Recommendations for tPA Thrombolysis in Children

Renal vein thrombosis in neonates: a case series of diagnosis, treatment and childhood kidney function follow-up

BACKGROUND

Neonatal renal vein thrombosis (NRVT) is a rare condition with little data available.

METHODS

We retrospectively analyzed newborns diagnosed with NRVT admitted to 3 pediatric nephrology units in Paris from 2005 to 2020.

RESULTS

Twenty-seven patients were analyzed (male = 59%). The median age at diagnosis was 2.5 days (1 - 4.5). Diagnosis was suspected based on at least one of the three cardinal signs of renal vein thrombosis in 93%: flank mass (67%), hematuria (67%) and thrombocytopenia (70%). In all patients, diagnosis was confirmed by ultrasound. All patients had at least one known perinatal risk factor. A prothrombotic risk factor was found in 13 patients (48%). NRVT was unilateral in 70%, involving the left renal vein in 58%. Among 25 treated patients, 19 (76%) received low molecular weight heparin (LMWH) as initial therapy, 2 (8%) received unfractionated heparin and 4 (16%) received fibrinolysis. Median duration of treatment was 8 weeks (4 - 12). Bleeding occurred significantly more often with fibrinolysis than with LMWH/supportive therapy (3 of 4: 75% vs 0 of 4: 0%, p = 0.05). Clot resolution in patients treated with fibrinolysis did not differ significantly from those treated with LMWH/supportive therapy. After a median follow-up of 5.7 years (3 years - 9.9 years), pathological kidney features were observed in 73% of the patients (19 of 26), kidney atrophy in 18 (69%), hypertension in 2 (8%), chronic kidney disease (CKD) in 1 (4%) and proteinuria in 2 (8%).

CONCLUSIONS

NRVT remains a challenging condition, which still requires further study because of its associated morbidity. A higher resolution version of the Graphical abstract is available as Supplementary information.

Treating a limb-threatening arterial clot in a newborn with catheter-directed thrombolysis

Non-catheter related arterial thromboembolism in the neonatal population is rare and carries a significant risk of organ damage or limb loss. Thrombolysis, whether systemic or catheter- directed, is reserved either for limb or life-threatening thrombosis due to risk of bleeding especially in premature neonates. In this case, an infant male born at 34 weeks and 4 days gestational age presented with limb-threatening clot in the distal right subclavian artery and proximal right axillary artery with no known cause. After discussion of risks and benefits of various treatment options, he received thrombolysis treatment with low dose recombinant TPA via an umbilical artery catheter. There was complete resolution of the thrombus with this treatment and the patient had no significant bleeding while receiving treatment. Further investigation is needed to identify the patient population that will benefit from catheter-directed thrombolytic therapy and how to best monitor these patients.

Appendix to the Society of Interventional Radiology Consensus Guidelines for the Periprocedural Management of Thrombotic and Bleeding Risk in Patients Undergoing Percutaneous Image-Guided Interventions: Pediatric Considerations

PURPOSE

To provide guidance on the use of anticoagulant and antithrombotic agents in pediatric patients undergoing interventional radiology procedures.

MATERIALS AND METHODS

A multidisciplinary writing group conducted a comprehensive literature search to identify studies on the topic of interest. Recommendations were developed for procedural risk and medication dosage and withholding. A modified Delphi technique was used to achieve consensus agreement on the recommendations.

RESULTS

A total of 24 studies, including systematic reviews and meta-analyses, randomized controlled trials, and prospective and retrospective cohort studies, were identified as relevant. The expert writing group agreed on procedural risk categorization, laboratory testing thresholds, and medication dosage and withholding recommendations specific to pediatric practice. They additionally described the nuances of anticoagulation in clinical conditions specific to pediatrics.

CONCLUSIONS

The Society of Interventional Radiology recommends following the guidance provided in the document when developing multidisciplinary management protocols for anticoagulation and antithrombotic treatment in pediatric patients undergoing interventional radiology procedures.

