Cardiovascular and abdominal flow alterations in adults with morphologic evidence of liver disease post Fontan palliation

Highlights

• Magnetic resonance imaging (MRI) can quantify abdominal flows using phase contrast (PC) imaging.

• Fontan patients with morphologic liver disease have decreased hepatic and intestinal flows on PC MRI.

• Adverse cardiovascular events were not increased in Fontan patients with liver disease on MRI.

Abstract

Background

Although morphologic abnormalities in the liver are commonly encountered post Fontan palliation, the relationships between hepatic morphology, vascular flows, and clinical status remain incompletely understood. We therefore aimed to explore flow characteristics in hepatic and intestinal vessels and to examine cardiovascular associations with liver disease.

Methods

This was a retrospective study of adults post Fontan palliation undergoing clinically indicated cardiovascular magnetic resonance imaging (MRI). Patients were included if MRI flow quantification was available for cardiac, hepatic and intestinal vessels; patients were excluded if phase-contrast flow imaging was insufficient for analysis.

Results

Thirty patients were studied (median age at MRI 28.5 years [range 19–47]). Eighteen subjects (60%) were classified as having morphologic liver disease according to validated criteria based on available MRI imaging. Abdominal and cardiovascular flows were quantified. Patients with morphologic liver disease had a 41% reduction in superior mesenteric artery (211 ± 124 versus 358 ± 181 mL/min/m², p = .004), a 36% reduction in hepatic vein (496 ± 247 versus 778 ± 220 mL/min/m², p = .01), a 31% reduction in portal vein (399 ± 133 versus 580 ± 159 mL/min/m², p = .004), and an 18% reduction in Fontan pathway flows (1358 ± 429 versus 1651 ± 270 mL/min/m², p = .04) compared with the remaining population. Adverse cardiovascular events were not associated with morphologic liver disease.

Conclusion

Morphologic liver disease appears to be associated with flow alterations within the heart, liver and intestine post Fontan palliation. These novel observations suggest that a potential relationship exists between morphologic disease and vascular flows thereby providing further insights into the pathophysiology of liver disease in this high-risk population.

Introduction

Creation of a Fontan circulation is the typical surgical strategy used for management of patients born with univentricular physiology. Irrespective of underlying cardiac anatomy or type of Fontan connection, ubiquitous alterations in hemodynamics are observed which include chronically elevated systemic venous pressures and decreased cardiac output; these adaptive changes can result in deleterious effects on a myriad of organs [1]. Fibrotic change in the liver has been described during childhood, even before Fontan completion [2,3]. Chronic hepatic congestion can translate into morphologic changes, including generalized fibrosis and cirrhotic remodeling, which may in turn result in increased risk of hepatocellular carcinoma (HCC), an increasingly recognized and potentially lethal late outcome in the Fontan population [4,5]. While routine biochemical monitoring is recommended in adults with a Fontan circulation, it has been recognized that synthetic function is typically preserved, irrespective of the presence of underlying fibrosis or even progressive liver disease [4]. Although liver biopsy remains the gold standard for the diagnosis of liver cirrhosis, it is an invasive procedure with inherent risk of associated complications, therefore its application within the Fontan population is typically reserved for circumstances where liver staging will have direct implications for clinical management, such as those with evidence of liver disease who are exploring candidacy for transplantation or if HCC becomes evident [6].

Non-invasive imaging modalities are consequently assuming increasing importance for evaluation of liver disease in adults with congenital heart disease. Multi-modality imaging may contribute to the characterization of Fontan associated liver disease (FALD) through identification of morphologic disease, which may be associated with early cirrhosis, as well as quantification of liver stiffness, which may be seen in the context of chronic hepatic congestion or increased fibrosis. However, available techniques do not accurately represent the extent of disease at the histologic level [[7], [8], [9], [10]]. Shortcomings of current non-invasive approaches highlight the pressing need for identification of alternative strategies for liver evaluation. Incomplete understanding of the pathophysiology of hepatic disease post Fontan palliation has limited the efficacy of surveillance testing in this high-risk population. The aims of the current study were therefore to characterize: (i) morphologic changes in the liver during clinical cardiovascular magnetic resonance imaging studies (MRI); (ii) cardiovascular and abdominal flows using phase-contrast (PC) velocity mapping during MRI and examine the relationship between flows and morphologic liver disease; and (iii) relationships between morphologic changes in the liver and adverse cardiovascular events in adults with a Fontan circulation.