Fontan venovenous collaterals and hepatic fibrosis

Alterations in Liver Perfusion in Adults With Fontan Circulation as Assessed by Dual Cholate Clearance

BACKGROUND

Fontan circulation (FC) in complex congenital heart disease is characterized by altered hemodynamics and associated with Fontan-associated liver disease. Patients with FC may exhibit abnormalities in cholate clearance due to abnormal perfusion. We aimed to compare cholate clearance in adults with FC to healthy controls and explore associations between cholate clearance and clinical features.

METHODS AND RESULTS

This is a prospective cohort study of patients with FC ≥18 years of age between 2019 and 2022. Systemic and portal hepatic clearance of cholate was assessed using a dual cholate clearance assay (HepQuant Shunt), measuring systemic and portal hepatic filtration rates (HFRs). Systemic HFR/portal HFR ratio (SHUNT%) was calculated. Participants with FC and healthy controls were compared using the Fisher exact test and Wilcoxon test. Univariable regression and multivariable analyses determined associations with clinical variables. There were 35 participants with FC (54% women; median age 29.0 years [interquartile range, 24.0-36.0], 91% White) and 26 controls. In addition to lower platelet counts and higher aspartate aminotransferase to platelet ratio index, and Fibrosis-4 indices, FC participants had lower systemic HFR and portal HFR. SHUNT% was comparable with controls but ranged from 8% to 76%, with 8 (23%) having SHUNT% >30%. In those with FC, increase in SHUNT% was associated with elevated Fontan pressure, higher aortopulmonary collateral flow, decreased oxygen saturation, elevated NT-proBNP (N-terminal pro-B-type natriuretic peptide) levels, thrombocytopenia, and Fibrosis-4 ≥1.45.

CONCLUSIONS

Cholate clearance, as defined by systemic and portal HFR, is impaired in those with FC. Features of worse Fontan physiology correlate with higher SHUNT%, supporting the hypothesis that hemodynamic derangements play a role in progression of Fontan-associated liver disease.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT03726229.

Transcatheter occlusion of venovenous collaterals in the total cavopulmonary Fontan circulation

BACKGROUND

Venovenous collaterals are abnormal connections between the systemic and pulmonary venous systems. They are commonly seen in the Fontan circulation and may lead to significant hypoxaemia. Transcatheter closure of venovenous collaterals is a potential but controversial treatment as the long-term benefits and outcomes are not well understood.

METHODS

This retrospective cohort study utilised data from the Australian and New Zealand Fontan Registry. Patients who underwent transcatheter venovenous collateral occlusion for hypoxemia from the year 2000 onwards were included. Atriopulmonary and Kawashima-type Fontan circulations were excluded to reflect a more contemporary Fontan cohort.

RESULTS

Nineteen patients (age 19.3 ± 7.8 years, 53% female) underwent transcatheter venovenous collateral occlusion. Compared to baseline, mean oxygen saturation was improved at latest follow-up (90.5% vs 87.0%; p = 0.003). Nine patients achieved a clinically significant response (defined as an increase of at least 5% to 90% or greater), and this was associated with lower baseline Fontan pressures (12.9 v 15.6 mmHg; p = 0.02). No heart failure hospitalisations, arrhythmia, transplant referrals, or mortality were observed during the median follow-up period of 4 years. Two patients experienced thromboembolic events and five patients underwent re-intervention.

CONCLUSION

Transcatheter occlusion of venovenous collaterals in Fontan patients with chronic hypoxaemia resulted in a modest increase in oxygenation over a median follow-up of 4 years and longer-term prognosis did not appear to be adversely affected. Lower Fontan pressures at baseline were associated with a greater improvement in oxygenation.

Transcatheter Interventions in Adult Congenital Heart Disease

Congenital heart disease (CHD) is the most common congenital birth defect with an incidence of 1 in 100. Current survival to adulthood is expected in 9 out of 10 children with severe CHD as the diagnostic, interventional, and surgical success improves. The adult CHD (ACHD) population is increasingly diverse, reflecting the broad spectrum of CHD and evolution of surgical techniques to improve survival. Similarly, transcatheter interventions have seen exponential growth and creativity to reduce the need for repeat sternotomies. This article focuses on newer data and evolving techniques for transcatheter interventions specific to certain ACHD populations.

