Thrombosis during infancy and childhood: what we know and what we do not know

Bir ergende sifilize ikincil abdominal ven trombozu

Bilateral renal venlerden vena cava inferiora uzanan sifilize sekonder trombozu olan bir ergeni sunuyoruz. On altı yaşında erkek hasta, on iki saattir şiddetli karın ve sırt ağrısı ile acil servise başvurdu. Akut karın ayırıcı tanısı için karın ultrasonografisi yapıldı ve radyolog renal venler seviyesinden başlayarak, vena cava inferior, her iki taraftaki ana iliak venler ve eksternal iliyak venlerin proksimal kısmını tıkayan kronik trombüs bildirdi. Klinik öyküsünden yaklaşık bir aydır iki-üç günde bir ateşi olduğu öğrenildi. Yaklaşık iki yıl önce seks işçisi ile cinsel ilişkiye girdiği öğrenilen olgu cinsel yolla bulaşan hastalıklar açısından tarandı ve western blot testi sifiliz için pozitif sonuçlandı. Heparin tedavisinin 5. gününde varfarin başlandı ve dördüncü haftada kontrol doppler USG'de rekanalizasyon izlendi.

Venous Thromboembolism in Female Adolescents: Patient Characteristics

STUDY OBJECTIVE

Our goal was to describe the period prevalence of venous thromboembolism (VTE) and characterize adolescent female patients diagnosed with VTE by describing their age, race, and number of comorbidities. Female adolescents with estrogen exposure were of particular interest because estrogen-containing contraceptives increase the risk of VTE.

DESIGN, SETTING, PARTICIPANTS, AND INTERVENTIONS

We queried the Pediatric Health Information System database for International Classification of Diseases, Ninth/Tenth Revision, Clinical Modification codes to identify female patients aged 12-18 years diagnosed with a VTE or pulmonary embolism from April 2006 to March 2016 in the United States. Patient demographic characteristics and comorbidities were also analyzed. We divided our study population into two five-year groups and calculated the change in period prevalence of VTE between those groups.

MAIN OUTCOME MEASURES

Primary diagnosis of VTE in the extremities, or pulmonary embolism.

RESULTS

The period prevalence of VTE increased from 2.3 female adolescents per 10,000 hospitalized children (group 1) to 3.3 per 10,000 (group 2), representing a statistically significant increase of 0.010% (P < .001). Caucasian and black individuals were most commonly affected. The number of girls affected increased steadily from ages 12 to 16 years and a large percentage (59.6%) had four or more comorbidities. In patients (n = 32) with estrogen exposure, more than 96% had one or more comorbidity in addition to estrogen exposure.

CONCLUSION

Pediatric health care providers should be aware that the period prevalence of VTEs in female adolescents is increasing. Those with a history of estrogen exposure rarely develop VTEs from estrogen alone and they typically have multiple comorbidities.

Deep vein thrombosis in pediatric patients

Due to advances in caring for critically ill children and those with chronic diseases, rates of deep vein thrombosis (DVT) are increasing in children. Risk factors consist of central venous catheters, chronic medical conditions, thrombophilia, and various medications. Compression Doppler ultrasonography is the method most commonly used to diagnose DVT, and patients will usually present with pain and swelling of the affected limb. Anticoagulation via subcutaneous injection is the most common treatment regime for children with DVT, and the new, direct oral anticoagulants are currently under investigation. Prevention techniques are not established, but clinical studies are addressing this need.

Cohort Study: Central Venous Catheter-Related Complications in Children with Hematologic Diseases at a Single Center

Objective:

This study aims to document and analyze the central venous catheter (CVC)-related complications in children with hematological diseases who were treated within a single institution.

Materials and Methods:

A retrospective investigation was conducted in 106 pediatric patients in whom 203 CVCs were inserted. A total of 175 catheter-related complications occurred in 5 years.

