterial catheters were included in the study. There was a relatively high incidence of minor complications (23.7%), with the most common being catheter occlusion. The incidence of major arterial catheter complications was low (2.63%). Duration of catheter use was positively correlated to the incidence of complications. There was also a significant correlation between catheters used for intensive care unit monitoring and incidence of complications. All cats with catheter complications survived to discharge.

CONCLUSIONS AND RELEVANCE

The low incidence of major arterial catheter complications in this population of cats illustrates that arterial catheterization is a safe monitoring and diagnostic tool. The duration of catheter placement is significantly associated with the incidence of catheter complications.

Pediatric arterial catheters: Complications and associated risk factors

BACKGROUND/PURPOSE

Arterial catheter complications are a common problem in a pediatric critical care setting, but reported complication rates and risk factors associated with peripheral arterial catheter complications vary. We conducted a retrospective cohort study to identify risk factors in a pediatric patient population.

METHODS

We performed a detailed abstraction of provider notes in the electronic medical records of inpatients ≤18years of age who underwent arterial line placement between January 1, 2008 and January 1, 2013 at a university-affiliated standalone pediatric hospital. Inpatient records were assessed for complications associated with arterial catheterization and risk factors inherent to arterial catheter insertion.

RESULTS

Two hundred twenty-eight children were identified, of whom 75 (33%) had a total of 106 arterial catheter complications. Complications included line malfunctions (59%, n=63), bleeding (16%, n=17), multiple complications (11%, n=12), infiltration (8%, n=9), and hematoma (4%, n=4). Line malfunction was reported in all patients with multiple complications. Independent predictors of complications associated with arterial catheterization were the presence of more than one provider during the insertion (p=0.007) and insertion attempts at multiple sites (p=0.036).

CONCLUSIONS

Our analysis suggests the need for a prospective study to comprehensively assess provider-related risk factors associated with arterial catheter complications in children.

LEVEL OF EVIDENCE

IV.

Thrombolysis Using Tissue Plasminogen Activator: Experience from a Critical Care Setting

To describe the experience of thrombolysis using tissue plasminogen activator (tPA) in critically ill children admitted to the pediatric intensive care unit (PICU), retrospective review of medical records of all children (1 month-16 years), who were admitted in PICU since January 2014 to December 2017 and received systemic tPA for thrombolysis was done. Data was collected on a structured proforma and included thrombus location, tPA dose and duration, outcome (resolution, survival) and complications (bleeding). Total 9 patients (7 males, 2 females) received systemic tPA therapy for thrombolysis with mean age of 74.64 ± 69.58 months. Two patients had thrombus in femoral artery, 3 in IVC and 4 had intra-cardiac thrombosis. Median number of doses was 2 with a range of 1-5 doses. Complete resolution of the clot was noted in all except one patient. A standard starting dose of 0.01 mg/kg/h was used in all patients. Only one patient developed melena after TPA therapy which self-resolved. Systemic tPA therapy was very safe in pediatric critically ill patients and was effective for thrombolysis and did not show any adverse effects in children with varying underlying diagnosis.

Arterial reconstructions for chronic lower extremity ischemia in preadolescent and adolescent children

OBJECTIVE

Chronic lower extremity ischemia in pediatric patients is uncommon. The intent of this study was to better define the arterial reconstructive options and their long-term durability in preadolescent and adolescent children having clinically relevant arterial occlusions affecting the lower extremity.

METHODS

The medical records of 33 consecutive pediatric patients who underwent lower extremity revascularization for chronic ischemia at the University of Michigan from 1974 to 2016 were reviewed. Patients were categorized by age, clinical manifestation, surgical intervention undertaken, and outcomes.

