Iron deficiency anemia and thrombosis risk in children-revisiting an old hypothesis

Iron deficiency anemia has a high prevalence in children and has repeatedly been implicated as a risk factor for arterial and venous thrombosis. As an effective therapy for iron deficiency anemia is available, understanding the association between this form of anemia and the potentially severe thrombosis phenotype is of major clinical interest. Recent findings shed light on pathophysiology of hypercoagulability resulting from iron-restricted erythropoiesis. Specifically, an animal model of induced iron deficiency allowed identifying multiple mechanisms, by which iron deficiency anemia results in increased thrombus formation and thrombus progression both in arterial and venous thrombosis. These findings complement and support conclusions derived from clinical data. The purpose of this mini review is to summarize current evidence on the association of iron deficiency anemia and thrombosis. We want to increase the awareness of iron deficiency as a risk factor for thrombosis in the pediatric population. We discuss how novel pathophysiological concepts can be translated into the clinical settings and suggest clinical studies on prevention and treatment strategies in high-risk patient groups.

Case Study of Pediatric Cerebral Sinus Venous Thrombosis Center of a Low Middle-Income Country

Pediatric cerebral venous sinus thrombosis (CVST) is rare but a potentially fatal disease requiring its understanding in local setting. In this study, we observed the clinical course, management, and outcome of pediatric patients with sinus thrombosis in a tertiary care center at Pakistan. Patients between age 0 to 18 years of both genders diagnosed with sinus thrombosis during 2011 to 2020 were included. Data was collected through in-house computerized system and SPSS version 19 was used for analysis. Of 143492 pediatric admissions, 32 (21 males and 11 females) patients with a median (IQR) age of 4.5 years (0-16) had CVST. This is equivalent to 18.5 CVST events per million pediatric admissions. Adolescents were mostly affected, and the overall mortality was 7%. Primary underlying disorders were infections (59%), hematological neoplasms (12.5%), thrombotic thrombocytopenic purpura (3%) and antiphospholipid syndrome (3%). Activated protein C resistance (44%) was the most common inherited thrombophilia. Twenty-one (66%) patients were anemic with a mean (±SD) hemoglobin of 9.0 g/dL (±2.3). Regression analysis showed a positive association of anemia with multiple sinus involvement (P-value 0.009) but not with duration of symptoms (P-value 0.344), hospital stay (P-value 0.466), age (P-value 0.863) or gender (P-value 0.542) of the patients. SARS-COV2 was negative in patients during 2020. Adolescents were primarily affected by sinus thrombosis and infections was the predominant risk factor for all age groups, with a low all-cause mortality. A high index of clinical suspicion is required for prompt diagnosis and intervention.

Risk Assessment and Outcome of Venous Thromboembolism in Pediatric Population in an Academic Care Center of a Low-Middle Income Country

Venous thromboembolism (VTE) is a recognized complication of hospital stay in young patients in many developed countries, but such an information is largely unavailable from a low middle-income country (LMIC). This study aimed at identifying the frequency, risk factors, treatment options and outcome of deep venous thrombosis/pulmonary embolism (DVT/PE) in pediatric population in a tertiary care center from a LMIC. International classification of disease, ninth revision (ICD-9) was used to identify VTE in patients aged 0-18 years during January 2011 to September 2019. In-house computerized system was used to collect data for demographics, clinical and laboratory details. SPSS version 19 was used to analyzed data. The study was approved by Institutional ethical review committee (3872-Pat-ERC-15). During the study period, 134617 pediatric patients were hospitalized, DVT/PE was observed in 77 unique patients (47 males and 30 females) with a median (IQR) age of 14 (5-16) years equivalent to 5.9 VTE events /10,000 hospital admissions. Malignancy, community acquired infections and autoimmune diseases were the predominant risk factors (75%) in adolescent age-group while surgery for congenital heart anomalies was the primary reason (71%) in infants. Overall, lower extremity thrombosis was the most frequent (51%) followed by pulmonary embolism (25%). and upper extremity thrombosis (24%). Enoxaparin and unfractionated heparin were mainly used to treat VTE and all-cause mortality was 13% in the cohort studied. We observed substantial VTE events in pediatric patients during their hospital stay in a tertiary care center of a low-middle income country.