Clinical characteristics and outcomes of combined thrombolysis and anticoagulation for pediatric and young adult lower extremity and inferior vena cava thrombosis

Effective treatment for acute, extensive, symptomatic lower extremity (LE) thrombosis involves thrombolysis in addition to anticoagulation. There is limited available data on the outcomes and safety of thrombolysis to help guide its use in pediatrics and young adults. A retrospective study of children and young adults (<21 years of age) that received catheter directed thrombolysis (CDT) for LE and inferior vena cava (IVC) thrombosis was performed over a 5-year span at a pediatric tertiary care center. A total of 29 patients were identified for inclusion in the study, 76% (n = 22) received overnight CDT while 24% (n = 7) received tissue plasminogen activator as a bolus dose during a single interventional procedure. The median age of the cohort was 15.8 years (range 0-19.1). All patients were treated with a course of therapeutic anticoagulation. The thromboses represented were extensive, with 93% (n = 27) being occlusive and affecting multiple venous segments. Thrombus resolution occurred in 35% (n = 10) of patients. Rivaroxaban use (p < 0.01) during the course of anticoagulation and estrogen-containing hormonal therapy (p = 0.01) use prior to diagnosis were associated with thrombus resolution, while Hispanic ethnicity (p = 0.06) had a trend toward thrombus persistence. There were one major and 3 minor bleeding events that occurred as complications of thrombolysis and no treatment related deaths. This study provides baseline information that can be used to help guide clinicians treating similar patients and suggests the need to develop an improved, uniform treatment approach for superior resolution rates.

Pediatric Stroke: Overview and Recent Updates

Stroke can occur at any age or stage in life. Although it is commonly thought of as a disease amongst the elderly, it is important to highlight the fact that it also affects infants and children. In both populations, strokes have a high rate of morbidity and mortality. Arguably, it is more detrimental in the pediatric population given the occurrence at a younger age and therefore, a longer duration of disability, potentially over the entire lifespan. The high rate of morbidity and mortality in pediatrics is attributed to significant delays in diagnosis, as well as misdiagnosis. Acute stroke management is time dependent. Patients who receive acute treatment with either intravenous (IV) tissue plasminogen activator (tPA) or mechanical thrombectomy, have improved mortality and functional outcomes. Additionally, the earlier treatment is initiated, the higher the likelihood of preserving penumbra, restoring cerebral blood flow and potentially reversing symptoms, thereby limiting disability. Prompt identification is essential as it leads to improved patient care in such a narrow therapeutic window. It enhances the care received during hospitalization and reduces the risk of early stroke recurrence. Despite limited data and lack of large randomized clinical trials in pediatrics, both IV tPA and mechanical thrombectomy have been successfully used. Bridging the gap of acute stroke management in the pediatric population is an essential part of minimizing adverse outcomes. In this review, we discuss the epidemiology of pediatric stroke, the diverse etiologies, presentation as well as both acute and preventative management.

Role of tenecteplase (rtPA) to re-establish flow in intraprocedural stent thrombosis in infants undergoing ductal stenting for duct-dependent pulmonary circulation-a case series

Ductal stenting in patients with duct-dependent pulmonary circulation has allowed growth of pulmonary arteries prior to definitive surgical procedures. Intraprocedural stent thrombosis (IPST) of the arterial duct is a life-threatening complication as it leads to total circulatory collapse. Previous reports have described use of tissue plasminogen activators in infants for less emergent settings. We report three infants with IPST and the use of tenecteplase to overcome this. Also discussed are the predisposing mechanisms in each scenario and a possibility of direct catheter-guided tenecteplase administration. Judicious use of tenecteplase can be life-saving and rapid access to this drug may obviate the need for emergency extracorporeal life support.

Pediatric Fibrinogen PART II-Overview of Indications for Fibrinogen Use in Critically Ill Children

Bleeding is frequently seen in critically ill children and is associated with increased morbidity and mortality. Fibrinogen is an essential coagulation factor for hemostasis and hypofibrinogenemia is an important risk factor for bleeding in pediatric and adult settings. Cryoprecipitate and fibrinogen concentrate are often given to critically ill children to prevent bleeding and improve fibrinogen levels, especially in the setting of surgery, trauma, leukemia, disseminated intravascular coagulopathy, and liver failure. The theoretical benefit of fibrinogen supplementation to treat hypofibrinogenemia appears obvious, yet the evidence to support fibrinogen supplementation in children is sparce and clinical indications are poorly defined. In addition, it is unknown what the optimal fibrinogen replacement product is in children and neonates or what the targets of treatment should be. As a result, there is considerable variability in practice. In this article we will review the current pediatric and applicable adult literature with regard to the use of fibrinogen replacement in different pediatric critical care contexts. We will discuss the clinical indications for fibrinogen supplementation in critically ill children and the evidence to support their use. We summarize by highlighting current knowledge gaps and areas for future research.