Results:

The rates of clinical catheter infections, local catheter infections, venous thromboembolism, bleeding, and mechanical complications were 2.6, 1.1, 0.2, 0.2, and 0.2 per 1000 catheter days. Methicillin-resistant Staphylococcus epidermidis was the predominant infectious organism in blood and catheter cultures. The children with leukemia had a significantly higher frequency of clinical catheter infections (p=0.046). The children who underwent bone marrow transplantation had a significantly lower frequency of clinical catheter infections (p=0.043) and higher frequency of local catheter infections (p=0.003). The children with implanted catheters had a significantly lower frequency of clinical catheter infections (p=0.048). The children with thrombocytopenia had significantly fewer local catheter infections and significantly more clinical catheter infections and catheter-related bleeding (respectively p=0.001, p=0.042, and p=0.024).

Conclusion:

Leukemia, bone marrow transplantation, and thrombocytopenia are risk factors for CVC-associated complications. The relatively higher number of interventions performed via permanent catheters may be responsible for the significantly increased incidence of systemic infections and mechanical injury.

Association of Obesity and Pediatric Venous Thromboembolism

BACKGROUND

The incidence of venous thromboembolism (VTE) is increasing among pediatric patients in the United States. Previous studies on obesity as a risk factor have produced mixed results.

METHODS

We completed a retrospective chart review of patients aged 2 to 18 years with VTE identified by using International Classification of Diseases, Ninth Revision, codes and confirmed by imaging. Patients were admitted between January 2000 and September 2012. Control subjects were matched on age, gender, and the presence of a central venous catheter. Data were collected on weight, height, and risk factors, including bacteremia, ICU admission, immobilization, use of oral contraceptives, and malignancy. Underweight patients and those without documented height and weight data were excluded. Independent predictors of VTE risk were identified by using univariate and multivariate analyses.

RESULTS

We identified 88 patients plus 2 matched control subjects per case. The majority of cases were nonembolic events (77%) of the lower extremity (25%) or head and neck (22%) confirmed by ultrasound (43%) or computed tomography scan (41%). A statistically significant association was found between VTE and increased BMI z score (P = .002). In multivariate analysis, BMI z score (odds ratio [OR]: 3.1; P = .007), bacteremia (OR: 4.9; P = .02), ICU stay (OR: 2.5; P = .02), and use of oral contraceptives (OR: 17.4; P < .001) were significant predictors.

CONCLUSIONS

In this single-institution study, the diagnosis of VTE was significantly associated with overweight and obesity. Further study is needed to fully define this association.

Deep Venous Thrombosis in Teen With Crouzon Syndrome Post-Le Fort III Osteotomy With Rigid External Distraction

Venous thromboembolic events are rare in pediatric patients. Risk factors associated with the development of venous thromboembolic events in pediatric patients include the use of central venous catheters, hospitalization, cancer, sepsis, trauma, surgery, and congenital prothrombotic disorders.The authors present the case of a 14-year-old man with Crouzon syndrome who required Le Fort III osteotomy with rigid external distraction for significant midface hypoplasia who presented postoperatively with an extensive deep venous thrombosis. This is the first reported case of symptomatic venous thrombosis post-Le Fort III osteotomy and rigid external distraction. Although rare, surgeons should be aware of this potential complication.

Clinical variables and Staphylococcus aureus virulence factors associated with venous thromboembolism in children

OBJECTIVES

Children with Staphylococcus aureus (SA) bacteremia risk developing venous thromboembolism (VTE). We sought to identify clinical variables and bacterial virulence factors associated with VTE in SA bacteremia.

STUDY DESIGN

This is a single-institution retrospective study of 229 children with SA bacteremia hospitalized from 2005 to 2008. Clinical data were abstracted from patient charts. Two-hundred three SA isolates were analyzed by polymerase chain reaction. The Pediatric Health Information System (PHIS) database was queried to identify subjects with a central venous line (CVL) or complex chronic conditions (CCC). Logistic regression analysis was employed to determine which factors most greatly influenced VTE.

RESULTS

VTE was present in 9.2% (n=21/229). Superficial thrombi were excluded. Mortality was greater in patients with VTE [24% vs. 6% (p=0.016)]. Among SA isolates available for virulence testing, the majority (70%; n=139) were methicillin-sensitive SA (MSSA). Methicillin-resistant SA (MRSA) infection was associated with VTE (p=0.01). The most common sites of thrombosis were extremity deep vein (58%; n=14/24), head/neck (29%; n=7), and visceral (13%; n=3). One subject had a pulmonary embolism. The presence of a CVL or a CCC was not associated with VTE. Independent predictors of VTE were C-reactive protein (CRP)≥20mg/dl [OR 4.2, 95% CI 1.16-15.25] and hemoglobin nadir ≤9g/dl [OR 5.2, 95% CI 1.3-20.64].

