Hepatic Changes in the Fontan Circulation: Identification of Liver Dysfunction and an Attempt to Streamline Follow-up Screening

Long-Term Renal Involvement in Association with Fontan Circulation

Multiorgan dysfunction is a concern of Fontan patients. To clarify the pathophysiology of Fontan nephropathy, we characterize renal disease in the long-term observational study. Medical records of 128 consecutive Fontan patients [median age: 22 (range 15-37) years old] treated between 2009 and 2018 were reviewed to investigate the incidence of nephropathy and its association with other clinical variables. Thirty-seven patients (29%) showed proteinuria (n = 34) or < 90 mL/min/1.73 m2 of estimated glomerular filtration rate (eGFR) (n = 7), including 4 overlapping cases. Ninety-six patients (75%) had liver dysfunction (Forns index > 4.21). Patients with proteinuria received the Fontan procedure at an older age [78 (26-194) vs. 56 (8-292) months old, p = 0.02] and had a higher cardiac index [3.11 (1.49-6.35) vs. 2.71 (1.40-4.95) L/min/m2, p = 0.02], central venous pressure [12 (7-19) vs. 9 (5-19) mmHg, p < 0.001], and proportion with > 4.21 of Forns index (88% vs. 70%, p = 0.04) than those without proteinuria. The mean renal perfusion pressure was lower in patients with a reduced eGFR than those without it [55 (44-65) vs. 65 (45-102) mmHg, p = 0.03], but no other variables differed significantly. A multivariable analysis revealed that proteinuria was associated with an increased cardiac index (unit odds ratio 2.02, 95% confidence interval 1.12-3.65, p = 0.02). Seven patients with severe proteinuria had a lower oxygen saturation than those with no or mild proteinuria (p = 0.01, 0.03). Proteinuria or a decreased eGFR differentially occurred in approximately 30% of Fontan patients. Suboptimal Fontan circulation may contribute to the development of proteinuria and reduced eGFR.

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.

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.

T1 mapping of the myocardium and liver in the single ventricle population

BACKGROUND

Fontan associated liver disease (FALD) is an increasingly recognized complication of the single ventricle circulation characterized by hepatic venous congestion leading to hepatic fibrosis. Within the Fontan myocardium, fibrotic myocardial remodeling may occur and lead to ventricular dysfunction. Magnetic resonance imaging (MRI) T1 mapping can characterize both myocardial and liver properties.

OBJECTIVE

The aim of this study was to compare myocardial and liver T1 between single ventricle patients with and without a Fontan and biventricular controls.

MATERIALS AND METHODS

A retrospective study of 3 groups of patients: 16 single ventricle patients before Fontan (SV_pre 2 newborns, 9 pre-Glenn, 5 pre-Fontan, 31% single right ventricle [SRV]), 16 Fontans (56% SRV) and 10 repaired d-transposition of the great arteries (TGA). Native modified Look-Locker inversion T1 times were measured in the myocardium and liver. Cardiac MRI parameters, myocardial and liver T1 values were compared in the three groups. Correlations were assessed between liver T1 and cardiac parameters.

RESULTS

Myocardial T1 was higher in SV_pre (1,056 ± 48 ms) and Fontans (1,047 ± 41 ms) compared to TGA (1,012 ± 48 ms, P < 0.05). Increased liver T1 was found in both SV_pre (683 ± 82 ms) and Fontan (727 ± 49 ms) patients compared to TGA patients (587 ± 58 ms, P < 0.001). There was no difference between single left ventricle (SLV) versus SRV myocardial or liver T1. Liver T1 showed moderate correlations with myocardial T1 (r = 0.48, confidence interval [CI] 0.26-0.72) and ejection fraction (r = -0.36, CI -0.66-0.95) but not with other volumetric parameters.

CONCLUSION

Increased liver T1 at both pre- and post-Fontan stages suggests there are intrinsic liver abnormalities early in the course of single ventricle palliation. Increased myocardial T1 and its relationship to liver T1 suggest a combination of edema from passive venous congestion and/or myocardial fibrosis occurring in this population. Liver T1 may provide an earlier marker of liver disease warranting further study.

