Long-term outcomes of warfarin versus aspirin after Fontan surgery.

OBJECTIVES: Because of the nature of the Fontan physiology, patients are at an increased risk of thromboembolic complications. As such, warfarin or aspirin is generally prescribed lifelong for thromboprophylaxis. This study aimed to compare long-term rates of cerebrovascular injury, thrombosis, bleeding, bone mineral density, and quality of life in people living with Fontan circulation receiving warfarin compared with aspirin. METHODS: This was a multicenter study of a selected cohort from the Australia and New Zealand Fontan population. Participants underwent cerebral magnetic resonance imaging to detect the presence of cerebrovascular injury (n = 84) and dual-energy X-ray absorptiometry to assess bone mineral density (n = 120). Bleeding (n = 100) and quality of life (n = 90) were assessed using validated questionnaires: Warfarin and Aspirin Bleeding assessment tool and Pediatric Quality of Life Inventory, respectively. RESULTS: Stroke was detected in 33 participants (39%), with only 7 (6%) being clinically symptomatic. There was no association between stroke and Fontan type or thromboprophylaxis type. Microhemorrhage and white matter injury were detected in most participants (96% and 86%, respectively), regardless of thromboprophylaxis type. Bleeding rates were high in both groups; however, bleeding was more frequent in the warfarin group. Bone mineral density was reduced in our cohort compared with the general population; however, this was further attenuated in the warfarin group. Quality of life was similar between the warfarin and aspirin groups. Home international normalized ratio monitoring was associated with better quality of life scores in the warfarin group. CONCLUSIONS: Cerebrovascular injury is a frequent occurrence in the Australia and New Zealand Fontan population regardless of thromboprophylaxis type. No benefit of long-term warfarin prophylaxis could be demonstrated over aspirin; however, consideration must be given to important clinical features such as cardiac function and lung function. Furthermore, the association of reduced bone health in children receiving warfarin warrants further mechanistic studies.

After an end-of-life decision: Parents' reflections on living with an end-of-life decision for their child.

AIM: Parents' role as end-of-life decision-makers for their child has become largely accepted Western health-care practice. How parents subsequently view and live with the end-of-life decision (ELD) they made has not been extensively examined. To help extend understanding of this phenomenon and contribute to care, as a part of a study on end-of-life decision-making, bereaved parents were asked about the aftermath of their decision-making. METHODS: A qualitative methodology was used. Semi-structured interviews were conducted with parents who had discussed ELDs for their child who had a life-limiting condition and had died. Data were thematically analysed. RESULTS: Twenty-five bereaved parents participated. Results indicate that parents hold multi-faceted views about their decision-making experiences. An ELD was viewed as weighty in nature, with decisions judged against the circumstances that the child and parents found themselves in. Despite the weightiness, parents reflected positively on their decisions, regarding themselves as making the right decision. Consequently, parents' comments demonstrated being able to live with their decision. When expressed, regret related to needing an ELD, rather than the actual decision. The few parents who did not perceive themselves as their child's decision-maker subsequently articulated negative reactions. Enduring concerns held by some parents mostly related to non-decisional matters, such as the child's suffering or not knowing the cause of death. CONCLUSION: Results suggest that parents can live well with the ELDs they made for their child. End-of-life decision-making knowledge is confirmed and extended, and clinical support for parents informed.

Identifying low-grade cellular rejection after heart transplantation in children by using gene expression profiling.