RESULTS

Operative treatments involved 26 preadolescent children (mean age, 6.1 years; range, 3-9 years) and 7 adolescent children (mean age, 13.9 years; range, 10-17 years). Occlusions were due to earlier injury related to catheter (14), cannula (2), or both catheter and cannula (14); penetrating trauma (2); and vasculitis (1). Preoperative manifestations included symptomatic extremity ischemia (25), growth retardation manifested by documented limb length discrepancies (21), and scoliosis (5). Primary arterial reconstructions were delayed after the precipitating vascular event an average of 5.3 and 11.2 years in the preadolescent and adolescent children, respectively. Primary procedures involved revascularizations of 36 extremities (in preadolescents and adolescents) including autologous vein (26/5), polyethylene terephthalate (Dacron; 1/0), and expanded polytetrafluoroethylene (0/3) bypasses and vein patch angioplasty (0/1). Vein grafts traversing the abdominal cavity (15) were wrapped with a synthetic mesh. Excluding one early graft occlusion, there were no major early postoperative complications after the primary procedures. Secondary operations followed 31% of the primary operations, being performed an average of 8.8 and 6.7 years later (in 8 preadolescent and 3 adolescent children, respectively) for late graft occlusions (6), graft stenoses (3), aneurysmal vein grafts (2), and anastomotic pseudoaneurysm (1). The unassisted primary graft patency rate was 69%, and the assisted secondary graft patency rate was 94%. Symptomatic ischemia resolved in all but two children. Mean postoperative ankle-brachial indices improved to 1.08 from 0.76 preoperatively. Among children having postoperative documentation of limb lengths, the limb length discrepancies became less (11), were unchanged (1), or progressed (3). Follow-up averaged 8.0 years. There was no operative mortality in this experience.

CONCLUSIONS

Primary lower extremity arterial reconstructions in children with chronic lower extremity ischemia can be successfully undertaken with excellent results. Nevertheless, the potential for late primary graft failures, evident in nearly a third of this experience, mandates careful long-term follow-up and may necessitate secondary interventions to maintain satisfactory outcomes.

Lack of difference between continuous versus intermittent heparin infusion on maintenance of intra-arterial catheter in postoperative pediatric surgery: a randomized controlled study

OBJECTIVE:

To compare two systems of arterial catheters maintenance in postoperative pediatric surgery using intermittent or continuous infusion of heparin solution and to analyze adverse events related to the site of catheter insertion and the volume of infused heparin solution.

METHODS:

Randomized control trial with 140 patients selected for continuous infusion group (CIG) and intermittent infusion group (IIG). The variables analyzed were: type of heart disease, permanence time and size of the catheter, insertion site, technique used, volume of heparin solution and adverse events. The descriptive variables were analyzed by Student's t-test and the categorical variables, by chi-square test, being significant p<0.05.

RESULTS:

The median age was 11 (0-22) months, and 77 (55%) were females. No significant differences between studied variables were found, except for the volume used in CIG (12.0±1.2mL/24 hours) when compared to IIG (5.3±3.5mL/24 hours) with p<0.0003.

CONCLUSIONS:

The continuous infusion system and the intermittent infusion of heparin solution can be used for intra-arterial catheters maintenance in postoperative pediatric surgery, regardless of patient's clinical and demographic characteristics. Adverse events up to the third postoperative day occurred similarly in both groups. However, the intermittent infusion system usage in underweight children should be considered, due to the lower volume of infused heparin solution [ClinicalTrials.gov Identifier: NCT01097031].

Different unfractionated heparin doses for preventing arterial thrombosis in children undergoing cardiac catheterization

BACKGROUND

The role of cardiac catheterization in pediatrics has progressed significantly over the last two decades, evolving from a primary diagnostic tool to a primary treatment modality in children with congenital heart disease. Vascular complications, particularly arterial thrombosis, are among the most common unwanted post-cardiac catheterization events. In 1974, unfractionated heparin proved to be superior to placebo in decreasing the incidence of arterial thrombosis in pediatric patients. However, the optimal dose of unfractionated heparin to be utilized in this setting remains a matter of controversy.

OBJECTIVES

To evaluate the use of low-dose (< 100 units/kg) versus high-dose (≥ 100 units/kg) unfractionated heparin administered as an intravenous bolus at the time of initiation of cardiac catheterization (that is, immediately after arterial puncture), with or without subsequent heparin maintenance doses, for the prevention of post-procedural arterial thrombosis in children.

SEARCH METHODS

The Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator searched the Specialised Register (last searched November 2013) and CENTRAL (2013, Issue 10). The authors searched MEDLINE, EMBASE, and the Virtual Health Library. Clinical trials databases and sources of grey literature were searched. No language restrictions were applied.

SELECTION CRITERIA

Randomized or quasi-randomized trials that compared low dose to high dose unfractionated heparin administered prior to cardiac catheterization were included. We selected studies conducted in children aged 0 to 18 years.

DATA COLLECTION AND ANALYSIS

The first screening of potentially eligible studies was conducted by one of the authors (MLA). The second screening, quality assessment and data extraction were independently conducted by two authors (MLA, LRB). Outcomes (thrombotic events, bleeding complications, other complications) were treated as dichotomous variables. The effect measures used were risk ratio (RR), risk difference (RD) and number needed to treat (NNT), with 95% confidence intervals (CI).