Pulmonary Embolism in a Neonate Following Modified Norwood Procedure With Sano Shunt

Pulmonary embolism is a rare but potentially fatal complication in neonates with congenital heart disease. The authors report a case of pulmonary embolism in the immediate postoperative period following modified Norwood procedure with Sano shunt. In addition, this report discusses the initial evaluation and available anticoagulation options to treat pulmonary embolism in children with congenital heart disease.

Risk factors and outcomes of intravenous tissue plasminogen activator and endovascular thrombectomy utilization amongst pediatrics acute ischemic stroke

BACKGROUND

Pediatric stroke is a debilitating disease. There are several risk factors predisposing children to this life-threatening disease. Although, published literature estimates a relatively high incidence of pediatric stroke, treatment guidelines on intravenous tissue plasminogen activator and endovascular thrombectomy utilization remain a dilemma. There is a lack of large population-based studies and clinical trials evaluating the efficacy and safety outcomes associated with these treatments in this unique population.

AIM

We sought to determine the prevalence of risk factors, concurrent utilization of intravenous tissue plasminogen activator and endovascular thrombectomy, and associated outcomes in pediatric stroke hospitalizations.

METHODS

We performed a retrospective analysis of the Nationwide Inpatient Sample data (2003-2014) in pediatric (1-21 years of age) acute ischemic stroke hospitalizations using ICD-9-CM codes. The multivariable survey logistic regression model was weighted to account for sampling strategy, evaluate predictors of hemorrhagic conversion, and treatment outcomes (mortality, morbidity, and discharge disposition) amongst pediatric stroke hospitalizations.

RESULTS

In this analysis, 9109 patients between 1 and 21 years of age were admitted during 2003-2014 for acute ischemic stroke. Of these 9109 patients, 119 (1.30%) received endovascular thrombectomy alone, 256 (2.82%) intravenous recombinant tissue plasminogen activator, and 69 (0.75%) both endovascular thrombectomy and intravenous recombinant tissue plasminogen activator. We found overall high prevalence of conditions like epilepsy (19.59%), atrial septal defect (11.76%), sickle cell disease (8.63%), and moyamoya disease (5.41%) in pediatric acute ischemic stroke patients. Unadjusted analysis showed high prevalence of all-cause in-hospital mortality in combined endovascular thrombectomy and intravenous recombinant tissue plasminogen activator utilization group, and higher prevalence of hemorrhagic conversion and morbidity in endovascular thrombectomy utilization group compared to other groups (p < 0.0001). Multivariate adjusted analysis showed that children with endovascular thrombectomy utilization (aOR: 19.19; 95% CI: 2.50-147.29, p = 0.005), intravenous recombinant tissue plasminogen activator utilization (aOR: 8.85; 95% CI: 1.92-40.76, p = 0.005), and both (endovascular thrombectomy and intravenous recombinant tissue plasminogen activator) utilization (aOR: 7.55; 95% CI: 1.16-49.31, p = 0.035) had higher odds of hemorrhagic conversion compared to no-treatment group.

CONCLUSION

We found various risk factors associated with pediatric stroke. The early identification can be useful to formulate preventive strategies and influence the incidence of pediatric stroke. Our study results showed that use of intravenous recombinant tissue plasminogen activator and endovascular thrombectomy increase risk of mortality and hemorrhagic conversion, but we suggest to have more clinical studies to evaluate the idea candidates for utilization of intravenous recombinant tissue plasminogen activator and endovascular thrombectomy based on risk: benefit ratio.

An MR-based quantitative intraventricular hemorrhage porcine model for MR-guided focused ultrasound thrombolysis

PURPOSE

Intraventricular hemorrhage (IVH) affects approximately 50% of premature births where 50% further develop post-hemorrhagic ventricular dilation (PHVD). Patients face significant impact to long-term development if PHVD is not managed. Unfortunately, there is no accepted treatment to remove the thrombus caused by IVH. This paper describes an acute and chronic IVH model for use with magnetic resonance-guided focused ultrasound (MRgFUS) thrombolysis.