CONCLUSIONS

In addition to MRSA infection, CRP≥20mg/dl and hemoglobin nadir ≤9g/dl were associated with VTE in SA bacteremia. These factors may serve as markers for increased risk of VTE with invasive SA disease.

Deep venous thrombosis in children with sickle cell disease

BACKGROUND

Deep venous thrombosis (DVT) is rare in children compared to adults. Its incidence and risk factors in children are not well known. This study determined these aspects of DVT in children with sickle cell disease (SCD).

PROCEDURE

A retrospective, observational and descriptive study was performed. Patients born between October 2000 and October 2012 with SCD and registered in HEMORIO, including those who died in HEMORIO, were included in this study. Patients whose medical records were inaccessible, who died in institutions other than HEMORIO, who died with implanted deep venous catheters, and those who were not monitored in HEMORIO for a period of 1 year or more were excluded from the study. Of a total of 1,519 patients, 456 were excluded and 1,063 patients were included in the study. Data were obtained from the computer system and the medical records at HEMORIO.

RESULTS

Of the 1,063 patients, 2 (0.2%) developed DVT with both cases being related to central venous catheters (CVCs) (P-value <0.001). Of the patients who required CVCs, the prevalence of DVT was 10%. No other variable was clinically or statistically significant with respect to DVT.

CONCLUSION

The establishment of CVCs in children with SCD poses a high risk for DVT. If this procedure is necessary, the internal jugular vein should be utilized instead of the subclavian and femoral veins. The identification of associated risk factors may justify antithrombotic prophylaxis.

Risk factors for venous thromboembolism in hospitalized children and adolescents: a systemic review and pooled analysis

We performed a systematic review of published studies that evaluated the potential risk factors and outcomes of venous thromboembolism (VTE) in hospitalized children. A total of 761 VTE patients from six published studies were identified. The mean prevalence of VTE in children admitted to the hospital was 9.7/10 000 admissions. The presence of a central venous catheter was found to be the single most important predisposing cause of VTE, with a pooled percentage of 29%. Infection was the second most common cause of the disease (20%). Pulmonary embolism occurred in 15% (113/745) of the patients. The overall recurrence rate of VTE was 16% (74/464) and the mortality rate was 8% (59/704). Although uncommon, orthopedic surgeons need to be aware of the unique risk factors for VTE among pediatric inpatients. Hospitalized children and adolescents with known risk factors for VTE should be considered candidates for VTE screening or prophylaxis.

Thromboprophylaxis in a pediatric hospital

Venous thromboembolism (VTE) in children is an emerging area of focus in pediatric hospitals in recent years. Although VTE in hospitalized children occurs much less often than in adults, there are a significant number of children at risk of VTE who may benefit from thromboprophylaxis. The risk factors for VTE in children are known, and are usually multi-factorial, but the indications for pharmacologic prophylaxis are not clearly established. There are available clinical guidelines that have brought forward current initiatives around thromboprophylaxis in pediatric hospitals addressing this safety practice in children.

Developing a pediatric endovascular thrombolysis program: a single-center experience

Deep venous thrombosis (DVT) is being increasingly recognized as a significant issue in children. Despite the low incidence of DVT, the risks of pulmonary embolism and death in children are significant. Post-thrombotic syndrome, a syndrome of chronic venous insufficiency, can have long-term adverse consequences in children and adolescents. Adult studies have shown that catheter-directed therapy can reduce the incidence of post-thrombotic syndrome. Safety of catheter-directed therapy in adolescents has also been demonstrated. These reasons compelled us to institute a pediatric endovascular thrombolysis program at our institute for management of pediatric DVT. We describe the process of developing a multi-disciplinary thrombolysis program involving interventional radiology (pediatric and adult), pediatric hematology, critical care, anesthesia and vascular surgery, and describe the role of each specialty in the development of the program. We also describe our experience with patient selection, endovascular therapy procedure, pre-, intra- and post-procedure monitoring, and follow-up management for endovascular therapy for DVT.

