Rett syndrome (RTT), an X-linked dominant neurodevelopmental disorder caused by mutations in MECP2, is associated with a peculiar breathing disturbance exclusively during wakefulness that is distressing, and can even prompt emergency resuscitation. Through the RTT Natural History Study, we characterized cross sectional and longitudinal characteristics of awake breathing abnormalities in RTT and identified associated clinical features. Participants were recruited from 2006 to 2015, and cumulative lifetime prevalence of breathing dysfunction was determined using the Kaplan-Meier estimator. Risk factors were assessed using logistic regression. Of 1205 participants, 1185 had sufficient data for analysis, including 922 females with classic RTT, 778 of whom were followed longitudinally for up to 9.0 years, for a total of 3944 person-years. Participants with classic or atypical severe RTT were more likely to have breathing dysfunction (nearly 100% over the lifespan) compared to those with atypical mild RTT (60-70%). Remission was common, lasting 1 year on average, with 15% ending the study in terminal remission. Factors associated with higher odds of severe breathing dysfunction included poor gross and fine motor function, frequency of stereotypical hand movements, seizure frequency, prolonged corrected QT interval on EKG, and two quality of life metrics: caregiver concern about physical health and contracting illness. Factors associated with lower prevalence of severe breathing dysfunction included higher body mass index and head circumference Z-scores, advanced age, and severe scoliosis or contractures. Awake breathing dysfunction is common in RTT, more so than seizures, and is associated with function, quality of life and risk for cardiac dysrhythmia.

Many chemicals have been used to increase the safety of consumer products by reducing their flammability and risk for ignition. Recent focus on brominated flame retardants, such as polybrominated diphenyl ethers (PBDEs) has shown them to contribute to neurobehavioral deficits in children, including learning and memory. As the manufacture and use of PBDEs has been reduced, replacement chemicals, such as hexabromocyclododecane (HBCDD) have been substituted. Our current study evaluated the neurotoxicity of HBCDD, concentrating on dopaminergic innervation to the hippocampus. Using an in vivo model, we exposed male mice to HBCDD and then assessed alterations to the dopamine synapse 6 weeks later. These exposures elicited significant reductions in presynaptic dopaminergic proteins, including TH, COMT, MAOB, DAT, VMAT2, and alpha-synuclein. In contrast, postsynaptic dopamine receptors were not impaired. These findings suggest that the mesohippocampal dopamine circuit is vulnerable to HBCDD and the dopamine terminal may be a selective target for alteration.

Background: Advances in surgical techniques and post-operative management of children with CHD have significantly lowered mortality rates. Unplanned cardiac interventions are a significant complication with implications on morbidity and mortality. Methods: We conducted a single-centre retrospective case–control study for patients (<18 years) undergoing cardiac surgery for repair of Tetralogy of Fallot between January 2009 and December 2019. Data included patient characteristics, operative variables and outcomes. This study aimed to assess the incidence and risk factors for reintervention of Tetralogy of Fallot after cardiac surgery. The secondary outcome was to examine the incidence of long-term morbidity and mortality in those who underwent unplanned reinterventions. Results: During the study period 29 patients (6.8%) underwent unplanned reintervention, and were matched to 58 patients by age, weight and sex. Median age was 146 days, and median weight was 5.8 kg. Operative mortality was 7%, and 1-year survival was 86% for the entire cohort (cases and controls). Hispanic patients were more likely to have reinterventions (p = 0.04) in the unadjusted analysis, while Asian, Pacific Islander and Native American (p = 0.01) in the multi-variate analysis. Patients that underwent reintervention were more likely to have post-op arrhythmia, genetic syndromes and higher operative and 1-year mortality (p < 0.05). Conclusion: Unplanned cardiac interventions following Tetralogy of Fallot repair are common, and associated with increased operative, and 1-year mortality. Race, genetic syndromes and post-operative arrhythmia are associated with increased odds of unplanned reinterventions. Future studies are needed to identify modifiable risk factors to minimise unplanned reinterventions.

Background: A subset of patients who develop post-surgical heart block have recovery of atrioventricular node function. Factors predicting recovery are not understood. We investigated our centre’s incidence of post-surgical heart block and examine factors associated with recovery of atrioventricular node function. Methods: We conducted a single-centre retrospective study of patients 0 – 21 years who underwent cardiac surgery between January 2010 and December 2019 and experienced post-operative heart block. Data including patient and clinical characteristics and operative variables were collected and analysed. Results: Of 6333 surgical hospitalisations, 128 (2%) patients developed post-operative heart block. Of the 128 patients, 90 (70%) had return of atrioventricular node function, and 38 (30%) had pacemaker placement. Of the 38 patients who underwent pacemaker placement, 6 (15.8%) had recovery of atrioventricular node function noted on long-term follow-up. Median time from onset of heart block to late atrioventricular node recovery was 13 days (Interquartile range: 5 – 117). Patients with single-ventricle physiology (p = 0.04), greater weight (p = 0.03), and shorter cardiopulmonary bypass time (p = 0.015) were more likely to have recovery. The use of post-operative steroids was similar between all groups (p = 0.445). Infectious or wound complications were similar between pacemaker groups (p = 1). Conclusions: Two per cent of patients who underwent congenital cardiac surgery developed post-operative heart block, and 0.6% underwent pacemaker placement. Early recovery of atrioventricular node was associated with greater weight at the time of surgery, single-ventricle physiology, and shorter cardiopulmonary bypass time. Late recovery of atrioventricular node conduction following pacemaker placement occurred in 15.8% of patients.

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