METHODS

A total of 12 pigs (~ 1 month in age) were used in the model (eight acute and four chronic). A pre-operative brain MRI was obtained for ventricular targeting. 1.25 cm³/kg of autologous blood was injected through a burr hole lateral to the midline and anterior of the coronal suture at a rate of 0.6 cm³/min. A craniotomy was performed to simulate a "fontanelle". Post-operative MRI was used to calculate the clot volume. Chronic piglets were recovered, monitored daily with a neurological scoring system (NSS), and MRI scanned for 21 days.

RESULTS

The clot injection was well tolerated. The average clot size was 3987 mm³ (median = 4330 mm, standard deviation = 739 mm³). Postmortem examination validated the presence of the clot. In the chronic animals, there was an increase in ventricular volume of 30%. Transient neurological impairment immediately followed clot injection and with onset of hydrocephalus in the chronic animals.

CONCLUSIONS

This model establishes a measurable and targetable IVH clot in an MRI-based neonatal porcine model. The progressive post-hemorrhagic ventricular dilation in the chronic model is a potential alterable outcome from MRgFUS thrombolysis.

Myocardial infarction in a neonate. Lessons for neonatal and internal medicine

Due to the lack of evidence-based guidelines, management strategies for neonatal MI should be individualized and administered largely at the discretion of responsible treating teams. Supportive care with a focus on preserving adequate circulation and antithrombotic therapy with a view to restoring vascular patency are the mainstays of treatment. Thrombolytic therapy of neonatal MI includes a chance to completely restore myocardial function. Understanding the resilience of the neonatal heart and mechanism of cardiac cell repair in neonates may spark novel treatment strategies for severe MI in the large number of affected individuals in an aging population.

Pediatric Thrombolysis: A Practical Approach

The incidence of pediatric venous thromboembolic disease is increasing in hospitalized children. While the mainstay of treatment of pediatric thrombosis is anticoagulation, reports on the use of systemic thrombolysis, endovascular thrombolysis, and mechanical thrombectomy have steadily been increasing in this population. Thrombolysis is indicated in the setting of life- or limb-threatening thrombosis. Thrombolysis can rapidly improve venous patency thereby quickly ameliorating acute signs and symptoms of thrombosis and may improve long-term outcomes such as postthrombotic syndrome. Systemic and endovascular thrombolysis can result in an increase in minor bleeding in pediatric patients, compared with anticoagulation alone, and major bleeding events are a continued concern. Also, endovascular treatment is invasive and requires technical expertise by interventional radiology or vascular surgery, and such expertise may be lacking at many pediatric centers. The goal of this mini-review is to summarize the current state of knowledge of thrombolysis/thrombectomy techniques, benefits, and challenges in pediatric thrombosis.

Pulmonary Embolism in Children

Pulmonary embolism (PE) in the pediatric population is relatively rare when compared to adults; however, the incidence is increasing and accurate and timely diagnosis is critical. A high clinical index of suspicion is warranted as PE often goes unrecognized among children leading to misdiagnosis and potentially increased morbidity and mortality. Evidence-based guidelines for the diagnosis, management, and follow-up of children with PE are lacking and current practices are extrapolated from adult data. Treatment options include thrombolysis and anticoagulation with heparins and oral vitamin K antagonists, with newer direct oral anticoagulants currently in clinical trials. Long-term sequelae of PE, although studied in adults, are vastly unknown among children and adolescents. Additional research is needed in order to provide pediatric focused care for patients with acute PE.

Systemic thrombolysis with recombinant tissue plasminogen activator for acute life-threatening Blalock-Taussig shunt obstruction

Modified Blalock-Taussig shunt (mBTS) obstruction can be life-threatening, especially when it represents the only source of pulmonary blood flow. Current therapeutic options to reverse obstruction include surgical shunt revision/replacement, interventional endovascular procedures including balloon angioplasty and/or stent placement, and a combination of local and systemic thrombolytic therapy. We report two cases of acute mBTS thrombosis successfully treated with systemic recombinant tissue plasminogen activator in infants convalescing after cardiac surgery when the clinical status and resources precluded traditionally described rescue therapies.