Non-invasive assessment of liver abnormalities in pediatric Fontan patients

Liver abnormalities are well known among long-term survivors of Fontan palliation, which remains the definite surgery for complex congenital heart disease and single ventricle physiology. Pediatric data however are scarce. We assessed the prevalence and degree of liver abnormalities in pediatric Fontan patients through non-invasive investigations suitable for longitudinal follow-up. Thirty-five patients with a median age of 11.8 years (5.2-16.6) and median time since Fontan of 6 years (1.17-13.83) were studied. Each child underwent a blood test, liver Doppler ultrasound (US), and transient elastography (TE). Healthy children were used as controls for TE measurement. AST, ALT, γGT, and direct bilirubin were abnormal in respectively 12 (34%), 5 (14%), 24 (69%), and 7 (20%) patients, while platelet count was decreased in 7 (20%). Splenomegaly was present in 7 (20%) patients. Portal vein mean flow velocity was < 15 cm/s in 19 (54%) patients indicative of portal hypertension. Twenty-two patients (63%) showed inferior vena cava collapsibility index values below 17%, indicating venous congestion. Hepatic artery and superior mesenteric artery resistance index were inversely correlated with time post Fontan (p < 0.05). TE values in Fontan patients were significantly higher than controls, with a median of 12.6 versus 4.6 kPa (p < 0.001) and were already increased shortly after Fontan completion. Conclusion: Liver abnormalities are frequently observed in pediatric Fontan patients. The non-invasive investigations used were not able to confirm liver fibrosis or differentiate hepatic congestion from fibrosis. Based on our findings, we propose a prospective screening protocol with serial measurements of laboratory, (Doppler) US, and TE parameters. What is Known: • Hepatic dysfunction is a well-known consequence of the Fontan circulation. • The natural history of Fontan-associated liver disease in the pediatric age group remains unclear. What is New: • Liver abnormalities are frequently observed in pediatric Fontan patients; however, differentiating liver fibrosis and hepatic congestion with non-invasive investigations remains challenging. Sonographic Doppler measurements may improve our insight in both Fontan-associated liver disease development and the functioning of the Fontan circulation. • A prospective screening protocol is proposed to improve our ability to detect Fontan-associated liver disease early on and understand its natural history.

Fontan-associated liver disease

OBJECTIVE

To review the pathophysiology of Fontan-associated liver disease, its histologic changes, and its radiologic manifestations.

CONCLUSIONS

Fontan-associated liver disease is the result of a set of structural and functional changes in the liver that occur secondary to hemodynamic changes brought about by Fontan surgery. The radiologic manifestations of Fontan-associated liver disease consist of changes in the size and shape of the liver, alterations in the signal intensity or pattern of enhancement, abnormalities in the vascular structures, and focal lesions, which include benign nodules with intense uptake in the arterial phase and hepatocellular carcinoma. Radiologists need to be familiar with this disease and its complications, because the number of patients who undergo Fontan surgery continues to increase, and these patients undergo an increasing number of imaging tests.

Quantification of Hepatic and Splenic Stiffness After Fontan Procedure in Children and Clinical Implications

We aimed to investigate Fontan associated liver disease in children by shear wave elastography (SWE). This is a single-center, prospective case-control study included 41 patients with Fontan physiology and 30 healthy controls. Hepatic and splenic shear wave elasticity values were exhibited both as kPa and m/s. The mean hepatic SWE values of Fontan patients (n = 41; 15.8 ± 3.2 kPa or 2.5 ± 1.8 m/s) were significantly higher than the control group (n = 30; 5.59 ± 0.6 kPa or 1.37 ± 0.07 m/s) (P < 0.001). The mean splenic SWE values of Fontan patients were (25.6 ± 4.61 kPa or 2.85 ± 0.22 m/s) significantly higher than the control group (15.9 ± 1.44 kPa or 2.29 ± 0.1 m/s) (P < 0.001). There were statistically significant positive correlations among the follow-up duration after the Fontan procedure with NT-proBNP (P = 0.008, r = 1) and prothrombin time (P = 0.009, r = 0.4) as well as the hepatic SWE values with alanine aminotransferase (P = 0.039, r = 0.32), gamma-glutamyl transferase (P = 0.045, r = 0.31), and PT (P = 0.011, r = 0.39). There has been statistically significant moderate positive correlations of splenic stiffness values with PT (P = 0.047, r = 0.34), and INR (P = 0.038, r = 0.35). The sensitivity and specificity of liver stiffness cutoff value as 11.1 kPa for detection of Fontan associated liver disease were 95% and 100%, respectively. The hepatic and splenic stiffness increase independently in Fontan patients due to parenchymal disease. Hepatic SWE is a reliable and noninvasive predictor of early hepatic alterations that could not be detected only by biochemical results or routine ultrasound examinations.

Hepatic and splenic sonographic and sonoelastographic findings in pulmonary arterial hypertension

Purpose

The aim of this study was to evaluate the associations of sonographic and sonoelastographic parameters with clinical cardiac parameters, as well as to assess their value in predicting survival in patients with pulmonary arterial hypertension (PAH).