Percutaneous closure of veno-venous collaterals in adult patients with univentricular physiology after Fontan palliation: Single centre experience and systematic review

Background

The Fontan operation resulted in improved survival of patients with congenital heart defects not equipped to sustain biventricular circulation. Long-term complications are common, such as veno-venous collaterals (VVC). The aim of this study was to evaluate patient characteristics, percutaneous treatment strategy and (short-term) outcomes in adult Fontan patients with VVC, and review literature to date.

Methods

In this single-centre retrospective observational cohort study, patients who underwent percutaneous VVC closure between 2017 and 2023 were identified.

Results

Thirteen patients underwent percutaneous VVC closure (77 % female, age at intervention 24 ± 4 years, 77 % systemic left ventricle, 77 % extracardiac tunnel, median conduit size 16 [16-20]mm). Indications for closure were symptoms and/or significant exercise-related hypoxia. Mean Fontan pressure was 10±4 mmHg. The VVC originated from tributaries of the vena cava superior (VCS) and connected to pulmonary veins (8 VVC, 32 %), VCS to systemic atrium (3 VVC, 12 %), VCS to coronary sinus (3 VVC, 12 %) and tributaries of vena cava inferior to pulmonary veins (11 VVC, 44 %). Twenty-three VVC were occluded using coils and/or plugs. No periprocedural complications occurred. At first follow-up at least 6 months after closure (n = 11), 9 patients (82 %) reported symptom reduction. Saturation at rest and peak exercise increased significantly (96 ± 3 to 98 ± 1 %, p = 0.040; 89 ± 3 to 93 ± 5 %, p = 0.024, respectively). Exercise capacity remained unchanged.

Conclusions

VVC typically connect the tributaries of the vena cava inferior and/or superior with the pulmonary veins. Low Fontan pressures do not exclude the presence of VVC. Percutaneous closure of VVC is technically feasible, safe, and associated with symptom reduction and a significant rise in resting and exercise oxygen saturation.

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.

Hepatic Fibrosis Risk Factors in Extracardiac-Fontan Patients: Observations From a Single Center

Objective: We reviewed our experience with transvenous liver biopsy-derived hepatic fibrosis scores and possible associated risk factors in those postextracardiac Fontan patients. Methods: We identified extracardiac-Fontan patients with postoperative durations <20 years who underwent cardiac catheterizations with transvenous hepatic biopsies between April 2012 and July 2022. If a patient underwent two liver biopsies, we averaged the two total fibrosis scores and concurrent time, pressure, and oxygen saturation data. We grouped patients by the following factors: (1) sex, (2) venovenous collaterals, and (3) type of functionally univentricular heart. We identified potential hepatic fibrosis risk factors as the following: female, presence of venovenous collaterals, and a functional univentricle of right-ventricular type. For statistical analysis, we used Kruskal-Wallis nonparametric testing. Results: We identified 127 patients who underwent 165 transvenous biopsies, with 38 patients undergoing 2 biopsies. We found that females with two additional risk factors had the highest median total fibrosis scores, 4 (1-8); males with <2 risk factors had the lowest median total fibrosis scores, 2 (0-5); and females with <2 additional risk factors and males with two risk factors were in the middle, median total fibrosis score 3 (0-6), P =.002; and there were no statistical differences for the other demographic or hemodynamic variables. Conclusions: For extracardiac-Fontan patients with similar demographic and hemodynamic variables, identifiable risk factors are associated with the degree of hepatic fibrosis.

Hepatic fibrosis gender differences in extracardiac Fontan patients

OBJECTIVE

We investigated possible gender differences for hepatic fibrosis in extracardiac-Fontan patients.

METHODS

We identified extracardiac Fontan, performed between 2000 and 2016, who underwent cardiac catheterizations with transvenous hepatic biopsies between April 2012 and June 2022. We divided the patients by gender for analysis.