Renal vascular thrombosis in the newborn

Neonatal renal vascular thrombosis is rare but has devastating sequelae. The renal vein is more commonly affected than the renal artery. Most neonates with renal vein thrombosis present with at least one of the three cardinal signs, namely, abdominal mass, macroscopic hematuria and thrombocytopenia, while unilateral renal artery thrombosis presents with transient hypertension. Contrast angiography is the gold standard for diagnosis but because of exposure to radiation and contrast agents, Doppler ultrasound scan is widely used instead. Baseline laboratory tests for platelet count, prothrombin time, activated partial thromboplastin time and fibrinogen concentration are essential before therapy is initiated. Maternal blood is tested for lupus anticoagulant and anticardiolipin antibody. Evaluation for prothrombotic disorders is warranted when thrombosis is clinically significant, recurrent or spontaneous. Management should involve a multidisciplinary team that includes neonatologists, radiologists, pediatric hematologists and nephrologists. In addition to supportive therapy, recent guidelines recommend at least prophylactic heparin therapy in the majority of cases to prevent thrombus extension. Thrombolytic therapy is reserved for bilateral thrombosis compromising kidney function. Long-term sequelae, such as kidney atrophy, systemic hypertension and chronic kidney disease, are common, and follow-up by pediatric nephrologists is recommended for monitoring of kidney function, early detection and management of hypertension and chronic kidney disease.

Tissue Plasminogen Activator Use in Children: Bleeding Complications and Thrombus Resolution

OBJECTIVE

To review our institutional experience with tissue plasminogen activator (tPA) to determine outcomes related to bleeding complications and thrombus resolution.

STUDY DESIGN

We performed a retrospective review of all patients who received systemic tPA for thrombolysis. Data points included location of thrombus, initial and maximum tPA dose, and duration of tPA. The primary endpoint was bleeding complication.

RESULTS

Between 2005 and 2014, 46 patients received systemic tPA for thrombolysis: 17 (37%) were patients with a primary cardiac diagnosis, there were 17 (37%) hematology/oncology patients, and 12 (26%) patients with noncardiac, nonhematology/oncology diagnoses. The indication for tPA was central venous thrombus (n = 23), pulmonary artery thrombus (n = 9), and cardiac or aortic thrombus (n = 14). Bleeding complications occurred in 15 patients (33%). Median initial tPA dose in the bleeding complication group was 0.10 mg/kg/h vs 0.03 mg/kg/h in the group without bleeding complication group (P = .01). Cardiac patients experienced more bleeding complications (P = .01). Multivariate analysis indicated that dose of tPA (P = .01) and diagnostic category (P < .01) were associated with bleeding complication. Complete thrombus resolution occurred in 21 patients, partial in 10 patients, and no resolution in 15 patients. Complete resolution of thrombus was not associated with diagnosis, thrombus location, tPA dose, or duration.

CONCLUSIONS

Cardiac patients appear to be at highest risk of bleeding complication; bleeding complications were associated with higher doses of tPA, and cardiac patients were the cohort who received the highest doses of tPA. Higher tPA doses are associated with increased risk of bleeding complication but are not associated with successful thrombus resolution.

Successful thrombolytic treatment of neonatal arterial thromboses

Compared to children of other age groups neonates show an increased thrombotic risk. The acute therapy depends on thrombus age, the localisation of vascular occlusion and the severity of the underlying disease. The treatment of choice is represented by the administration of unfractionated (UFH) or low molecular weight heparin (LMWH). If loss of limbs or organs is imminent, the application of thrombolytic treatment with recombinant tissue-type plasminogen activator (rt-PA) should be considered whilst taking into account the associated bleeding risk. We report on two patients in which thrombolytic therapy has been conducted successfully.

Treatment of neonatal fungal infective endocarditis with recombinant tissue plasminogen: activator in a low birth weight infant case report and review of the literature

With advances in medical sciences, an increase in survival rates of low birth weight; increased incidence in use of catheter and antibiotics, and total parenteral nutrition are reported, therefore, the rate of fungal infections in late and very late onset neonatal sepsis have increased. Although fungal endocarditis rarely occur in newborns, it has a high morbidity and mortality. Antifungal therapy is often insufficient in cases who develop fungal endocarditis and surgical treatment is not preferred due to its difficulty and high mortality. Herein, fungal endocarditis in a preterm newborn treated with single-dose recombinant tissue plasminogen activator in addition to antifungal therapy is presented and relevant literature has been reviewed. The vegetation completely disappeared following treatment and no complication was observed.