Endomyocardial biopsy (EMB) remains the gold standard for detecting rejection after heart transplantation but is costly and invasive. This study aims to distinguish no rejection (0R) from low-grade rejection (1R/2R) after heart transplantation in children by using global gene expression profiling in blood. A total of 106 blood samples with corresponding EMB from 18 children who underwent heart transplantation from 2011 to 2014 were analyzed (18 baseline/pretransplantation samples, 88 EMB samples). Corresponding rejection grades for each blood sample were 0R in 39% (34/88), 1R in 51% (45/88), and 2R in 10% (9/88). mRNA from each sample was sequenced. Differential expression analysis was performed at the gene level. A k-nearest neighbor (kNN) analysis was applied to the most differentially expressed (DE) genes to identify rejection after transplantation. Mean age at transplantation was 10.0 ± 5.4 yr. Expression of B cell and T cell receptor sequences was used to measure the effect of posttransplantation immunosuppression. Follow-up samples had lower levels of immunoglobulin gene families compared with pretransplantation ( P < 3E-5) (lower numbers of activated B cells). T cell receptor alpha and beta gene families had decreased expression in 0R samples compared with pretransplantation ( P < 4E-5) but recovered to near baseline levels in 1R/2R samples. kNN using the most DE gene (MKS1) and k = 9 nearest neighbors correctly identified 83% (73/88) of 1R/2R compared with 0R by leave-one-out cross validation. Using a genomic approach we can distinguish low-grade cellular allograft rejection (1R/2R) from no rejection (0R) after heart transplantation in children despite a wide age range.

Expression of Biglycan in First Trimester Chorionic Villous Sampling Placental Samples and Altered Function in Telomerase-Immortalized Microvascular Endothelial Cells.

OBJECTIVE: Biglycan (BGN) has reduced expression in placentae from pregnancies complicated by fetal growth restriction (FGR). We used first trimester placental samples from pregnancies with later small for gestational age (SGA) infants as a surrogate for FGR. The functional consequences of reduced BGN and the downstream targets of BGN were determined. Furthermore, the expression of targets was validated in primary placental endothelial cells isolated from FGR or control pregnancies. APPROACH AND RESULTS: BGN expression was determined using real-time polymerase chain reaction in placental tissues collected during chorionic villous sampling performed at 10 to 12 weeks' gestation from pregnancies that had known clinical outcomes, including SGA. Short-interference RNA reduced BGN expression in telomerase-immortalized microvascular endothelial cells, and the effect on proliferation, angiogenesis, and thrombin generation was determined. An angiogenesis array identified downstream targets of BGN, and their expression in control and FGR primary placental endothelial cells was validated using real-time polymerase chain reaction. Reduced BGN expression was observed in SGA placental tissues. BGN reduction decreased network formation of telomerase-immortalized microvascular endothelial cells but did not affect thrombin generation or cellular proliferation. The array identified target genes, which were further validated: angiopoetin 4 (ANGPT4), platelet-derived growth factor receptor α (PDGFRA), tumor necrosis factor superfamily member 15 (TNFSF15), angiogenin (ANG), serpin family C member 1 (SERPIN1), angiopoietin 2 (ANGPT2), and CXC motif chemokine 12 (CXCL12) in telomerase-immortalized microvascular endothelial cells and primary placental endothelial cells obtained from control and FGR pregnancies. CONCLUSIONS: This study reports a temporal relationship between altered placental BGN expression and subsequent development of SGA. Reduction of BGN in vascular endothelial cells leads to disrupted network formation and alterations in the expression of genes involved in angiogenesis. Therefore, differential expression of these may contribute to aberrant angiogenesis in SGA pregnancies.

Prehospital Emergency Care in Childhood Arterial Ischemic Stroke.

BACKGROUND AND PURPOSE: Immediately calling an ambulance is the key factor in reducing time to hospital presentation for adult stroke. Little is known about prehospital care in childhood arterial ischemic stroke (AIS). We aimed to determine emergency medical services call-taker and paramedic diagnostic sensitivity and to describe timelines of care in childhood AIS. METHODS: This is a retrospective study of ambulance-transported children aged <18 years with first radiologically confirmed AIS, from 2008 to 2015. Interhospital transfers of children with preexisting AIS diagnosis were excluded. RESULTS: Twenty-three children were identified; 4 with unavailable ambulance records were excluded. Nineteen children were included in the study. Median age was 8 years (interquartile range, 3-14); median Pediatric National Institutes of Stroke Severity Scale score was 8 (interquartile range, 3-16). Emergency medical services call-taker diagnosis was stroke in 4 children (21%). Priority code 1 (lights and sirens) ambulances were dispatched for 13 children (68%). Paramedic diagnosis was stroke in 5 children (26%), hospital prenotification occurred in 8 children (42%), and 13 children (68%) were transported to primary stroke centers. Median prehospital timelines were onset to emergency medical services contact 13 minutes, call to scene 12 minutes, time at scene 14 minutes, transport time 43 minutes, and total prehospital time 71 minutes (interquartile range, 60-85). CONCLUSIONS: Emergency medical services call-taker and paramedic diagnostic sensitivity and prenotification rates are low in childhood AIS.

