73 Longer-Term Outcomes and Management for Patients With a Functionally Univentricular Heart
Fontan-Associated Liver Disease
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as demonstrated by their lower serum creatinine concentration compared with age-matched controls Nevertheless, elevated serum creatinine is a strong predictor of death or cardiac transplantation, whether as an independent variable or as part of the Model for End-stage Liver Disease Excluding INR (MELD-XI) score.154 The decline in renal function is insidious and protracted but is likely to play an important role in the prognostication of late survivors Fontan-Associated Liver Disease As survival rates following staged reconstruction have improved, many patients are currently living into their third and fourth decade The long-term consequences of elevated CVP and low cardiac output have become more apparent.89,153,155–160 Although the Fontan circulation affects many organ systems outside the heart, its impact on the liver may be the most prevalent complication Despite this, understanding of the evolution of liver injury is limited, and the role of various screening tests is only now evolving as new information becomes available.148,158,161–164 For children with single-ventricle physiology, the insult to the liver probably begins well before the creation of the Fontan circulation (Fig 73.19) Shortly after birth, infants with functionally univentricular heart disease are subject to one or more surgeries and associated alterations in hemodynamics and oxygen saturations These derangements may have a profound impact on the architecture of the liver as hepatocytes are subjected to impaired perfusion and hypoxemia In a series of children who did not survive beyond the Fontan circulation, autopsy demonstrated the consistent finding of fibrosis, confirming the notion that liver injury begins prior to the Fontan.165 FIG 73.19 Factors contributing to, and consequence of, liver injury in the Fontan patient Although liver injury may not start with the Fontan operation, it is clear that additional changes to the hepatic environment are relatively immediate following Fontan completion In a study in which an abdominal ultrasound was performed just prior to the Fontan and then repeated 3 to 6 months following total cavopulmonary connection, the liver span was increased and velocities within the hepatic arteries were decreased after the Fontan procedure.162 This finding is consistent with hepatic congestion and, when coupled with a mild elevation in liver enzymes, suggests that congestion is immediate and likely begins a process of chronic low-level liver injury Hepatic congestion and the resultant fibrosis are not a static process but rather one that progresses slowly over time In a study of adolescents with Fontan physiology, the only confirmed risk factor for the degree of fibrosis was the amount of time that had passed since the initial Fontan operation.158 Although the sample size was relatively small, ventricular morphology, atrioventricular valve regurgitation, and ventricular function were not associated with the degree of liver fibrosis Interestingly, systemic venous pressure was not associated with the degree of fibrosis This may have been related to the relatively narrow range of Fontan pressures of the patients included in the analysis In another recent