Neonatal haemostasis and the management of neonatal thrombosis

Two detailed reviews of the management of neonatal thrombosis were published in 2012; one was an up-dated version of guidance first issued in 2004 and the other was a comprehensive review. Both of these publications gave very similar advice regarding the practical aspects of the indications, dosage and management of antithrombotic therapy. The authors stated that the evidence supporting most of their recommendations for anti-thrombotic therapy in neonates remained weak and so the therapy for a neonate with a thrombosis has to be based on an individualized assessment of estimated risk versus potential benefit. The aim of this present review is to give the treating physician an outline of the unique physiology of neonatal coagulation and how this affects the monitoring, dosing and even the choice of therapeutic strategy for the management of thrombosis in the neonate.

Antithrombotic therapies: anticoagulation and thrombolysis

Pediatric deep vein thrombosis is an increasingly recognized phenomenon, especially with advances in treatment and supportive care of critically ill children and with better diagnostic capabilities. High-quality evidence and uniform management guidelines for antithrombotic treatment, particularly thrombolytic therapy, remain limited. Optimal dosing, intensity and duration strategies for anticoagulation as well as thrombolytic regimens that maximize efficacy and safety need to be determined through well-designed clinical trials using use of a risk-stratified approach.

Thrombolysis for children with acute ischemic stroke: a perspective from the kids' inpatient database

BACKGROUND

Thrombolysis for acute ischemic stroke (AIS) in children is yet to be proven efficacious, and there is limited information about its safety in large pediatric samples. Here we evaluate the safety outcomes associated with thrombolysis in children as well as the trend of hospital utilization over the past decade in the United States.

METHODS

A cohort of children with acute ischemic stroke was identified from the Kids' Inpatient Database for the years 1998-2009. Acute ischemic stroke was identified by the International Classification of Diseases-9 clinical classification software codes (109 and 110). Multivariate logistic regression analyses were used to assess covariates associated with outcomes of hospital mortality and intracerebral hemorrhage. The Cochran-Armitage test was employed for linear trend of discrete variables.

RESULTS

In this analysis, 9257 children were admitted with the diagnosis of acute ischemic stroke; only 67 (0.7%) received thrombolysis. Thrombolysis-treated children were older than the rest of the cohort (13.1 ± 7.3 vs 8.18 ± 7.5; P < 0.0001) and they had a longer hospital stay (median 11 vs 6 days; P < 0.0001). Gender, race, and family income approximated by postal code were similar among the treated and untreated children. Unadjusted analysis showed higher hospital mortality (10.45% vs 6.14%; P = 0.06) and intracerebral hemorrhage (2.99% vs 0.77%; P = 0.08) in the thrombolysis group. Adjusted analysis showed that intracerebral hemorrhage is predictive of a higher hospital mortality (odds ratio 3.43; 95% confidence interval 1.89-6.22), whereas thrombolysis was not (odds ratio 1.78; 95% confidence interval 0.86-3.64). The overall rate of thrombolysis per 3 years intervals had increased from 5.2 to 9.7 per 1000 children with acute ischemic stroke (P = 0.02). This increase was mainly seen in non-children hospitals (P = 0.01).

CONCLUSION

Thrombolysis for acute ischemic stroke is infrequently used in children. There is a trend toward higher risks of intracerebral hemorrhage and hospital mortality, although these risks are as low as those reported in adult population. The hospitals' utilization of thrombolysis in children has increased during the study period.

Clot dissolution: a novel treatment of midgut volvulus

Midgut volvulus due to malrotation may result in loss of the small bowel. Until now, after derotation of the volvulus, pediatric surgeons do not deal with the mesenteric thrombosis, which causes continuing ischemia of the intestine. On occasion, a "second look" laparotomy is performed in the hope that some improvement in blood supply to the intestine has occurred. We describe a new combined treatment to restore intestinal perfusion based on digital massage of the superior mesenteric vessels after derotation and systemic infusion of tissue-type plasminogen activator. This new therapy has been successful in 2 neonates with severe intestinal ischemia due to volvulus.

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.

Perinatal stroke: a case-based review

Neonatal stroke is a diverse clinical entity. Terminology and aetiology described in the literature are very varied. While numerous risk factors are cited, only few case-control studies have investigated them in a systematic fashion. This equipoise extends to the investigational and management profile of perinatal stroke too. Controversy persists about the suitability of detailed haematological thrombophilia workup in the neonatal period. This case-based review details the variable clinical presentation in term and preterm neonates, discusses the current literature, ascertains the respective roles of various imaging modalities, explores relevant new neuroprotective interventions and proposes a systematic approach to clinical and neuroimaging workup. Long-term follow-up is important as many infants suffer neuro-disability, which might need early intervention strategies.