The Developing Balance of Thrombosis and Hemorrhage in Pediatric Surgery: Clinical Implications of Age-Related Changes in Hemostasis

Bleeding and thrombosis in critically ill infants and children is a vexing clinical problem. Despite the relatively low incidence of bleeding and thrombosis in the overall pediatric population relative to adults, these critically ill children face unique challenges to hemostasis due to extreme physiologic derangements, exposure of blood to foreign surfaces and membranes, and major vascular endothelial injury or disruption. Caring for pediatric patients on extracorporeal support, recovering from solid organ transplant or invasive surgery, and after major trauma is often complicated by major bleeding or clotting events. As our ability to care for the youngest and sickest of these children increases, the gaps in our understanding of the clinical implications of developmental hemostasis have become increasingly important. We review the current understanding of the development and function of the hemostatic system, including the complex and overlapping interactions of coagulation proteins, platelets, fibrinolysis, and immune mediators from the neonatal period through early childhood and to young adulthood. We then examine scenarios in which our ability to effectively measure and treat coagulation derangements in pediatric patients is limited. In these clinical situations, adult therapies are often extrapolated for use in children without taking age-related differences in pediatric hemostasis into account, leaving clinicians confused and impacting patient outcomes. We discuss the limitations of current coagulation testing in pediatric patients before turning to emerging ideas in the measurement and management of pediatric bleeding and thrombosis. Finally, we highlight opportunities for future research which take into account this developing balance of bleeding and thrombosis in our youngest patients.

The Role of Factor V Leiden, Prothrombin G20210A, and MTHFR C677T Mutations in Neonatal Cerebral Sinovenous Thrombosis

Little is known about the pathogenesis of cerebral sinovenous thrombosis (CSVT) in the neonate. Although thrombophilia has been described as increasing the risk of CSVT in adults, it remains controversial in pediatric patients, and prospective case–control studies regarding neonatal CSVT are lacking. From 2008 to 2017, all 26 consecutive newborn infants ≥35 weeks of gestation diagnosed with neonatal CSVT, and their mothers, were tested for factor V Leiden (FV) G1691A, FII G20210A, and methylenetetrahydrofolate reductase C677T (MTHFR C677T) mutations. Eighty-five mother–infant pairs were recruited as controls. All infants except 1 with CSVT were suspected due to clinical symptoms, mainly seizures (22/25). Magnetic resonance imaging was performed in 24/26 infants. Heterozygous FV G1691A, FII G20210A, and homozygous MTHFR C677T mutations were present in 1/26, 3/26, and 3/20 infants with CSVT, respectively. FII (odds ratio: 10.96; 95% confidence interval [CI]: 1.09-110.35) and male sex (3.93; 95% CI: 1.43-10.76) were associated with CSVT. When FII G20210A analysis was adjusted for sex, the OR for FII G20210A was 6.70 (95% CI: 0.65-69.22). No differences were found for FV G1691A or homozygous MTHFR mutations between neonates with CSVT and their mothers, compared to controls.

Management of antithrombin deficiency: an update for clinicians

Introduction. Antithrombin is a serpin that inhibits multiple procoagulant serine proteases and acts as an endogenous anticoagulant. Thus, congenital antithrombin deficiency constitutes a major thrombophilic state, the most severe so far. Areas covered. In the present work, we globally review the biology, genetics, diagnosis, and management of congenital antithrombin deficiency, and also discuss puzzling questions and future perspectives regarding this severe inherited thrombophilia. Expert opinion. Although this disorder exerts high clinical heterogeneity, many carriers will need careful and long-term anticoagulation and/or thromboprophylaxis, especially in high-risk situations, such as surgery and pregnancy. Notably, antithrombin concentrates constitute a considerable arsenal for both treatment and prevention of acute venous thrombosis in subjects with antithrombin deficiency. Current evidences are based almost exclusively on retrospective case series, so an integrated functional, biochemical and molecular characterization will be of clinical relevance and guide hematologists' personalized decisions.