Neonatal and infant pulmonary thromboembolism: a literature review

Pulmonary thromboembolism (PTE) is rare in neonates and infants; however evidence suggests it is underdiagnosed. The primary objective is to conduct a scientific review to determine if the presentation, diagnosis, treatment and outcomes of neonates and infants with PTE are consistent across studies. Secondly, to develop an algorithm to establish the diagnosis and management of the condition based on current information. Two authors searched the literature independently using existing databases and verified that identical articles were assembled. Infants aged less than 1 year with PTE were included and further categorized into neonates 28 days or less and infants 29 days to 1 year or less. Forty-five articles with 157 cases (121 neonates; 36 infants) were identified with PTE. All of the reports were descriptive and neither randomized controlled trials nor prospective or case-control studies were identified. The reports are sub-classified into cases of pulmonary air embolism (PAE) with a higher mortality rate and patients with PTE. Diagnostic and treatment strategies varied widely and were individually case-based, dependent on clinical findings, which influenced patient outcomes. Scientific data to guide an evidence-based, diagnostic and treatment approach to PTE is limited because of the absence of rigorous clinical trials. Large scale, multicenter collaborative studies are required to firmly establish the management of PTE in this population.

Characteristics of abdominal vein thrombosis in children and adults

The demographic and clinical characteristics of adults and children with lower extremity deep-vein thrombosis and/or pulmonary embolism (LE DVT/PE) may differ from those with abdominal vein thrombosis (abdominal VT). Abdominal VT can be a presenting sign of an underlying prothrombotic state, and its presence in the setting of known disease might have prognostic implications different from LE DVT/PE. This study describes clinical presentations of abdominal VT compared to LE DVT/PE in adults and children. We analysed prospectively-collected data from consecutive consenting patients enrolled in one of seven Centers for Disease Control and Prevention (CDC) funded Thrombosis and Hemostasis Network Centers from August 2003 to April 2011 to compare the demographic and clinical characteristics of adults and children with abdominal VT. Both adults and children with abdominal VT tended to be younger and have a lower body mass index (BMI) than those with LE DVT/PE. Of patients with abdominal VT, children were more likely to have inferior vena cava (IVC) thrombosis than adults. For adults with venous thromboembolism (VTE), relatively more women had abdominal VT than LE DVT/PE, while the proportions with LE DVT/PE and abdominal VT by sex were similar in children. Children with abdominal VT were more likely to have diagnosed inherited thrombophilia, while trauma was more common in children with LE DVT/PE. In conclusion, both children and adults with abdominal VT were younger with a lower BMI than those with LE DVT/PE. Significant differences exist between children and adults in respect to abdominal VT compared to LE DVT/PE.

Risk-prediction tool for identifying hospitalized children with a predisposition for development of venous thromboembolism: Peds-Clot clinical Decision Rule

BACKGROUND

The prevalence of VTE is increasing in tertiary pediatric hospitals. Identification of high-risk populations using uniform criteria is required to develop evidence-based VTE prevention guidelines.

OBJECTIVE

To develop a VTE risk prediction rule, the Peds-Clot clinical Decision Rule (PCDR), to identify high-risk children who were at increased risk of developing VTE.

METHODS

This retrospective case-control study developed the PCDR using a derivation cohort (173 cases, 346 controls) and validated it on a separate validation cohort (100 cases, 100 controls). A uniform data collection strategy was applied to derive both the samples. Conditional logistic regression analyses were used to develop a risk-prediction model. Each significant predictor was assigned a score based on its beta coefficient and the PCDR was developed. ROC curves were derived to test the performance of the PCDR.

RESULTS

Characteristics of derivation and validation cohorts were comparable. Six risk factors (positive blood stream infection, central venous catheter, direct admission to ICU/NICU, hospitalization for ≥ 7 days, immobilization for > 72 h, and use of birth control pills) formed the final risk prediction model (risk score range, 0.5-9.5). A risk score of 3 or more identified high-risk children at a sensitivity of 70% and specificity of 80% and AUC of 0.852 (95% confidence interval, 0.814-0.890). The application of a risk score to the validation sample showed sensitivity 57% and specificity 88% and an AUC of 0.875 (95% confidence interval, 0.82-0.924).