Use of tissue plasminogen activator to treat intracardiac thrombosis in extremely low-birth-weight infants

OBJECTIVE

Intracardiac thrombosis is a life-threatening complication of extreme prematurity. We describe the use of tissue plasminogen activator to treat intracardiac thrombosis in extremely low-birth-weight preterm infants.

DESIGN

Case series, literature review, and practice guideline for recombinant tissue plasminogen activator treatment of intracardiac thrombosis in extremely low-birth-weight preterm infants.

SETTING

Neonatal intensive care.

PATIENTS

Four extremely low-birth-weight preterm infants coincidentally diagnosed with intracardiac thrombosis during neonatal intensive care.

INTERVENTIONS

Recombinant tissue plasminogen activator in a starting dose of 20 μg/kg/hr, increasing to 200-400 μg/kg/hr, infused for 2-6 days.

MEASUREMENTS AND MAIN RESULTS

Thrombolytic therapy with recombinant tissue plasminogen activator helped achieve rapid clot resolution in all infants and none had any major hemorrhagic complication associated with treatment.

CONCLUSIONS

Tissue plasminogen activator may safely be used to treat intracardiac thrombosis in extremely low-birth-weight preterm infants. Close monitoring of therapy is imperative. Further data are required to confirm the safety of tissue plasminogen activator in preterm infants.

The use of recombinant tissue-type plasminogen activator in a newborn with an intracardiac thrombus developed during extracorporeal membrane oxygenation

Extracorporeal membrane oxygenation (ECMO) support is often used to support infants and children with hemodynamic or respiratory failure. One of the major obstacles of safely treating a child with ECMO is balancing the risk of hemorrhage with the potential for thrombus development. Managing thrombosis in the setting of ECMO is challenging and has no defined algorithm. The use of recombinant tissue-type plasminogen activator (tPA) for thrombolysis has been previously described in cases where thrombi have developed despite adequate anticoagulation. In such situations, the risk of hemorrhage must be carefully balanced with the benefit of dissolving the clot and reestablishing flow. We present a case of an infant who required ECMO because of severe primary pulmonary hypertension and subsequently developed a right atrial thrombus adjacent to the ECMO cannula. The patient was treated with tPA with immediate improvement but had fatal intracranial hemorrhage almost 3 days after the tPA was administered. In this report, we review the current literature on tPA use during ECMO support and suggest a rational approach.

Pneumothorax, pneumomediastinum, and pulmonary embolism

This article discusses pneumothorax, pneumomediastinum, and pulmonary embolism in pediatric practice. Although children appear to have better outcomes than adults, the risk factors are substantial. Topics covered include the pathophysiology incidence, presentation, diagnosis, and management of these diseases.

Clinical experience with alteplase in the management of intracardiac and major cardiac vessels thrombosis in pediatrics: a case series

BACKGROUND AND OBJECTIVES

Experience with alteplase in pediatric patients is limited and recommendations are extrapolated from adult data. Comprehensive guidelines on the management of thromboembolic events in this group are lacking. We assessed the efficacy and safety of alteplase (recombinant tissue plasminogen activator) in the management of intracardiac and major cardiac vessel thrombosis in pediatric patients.

METHODS

All pediatric patients, 14 years of age and younger, with intracardiac or major cardiac vessel thrombus who were treated with alteplase from 1997 to 2004 at our tertiary care institute were identified through the pharmacy database. Patient data were retrospectively evaluated for the efficacy and safety of altepase.

RESULTS

Five cases were eligible out of nineteen who received alteplase. Patient ages ranged from 40 days to 13 years. The initial dose of alteplase ranged from 0.3 to 0.6 mg/kg followed by a continuous infusion in three patients with a dosage range between 0.05 and 0.5 mg/kg/hr, while intermittent infusion was used in the other two patients. The duration of therapy ranged from 2 to 4 days. By the end of the treatment, two patients had complete resolution of thrombus and one had partial resolution. Two patients failed to respond and had "old" thrombus. Major bleeding events were reported in three patients. The rest had minor bleeding events.

CONCLUSION

Alteplase may effectively dissolve intracardiac thrombi, particularly when freshly formed. Continuous infusion for a long duration appears to be associated with an increased risk of major bleeding. Optimal dose and duration of infusion are still unknown.