Antiangiogenic effects of decorin restored by unfractionated, low molecular weight, and nonanticoagulant heparins.

Pregnancies affected by preeclampsia (PE) or fetal growth restriction (FGR) display increases in thrombin generation and reductions in angiogenesis and cell growth. There is significant interest in the potential for low molecular weight heparins (LMWHs) to reduce the recurrence of PE and FGR. However, LMWH is associated with an increased risk of bleeding. Therefore, it is of vital importance to determine the exact molecular function of heparins in pregnancy if they are used as therapy for pregnant women. We aimed to determine this using our model for PE/FGR in microvascular endothelial cells. The expression of decorin, a proteoglycan, was reduced to mimic PE/FGR in these cells compared with controls. Four concentrations of unfractionated heparin (UFH), LMWH, and nonanticoagulant heparin (NAC) were added to determine the effect on thrombin generation, angiogenesis, and cell growth. Treatment with UFH and LMWH reduced thrombin generation and restored angiogenesis but decreased cell growth. Treatment with NAC did not affect thrombin generation, restored angiogenesis, and showed a trend toward cell growth. In conclusion, treatment with NAC produced the same, if not better, results as treatment with UFH or LMWH, without the same impact on coagulation. Therefore, NAC could potentially be a better therapeutic option for prevention of PE/FGR in high-risk women, without the risk of the adverse effects of traditional anticoagulants.

Hypertension at time of diagnosis and long-term outcome after childhood ischemic stroke.

OBJECTIVE: To determine the prevalence of hypertension (HPT) in the acute phase after ischemic stroke (IS) and explore its relationship to outcome. METHODS: We performed a retrospective review of children aged 1 month to 18 years with first IS admitted to a tertiary hospital between 2003 and 2008. Blood pressure readings recorded over the first 72 hours after diagnosis and morbidity or mortality at 12 months were documented. HPT was defined as 2 consecutive readings of systolic blood pressure ≥95th percentile for age. RESULTS: Ninety children were identified (median age 3.8 years). Fifty-three of 84 patients (63%) who had blood pressure readings available had at least 1 episode of HPT and 19 (22%) had HPT on 3 consecutive days. HPT was more prevalent at both ends of the age spectrum. The relative risk of 12-month mortality was 4.5 times higher (95% confidence interval = 0.6-34.5, p = 0.096) and relative risk of death in the hospital was 1.7 times higher (95% confidence interval = 1.4-2.0, p = 0.05) if the patient experienced HPT. There was no association between HPT and vascular territory, etiology, or neurologic disability. CONCLUSIONS: HPT is prevalent in children with IS in the first 3 days after diagnosis and is associated with increased risk of death. Larger prospective studies involving systematic recording of blood pressure are required to delineate the impact of HPT on risk of death or disability.

Inherited thrombophilias and adverse pregnancy outcomes: a case-control study in an Australian population.

OBJECTIVE: The primary aim of this study was to examine the association between inherited thrombophilias and adverse pregnancy outcomes in an Australian population. DESIGN: Case-control study. SETTING: Two Australian tertiary level maternity hospitals. POPULATION: One hundred and fifteen cases with adverse pregnancy outcomes, comprising severe pre-eclampsia (n=45), fetal growth restriction (n=44), placental abruption (n=16) or stillbirth (n=10), and 115 controls matched for ethnicity, parity and maternal age. METHODS: Genotyping for factor V Leiden, prothrombin gene mutation, methylenetetrahydrofolate reductase 677 and 1298 and thrombomodulin polymorphism was performed using Taqman assays in an ABI prism 7700 Sequencer. Pregnancy outcome data were extracted from the medical record at the time of recruitment. MAIN OUTCOME MEASURES: Prevalence of inherited thrombophilias in women with adverse pregnancy outcomes and matched control women. RESULTS: There were no differences in baseline characteristics between cases and control women, apart from duration of gestation and neonatal birthweight. Overall, there was no significant difference in the prevalence of these inherited thrombophilia polymorphisms between cases and control women. Heterozygosity for the factor V Leiden mutation, however, was significantly associated with an increased risk of both stillbirth (odds ratio 9.33, 95% confidence interval 1.36-64.15, p=0.02) and placental abruption (odds ratio 8.62, 95% confidence interval 1.57-47.17, p=0.01). CONCLUSIONS: Overall, this study does not support a significant association between inherited thrombophilia polymorphisms and adverse pregnancy outcomes. Our two statistically significant findings should be interpreted with caution given the small number of patients in these subgroups (10 stillbirths and 16 placental abruption cases) and the wide confidence intervals.