RESULTS

We identified 116 patients who underwent 145 transvenous biopsies, with 29 patients undergoing 2 biopsies at an average interval of 5 ± 1 years. We divided the 145 biopsies into two groups: 1) 98/145 (68%) males and 2) 47/145 (32%) females. For the 47 female liver biopsy specimens, the median total fibrosis score was 3 (0-8), and for the 98 male liver biopsy specimens, the median total fibrosis score was 2 (0-6), p = .007. The average age at surgery for females was 3 ± 1 years and for males 3 ± 1 years, p = .99. Average Fontan duration at biopsy for females was 11 ± 5 years and for males, 10 ± 4 years, p = .23. No other demographic, anatomic, echocardiographic, laboratory, or hemodynamic findings demonstrated statistically significant gender differences.

CONCLUSIONS

Females had statistically significantly higher median total fibrosis scores than males for the similar average age at extracardiac Fontan and average Fontan duration.

Prevalence of Venovenous Shunting and High-Output State Quantified with 4D Flow MRI in Patients with Fontan Circulation

PURPOSE

To assess the ability of four-dimensional (4D) flow MRI to quantify flow volume of the Fontan circuit, including the frequency and hemodynamic contribution of systemic-to-pulmonary venovenous collateral vessels.

MATERIALS AND METHODS

In this retrospective study, patients with Fontan circulation were included from three institutions (2017-2021). Flow measurements were performed at several locations along the circuit by two readers, and collateral shunt volumes were quantified. The frequency of venovenous collaterals and structural defects were tabulated from concurrent MR angiography, contemporaneous CT, or catheter angiography and related to Fontan clinical status. Statistical analysis included Pearson and Spearman correlation and Bland-Altman analysis.

RESULTS

Seventy-five patients (mean age, 20 years; range, 5-58 years; 46 female and 29 male patients) were included. Interobserver agreement was high for aortic output, pulmonary arteries, pulmonary veins, superior vena cava (Glenn shunt), and inferior vena cava (Fontan conduit) (range, ρ = 0.913-0.975). Calculated shunt volume also showed strong agreement, on the basis of the difference between aortic and pulmonary flow (ρ = 0.935). A total of 37 of 75 (49%) of the patients exhibited shunts exceeding 1.00 L/min, 81% (30 of 37) of whom had pulmonary venous or atrial flow volume step-ups and corresponding venovenous collaterals. A total of 12% of patients (nine of 75) exhibited a high-output state (>4 L/min/m2), most of whom had venovenous shunts exceeding 30% of cardiac output.

CONCLUSION

Fontan flow and venovenous shunting can be reliably quantified at 4D flow MRI; high-output states were found in a higher proportion of patients than expected, among whom venovenous collaterals were common and constituted a substantial proportion of cardiac output.Keywords: Pediatrics, MR Angiography, Cardiac, Technology Assessment, Hemodynamics/Flow Dynamics, Congenital Supplemental material is available for this article. © RSNA, 2021.

Fontan-associated liver disease and total cavopulmonary anatomical flow effectors

OBJECTIVE

We investigated a relationship between a composite index comprised of Fontan-circuit anatomical features and hepatic fibrosis scores from biopsy.

METHODS

We identified living extracardiac Fontan patients, ≥7 years old and ≥5 but <20 years postoperative, that underwent cardiac catheterization and transvenous liver biopsy between March 2012 and September 2020. We divided patients into anatomical groups and applied a risk score to each patient. We compared average anatomical risk scores with average hepatic total fibrosis scores by group.

RESULTS

We identified 111 patients that met inclusion criteria. After excluding four patients, we assigned 107 to one of 12 anatomical variant groups (n ≥ 3). For the 107, the average age at liver biopsy was 14 ± 6 years old. Of the 107, 105 (98%) were New York Heart Association Class 1. We found average anatomical risk scores by group correlated with average total fibrosis scores by group (R = 0.8; p = .005). An average Fontan duration to biopsy of 10 ± 1 years was similar for all 12 anatomical groups. We found no other clinical variables, laboratory, or hemodynamic values that trended with anatomical risk scores or hepatic total fibrosis scores.

CONCLUSIONS

In a cohort of relatively young, stable extracardiac Fontan patients, average composite anatomical risk scores strongly correlated with average hepatic total fibrosis scores by anatomical group. These findings suggest that some anatomical variants in extracardiac Fontan patients are associated with higher Fontan-associated liver disease (FALD)-related hepatic total fibrosis scores than others, despite similar Fontan durations.