Spectrum of Fontan-associated liver disease assessed by MRI and US in young adolescents

Fontan-Associated Liver Disease: A Review

Fontan-associated liver disease (FALD) is a chronic complication of the Fontan procedure, a palliative surgery for patients with congenital heart disease that results in a single-ventricle circulation. The success of the Fontan procedure has led to a growing population of post-Fontan patients living well into adulthood. For this population, FALD is a major cause of morbidity and mortality. It encompasses a spectrum of hepatic abnormalities, ranging from mild fibrosis to cirrhosis and hepatocellular carcinoma. The pathophysiology of FALD is multifactorial, involving hemodynamic and inflammatory factors. The diagnosis and monitoring of FALD present many challenges. Conventional noninvasive tests that use liver stiffness as a surrogate marker of fibrosis are unreliable in FALD, where liver stiffness is also a result of congestion due to the Fontan circulation. Even invasive tissue sampling is inconsistent due to the patchy distribution of fibrosis. FALD is also associated with both benign and malignant liver lesions, which may exhibit similar imaging features. There is therefore a need for validated diagnostic and surveillance protocols to address these challenges. The definitive treatment of end-stage FALD is also a subject of controversy. Both isolated heart transplantation and combined heart-liver transplantation have been employed, with the latter becoming increasingly preferred in the US. This article reviews the current literature on the epidemiology, pathophysiology, diagnosis, and management of FALD, and highlights knowledge gaps that require further research.

Imaging of Fontan-Associated Liver Disease

ABSTRACT

The Fontan procedure is the definitive treatment for patients with single-ventricle physiology. Surgical advances have led to a growing number of patients surviving into adulthood. Fontan-associated liver disease (FALD) encompasses a spectrum of pathologic liver changes that occur secondary to altered physiology including congestion, fibrosis, and the development of liver masses. Assessment of FALD is difficult and relies on using imaging alongside of clinical, laboratory, and pathology information. Ultrasound, computed tomography, and magnetic resonance imaging are capable of demonstrating physiologic and hepatic parenchymal abnormalities commonly seen in FALD. Several novel imaging techniques including magnetic resonance elastography are under study for use as biomarkers for FALD progression. Imaging has a central role in detection and characterization of liver masses as benign or malignant. Benign FNH-like masses are commonly encountered; however, these can display atypical features and be mistaken for hepatocellular carcinoma (HCC). Fontan patients are at elevated risk for HCC, which is a feared complication and has a poor prognosis in this population. While imaging screening for HCC is widely advocated, no consensus has been reached regarding an optimal surveillance regimen.

EASL-ERN position paper on liver involvement in patients with Fontan-type circulation

Fontan-type surgery is the final step in the sequential palliative surgical treatment of infants born with a univentricular heart. The resulting long-term haemodynamic changes promote liver damage, leading to Fontan-associated liver disease (FALD), in virtually all patients with Fontan circulation. Owing to the lack of a uniform definition of FALD and the competitive risk of other complications developed by Fontan patients, the impact of FALD on the prognosis of these patients is currently debatable. However, based on the increasing number of adult Fontan patients and recent research interest, the European Association for The Study of the Liver and the European Reference Network on Rare Liver Diseases thought a position paper timely. The aims of the current paper are: (1) to provide a clear definition and description of FALD, including clinical, analytical, radiological, haemodynamic, and histological features; (2) to facilitate guidance for staging the liver disease; and (3) to provide evidence- and experience-based recommendations for the management of different clinical scenarios.

Transient liver elastography in the follow-up of Fontan patients: results of a nation wide survey in Germany

Introduction

Fontan-palliated patients are at risk for the development of Fontan-associated liver disease (FALD). Currently, there is no consensus on how to stage FALD. Transient elastography (TE) is a rapid, non-invasive method to assess FALD and liver fibrosis.

Method

To assess the availability and conditions of using TE to monitor liver disease in Fontan patients in german centers for pediatric cardiology and to propose the introduction of a standardized national protocol for the monitoring of liver disease, we developed a questionnaire.

Results

In total, 95 valid questionnaires were collected. Only 20% of the centers offer the TE investigation directly. Most of the centers transfer the patients to another department or center (40%) or didńt offer TE (40%). In only 2.6% of the centers TE is performed directly by the cardiologist. Most of the centers transfer the patients to a other department. In 29.2% TE is performed only at a certain age of the patients and in 27.7% it is performed if the patients present symptoms of failing Fontan. In only 13.9% of the centers TE is proposed in all the Fontan patients on a routine basis. Most often TE is performed only from the beginning of the adolescence. In the majority of answers it was not known if the patients are fasting for the examination (68%) or not and if the TE examination had to be performed in a specific breathing phase during TE (Inspiration/Expiration, 90%). In the majority, TE is not offered routinely (46.9%).

