Thrombolytic therapy in the management of paediatric thromboembolic disease

Successful Use of Thrombolysis in an Extremely Low Birth Weight, Premature Infant With Aortic Thrombosis

BACKGROUND

Severe neonatal aortic thrombosis is rare but can lead to significant morbidity or death if inadequately treated. Thrombolytic therapy is indicated for thrombi which are life-threatening, organ-threatening, or limb-threatening, but dosing consensus has not been established.

OBSERVATION

We report a case of a 700 g preterm neonate with spontaneous intestinal perforation who developed an occlusive aortic thrombus with signs of limb ischemia. He was treated successfully with tissue plasminogen activator without hemorrhagic complications. He was started at a dose of 0.06 mg/kg/h and received a maximum dose of 0.3 mg/kg/h. Long-term follow-up at 3 years and 3 months showed no negative sequelae.

CONCLUSION

Alteplase may be considered in premature, extremely low-birth weight infants with careful assessment of risk and benefits, along with frequent surveillance and supportive care.

Acute Limb Ischemia in an 8-Year-Old Patient: A Case Report

We report the case of an 8-year-old patient with a history of nephrotic syndrome, who presented to the emergency department with right foot pain. The patient's mother described intermittent pain that woke her son from sleep and was accompanied by the foot turning purple and becoming cold to touch. Physical examination revealed capillary refill of over 10 seconds in the right and less than 2 seconds in the left foot. Ankle-brachial indices (ABIs) were 0.0 on the right and 0.96 on the left. The patient was admitted and started on therapeutic intravenous heparin. After consultation with his parents, right lower extremity angiography and thrombolysis was performed over 2 days. He subsequently underwent fasciotomy and amputation of the tip of all 5 toes. Eighteen months later, there is no leg length discrepancy, he is walking with foot inserts and has normal ABIs bilaterally.

Intracardiac thrombus in children: the fine equilibrium between the risk and the benefit

The medical records of 16 patients diagnosed as intracardiac thrombus were searched. The size, location and outcome of thrombus together with demographic data of patients were assessed. The median age of the patients was 2.2 years. Six patients were newborn and two patients were infant. The median size of thrombus was 9 mm. The localization was right atrium in seven, right ventricle in five, left ventricle in one, pulmonary artery in one, and superior vena cava in two patients. There was prematurity in five, ciyanotic congenital heart disease in one, blood culture positivity in three, malignancy in four, nephrotic syndrome in one, indwelling catheters in 10, and acquired or genetic thrombophilia in six patients as risk factors. In the treatment, the first choice was tissue plasminogen activator in two patients, heparin infusion in one patient and low molecular weight heparin in remaining 12 patients. In nine patients, therapy included parenteral antimicrobials together with anticoagulants. The result was complete resolution in 15 patients and in one patient thrombus was surgically removed. The median time was 16 (2-70) days for 50% resolution and 26 (3-93) days for complete resolution. There was a statistically significant (P = .027 and r = 0.5) correlation between the size and the complete resolution time. There was no anticoagulant therapy related major complication. In patients with intracardiac thrombus, selection of anticoagulant therapy may decrease the risk of complications. Surgery is rarely required and thrombolytics are not usually necessary for resolution of thrombus.

Treatment of infective endocarditis with recombinant tissue plasminogen activator

Infective endocarditis (IE) caused by microbial infection is virtually always fatal if untreated. High-dose and long-term antibiotic treatment is required to eradicate microorganisms. If increased risk of embolic events, persistent infection, and progressive cardiac failure are present, surgery is indicated. However, surgery can carry an increased risk of mortality and morbidity in critically ill children of whom other treatment options such as administering, a thrombolytic agent; recombinant tissue plasminogen activator (r-tPA) could be an alternative choice. Here, we report a 14-year-old male with Down syndrome and acute myeloblastic leukemia, diagnosed with IE characterized by two large vegetations on aortic and mitral valves, who was successfully treated with r-tPA.

Thrombolysis of venous and arterial thrombosis by catheter-directed low-dose infusion of tissue plasminogen activator in children

Thrombolytic therapy is a well-defined treatment option for arterial and venous thrombosis in adults. In contrast, uniform recommendations regarding the indication, route of administration, and dosing of thrombolytic therapy in children are not available. The authors report the successful resolution of bilateral pulmonary embolism and popliteal artery thrombosis in an 11-year-old girl and 13-year-old girl, respectively, by catheter-directed thrombolysis with low-dose recombinant tissue plasminogen activator. Catheter-directed low-dose thrombolysis is an efficient treatment option for severe venous and arterial thrombosis in children.