CONCLUSION

Incorporation of the PCDR in routine clinical care can be an attractive strategy to identify high-risk hospitalized children with a predisposition for VTE. The clinical utility of the PCDR needs validation in prospective studies.

Early recognition of pediatric venous thromboembolism: a risk-assessment tool

BACKGROUND

The incidence of venous thromboembolism in children has increased dramatically, with most cases occurring in children with cancer, surgery, trauma, congenital heart disease, and systemic lupus erythematosus. Early assessment of risk factors present in children would minimize morbidity and mortality from these events.

OBJECTIVES

To evaluate the reliability and validity of a tool for assessing risk for venous thromboembolism in children.

METHODS

The tool was developed after a review of the literature with assessment of content validity by a multidisciplinary team of experts. Patients' charts were reviewed retrospectively to establish reliability and validity of the tool. A P value less than .05 was considered statistically significant.

RESULTS

Thirty-five charts were assessed for tool validity and were found to be statistically significant for all 3 risk score assessment categories. Logistic regression was used to assess 1001 patients' charts for internal consistency, which was found to be high (χ(2)(5)[n = 1001] = 100.6, P < .001). Results indicated that most patients at risk for venous thromboembolism were between the ages of 13 and 17 years, with females having more than 7 times greater risk than males.

CONCLUSIONS

Descriptive statistics show that the assessment tool displays strong reliability and validity. Results validated a significant relationship between the risk score and the incidence of venous thromboembolism. Findings suggest that use of the assessment tool could significantly reduce adverse outcomes associated with venous thromboembolism in children.

Venous thrombosis in children: an emerging issue

More and more cases of venous thrombosis are diagnosed in children thanks to newer imaging modalities. Central venous catheters have become commonplace in the care of critically ill children and have contributed to the increased rate of thrombotic events. Lastly, children who develop life-threatening or chronic medical conditions are surviving longer because of advanced medical therapies; these intensive therapies can be complicated by events such as thrombosis. Over the last 10 years, specific guidelines for treating thrombosis in children have become available. Nevertheless, in many situations anticoagulant treatment is specially tailored to each individual patient's needs. Some new antithrombotic drugs which have undergone clinical testing in adults might be beneficial to paediatric patients with thromboembolic disorders; unfortunately, clinical data and reports on the use of these drugs in children, when available, are extremely limited. The aim of this review is to provide physicians with enough background information to be able to manage thrombosis in children. First, by helping them detect a thrombotic event in a child. Upon confirmation of the diagnosis, the physician will request the appropriate tests and will choose the best treatment on the basis of the guidelines and recommendations. Moreover, the paediatrician will have the information he or she needs to identify which children are at highest risk of acute thrombotic events and relevant long-term sequelae and, therefore, to decide on the appropriate prophylactic or pharmacologic strategy. Lastly, we would like to provide the paediatrician with information on future drugs with regard to the treatment and prophylaxis of thrombosis.

Risk factors for in-hospital venous thromboembolism in children: a case-control study employing diagnostic validation

BACKGROUND

Studies evaluating risk factors for in-hospital venous thromboembolism in children are limited by quality assurance of case definition and/or lack of controlled comparison. The objective of this study is to determine risk factors for the development of in-hospital venous thromboembolism in children.

DESIGN AND METHODS

In a case-control study at The Children's Hospital, Colorado, from 1(st) January 2003 to 31(st) December 2009 we employed diagnostic validation methods to determine pediatric in-hospital venous thromboembolism risk factors. Clinical data on putative risk factors were retrospectively collected from medical records of children with International Classification of Diseases, 9th edition codes of venous thromboembolism at discharge, in whom radiological reports confirmed venous thromboembolism and no signs/symptoms of venous thromboembolism were noted on admission.

RESULTS

We verified 78 cases of in-hospital venous thromboembolism, yielding an average incidence of 5 per 10,000 hospitalized children per year. Logistical regression analyses revealed that mechanical ventilation, systemic infection, and hospitalization duration of five days or over were statistically significant, independent risk factors for in-hospital venous thromboembolism (OR=3.29, 95%CI=1.53-7.06, P=0.002; OR=3.05, 95%CI=1.57-5.94, P=0.001; and OR=1.03, 95%CI=1.01-1.04, P=0.001, respectively). Using these factors in a risk model, post-test probability of venous thromboembolism was 3.6%.