Discussion

To date in Germany, TE is only used in a few numbers of centers specialized in Fontan follow-up. A standardized protocol to use TE is currently not existing. With regard to the feasibility of the examination, it is evident that TE is a quick, cheap and easy method to distinguish between cases with and without progressive FALD. This makes TE a useful and prognostic tool for screening of liver disease and to failing Fontan circulation.

Conclusion

We propose a systematic TE evaluation of possible liver congestion and fibrosis, as a part of the routine follow-up of Fontan patients.

Assessment of liver fibrosis using a 3-dimensional high-resolution late gadolinium enhancement sequence in children and adolescents with Fontan circulation

OBJECTIVES

To assess abnormal liver enhancement on 15-20 min delayed 3D high-resolution late gadolinium enhancement (3D HR LGE) sequence in patients with Fontan circulation.

METHODS

Retrospective study of pediatric Fontan patients (< 18 years old) with combined cardiac-liver MRI from January 2018 to August 2021. Abnormal hepatic enhancement was graded (0-3) for each lobe, summed for a total liver enhancement score (0-6), and compared to repaired tetralogy of Fallot (rTOF) patients. Correlations with other hepatic imaging biomarkers were performed. Temporal relationships of enhancement compared to traditional early portal venous and 5-7-min delayed phase liver imaging were analyzed.

RESULTS

The Fontan group (n = 35, 13 ± 3.4 years old, median time from Fontan 10 (9-12) years) had 23/35 (66%) with delayed 3D HR LGE total liver enhancement score > 0 (range 0-5), with greater involvement of the right lobe (1 (0-1) vs 0 (0-1), p < 0.01). The rTOF group (n = 35, 14 ± 2.6 years old) had no abnormal enhancement. In the Fontan group, total liver enhancement was 3 (2-4) in the early portal venous phase, lower at 1 (1-2) in the 5-7-min delayed phase (p < 0.01), and lowest at 1 (0-2) in the 15-20-min delayed phase (p = 0.03). 3D HR LGE enhancement correlated inversely with portal vein flow (rs =  - 0.42, p = 0.01) and positively with left lobe stiffness (rs = 0.51, p < 0.01). The enhancement score decreased in 13/35 (37%) between the 5-7- and 15-20-min delayed phases.

CONCLUSIONS

Liver fibrosis can be assessed on 3D HR LGE sequences in patients with Fontan circulation, correlates with other imaging biomarkers of Fontan liver disease, and may add information for hepatic surveillance in this population.

KEY POINTS

• Abnormal liver enhancement on 3D HR LGE sequences in Fontan patients likely represents liver fibrosis and is seen in up to 66% of children and adolescents with variable distribution and severity. • The degree of 3D HR LGE liver enhancement correlates with decreased portal vein flow and increased left hepatic lobe stiffness.

Issues in multi-organ transplantation of the liver with kidney or heart in polycystic liver-kidney disease or congenital heart disease: Current practices and immunological aspects

Solid organ transplantation has become an integral part of the management of patients with end-stage diseases of the kidney, liver, heart and lungs. Most procedures occur in isolation, but multi-organ transplantation of the liver with either the kidney or heart has become an option. As more patients with congenital heart disease and cardiac cirrhosis survive into adulthood, particularly after the Fontan procedure, liver transplant teams are expected to face questions regarding multi-organ (heart-liver) transplantation. Similarly, patients with polycystic kidneys and livers may be managed by multi-organ transplantation. Herein, we review the indications and outcomes of simultaneous liver-kidney transplantation for polycystic liver-kidney disease, and discuss the indications, timing and procedural aspects of combined heart-liver transplantation. We also summarise the evidence for, and potential mechanisms underlying, the immunoprotective impact of liver allografts on the simultaneously transplanted organs.

Fontan-associated liver disease: Diagnosis, surveillance, and management

The Fontan operation is a lifesaving procedure for patients with functional single-ventricle congenital heart disease, where hypoplastic left heart syndrome is the most frequent anomaly. Hemodynamic changes following Fontan circulation creation are now increasingly recognized to cause multiorgan affection, where the development of a chronic liver disease, Fontan-associated liver disease (FALD), is one of the most important morbidities. Virtually, all patients with a Fontan circulation develop liver congestion, resulting in fibrosis and cirrhosis, and most patients experience childhood onset. FALD is a distinctive type of congestive hepatopathy, and its pathogenesis is thought to be a multifactorial process driven by increased nonpulsatile central venous pressure and decreased cardiac output, both of which are inherent in the Fontan circulation. In the advanced stage of liver injury, complications of portal hypertension often occur, and there is a risk of developing secondary liver cancer, reported at young age. However, FALD develops with few clinical symptoms, a surprisingly variable degree of severity in liver disease, and with little relation to poor cardiac function. The disease mechanisms and modifying factors of its development are still not fully understood. As one of the more important noncardiac complications of the Fontan circulation, FALD needs to be diagnosed in a timely manner with a structured monitoring scheme of disease development, early detection of malignancy, and determination of the optimal time point for transplantation. There is also a clear need for consensus on the best surveillance strategy for FALD. In this regard, imaging plays an important role together with clinical scoring systems, biochemical workups, and histology. Patients operated on with a Fontan circulation are generally followed up in cardiology units. Ultimately, the resulting multiorgan affection requires a multidisciplinary team of healthcare personnel to address the different organ complications. This article discusses the current concepts, diagnosis, and management of FALD, with special emphasis on the role of different imaging techniques in the diagnosis and monitoring of disease progression, as well as current recommendations for liver disease surveillance.