Methods

Thirty-six patients with PAH and normal liver function were prospectively enrolled in this prospective study along with 26 healthy controls, all of whom underwent ultrasound and point shear wave elastography examinations. Additionally, the portal vein pulsatility index (PVPI), inferior vena cava collapsibility index, and clinical cardiac variables were obtained in PAH patients. The values of hepatic (LV_s) and splenic shear wave velocity (SV_s) were compared between PAH patients and controls. The relationships between all sonographic and clinical parameters in the PAH patients were analyzed. Furthermore, their prognostic value in predicting survival was investigated.

Results

LV_s values in PAH patients (median, 1.62 m/s) were significantly higher than in controls (median, 0.99 m/s), while no significant difference was observed in SV_s values. Patients with higher grades of tricuspid regurgitation (TR) had significantly different values of PVPI (P=0.010) and sonoelastographic parameters (P<0.001 for LV_s and P=0.004 for SV_s) compared to those with less severe TR. Tricuspid annular plane systolic excursion values were the only investigated parameter found to be associated with survival (hazard ratio, 0.814; 95% confidence interval, 0.694 to 0.954; P=0.011).

Conclusion

Our results demonstrated a direct association between cardiac congestion (i.e., the severity of TR) and liver stiffness, which should be kept in mind during the assessment of fibrosis in patients with PAH.

Portal vein thrombosis in Fontan-associated liver disease

A 25-year-old patient with signs of cirrhosis on ultrasound and CT presented with portal vein thrombosis on routine follow-up examinations; retrograde hepatic wedge angiography demonstrated only the right-sided portal vein branch. Development of a portosystemic collateral vessel to the left-sided renal vein prevented signs of hypersplenism. This unique complication of portal vein thrombosis should be considered during long-term surveillance.

Relation of Magnetic Resonance Elastography to Fontan Failure and Portal Hypertension

Fontan associated liver disease is associated with morbidity and mortality in palliated single-ventricle congenital heart disease patients. Magnetic resonance elastography (MRE) provides a quantitative assessment of liver stiffness in Fontan patients. We hypothesized that MRE liver stiffness correlates with liver enzymes, hemodynamics, portal hypertension, and Fontan failure (FF). All adult Fontan patients who had MRE between 2011 and 2018 were included. Radiologic portal hypertension was defined as splenomegaly, ascites, and/or varices. FF was defined as death, transplantation, or heart failure symptoms requiring escalation of diuretics. Seventy patients with a median age of 24.7 years and a median follow-up from MRE of 3.9 years were included. The median liver stiffness was 4.3 kPa (interquartile range [IQR]: 3.8 to 5.0 kPa). There was a weak, positive correlation between liver stiffness and Fontan pathway pressure (r = 0.34, p = 0.03). There was a moderate negative correlation of liver stiffness with ventricular ejection fraction (r = -0.52, p = 0.03). Liver stiffness was weakly positively correlated with liver transaminases and gamma glutamyl transferase. Patients with portal hypertension had higher liver stiffness compared to patients without (5.2 ± 1.3 vs 4.2 ± 0.8 kPa, p = 0.03). At MRE or during follow-up, 13 patients (19%) met definition of FF and had significantly higher liver stiffness compared to patients without FF (5.1 [IQR: 4.3 to 6.3] vs 4.2 [IQR: 3.7 to 4.7] kPa, p = 0.01). Liver stiffness above 4.5 kPa differentiated FF with a sensitivity of 77% and specificity of 77%. In conclusion, elevated MRE-derived liver stiffness is associated with worse hemodynamics, liver enzymes and clinical outcomes in Fontan patients. This measure may serve as a global imaging biomarker of Fontan health.

Liver disease secondary to congenital heart disease in children

Introduction: Hepatic fibrosis and hepatocellular carcinoma (HCC) can develop in children with congenital heart disease. Although hepatic fibrosis and HCC are prone to develop after the Fontan operation, they can also develop in patients suffering from congenital heart disease who have not undergone Fontan operation. Area covered: The history of cardiac hepatopathy including Fontan-associated liver disease is described. Patient characteristics, liver histology, imaging examinations and blood tests are reviewed to elucidate the mechanism of cardiac hepatopathy. In addition, a flowchart for the follow-up management of cardiac hepatopathy in children with congenital heart disease is proposed. Expert opinion: Congestion and low cardiac output are the main causes of cardiac hepatopathy. Advanced hepatic fibrosis is presumed to be associated with HCC. HCC can develop in both adolescents and young adults. Regardless of whether the Fontan operation is performed, children with a functional single ventricle and chronic heart failure should be regularly examined for cardiac hepatopathy. There is no single reliable laboratory parameter to accurately detect cardiac hepatopathy; hepatic fibrosis indices and elastography have shown inconsistent results for detection of this disease. Further studies using liver specimen-confirmed patients and standardization of evaluation protocols are required to clarify the pathogenesis of cardiac hepatopathy.