In the majority of patients JET can be safely ablated with the use of cryotherapy. Foci not identified in the lower 2/3 of the TOK are associated with longer procedures, more lesions, and decreased chance for long-term success.

Background:The biochemical mechanisms underlying ␣-smooth muscle actin-mediated vascular disease are unknown. Results: The R256H mutation in actin alters polymerization kinetics and causes misregulation by the nucleation factor, formin. Conclusion: Mutation-based changes in conformation affect filament stability and regulation of polymerization. Significance: The Arg-256 residue stabilizes the actin helix and maintains filament conformation required for formin regulation.

Twenty-two missense mutations in ACTA2, which encodes ␣-smooth muscle actin, have been identified to cause thoracic aortic aneurysm and dissection. Limited access to diseased tissue, the presence of multiple unresolvable actin isoforms in the cell, and lack of an animal model have prevented analysis of the biochemical mechanisms underlying this pathology. We have utilized actin from the yeast Saccharomyces cerevisiae, 86% identical to human ␣-smooth muscle actin, as a model. Two of the known human mutations, N115T and R116Q, were engineered into yeast actin, and their effect on actin function in vivo and in vitro was investigated. Both mutants exhibited reduced ability to grow under a variety of stress conditions, which hampered N115T cells more than R116Q cells. Both strains exhibited abnormal mitochondrial morphology indicative of a faulty actin cytoskeleton. In vitro, the mutant actins exhibited altered thermostability and nucleotide exchange rates, indicating effects of the mutations on monomer conformation, with R116Q the most severely affected. N115T demonstrated a biphasic elongation phase during polymerization, whereas R116Q demonstrated a markedly extended nucleation phase. Allele-specific effects were also seen on critical concentration, rate of depolymerization, and filament treadmilling. R116Q filaments were hypersensitive to severing by the actinbinding protein cofilin. In contrast, N115T filaments were hyposensitive to cofilin despite nearly normal binding affinities of actin for cofilin. The mutant-specific effects on actin behavior suggest that individual mechanisms may contribute to thoracic aortic aneurysm and dissection.

Introduction: Congenital heart disease (CHD) is multifactorial in origin, resulting from an interaction between environmental and genetic factors. Multifactorial growth delay is common in infants with CHD. The impact of a genetic abnormality and CHD on the growth of an infant is lacking in the literature. The aim of this study is to compare the growth and method of feeding following neonatal cardiac surgery in infants with normal versus abnormal genetic testing. Methods: A retrospective chart review of neonates who underwent a Risk Adjustment in Congenital Heart Surgery IV–VI procedure between 1 January, 2006 and 22 September, 2016 was performed at our institution. Weight, length, head circumference measurements, and feeding method were collected at birth, time of neonatal surgery, and monthly up to 6 months of age. Results: A total of 53 infants met inclusion criteria, of which 22 had abnormal genetic testing. Approximately 90% of infants were discharged following neonatal cardiac surgery with supplemental tube feeds. At each monthly follow-up visit, more infants were exclusively fed orally: 80% of infants with normal genetics at 5 months post-operative follow-up versus 60% of infants with abnormal genetic testing, although statistically insignificant. Growth was not different among the two groups. Conclusions: Infants with critical CHD with or without genetic abnormalities are at risk for growth delays and many need supplemental tube feeds post-operatively and throughout follow-up. Infants with genetic abnormalities are slower to achieve oral feeds and more likely to require tube feedings. It is important to have a systematic protocol for managing these high-risk infants.

Introduction: The prevalence of attention deficit/hyperactivity disorder in the general population is common and is now diagnosed in 4%–12% of children. Children with CHD have been shown to be at increased risk for attention deficit/hyperactivity disorder. Case reports have led to concern regarding the use of attention deficit/hyperactivity disorder medications in children with underlying CHD. We hypothesised that medical therapy for patients with CHD and attention deficit/hyperactivity disorder is safe. Methods: A single-centre, retrospective chart review was performed evaluating for adverse events in patients aged 4–21 years with CHD who received attention deficit/hyperactivity disorder therapy over a 5-year span. Inclusion criteria were a diagnosis of CHD and concomitant medical therapy with amphetamines, methylphenidate, or atomoxetine. Patients with trivial or spontaneously resolved CHD were excluded from analysis. Results: In 831 patients with CHD who received stimulants with a mean age of 12.9 years, there was only one adverse cardiovascular event identified. Using sensitivity analysis, our median follow-up time was 686 days and a prevalence rate of 0.21% of adverse events. This episode consisted of increased frequency of supraventricular tachycardia in a patient who had this condition prior to initiation of medical therapy; the condition improved with discontinuation of attention deficit/hyperactivity disorder therapy. Conclusion: The incidence of significant adverse cardiovascular events in our population was similar to the prevalence of supraventricular tachycardia in the general population. Our single-centre experience demonstrated no increased risk in adverse events related to medical therapy for children with attention deficit/hyperactivity disorder and underlying CHD. Further population-based studies are indicated to validate these findings.