Successful treatment of a thrombus in the left aortic coronary sinus in a child with systemic lupus erythematosus

We report our experience in a 12 year old boy referred with suspected myocardial infarction. He has previously been diagnosed with systemic lupus erythematosus, and was being treated with steroids. Echocardiographic examination revealed a thrombus in the left aortic coronary sinus of Valsalva partially occluding the orifice of the left coronary artery. The thrombosis was successfully treated by venous thrombolysis using recombinant tissue plasminogen activator.

Varied opinions on thrombolysis for venous thromboembolism in infants and children: findings from a survey of pediatric hematology-oncology specialists

BACKGROUND

Recent guidelines discourage routine use of thrombolytic agents for treatment of venous thromboembolism (VTE) in pediatric patients, but actual practice patterns are unknown.

PROCEDURE

An electronic survey was emailed to all active and trainee members of the American Society of Pediatric Hematology/Oncology in April 2008. Respondents were asked a series of multiple-choice questions based on hypothetical case scenarios describing pediatric VTE, pertinent to the implementation of thrombolytic therapy and other professional demographic information.

RESULTS

Two hundred eighty-five evaluable responses were obtained (22% response rate) which varied greatly with respect to all spheres of questioning. Tissue plasminogen activator (tPA) was the thrombolytic agent chosen by most respondents, but no clear consensus emerged as to appropriate indications (although preference for thrombolytic therapy increased with severity of the posed clinical scenario), mode of tPA delivery (systemic vs. catheter-directed), dose (high-dose vs. low-dose regimen) or a suitable maximum duration of therapy (range: 1-168 hr; varied according to specific dosing regimen chosen). Expertise in pediatric thrombosis, years out from fellowship training and volume of experience with cases of pediatric thrombosis were not largely associated with respondent choices; however, institutional experience with pharmacologic thrombolysis exhibited the most notable association of the professional demographic factors analyzed.

CONCLUSIONS

The survey results support that clinical practice pertaining to use of thrombolytic agents in pediatric VTE varies widely but also provide useful benchmarks to aid clinical decision-making and future clinical trial design. Such varied practices stem from the lack of strong evidence supporting one therapeutic approach versus another.

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).

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.

Neonatal thromboembolic emergencies

Thrombosis risk is multifactorial, with interaction of hereditary risk factors and acquired environmental and clinical conditions. Newborns are at particular risk for thrombotic emergencies secondary to the unique properties of their hemostatic system, influences of the maternal-fetal environment, and perinatal complications and interventions. Thrombotic complications range from arterial and venous catheter thrombosis to purpura fulminans. Prompt identification and appropriate management of thrombotic emergencies is critical in avoiding limb-, organ-, and life-threatening complications. Treatment strategies have been extrapolated from adult literature but clinical experience from small-scale neonatal studies has resulted in therapeutic guidelines, which should be individualized for each neonate, taking into consideration age and clinical status.

Long-term treatment of thrombosis with enoxaparin in pediatric and adolescent patients

Thrombosis is a rare event in childhood and adolescence. Nevertheless, increasing numbers of invasive diagnostic and therapeutic procedures also result in increasing numbers of thromboses in pediatric cases, necessitating effective antithrombotic treatment regimens. In recent years, low-molecular-weight heparins (LMWH) in particular have been proved to be a safe and effective alternative to unfractioned heparins. However, the application of LMWH in pediatric patients has not been supported by a single controlled study so far. Furthermore, there is no official approval of these drugs for children. In this pilot study 27 children with deep venous thromboses (DVT) were treated with the LMWH enoxaparin at a dosage of 1.5 mg/kg body weight b.i.d. in neonates and infants and 1 mg/kg body weight b.i.d. in children. This dosage was lowered for prophylaxis if therapeutic success was achieved. The aim of the study was to investigate both, efficacy with respect to patency rates and safety during acute and long-term follow-up. Sufficient therapeutic success required a rapid production of anti-Xa target activity and was reached in 85% of the treated patients, who showed patency of the affected vessel at last follow-up. The mean duration of treatment with full dosage was 16.5 days, followed by prophylaxis over a mean duration of 9.8 months. Rethrombosis or adverse events including heparin-induced thrombocytopenia were not observed in any patient. In conclusion, enoxaparin provides an effective and safe alternative to unfractioned heparins in the treatment of thrombosis in infancy, childhood and adolescence.