MAIN RESULTS

Two studies with a total of 492 participants were eligible for inclusion. Risk of bias was low for all domains in one of the studies and unclear for the other. One of the trials was stopped early. The quality of evidence for our key outcomes was moderate. The CI for the risk of arterial thrombotic events was compatible with benefits of either high or low unfractionated heparin dose regimens (RR low-dose versus high-dose 1.06, 95% CI 0.58 to 1.92). Only one of the studies reported the frequency of bleeding events for the cohort of patients and found no statistically significant difference in the incidence of major and minor bleeding events between arms (RR low-dose versus high-dose 1.38, 95% CI 0.46 to 4.13 for minor bleeding; RR low-dose versus high-dose 2.96, 95% CI 0.12 to 71.34 for major bleeding events). This study also reported on the incidence of deep vein thrombosis when comparing the high versus low dose of heparin and reported a non-significant difference (RR low-dose versus high-dose 0.34, 95% CI 0.01 to 8.28). The other study lacked information about bleeding. Side effects of heparin other than bleeding complications were not reported in either of the studies.

AUTHORS' CONCLUSIONS

Due to the limitations of the current evidence, small number of included studies, and lack of details reported in one study, we are unable to determine the effects of different dosing regimens of unfractionated heparin for the prevention of vascular thrombosis during cardiac catheterization in children. A further adequately powered, randomized clinical trial is needed.

Ischaemic distal limb necrosis and Klebsiella pneumoniae infection associated with arterial catheterisation in a cat

This case report describes dorsal pedal arterial thrombosis and infection with Klebsiella pneumoniae subsequent to arterial catheter placement in a cat. The complication led to avascular necrosis of the metatarsal and pedal soft tissue. The catheter was placed for blood pressure monitoring during surgery for correction of a peritoneopericardial diaphragmatic hernia. The exact mechanism of thrombosis was unclear. Amputation of the limb was required and the histopathological findings are presented. This is the first report of such a complication.

Aortic arch thrombosis in the neonate

Aortic arch thrombosis (AAT) of the neonate is rare but life-threatening by fatal compromise associated with thrombotic obstruction of the ascending aorta. We report a neonate with AAT who demonstrated a severe coarctation of the aorta and cerebral hypo-perfusion immediately after birth. Echocardiography confirmed the diagnosis of AAT on the findings of a large thrombus located on the transverse arch and blocking the cervical arterial branches. Low-molecular-weight heparin reduced the size of the thrombus and improved the hemodynamics of coarctation and cerebral perfusion. Echocardiography is a powerful tool to make a diagnosis and to monitor the size and regression of AAT.

Bilateral lower extremity acute thromboembolism as first presentation for cancer in a child: an interesting report

Although it rarely occurs in children, acute arterial thromboembolism can cause significant morbidity and mortality. Rapid diagnosis and prompt treatment can increase the chances of survival with a functional limb. We describe the case of a 10-year-old boy with acute bilateral lower extremity ischemia due to arterial thromboemboli originating from a rare cancer. We discuss diagnosis of and treatment strategies for acute arterial thromboembolism in the pediatric population, as well as the rare cancer the patient was diagnosed with.

Antithrombotic therapy in neonates and children: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines

BACKGROUND

Neonates and children differ from adults in physiology, pharmacologic responses to drugs, epidemiology, and long-term consequences of thrombosis. This guideline addresses optimal strategies for the management of thrombosis in neonates and children.

METHODS

The methods of this guideline follow those described in the Methodology for the Development of Antithrombotic Therapy and Prevention of Thrombosis Guidelines: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines.

RESULTS

We suggest that where possible, pediatric hematologists with experience in thromboembolism manage pediatric patients with thromboembolism (Grade 2C). When this is not possible, we suggest a combination of a neonatologist/pediatrician and adult hematologist supported by consultation with an experienced pediatric hematologist (Grade 2C). We suggest that therapeutic unfractionated heparin in children is titrated to achieve a target anti-Xa range of 0.35 to 0.7 units/mL or an activated partial thromboplastin time range that correlates to this anti-Xa range or to a protamine titration range of 0.2 to 0.4 units/mL (Grade 2C). For neonates and children receiving either daily or bid therapeutic low-molecular-weight heparin, we suggest that the drug be monitored to a target range of 0.5 to 1.0 units/mL in a sample taken 4 to 6 h after subcutaneous injection or, alternatively, 0.5 to 0.8 units/mL in a sample taken 2 to 6 h after subcutaneous injection (Grade 2C).

