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.