Antithrombotic therapies: anticoagulation and thrombolysis

Tissue Plasminogen Activator Use in Pediatric Patients: A Single Center Experience

INTRODUCTION

Thrombosis is rare in children and antithrombolytic treatment is controversial. Most commonly used thrombolytic agent is tissue plasminogen activator (t-PA) in pediatrics. In this study, we report our experience in the use of thrombolytic treatment.

METHODS

Eighteen patients who had received systemic t-PA between January 2006 and December 2013 were recorded. The response to t-PA was evaluated as complete, partial, and no. The bleeding complication during t-PA administration was graded as minor or major.

RESULTS

There were 18 patients (2 mo to 12 y) who received systemic t-PA. Three patients had venous, 14 patients had arterial, and 1 patient had intracardiac thrombosis. Thrombosis was related to cardiac catheterization (61.1%), central venous catheterization (16.7%), cardiac surgery (11.1%), and arrhythmia (5.5%). In 1 patient thrombosis occurred spontaneously (5.5%). Eighteen patients received 25 courses of systemic t-PA (0.15 to 0.3 mg/kg/h). A total of 55.6% of cases had complete, 27.8% had partial, and 16.6% showed no resolution.

CONCLUSION

t-PA infusion at doses of median 0.2 mg/kg/h (0.15 to 0.3) seems effective and safe. There is still no consensus on indications and dosing of antithrombolytic treatment in children but in selected patients it decreases long-term complications due to thrombosis.

Venous thromboembolism in childhood: where is Brazil after 20 years?

Due to the longer survival of critically ill children, venous thromboembolism is a problem which is becoming increasingly recognized in pediatric practice. In the last decades, several international studies have been published, shedding a light upon the epidemiology of this disease during childhood. These data show peculiarities in the clinical presentation and the significant morbidity and mortality. The new "epidemic of thrombosis" in pediatric hospitals points toward the urgent need for specific treatment and prevention protocols targeting this population. In Brazil, knowledge regarding this disease remains scarce. The lack of epidemiological data impacts both the clinical care and the design of specific public policies in the field. Thus, a national registry of pediatric venous thromboembolism is relevant to the proposal of an appropriate plan of action to create a qualified net of assistance. The improvement in educational initiatives related to the field of Pediatric Hemostasis is also very important. In this review, we have updated the epidemiological, clinical and therapeutic aspects of the disease, as well as the prevention strategies.

Thrombosis of the Abdominal Veins in Childhood

Abdominal venous thrombosis is a rare form of venous thromboembolic disease in children. While mortality rates are low, a significant proportion of affected children may suffer long-term morbidity. Additionally, given the infrequency of these thrombi, there is lack of stringent research data and evidence-based treatment guidelines. Nonetheless, pediatric hematologists and other subspecialists are likely to encounter these problems in practice. This review is therefore intended to provide a useful guide on the clinical diagnosis and management of children with these rare forms of venous thromboembolic disease. Herein, we will thus appraise the current knowledge regarding major forms of abdominal venous thrombosis in children. The discussion will focus on the epidemiology, presentation, diagnosis, management, and outcomes of (1) inferior vena cava, (2) portal, (3) mesenteric, (4) hepatic, and (5) renal vein thrombosis.

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.

Management and Outcomes of Patients with Occlusive Thrombosis after Pediatric Cardiac Surgery

OBJECTIVES

To evaluate management and outcomes of thrombosis after pediatric cardiac surgery and stratify thrombi according to risk of short- and long-term complications to better guide therapeutic choices.

STUDY DESIGN

Retrospective review was performed of 513 thrombi (400 occlusive) diagnosed after 213 pediatric cardiac operations. Long-term outcomes over time were assessed with the use of parametric hazard regression models.

RESULTS

Serious complications and/or high-intensity treatment occurred with 17%-24% of thrombi depending on location, most commonly in thrombi affecting the cardiac and cerebral circulation. Bleeding complications affected 13% of patients; associated factors included thrombolytics (OR 8.7, P < .001), greater daily dose of unfractionated heparin (OR 1.25 per 5 U/kg/day, P = .03), and extracorporeal support (OR 4.5, P = .007). Radiologic thrombus persistence was identified in 30% ± 3% at 12 months; associated factors included extracorporeal support (hazard ratio [HR] 1.9, P = .003), venous (HR 1.7, P = .003), and occlusive thrombi at presentation (HR 1.8, P = .001); greater oxygen saturation before surgery (HR 1.13/10%, P = .05) and thrombi in femoral veins (HR 1.9, P = .001) were associated with increased hazard of resolution. Freedom from postthrombotic syndrome was 83% ± 4% at 6 years, greater number of persistent vessel segment occlusions (HR 1.8/vessel, P = .001) and greater fibrinogen at diagnosis (HR 1.1 per g/L, P = .02) were associated with increased hazard.

CONCLUSIONS

Thrombosis outcomes after pediatric cardiac surgery remain suboptimal. Given that more intensive treatment would likely increase the risk of bleeding, the focus should be on both thrombosis-prevention strategies, as well as in tailoring therapy according to a thrombosis outcome risk stratification approach.

New developments in pediatric venous thromboembolism and anticoagulation, including the target-specific oral anticoagulants

PURPOSE OF REVIEW

Pediatric venous thromboembolism (VTE) can affect children of all ages, requiring considerable pharmacologic intervention and is often associated with significant morbidity. Current research efforts are directed toward the development of risk-stratified VTE prevention strategies employing pharmacologic thromboprophylaxis, the optimization of conventional anticoagulation, and the investigation of the safety and efficacy of target-specific oral anticoagulants (TSOACs) in children.

RECENT FINDINGS

Recent research has considerably improved the understanding of risk factors of hospital-acquired VTE and how these factors may be employed in risk-stratified paradigms for VTE prevention in children. Additional insight has been gained in the optimization of conventional anticoagulants in special populations such as neonates and children with inflammatory conditions, and in improving the overall safety and compliance with periprocedural anticoagulation and the use of home International Normalized Ratio monitoring. Furthermore, the use of TSOACs has been described in children and is the focus of numerous ongoing clinical trials that are evaluating the safety and efficacy of these agents in children with VTE.

SUMMARY

Identification of hospital-acquired VTE risk factors may inform pediatric VTE prevention strategies. Although initial use of TSOACs may be promising, investigation of safety and efficacy in children is still underway.