CONCLUSIONS

The evidence supporting most recommendations for antithrombotic therapy in neonates and children remains weak. Studies addressing appropriate drug target ranges and monitoring requirements are urgently required in addition to site- and clinical situation-specific thrombosis management strategies.

Incidence and predictors of indwelling arterial catheter-related thrombosis in children

BACKGROUND

 Indwelling arterial catheters (IACs) are used for monitoring and blood sampling purposes in intensive care units. Very limited information is available on the incidence and risk factors of IAC-related thrombosis in children.

OBJECTIVE

 To investigate the incidence and predictors of IAC-related thrombosis in a tertiary care pediatric hospital.

METHODS

  For a period of 12 months, detailed information was prospectively recorded for all consecutive children requiring IACs.

RESULTS

 Six hundred and fifteen IACs were placed in a total of 473 children at a median age of 0.56 years for a total of 47440.84 catheter hours. Of the 615 IACs, 418 (68%) were placed in the radial artery, 137 (22%) in the femoral artery, 26 (4%) in the umbilical artery, 11 (2%) in the brachial artery, and 23 (3.7%) in another artery. Thrombosis occurred in 20 cases, reflecting an overall incidence of 3.25%. Eighteen of the 20 IAC-related thrombi were located in the femoral arteries, reflecting a relative incidence of 13% (18/137). Newborn age, lower body weight, low cardiac output and increased hematocrit were significantly related with an increased risk of femoral artery thrombosis. In logistic regression analysis, younger age (P<0.001, odds ratio 6.51) was independently associated with an increased thrombotic risk.

CONCLUSIONS

 This study demonstrates that arterial thrombosis occurs with an increased incidence in children requiring IACs in the femoral location. Younger age is independently associated with an increased risk of thrombosis. The radial location is safe, and should be preferred to the femoral location.

Aspects of anticoagulation in children

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

Functional limb salvage following muscle rigor in a pediatric patient

Acute limb-threatening ischemia is a vascular surgical emergency. Traditionally, 4 to 6 hours are usually available from the onset of acute ischemia to successfully revascularize before irreversible damage occurs. The presence of ischemic rigor traditionally represents irreparable local damage to muscle in the adult population and is an indication for limb amputation. Although the literature is scarce on this topic, few authors have reported superior limb salvage rates in pediatric patients despite the presence of severely impaired arterial perfusion. We present a case of a 10-year-old girl with rigor of the left lower extremity, who underwent surgical reperfusion for acute ischemia approximately 14 hours after the initiation of symptoms. The patient presented with an insensate and paralyzed limb. Pulsatile flow was restored to her lower extremity. She regained protective sensation and suffered no significant sequelae of systemic reperfusion syndrome.

Management of neonatal aortic arch thrombosis with low-molecular weight heparin: a case series

Aortic arch thrombosis (AAT) is a potentially life threatening condition in neonates. We report 3 neonates with AAT and complete occlusion of a unilateral internal carotid artery with multiple cerebral infarcts. Multidisciplinary input led to deferral of thrombolytic therapy and surgical thrombectomy owing to the potential risk of hemorrhage within the infarcts. All the neonates were treated with low-molecular weight heparin treatment alone without any complications. Thrombus resolution was complete in 2 neonates, whereas it was near complete in one neonate. All the infants showed normal growth and development during follow-up. The rewarding outcome in these cases suggests that treatment with low-molecular weight heparin could be considered an option to treat AAT in selected patients.

Antithrombotic therapy in neonates and children: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition)