Pulmonary thromboembolism in children

Pulmonary thromboembolism (PTE) is uncommonly diagnosed in the pediatric patient, and indeed often only discovered on autopsy. The incidence of pediatric PTE depends upon the associated underlying disease, diagnostic tests used, and index of suspicion. Multiple risk factors can be found including: peripartum asphyxia, dyspnea, haemoptysis, chest pain, dehydration, septicemia, central venous lines (CVLs), trauma, surgery, ongoing hemolysis, vascular lesions, malignancy, renal disease, foreign bodies or, uncommonly, intracranial venous sinus thrombosis, burns, or nonbacterial thrombotic endocarditis. Other types of embolism can occur uncommonly in childhood and need to be recognized, as the required treatment will vary. These include pulmonary cytolytic thrombi, foreign bodies, tumor and septic emboli, and post-traumatic fat emboli. No single noninvasive test for pulmonary embolism is both sensitive and specific. A combination of diagnostic procedures must be used to identify suspect or confirmed cases of PTE. This article reviews the risk factors, clinical presentation and treatment of pulmonary embolism in children. It also highlights the current diagnostic tools and protocols used to evaluate pulmonary embolism in pediatric patients.

Analysis of pediatric thrombotic patients in Turkey

This study analyzes the data of thrombotic children who were followed up in different pediatric referral centers of Turkey, to obtain more general data on the diagnosis, risk factors, management, and outcome of thrombosis in Turkish children. A simple two-page questionnaire was distributed among contact people from each center to standardize data collection. Thirteen pediatric referral centers responded to the invitation and the total number of cases was 271. All children were diagnosed with thromboembolic disease between January 1995 and October 2001. Median age at time of first thrombotic event was 7.0 years. Of the children 4% of the cases were neonates, 12% were infants less than 1 year old, and 17% were adolescents. Thromboembolic event was mostly located in the cerebral vascular system (32%), deep venous system of the limbs, femoral and iliac veins (24%), portal veins (10%), and intracardiac region (9%). Acquired risk factors were present in 86% of the children. Infection was the most common underlying risk factor. Inherited risk factors were present in 30% of the children. FVL was the most common inherited risk factor. Acquired and inherited risk factors were present simultaneously in 19% of the patients. Eleven children had a history of familial thrombosis. Due to the local treatment preferences, the treatment of the children varied greatly. Outcome of the 142 patients (52%) was reported: 88 (62%) patients had complete resolution, 47 (33%) had complications, 12 (9%) had recurrent thrombosis, and 34 (24%) died. Three children (2.1%) died as a direct consequence of their thromboembolic disease. The significant morbidity and mortality found in this study supports the need for multicentric prospective clinical trials to obtain more generalizable data on management and outcome of thrombosis in Turkish children.

Neonatal thrombosis

NEONATAL VASCULAR THROMBOSIS is rare; however, it is emerging as a more frequent problem in tertiary neonatal care.1Both the incidence and severity of thromboembolic events are increasing in children, with newborns being the largest group affected.2A 1995 Canadian study estimated that the incidence of clinically diagnosed cases of neonatal thrombosis was 2.4 per 1,000 admissions.3A two-year study published in Germany in 1997 reported 5.1 per 100,000 births.4The first study reported that thrombotic disease diagnosed in neonates is most commonly associated with the presence of an indwelling intravascular catheter. The second study reported that most venous thromboses were diagnosed in the second week of life in premature or mature infants in the upper venous system and were directly associated with indwelling central catheters. Although spontaneous thrombosis does occur, it is usually confined to the renal veins.3

Successful treatment of infective endocarditis with recombinant tissue plasminogen activator

OBJECTIVES

In a prospective study, we examined the effect of treatment with recombinant tissue plasminogen activator (r-TPA) on survival and morbidity in a series of high-risk children with infectious endocarditis (IE) after prolonged treatment with indwelling catheters. We hypothesized that r-TPA is an adjunctive therapy for dissolution of infected thrombi in drug-resistant IE.