Placental syndecan expression is altered in human idiopathic fetal growth restriction.

Pregnancy represents a hypercoagulable state characterized by increased thrombin generation. However, placentas from fetal growth restriction (FGR) pregnancies are characterized by increased fibrin deposition and thrombi in the vasculature, indicative of a further increase in thrombin activation and a disturbance in coagulation in this clinical setting. The cause of the coagulation disturbance observed in FGR pregnancies is currently unknown. Anticoagulant mechanisms are crucial in the regulation of thrombin activity, and current evidence suggests that syndecans are the principal placental anticoagulant proteoglycans. The aim of this study was to determine the localization, distribution, and expression of syndecans 1 to 4 in placentas complicated by idiopathic FGR compared with gestation-matched controls. Immunohistochemistry results revealed that all of the syndecans were localized to cells located closely to the maternal and fetal circulation. The mRNA and protein expression levels of both syndecan 1 and syndecan 2 were significantly decreased in FGR samples compared with controls. This is the first study to demonstrate the differential expression of syndecans 1 to 4 in idiopathic FGR placentas compared with controls. Reduced levels of syndecan expression may result in increased placental thrombosis in the uteroplacental circulation and may therefore contribute to the pathogenesis of FGR.

Effect of warfarin on menstruation and menstrual management of the adolescent on warfarin.

AIM: The aim of this study was to review a consecutive cohort of adolescent females on warfarin to determine the effect of warfarin on menstruation, management options and their perceived efficacy. METHODS: All female patients on warfarin, over the age of 10 years, as of 31 August 2006, were identified using the Department of Haematology (Royal Children's Hospital) warfarin database. The presence of menorrhagia was defined by clinical indicators. RESULTS: Of 81 adolescent females on warfarin, 24 (30%) were referred to gynaecology due to a concern about heavy periods and one for anticipatory guidance, on the basis of impending menarche. In 18 cases (22% of the cohort), menorrhagia could be substantiated on the basis of clinical indicators. Nineteen patients required treatment for menorrhagia with the options for treatment being the combined oral contraceptive pill, subdermal hormone administrations, tranexamic acid and the progesterone-only contraceptive pill. Significant adolescent psychosocial stresses were identified in those adolescents taking warfarin. CONCLUSIONS: Adolescent females on warfarin commonly suffer from menorrhagia. Adolescent review of all teenage girls receiving warfarin therapy is indicated.

Hyperhaemolysis in sickle cell disease--an unusual and potentially life-threatening complication.

As sickle cell disease is increasing in Australia, paediatricians and other health care providers need to be aware of the broad range of complications that can occur in this condition. Although the complications of splenic sequestration and chest crises are well recognised, the infrequent but equally dramatic complication of hyperhaemolysis is less well appreciated. Here, we report a case of hyperhaemolysis in a Victorian paediatric patient.

Altered reference ranges for protein C and protein S during early pregnancy: Implications for the diagnosis of protein C and protein S deficiency during pregnancy.