This chapter about antithrombotic therapy in neonates and children is part of the Antithrombotic and Thrombolytic Therapy: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). Grade 1 recommendations are strong and indicate that the benefits do, or do not, outweigh risks, burden, and costs, and Grade 2 suggests that individual patient values may lead to different choices (for a full understanding of the grading, see Guyatt et al in this supplement, pages 123S-131S). In this chapter, many recommendations are based on extrapolation of adult data, and the reader is referred to the appropriate chapters relating to guidelines for adult populations. Within this chapter, the majority of recommendations are separate for neonates and children, reflecting the significant differences in epidemiology of thrombosis and safety and efficacy of therapy in these two populations. Among the key recommendations in this chapter are the following: In children with first episode of venous thromboembolism (VTE), we recommend anticoagulant therapy with either unfractionated heparin (UFH) or low-molecular-weight heparin (LMWH) [Grade 1B]. Dosing of IV UFH should prolong the activated partial thromboplastin time (aPTT) to a range that corresponds to an anti-factor Xa assay (anti-FXa) level of 0.35 to 0.7 U/mL, whereas LMWH should achieve an anti-FXa level of 0.5 to 1.0 U/mL 4 h after an injection for twice-daily dosing. In neonates with first VTE, we suggest either anticoagulation or supportive care with radiologic monitoring and subsequent anticoagulation if extension of the thrombosis occurs during supportive care (Grade 2C). We recommend against the use of routine systemic thromboprophylaxis for children with central venous lines (Grade 1B). For children with cerebral sinovenous thrombosis (CSVT) without significant intracranial hemorrhage (ICH), we recommend anticoagulation initially with UFH, or LMWH and subsequently with LMWH or vitamin K antagonists (VKAs) for a minimum of 3 months (Grade 1B). For children with non-sickle-cell disease-related acute arterial ischemic stroke (AIS), we recommend UFH or LMWH or aspirin (1 to 5 mg/kg/d) as initial therapy until dissection and embolic causes have been excluded (Grade 1B). For neonates with a first AIS, in the absence of a documented ongoing cardioembolic source, we recommend against anticoagulation or aspirin therapy (Grade 1B).

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.

O uso da estreptoquinase no tratamento da oclusão arterial aguda pós-cateterização da artéria femoral em crianças com menos de 10 kg

CONTEXTO: O tratamento da oclusão arterial aguda em menores de 5 kg tem constituído tema de discussão. OBJETIVOS: Avaliar o tratamento do quadro da oclusão arterial aguda pós-cateterismo da artéria femoral em crianças com menos de 10 kg com o uso de heparina isolada e também associada com estreptoquinase, e comparar os resultados do exame físico (como diagnóstico), da reversão da oclusão arterial, de complicações e de exames laboratoriais nos dois métodos MÉTODOS: Trinta casos de oclusão da artéria femoral foram identificados em 1.583 cateterismos em crianças no Instituto de Cardiologia de Porto Alegre, entre 1992 e 2000. Os pacientes foram divididos em dois grupos: um usou apenas heparina (14 casos), e o outro usou heparina associada com estreptoquinase (16 casos). Os exames laboratoriais (tempo de protrombina, tempo de tromboplastina parcial ativado e fibrinogênio) coletados antes e durante a infusão intravenosa foram avaliados estatisticamente, assim como o tempo de uso da medicação, as complicações e os resultados. RESULTADOS: O exame físico mostrou-se método fidedigno para avaliar a oclusão; no grupo que utilizou a associação de heparina e estreptoquinase, houve a resolução de 87% dos casos de oclusão arterial, e a principal complicação foi sangramento no sítio de punção em 56,3% dos pacientes. Os resultados apresentaram p < 0,05. Os exames laboratoriais não tiveram significado estatístico. CONCLUSÃO: A estreptoquinase associada com a heparina é mais efetiva do que a heparina isolada no tratamento da oclusão arterial aguda da artéria femoral pós-cateterismo, tanto que sua associação apresenta uma redução do risco relativo de 88% em relação à heparina isolada.

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.

Hyperbaric oxygen in treatment of neonatal arterial thromboembolism of lower extremities

Arterial thromboembolism (TE) in the absence of current or recent history of a central catheter is a rare condition in newborn period. We report a case of severe lower extremities arterial TE of unclear etiology in a full-term neonate. By adding hyperbaric oxygenation to thrombolytic and antithrombotic therapy, we achieved improved perfusion of the upper leg tissues, preserving the knee and enabling below-the-knee amputation.

Thrombosis in infants and children

During the last decade much progress has been made toward better understanding of the underlying reasons causing thromboembolism in children. A considerable number of acquired and hereditary thrombotic risk factors have been identified which may also have an impact on therapeutic decisions and prognosis concerning outcome and the risk of a second event. However, indications for therapeutic interventions, such as thrombolysis and prophylactic anticoagulation with respect to the different clinical conditions and their combination with other risk factors, are not yet well defined. The following article describes the causes, clinical presentation and management of thrombosis in neonates, infants and older children, focusing on the clinically most relevant conditions.