STUDY DESIGN

In the prospective 3-year study (1998-2001), we identified high-risk children with chronic illness and prolonged treatment with indwelling catheters who developed IE and overwhelming sepsis. Patients were allocated to receive r-TPA after persistent and enlarging intracardiac vegetations and failure to respond to conventional medical management. Complications associated with treatment, survival, and cardiac morbidity were observed.

RESULTS

Seven infants were treated prospectively with r-TPA. All infants responded promptly to treatment, with resolution of the intracardiac vegetations within 3 to 4 days of commencement and without any adverse complications. All patients survived without long-term cardiac morbidity.

CONCLUSION

Recombinant tissue plasminogen activator may offer a safe alternative to surgical intervention in the high-risk infant with IE.

Neonatal thrombosis

Neonatal thrombosis is a serious event that can cause mortality or result in severe morbidity and disability. The most important risk factor for the development of thrombosis during the neonatal period is the presence of an indwelling central line and consequently the vessels involved tend to be those most frequently used for catheterization. Other documented risk factors for the development of neonatal thrombosis include asphyxia, septicemia, dehydration, maternal diabetes and cardiac disease. Main laboratory findings for the diagnosis of hypercoagulable states, include shortened aPTT, decreased levels of inhibitors (AT III, Protein C and Protein S), increased resistance to activated protein C, defective fibrinolysis (basal and after stimuli), increased levels of clotting factors (fibrinogen, factor VII, factor VIII, etc.), increased and/or hyperactive platelets, increased whole blood and/or plasma viscosity, Antiphospholipid antibodies and presence of prothrombotic molecular defects like FV Leiden, P20210 and MTHFR. Approximately 4% and 2% respectively of Caucasians are heterozygous for these gene defects. Their causative role in neonatal thrombosis is unknown but they may have a contributory role in the pathogenesis of thrombosis in neonates.

Thromboembolic diseases of childhood

Over the last decade, pediatric thrombophilia programs have emerged around the world as a new discipline in pediatric hematology. These programs specialize in the diagnosis, prevention and treatment of children with thromboembolic events (TEs) in both the venous and arterial systems. The need for separate pediatric programs has been discussed previously. (J Pediatr Hematol Oncol 1997; 19: 7-22.) The following article will update previous reviews (Hematol Oncol Clin North Am 1998; 12: 1283-1312; Thromb Haemost 1997; 78: 715-725) and will concentrate on three aspects: (1) The risk factors for acquiring TEs; (2) The confirmatory diagnostic tests used in children with TEs; and (3) The different antithrombotic agents used for prevention and treatment. The current knowledge in respect to the above points is only the "tip of the iceberg". Well-designed prospective trials are required to establish the contribution of congenital prothrombotic disorders, appropriate diagnostic strategies, and optimal therapy for children with TEs.

The investigation and management of neonatal haemostasis and thrombosis

These guidelines address developmental aspects of neonatal haemostasis and thrombosis, the laboratory investigation of the neonate, and the diagnosis and clinical management of haemostatic and thrombotic conditions occurring in this period (defined as the first 4 weeks of life following birth). Relevant scientific papers were identified by a systematic literature review from Medline 1975-2000 using index terms which incorporated the various component subjects of these guidelines. Further publications were obtained from the references cited and from reviews known to the members of the working party and to the Haemostasis and Thrombosis Task Force. Evidence and graded recommendations presented in these guidelines are in accordance with the US Agency for Health Care Policy and Research, as described in the Appendix. It will be noted that there is a lack of a strong evidence base for many of the recommendations suggested, as the appropriate clinical and laboratory trials have not been and perhaps never will be undertaken in neonates. Most of the recommendations are therefore of Grade C evidence levels IV: higher levels are mentioned specifically throughout the document when relevant.

Prolonged use of tissue plasminogen activator for bilateral lower limb arterial occlusion in a neonate

The authors report the case of a 29-week-gestation twin with very severe vascular compromise of both lower limbs secondary to premature twin-twin transfusion. A tissue plasminogen activator (tPA) infusion was used locally for 13 days with complete recovery of perfusion to both legs, demonstrated by serial angiograms, thereby avoiding bilateral amputation. There were no side effects as a result of the continuous administration of tPA. The authors therefore suggest that the benefits of thrombolysis from a local infusion of tPA in neonates may outweigh the potential risks. This case report thus supports the view that under certain circumstances infusion of tPA in neonates may offer significant benefits. J Pediatr Surg 36:654-656.