Protein S, protein C and antithrombin are important regulators of coagulation. While deficiencies of these proteins have been linked to adverse pregnancy outcomes, testing for these deficiencies during pregnancy is limited by the use of non-pregnant reference ranges and a limited understanding of the changes that occur during pregnancy. Although several small studies have previously reported on the activity of these proteins during pregnancy, potentially important changes have been overlooked by continuing to compare the activity during pregnancy with non-pregnant reference ranges. In the current study, we investigated the activity of protein S, protein C and antithrombin during the first half of pregnancy in 440 otherwise asymptomatic women who went on to have uncomplicated singleton pregnancies. Consistent with previous studies, we found that antithrombin activity remained unchanged, while protein S activity decreased significantly to a mean level of 46%. We did not observe a progressive decrease in protein S during the second trimester as several studies have suggested previously. In contrast, we observed a potentially biologically significant increase in protein C activity throughout the first 22 weeks of pregnancy. Given the physiological role of protein C, we postulate that this increase may play a role in maintaining early pregnancy through both an anticoagulant and an inflammatory regulation pathway.

Inherited thrombophilia polymorphisms and pregnancy outcomes in nulliparous women.

OBJECTIVE: To estimate the association between five commonly inherited thrombophilia polymorphisms and adverse pregnancy outcomes in women who had no prior history of adverse pregnancy outcomes or personal or family history of venous thromboembolism. METHODS: Healthy nulliparous women (n=2,034) were recruited to this prospective cohort study before 22 weeks of gestation. Genotyping for factor V Leiden, prothrombin gene mutation, methylenetetrahydrofolate reductase enzyme (MTHFR) C677T, MTHFR A1298C, and thrombomodulin polymorphism was performed. Clinicians caring for women were blinded to the results of thrombophilia tests. The primary composite outcome was the development of severe preeclampsia, fetal growth restriction, placental abruption, stillbirth, or neonatal death. RESULTS: Complete molecular results and pregnancy outcome data were available in 1,707 women. These complications were experienced by 136 women (8.0%). Multivariable logistic regression demonstrated two statistically significant findings. Women who carried the prothrombin gene mutation had an odds ratio of 3.58 (95% confidence interval [CI] 1.20-10.61, P=.02) for the development of the composite primary outcome. Homozygous carriers of the MTHFR 1298 polymorphism had an odds ratio of 0.26 (95% CI 0.08-0.86, P=.03). None of the other polymorphisms studied showed a significant association with the development of the primary outcome in this cohort of women. CONCLUSION: Prothrombin gene mutation confers an increased risk for the development of adverse pregnancy outcomes in otherwise asymptomatic, nulliparous women, whereas homozygosity for MTHFR 1298 may protect against these complications. The majority of asymptomatic women who carry an inherited thrombophilia polymorphism have a successful pregnancy outcome. LEVEL OF EVIDENCE: II.

The prevalence of inherited thrombophilic polymorphisms in an asymptomatic Australian antenatal population.

AIM: Inherited thrombophilic polymorphisms have been linked to pregnancy-related thromboembolism and other adverse pregnancy outcomes. As there are limited data on the prevalence of these polymorphisms in Australian populations, we aimed to assess this in an antenatal population. METHODS: Healthy nulliparous women (n = 2031) were recruited to this study. The women had no past or family history of venous thromboembolism. Women were excluded if they or a family member was known to be a carrier of any thrombophilic marker. Genotyping from venous blood for the factor V Leiden, prothrombin 20210A, MTHFR 677 and 1298 and thrombomodulin C1418T polymorphisms was undertaken. RESULTS: Key findings were that 107 of 2019 (5.30, 95% confidence interval 4.36-6.37%) women tested were heterozygous carriers of factor V Leiden and one was homozygous (0.05, 0-0.27%); 2.43% of women were heterozygous carriers of the prothrombin gene mutation (1.80-3.20%) while no women were homozygous for this mutation; 11.62% (10.22-13.02%) and 9.98% (8.67-11.29%) were homozygous for the MTHFR 677 and 1298 polymorphisms, respectively, and 3.43% (2.63-4.22%) of women were homozygous for the thrombomodulin polymorphism. CONCLUSIONS: The prevalence of these polymorphisms is consistent with previously published data in Caucasian populations. These data will provide the basis for further assessment of the relationship between poor pregnancy outcome and these inherited thrombophilic polymorphisms in an asymptomatic antenatal population.

Reference values for kaolin-activated thromboelastography in healthy children.