Care Pattern for Fontan-Associated Liver Disease by Academic Pediatric Hepatologists in Canada

Fontan-Associated Liver Disease (FALD) is a common extracardiac complication seen in patients following the Fontan procedure. There are no consensus guidelines on screening and management of children with FALD.

Objective

The current study aims to determine academic pediatric hepatologists' practices and identify variability in management provided to children with FALD in Canada.

Methods

Using the infrastructure of the Canadian Pediatric Hepatology Research Group, a nationwide survey was distributed electronically to all pediatric hepatologists practicing in university-affiliated hospitals.

Results

Twelve pediatric hepatologists from 12 of 13 academic centers (92%) responded to the survey. The institutions of only 2 (17%) physicians offer post-Fontan care with a multidisciplinary team, both from different provinces. The screening for other comorbidities, use of noninvasive modality, and timing of liver biopsy for estimation of liver fibrosis and screening for esophageal varices differ from program to program. The frequency of outpatient clinic follow-up varies significantly. Education and counseling concerning liver health are generally used as treatment; only 58% of academic centers have a formal adult care transition plan.

Conclusions

Significant discrepancies exist in the care provided to children with FALD by hepatologists practicing in academic centers across Canada. Future study is needed to develop a standardized protocol for managing and following children and youth with FALD.

Semiquantitative characterization of dynamic magnetic resonance perfusion of the liver in pediatric Fontan patients

BACKGROUND

Dynamic contrast-enhanced magnetic resonance imaging (MRI) of the liver in pediatric Fontan patients often shows peripheral reticular areas of hypoenhancement, which has not been studied in detail.

OBJECTIVE

To semiquantitatively score the hepatic MR perfusion abnormality seen in pediatric Fontan patients, and to correlate the perfusion abnormality with functional clinical and hemodynamic parameters.

MATERIALS AND METHODS

All children (< 18 years old) after Fontan palliation with combined clinical cardiac and liver MRI performed between May 2017 and April 2019 were considered for inclusion. A semiquantitative perfusion score was used to assess the severity of the hepatic reticular pattern seen on dynamic contrast-enhanced liver imaging. The liver was divided into four sections: right posterior, right anterior, left medial and left lateral. Each liver section was assigned a score from 0 to 4 depending on the amount of abnormal reticular hypoenhancement. Scoring was assigned for each section of the liver across eight successive dynamic contrast-enhanced modified spoiled gradient echo runs. Scores were correlated with clinical and hemodynamic parameters.

RESULTS

All Fontan children showed hepatic reticular hypoenhancement by MRI, most severe in the early portal venous phase with a median maximum total perfusion abnormality score of 12 (range: 9-14). All perfusion abnormalities progressively resolved during the hepatic venous phase. Perfusion abnormality scores were greatest in the right compared to left hepatic lobes (7 range: [6-8] vs. 5 [range: 3-6], P < 0.01). The maximum left hepatic lobe perfusion abnormality scores were greatest in children with versus without imaging signs of portal hypertension (8 [range: 7-8] vs. 4 [range: 3-5], P < 0.01). High unconjugated bilirubin and low platelets correlated with greater perfusion abnormality (R = 0.450, P = 0.024, and R =  - 0.458, P < 0.01, respectively). Age at MRI, time from Fontan, focal liver lesions and cardiac MRI hemodynamic parameters did not show significant correlations with the severity of the liver perfusion abnormality.

CONCLUSION

All Fontan children have hepatic reticular hypoenhancement abnormalities seen with MRI that are most severe in the right hepatic lobe and universally show gradual resolution through the hepatic venous phase. Perfusion abnormality in the left hepatic lobe is worse in children with portal hypertension.

Fontan-Associated Liver Disease: Pathophysiology, Staging, and Management

Fontan-associated liver disease is the term used to encompass the disorders arising from abnormal hemodynamic alterations and systemic venous congestion after the Fontan procedure. The histological changes produced in the liver are similar but not equivalent to those seen in other forms of cardiac liver disease. While the natural history of this form of liver disease is poorly established, many Fontan patients ultimately develop portal hypertension-related complications such as ascites, esophageal varices, malnutrition, and encephalopathy. Fontan survivors also show an elevated risk of hepatocellular carcinoma. Adequate staging of the liver damage is essential to anticipate screening strategies and improve global management.