CONCLUSIONS

These data indicate that risk of in-hospital venous thromboembolism in children with this risk factor combination may exceed that of hospitalized adults in whom prophylactic anticoagulation is indicated. Substantiation of these findings via multicenter studies could provide the basis for future risk-stratified randomized control trials of pediatric venous thromboembolism prevention.

Incidence and risk factors associated with venous thrombotic events in pediatric intensive care unit patients

OBJECTIVE

To evaluate the incidence and risk factors associated with venous thromboembolism (VTE) in children admitted to pediatric intensive care units (PICUs).

DESIGN

Prospective observational study.

SETTING

Eleven tertiary care PICUs in the United States.

PATIENTS

Children who were admitted to PICUs and had radiographically confirmed VTE over a rolling 6-month period were enrolled in the study. Demographic, patient-related, and outcomes data were collected and compared with all children admitted during the same period.

INTERVENTIONS

None.

RESULTS

: Sixty-six symptomatic VTE were documented in sixty-two patients among 6653 patients admitted to 11 PICUs. Thirteen (19.7%) of the thrombi were present on admission. The incidence rate was 0.74% (range, 0-2.7% per PICU) with a point prevalence of 0.93%. Doppler ultrasound was most frequently used to diagnose or confirm a suspected VTE. Variables associated with unadjusted risk for VTE include: younger age (3.8 months for patients with VTE vs. 51 months for non-VTE patients, p < .001), cardiac diagnosis (41% in VTE cases vs. 15% in non-VTE, p < .001), pre-/post-operative status (63% in VTE cases vs. 40% in non-VTE, p = .001), presence of central venous catheter (88% in VTE case vs. 17% in non-VTE, p < .001), or mechanical ventilation (85% in VTE cases vs. 30% non-VTE, p < .001). Multivariate analysis showed increased risk of VTE with CVC (odds ratio 6.9; confidence interval 2.7-17.5) and mechanical ventilation (odds ratio 2.8; confidence interval 0.98-7.93). Children with VTE were sicker (Pediatric Index of Mortality 2 score risk of mortality of 3.0% vs. 0.9%; p<0.0001), stayed longer in the ICU (21.2 days vs. 1.6 days; p < .0001) and had increased mortality (10.2% vs. 2.6; p < .0001).

CONCLUSIONS

Children admitted to the PICU have an increased risk of VTE. The presence of a CVC is the strongest risk factor for VTE in this PICU population. Children with VTE were younger, sicker, stayed longer in PICU, and had a higher mortality rate.

Lipoprotein(a) and the risk of thromboembolism in Thai children

High lipoprotein(a) [Lp(a)] level was identified as a risk factor of both venous and arterial thromboembolism (TE), especially in Caucasian children. The Lp(a) level is affected by apo(a) gene. The genetic polymorphisms that associated with Lp(a) level are the size of apo(a) gene, pentanucleotide repeat (TTTTA)(n) and +93C/T at promoter region. The increasing size of apo(a) gene, more than 8 pentanucleotide repeats and +93C>T polymorphisms are associated with low level of Lp(a) in African and Caucasian populations. This cross - sectional, case control study, aims to identify the association of Lp(a) level and the risk for TE in Thai children. Forty-nine patients and 116 healthy children were enrolled. Mean ± SD for age of patients and controls were 7.6 ± 4.7 and 11.2 ± 1.7 years, with female:male ratios of 1:1.2 and 1.8:1, respectively. The median Lp(a) levels in patients was 8.2 (0-87.3) mg/dL and 7.9 (0-74.9) mg/dL in controls, which were not statistically different, P=0.65. The frequencies of 8 pentanucleotide repeats and +93C/T were different compared to Caucasian and African populations but similar to Chinese population. However, both polymorphisms did not affect the level of Lp(a).

Primary prophylaxis of venous thromboembolism in children

Venous thromboembolism (VTE) is rare in children and young adolescents, and occurs predominantly in those with congenital heart disease in whom guidelines exist for VTE prophylaxis. For other paediatric patients, the rarity of the event makes writing an evidence-based clinical practice guideline difficult because each of the known risk factors contributes only a small increase in risk. Thrombophilia screening is controversial because few results assist with prediction of likely thrombosis and may not alter recommendations for prophylaxis. Recent publications highlight the importance of non-pharmacological prevention of VTE in children and adolescents undergoing surgery and the importance of liaison among surgeon, anaesthetist and haematologist. This annotation was written with the aim of collating current evidence for VTE prophylaxis and emphasising the need for further research in vulnerable subgroups.

