Paediatrics (RCH) - Theses

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    End-organ consequences of the Fontan circulation
    Wilson, Thomas Gregory ( 2022)
    The Fontan procedure is the last in a series of staged surgical procedures offered to children born with complex congenital heart disease in whom a two-ventricle repair is not feasible. Since its first description, the Fontan procedure has undergone a number of technical modifications which have further improved survival and reduced associated morbidity. Due to improved survival, the number of people living with a Fontan circulation is growing, and the average age is increasing. However, with more patients surviving into adulthood we are unfortunately seeing that many will develop complications. Ventricular dysfunction, circulatory failure, atrioventricular valve (AVV) regurgitation, cardiac arrhythmias, protein-losing enteropathy, plastic bronchitis and thromboembolic phenomena have all been increasingly recognized as potential complications after the Fontan operation. Hepatic fibrosis, cirrhosis and hepatocellular carcinoma have also been described, as well as renal dysfunction in the form of reduced glomerular filtration rate (GFR) and microalbuminuria. The aim of this thesis was to (i) characterize the prevalence and severity of hepatic and renal complications in patients with a Fontan circulation, (ii) identify potential risk factors that may contribute to the development of hepatic and renal complications after the Fontan procedure, and (iii) inform screening practices for end-organ complications in these patients. In this thesis I have demonstrated that: (i) the majority of patients with a Fontan circulation have non-invasive evidence of liver fibrosis by early adulthood, (ii) a smaller but significant proportion of patients will be diagnosed with liver cirrhosis by early adulthood, (iii) a minority of patients will develop hepatocellular carcinoma, which may occur in adolescence or early adulthood, (iv) history of cardiac arrhythmia or AVV failure is associated with an increased risk of advanced liver disease, (v) mild renal dysfunction is common in patients with a Fontan circulation, however, does not appear to negatively impact mid-term outcomes, (vi) creatinine based estimated GFR should be interpreted with caution in children with a Fontan circulation, and tends to over-estimate true or measured GFR in children and adults with a Fontan circulation, (vii) many of the patients who were found to have hepatic or renal dysfunction were identified on routine screening. This thesis has drawn attention to the significant proportion of patients with a Fontan circulation who will develop hepatic or renal dysfunction during long-term follow-up. These findings encourage us to consider the implications of end-organ dysfunction on the medical management of a population that is growing in numbers and age. This work emphasizes the importance of routine surveillance in identifying those with significant liver and kidney dysfunction after the Fontan procedure, and identifies a number of potentially modifiable risk factors for more advanced disease. In the absence of any proven pharmacological treatment for these complications, it is likely that optimisation of the Fontan circulation itself in combination with the avoidance of secondary end-organ insults will be the key to minimising the burden of hepatic and renal disease in this population.
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    Rapid acute care genomics: Challenges and opportunities
    Lynch, Fiona Jacqueline ( 2021)
    Genomic technologies are showing great promise in the neonatal and paediatric acute care setting, with rapid genomic sequencing (rGS) facilitating results delivery within days. The use of rGS presents both novel genetic counselling issues and a unique impact on families. Although there is substantial enthusiasm surrounding this new application of genomics, it is important that implementation remains evidence-based and patient-centred. This research therefore aimed to understand current practice and perspectives in this setting as technology progresses. Qualitative, semi-structured interviews were conducted with 30 parents whose children had rGS in acute care, and 16 genetic counsellors (GCs) and four intensivists working in this setting. Interviews were audio-recorded, transcribed and analysed using a combination of content and thematic analysis. GCs identified practical challenges of counselling within a rapid turnaround time, including the lack of preparation time, less time to see families, and challenges of practicing outside of the traditional ‘9 to 5’ workday of genetic health professionals. However, they also saw similarities with genetic counselling in other contexts (such as the prenatal setting and the introduction of previous technologies). GCs also described the challenges of multidisciplinary teamwork in this setting, highlighting a need for education and training of other acute care health professionals and the role GCs may play in this. While some parents had a range of concerns and described deliberating about their decision, others readily consented to rGS and were resistant to pre-test counselling. Participants felt they were lucky to be offered special access to exciting, expensive and cutting-edge research, and valued the rapidity of the test, irrespective of the diagnostic outcome. However, factors putting pressure on parents to consent were evident in their descriptions of decision making for rGS. Interviews with intensivists and follow-up interviews with GCs who had greater experience in the delivery of rGS revealed the evolution of multidisciplinary practice in acute care. While there were initial challenges, both disciplines appeared to be benefiting from interdisciplinary learning, facilitating the movement towards truly integrated practice. Intensivists and GCs were working together to support parents’ informed decision making about rGS. Irrespective of the outcome of rGS, participants reported that families need post-test support for a variety of reasons. This study demonstrated maturation in the delivery of rGS over recent years and provided insight into the future delivery of genomic medicine in acute care. Practices reported around decision making are still putting pressure on parents to consent to rGS. Finally, a wider range of post-test needs were reported by health professionals compared to families undergoing rGS, making all perspectives essential for informing service delivery. While interviews revealed unique considerations for the delivery of rGS in acute care, there are existing areas of practice, theories and skills that can be drawn on to inform practice in this setting. The use of genomic technologies will continue to increase over time, therefore patient-centred care for families undergoing rGS will require ongoing investigation into their experiences and the changes in practice.