Management of Extremity Venous Thrombosis in Neonates and Infants: An Experience From a Resource Challenged Setting

We aimed to evaluate the outcome of different treatment modalities for extremity venous thrombosis (VT) in neonates and infants, highlighting the current debate on their best tool of management. This retrospective study took place over a 9-year period from January 2009 to December 2017. All treated patients were referred to the vascular and pediatric surgery departments from the neonatal intensive care unit. All patients underwent a thorough history-taking as well as general clinical and local examination of the affected limb. Patients were divided into 2 groups: group I included those who underwent a conservative treated with the sole administration of unfractionated heparin (UFH), whereas group II included those who were treated with UFH plus warfarin. Sixty-three patients were included in this study. They were 36 males and 27 females. Their age ranged from 3 to 302 days. Forty-one (65%) patients had VT in the upper limb, whereas the remaining 22 (35%) had lower extremity VT. The success rate of the nonsurgical treatment was accomplished in 81% of patients. The remaining 19% underwent limb severing, due to established gangrene. The Kaplan-Meier survival method revealed a highly significant increase in both mean and median survival times in those groups treated with heparin and warfarin compared to heparin-only group ( P < .001). Nonoperative treatment with anticoagulation or observation (ie, wait-and-see policy) alone may be an easily applicable, effective, and a safe modality for management of VT in neonates and infants, especially in developing countries with poor or highly challenged resource settings.

Comparison of the Coagulation Effect Achieved by OctaplasLG Versus Fresh Frozen Plasma in Pediatric Cardiac Surgical Patients

OctaplasLG is indicated for use in patients undergoing cardiac surgery who require replacement of multiple clotting factors. The use of OctaplasLG over single-donor fresh frozen plasma (FFP) may have beneficial effects when considering the transmission of enveloped viruses. Additionally, it has the potential for fewer adverse reactions, reduced disease transmission, and a more homogenous coagulation factor composition. However, its efficacy and safety have not yet been evaluated in the pediatric population. Pediatric patients aged less than 2 years old and less than 10 kg, who underwent complete tetralogy of Fallot repair and received either OctaplasLG or FFP intraoperatively were identified over a 10-year period for this retrospective analysis. A review of case notes, intra-operative, and laboratory data were used to assess intraoperative blood product usage, blood loss, and postoperative coagulopathy. Data were analyzed to assess the efficacy of OctaplasLG in achieving hemostasis when compared to FFP. Results showed clinically better hemostasis postoperatively in OctaplasLG group compared with FFP group and better coagulation results. OctaplasLG was as effective as FFP when used in pediatric patients undergoing cardiac surgery.

Inferior vena cava atresia predisposing to acute lower extremity deep vein thrombosis in children: A descriptive dual-center study

PURPOSE

Thrombosis in the healthy pediatric population is a rare occurrence. Little is known about the optimal treatment or outcomes of children with unprovoked acute lower extremity (LE) deep vein thrombosis (DVT) associated with atresia of the inferior vena cava (IVC).

METHODS

We retrospectively analyzed the records of patients with acute LE DVT subsequently found to have IVC atresia who presented to two tertiary pediatric institutions between 2008 and 2016. Data were reviewed for thrombophilia risk factors, treatment, and outcomes.

RESULTS

Eighteen patients, aged 13-18 years (median: 16 years), presenting with acute LE DVT were found to have IVC atresia. Three patients also presented with pulmonary embolism. Fourteen patients underwent site-directed thrombolysis in addition to anticoagulation. Five patients (28%) had confirmed or suspected recurrent thrombosis. Thirteen patients (72%) had no identified provocation for DVT. Ten patients (56%) had post-thrombotic syndrome, and 17 of 18 patients remain on indefinite anticoagulation.