A male adolescent with left iliac thrombophlebitis and heterozygosity for factor V Leiden mutation

The epidemiology of deep vein thrombosis in adolescents has 2 potential associations. First, there is a demonstrated association with a congenital anomaly of the inferior vena cava (Dean SM, Tytle TL. Vas Med. 2006;11:165-169; Schnieider JG, Eynatten MV, Dugi KA, et al. J Intern Med. 2002;252:276-280). Secondly, resistance to activated protein C as a result of factor V Leiden is associated with thromboembolic disease at an early age (Price DT, Ridker PM. Ann Intern Med. 1997;127:895-903). Imaging modalities, central venous catheters, and improved life expectancy for critically and chronically ill children have resulted in an increased diagnosis of thromboembolic disease in the pediatric population (Journeycake MM, Manco-Johnson MJ. Hematol Oncol Clin N Am. 2004;18;1315-1338), and evaluation for thrombophilia should be performed for any child with thromboembolic disease.

The evaluation and management of postnatal thromboses

In the pediatric population, neonates have the highest risk for thromboembolism (TE), most likely due to the frequent use of intravascular catheters. This increased risk is attributed to multiple risk factors. Randomized clinical trials dealing with management of postnatal thromboses do not exist, thus, opinions differ regarding optimal diagnostic and therapeutic interventions. This review begins with an actual case study illustrating the complexity and severity of these types of cases, and then evaluates the neonatal hemostatic system with discussion of the common sites of postnatal thrombosis, perinatal and prothrombotic risk factors, and potential treatment options. A proposed step-wise evaluation of neonates with symptomatic postnatal thromboses will be suggested, as well as future research and registry directions. Owing to the complexity of ischemic perinatal stroke, this topic will not be reviewed.

Pharmacokinetics of protein C and antithrombin in the fetal lamb: a model to predict human neonatal replacement dosing

BACKGROUND

The preterm infant is at risk for consumptive coagulopathy and thrombosis due to late maturation of coagulation regulatory proteins. Replacement proteins are available, but neonatal pharmacokinetic data are lacking.

OBJECTIVE

The objective was to determine the pharmacokinetic properties of antithrombin (AT) and protein C (PC) in order to provide data for estimating doses in human infants.

METHODS

A catheterized ovine model was used to determine pharmacokinetic properties of AT and PC, including plasma recovery, volume of distribution (V(d)), clearance (Cl) and half-life (t((1/2))), in the fetal lamb relative to the ewe.

RESULTS

AT studies showed statistically significant differences between ewes and fetuses in recovery (p < 0.0001), V(d) (p = 0.0002) and Cl (p < 0.0001). The AT t((1/2)) was significantly shortened among fetuses (5.55 h, 95% CI: 4.01-7.08) compared to ewes (18.7 h, 95% CI: 11.6-25.8). PC recovery (p < 0.0001), V(d) (p < 0.0001) and Cl (p = 0.004) differed significantly between ewes and singleton fetuses as did the t((1/2)): 3.86 h (95% CI: 3.35-4.36) and 11.9 h (95% CI: 10.9-12.9) in the singletons and ewes, respectively. All PC parameters were significantly different for twins compared to ewes.

CONCLUSIONS

AT and PC show decreased recovery and t((1/2)) in the fetal lamb. These data can be used to estimate dosing for human neonates in comparison with human adult dosing recommendations.

An adolescent with thigh pain

Musculoskeletal pain is a common symptom among active adolescent in the emergency department. The etiologic list is broad and range from benign to potential life-threatening conditions. Deep vein thrombosis is a rare cause of lower extremity pain in children. We report an adolescent who presented with lower extremity pain and a careful evaluation revealed an abdominal mass. Further investigation determined the presence of iliofemoral deep venous thrombosis and absence of the inferior vena cava. Absence of inferior vena cava is an uncommon congenital malformation in children and is a possible risk factor for the development of venous thrombosis. This case emphasizes the importance of thorough physical examination in children with nonspecific symptoms. If venous thrombosis is identified, especially in patients without any apparent risk factors, congenital anomalies of inferior vena cava should be considered. The pertinent literature is reviewed.