BACKGROUND: The hemostatic system of children changes with age and differs significantly from the hemostatic system of adults. Age-specific reference values are therefore required for most hemostatic variables. Thromboelastography (TEG) is a point-of-care coagulation test that may provide superior evaluation and management of coagulopathies after cardiac surgery, when large-dose unfractionated heparin is administered for cardiopulmonary bypass. In this study, we established reference values for kaolin-activated TEG in healthy children, to facilitate accurate interpretation of pediatric TEG results. METHODS: Kaolin-activated TEG was performed on 100 healthy children undergoing elective day surgery and 25 healthy adult volunteers. The following TEG variables were recorded: reaction time, coagulation time, alpha angle, maximum amplitude, percentage lysis 30 min after maximum amplitude was reached, and the coagulation index. Differences between age-groups were evaluated using analysis of variance. RESULTS: Age-specific reference values for kaolin-activated TEG in healthy children between 1 mo and 16 yr of age are presented. No significant differences between children and adults were observed. CONCLUSIONS: TEG results, from a particular clinical setting, must be compared to age-specific, as well as analyzer- and activator-specific, reference values to allow for correct interpretation of the results. Reference values provided here will be of use in acute clinical situations where a practical monitor of hemostasis is required.

Decreased concentrations of heparinoids are required to inhibit thrombin generation in plasma from newborns and children compared to plasma from adults due to reduced thrombin potential.

Thrombin generation is decreased and delayed in plasma from newborns and children compared to adults. We hypothesized that lower doses of heparinoid anticoagulants are required to give similar thrombin generation in newborn (umbilical cord) and child plasmas compared to that of adults. Thrombin generation was performed in either the absence or presence of unfractionated heparin (UFH), low molecular weight heparin (LMWH) or a covalent antithrombin-heparin complex (ATH). After contact activation and recalcification of each plasma, thrombin activity was measured by periodic sub-sampling into chromogenic substrate. UFH inhibited thrombin generation to a greater extent compared to LMWH in all plasmas. Cord plasma was more sensitive to inhibition and displayed a greater difference in the effectiveness of UFH compared to LMWH than other plasmas. Lower concentrations of UFH and LMWH were required to inhibit thrombin generation in cord and child plasmas compared to adult plasma. In comparison, ATH strongly inhibited thrombin generation in all 3 plasmas. Similar peak thrombin concentrations were observed at lower ATH concentrations (0.1 U/mL) compared to either UFH (0.25 U/mL) or LMWH (0.25 U/mL). As with UFH and LMWH, cord plasma was more sensitive to inhibition by ATH than the other plasmas and lower ATH concentrations inhibited thrombin generation in cord and child plasmas compared to adult plasma. Decreased thrombin generation with heparinoids in cord and child plasmas compared to adult plasma coincided with decreased rates of prothrombin consumption and increased proportion of thrombin-alpha2-macroglobulin inhibitor complexes. In summary, lower doses of UFH, LMWH or ATH result in similar peak thrombin generation in newborn and child plasmas compared to adult plasma. Cord plasma was the most sensitive to inhibition, with ATH being more effective than UFH or LMWH.

Mechanisms responsible for the failure of protamine to inactivate low-molecular-weight heparin.

Protamine is unable to completely reverse the anticoagulant effect of the low-molecular-weight heparins (LMWH), a fact of clinical importance given the rapid increase in use of LMWH in clinical practice. This investigation sought to determine the mechanism by which LMWH were able to resist protamine-mediated inactivation. Affinity fractionation of LMWH by passage through a protamine column, with subsequent determination of molecular mass and sulphate charge density, demonstrated that the protamine-resistant fraction in LMWH is an ultra-low-molecular-weight fraction with low sulphate charge density. This group of molecules was not found in unfractionated heparin, even when species of similar molecular mass were compared. We then determined that different commercially available LMWH varied in their ability to be neutralized by protamine, and that this variability correlated with the total sulphate content of the LMWH. We conclude that reduced sulphate charge, not molecular mass, is the principle reason that protamine is unable to fully inactivate LMWH. Furthermore, different LMWH vary in their ability to be neutralized by protamine, suggesting that product-specific recommendations for neutralization might be developed.