CONCLUSION

This study suggests that IVC atresia is a risk factor for LE DVT and pulmonary embolism in otherwise healthy children and highlights the importance of dedicated imaging of the IVC in young patients with unprovoked LE DVT. Indefinite anticoagulation may be considered in pediatric patients presenting with unprovoked thrombosis secondary to an atretic IVC.

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.

Factors Influencing ACT After Intravenous Bolus Administration of 100 IU/kg of Unfractionated Heparin During Cardiac Catheterization in Children

Anticoagulation using intravenous bolus administration of unfractionated heparin (UFH) aims to prevent thromboembolic complications in children undergoing cardiac catheterization (CC). Optimal UFH dosage is needed to reduce bleeding complications. We analyzed the effect of bolus UFH on activated clotting time (ACT) in children undergoing CC focusing on age-dependent, anesthesia-related, or disease-related influencing factors. This retrospective single-center study of 183 pediatric patients receiving UFH during CC analyzed ACT measured at the end of CC. After bolus administration of 100 IU UFH/kg body weight, ACT values between 105 and 488 seconds were reached. Seventy-two percent were within target level of 160 to 240 seconds. Age-dependent differences were not obtained ( P = .407). The ACT values were lower due to hemodilution (total fluid and crystalloid administration during CC, both P < .001), with premedication of acetylsalicylic acid ( P = .014) and low-molecular-weight heparin ( P = .049). Arterial thrombosis (3.85%), venous thrombosis (0.55%), and bleeding (1.65%) following CC did not correlate with ACT values but occurred more frequently in children between 1 month and 1 year of age (91%). In conclusion, with a bolus of 100 IU UFH/kg, an ACT target level of 160 to 240 seconds can be achieved during CC in children in 72%, which is influenced by hemodilution and anticoagulant and antiplatelet premedication but not by age.

Evaluation of the use of low-molecular-weight heparin in neonates: a retrospective, single-center study

Controversies exist over the currently recommended guidelines for the use of low-molecular-weight heparin (LMWH) in neonates. We retrospectively studied 30 neonates treated with LMWH and found a poor therapeutic response to recommended doses as measured by anti-Xa levels. Sixty percent of the study participants required their doses to be increased because of subtherapeutic anti-Xa levels during the initial course of their treatment. The mean starting enoxaparin dose was 1.53 ± 0.38 mg/kg. The mean enoxaparin dose, once therapeutic anti-Xa levels had been achieved, was 1.86 ± 0.50 mg/kg. Preterm and term infants required doses of 2.06 ± 0.61 mg/kg and 1.67 ± 0.26 mg/kg, respectively, to achieve therapeutic anti-Xa levels. In summary, our results suggest that higher initial doses are required to achieve therapeutic anticoagulation in neonates.

Predictive value of pediatric thrombosis diagnoses in the Danish National Patient Registry

Data on the validity of pediatric thrombosis diagnoses are missing. We aimed to examine the predictive value of a diagnosis of venous and arterial thrombosis using the Danish National Patient Registry (DNPR). We identified all first-time diagnoses among children and adolescents (aged 0–18 years) between 1994 and 2006 in DNPR. In total, 1138 potential cases of thrombosis were identified; the medical records were retrieved for 1112 (97.7%) and the positive predictive value (PPV) computed. Overall, the diagnosis of thrombosis was verified in 598 of the 1112 cases, corresponding to a PPV of 53.7% (95% confidence interval [CI]: 50.8–56.7). Diagnoses from wards had the PPV of 62.5% (95% CI: 59.4–65.6). The predictive value of a thrombosis diagnosis from wards was age-dependent, with a higher PPV (77.4%, 95% CI: 68.7–84.7) in neonates (<28 days) and adolescents (15–18 years) (68.2%; 95% CI: 63.2–72.5)) than in children (28 days–14 years) (51.2%; (95% CI: 46.0–56.4)). The PPV of a thrombosis diagnosis was improved by restricting the analysis to diagnoses from wards, primary diagnoses, and admissions with a length of stay of three or more days. The results indicate that an interpretation of nonvalidated hospital discharge data for pediatric thrombosis in a registry like DNPR should be made with caution.