Low molecular weight heparin in the successful treatment of a spontaneous aortic thrombosis in a neonate

Neonatal aortic arch thrombosis: analysis of thrombophilic risk factors and prognosis

Arterial thrombosis in neonates and children is a rare event and is often associated with external risk factors such as asphyxia or sepsis. We report our experiences with two neonates with spontaneous aortic arch thrombosis mimicking aortic coarctation. Despite single case reports until now, no data exist for the underlying thrombophilic risk factors and prognosis of this rare event. Both patients were carriers of a heterozygous factor V Leiden mutation, which has been reported once before as a risk factor for aortic arch thrombosis. One of our patients was operated upon successfully and is alive. The second patient suffered a large infarction of the right medial cerebral artery and had a thrombotic occlusion of the inferior caval vein. The patient obtained palliative care and died at the age of 6 days. In the literature, we identified 19 patients with neonatal aortic arch thrombosis. Of the 19 patients, 11 (58%) died. Including the two reported patients, the mortality rate of patients with multiple thromboses was 80% (8/10) compared with 18% (2/11) for patients with isolated aortic arch thrombosis; this difference reached statistical significance (p = 0.009). The analysis of thrombophilic disorders revealed that factor V Leiden mutation and protein C deficiency seem to be the most common risk factors for aortic arch thrombosis.

CONCLUSION

Neonatal aortic arch thrombosis is a very rare but life-threatening event, with a high rate of mortality, especially if additional thrombotic complications are present. Factor V Leiden mutation seems to be one important risk factor in the pathogenesis of this fatal disease.

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.

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.

Severe hypernatremic dehydration associated with cerebral venous and aortic thrombosis in the neonatal period

Severe neonatal hypernatremia is an important electrolyte disorder that has serious effects. Cerebral venous thrombosis and aortic thrombosis are relatively rare in severe neonatal hypernatremic dehydration. The authors report a case of cerebral venous thrombosis, associated with aortic thrombosis revealed by dehydration in a 9-day-old boy. Diagnostic was performed using Doppler ultrasound and imaging techniques. Thrombosis was resolved after anticoagulation treatment with low-molecular weight heparin for 1 month, and then was substituted by oral anticoagulant. The case report is followed by a review of the literature dealing with clinical, aetiological and therapeutic aspects of neonatal thrombosis.

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).

Antithrombotic Therapy in Children*

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).

Low molecular weight heparin for neonatal thrombosis

The clinical course of a term neonate (birthweight 3.14 kg) who developed thrombosis of the left common and internal iliac veins on day 21 following recovery from Streptococcus mitis septicemia, with shock diagnosed on day 13, is reported. Subcutaneous low molecular weight heparin (LMWH) was commenced (1.5 mg/kg 12 hourly for 10 days) after 13 h of standard heparin infusion, due to difficulties in securing a peripheral venous access. The inflammation of the left leg was completely resolved by day 5 of LMWH therapy. Prothrombin time, activated prothrombin time and fibrinogen levels were within normal limits during LMWH therapy. Treatment-related side effects, such as thrombocytopenia and bleeding tendency were not noted. Doppler studies 6 weeks after discharge home on day 33 revealed complete resolution of the thrombus. Apart from septicaemia and shock, the presence of an indwelling central venous catheter and a history of untreated maternal diabetes were additional risk factors for thrombosis. Because it is as effective as standard heparin, LMWH may be a therapeutic option for thrombosis in high-risk neonates, particularly given its ease of administration by the subcutaneous route, predictable pharmacokinetics and reduced incidence of adverse effects such as bleeding complications.