Venous thromboembolism in the neonatal period

Thromboembolism occurs more frequently in newborns than in older infants or children. The developing hemostasis system of neonates has decreased concentrations of procoagulant proteins and the naturally occurring anticoagulants and hemostatic control proteins. Overall, neonatal hemostasis provides protection from excessive bleeding at the expense of an increased risk for thromboembolism. Intensive medical care for premature and ill infants often requires central vascular assess, and the most frequent risk factor for thromboembolism is the presence of an indwelling vascular catheter. Management of venous thromboembolism in the newborn period varies depending on the location and extent of the thrombus as well as the risk for acute embolic complications and later vascular compromise. Therapeutic decisions are guided by practitioners' past experience, published case reports and case series, several large registries, and extrapolation from results of clinical trials in adults with thromboembolic disease. Valuable consensus guidelines have been compiled by the AACP Conference on Antithrombotic and Thrombolytic Therapy. Heparin, either unfractionated or a low molecular weight preparation, is the most commonly utilized anticoagulant to treat thromboembolism in newborn infants. Thrombolytic therapy may be considered if the thrombus is life or limb threatening and there is no hemorrhagic contraindication. Multicenter, prospective, controlled clinical trials in this important patient population are needed to provide evidence-based data to better inform optimal management.

Antiphospholipid antibodies in Turkish children with thrombosis

Antiphospholipid syndrome is a systemic disorder characterized by arterial and/or venous thrombosis, thrombocytopenia, recurrent fetal loss, and presence of antiphospholipid antibodies (APA). The importance of APA in Turkish children with thrombosis is unknown. This study aimed to evaluate the frequency of APA positivity, associated risk factors other than APA, and outcome in children with APA and thrombosis. The presence of APA was investigated in 138 children presenting for evaluation of thrombosis; other prothrombotic risk factors were also studied. The frequency of APA positivity among 138 children was 11.6% (16/138). The mean age of these 16 children (10 female, 62.5%) was 9.57 +/- 4.59 years (range, 2.5-18.0 years). The mean follow-up period was 31.7 +/- 21.7 months (range, 5-60 months). Recurrence was observed during follow-up in two patients (12.5%). Ten patients (62.5%) had arterial thrombosis, five patients (31.3%) venous thrombosis, and one patient (6.3%) purpura fulminans. Among the thrombotic children with APA, 11 (68.8%) had more than one prothrombotic risk factor other than circulating APA [five patients (31.3%) had two risk factors, two patients (12.5%) had three, and four patients (25.0%) had four]. Five patients (31.3%) had no additional risk factors. APA should be tested in all children with thrombosis, especially those with arterial thrombosis.

A thrombolytic regimen for high-risk deep venous thrombosis may substantially reduce the risk of postthrombotic syndrome in children

Important predictors of adverse outcomes of thrombosis in children, including postthrombotic syndrome (PTS), have recently been identified. Given this knowledge and the encouraging preliminary pediatric experience with systemic thrombolysis, we sought to retrospectively analyze our institutional experience with a thrombolytic regimen versus standard anticoagulation for acute, occlusive deep venous thrombosis (DVT) of the proximal lower extremities in children in whom plasma factor VIII activity and/or D-dimer concentration were elevated at diagnosis, from within a longitudinal pediatric cohort. Nine children who underwent the thrombolytic regimen and 13 who received standard anticoagulation alone were followed from time of diagnosis with serial clinical evaluation and standardized PTS outcome assessments conducted in uniform fashion. The thrombolytic regimen was associated with a markedly decreased odds of PTS at 18 to 24 months compared with standard anticoagulation alone, which persisted after adjustment for significant covariates of age and lag time to therapy (odds ratio [OR] = 0.018, 95% confidence interval [CI] = < 0.001-0.483; P = .02). Major bleeding developed in 1 child, clinically judged as not directly related to thrombolysis for DVT. These findings suggest that the use of a thrombolysis regimen may safely and substantially reduce the risk of PTS in children with occlusive lower-extremity acute DVT, providing the basis for a future clinical trial.