The Fontan Pathway: Change in Dimension and Catheter-Based Intervention over Time

"Fontan Conduit Stent-Angioplasty and Progression of Fontan-Associated Liver Disease"

Patients with Fontan circulation insidiously develop congestive hepatopathy related to chronically reduced cardiac output and central venous hypertension, also known as Fontan-associated liver disease (FALD). Fontan pathway obstruction is increasingly detected and may accelerate FALD. The impact of conduit stent angioplasty on FALD is unknown. Retrospective, single-center review of patients with Fontan circulation who underwent conduit stent angioplasty at cardiac catheterization over 5-year period. Demographics and cardiac histories were reviewed. Labs, liver ultrasound elastography, echocardiogram, hemodynamic and angiographic data at catheterization were recorded pre- and post-stent angioplasty. Primary outcome was change in hepatic function via MELD-XI scores and liver stiffness (kPa), with secondary outcomes of ventricular function, BNP, and repeat catheterization hemodynamics. 33 patients underwent Fontan conduit stent angioplasty, 19.3 ± 7.0 years from Fontan operation. Original conduit diameter was 19.1 ± 1.9 mm. Prior to angioplasty, conduit size was reduced to a cross-sectional area 132 (91, 173) mm2 and increased to 314 (255, 363) mm2 post-stent. Subjects' baseline median MELD-XI of 11 (9, 12) increased to 12 (9, 13) at 19 ± 15.5 months post-angioplasty (n = 22, p = 0.053). There was no significant change in liver stiffness at 12.1 ± 8.9 months post-angioplasty (n = 15, p = 0.13). Median total bilirubin significantly increased (1.4 [0.9, 1.8]), from baseline 1.1 [0.7, 1.5], p = 0.04), as did median BNP (41 [0, 148] from baseline 34 [15, 79]; p = 0.02). There were no significant changes in ventricular function or repeat invasive hemodynamics (n = 8 subjects). Mid-term follow-up of Fontan subjects post-conduit stent angioplasty did not show improvements in non-invasive markers of FALD.

Clinical Outcomes of Percutaneous Fontan Stenting in Adults

BACKGROUND

Fontan pathway stenosis is a well-known complication after palliation. Percutaneous stenting is effective for angiographic/hemodynamic relief of Fontan obstruction, but its clinical impact in adults remains unknown.

METHODS

This was a retrospective cohort of 26 adults undergoing percutaneous stenting for Fontan obstruction from 2014 to 2022. Procedural details, functional capacity, and liver parameters were reviewed at baseline and during follow-up.

RESULTS

Median age was 22.5 years (interquartile range [IQR] 19-28.8 y); 69% were male. After stenting, Fontan gradient significantly decreased (2.0 ± 1.9 vs 0 [IQR 0-1] mm Hg; P < 0.005), and minimal Fontan diameter increased (11.3 ± 2.9 vs 19.3 [IQR 17-20] mm; P < 0.001). One patient developed acute kidney injury periprocedurally. During a follow-up of 2.1 years (IQR 0.6-3.7 y), 1 patient had thrombosis of the Fontan stent and 2 underwent elective Fontan re-stenting. New York Heart Association functional class improved in 50% of symptomatic patients. Changes in functional aerobic capacity on exercise testing were directly related to pre-stenting Fontan gradient (n = 7; r = 0.80; P = 0.03) and inversely related to pre-stenting minimal Fontan diameter (r = -0.79; P = 0.02). Thrombocytopenia (platelet count < 150 109/L) was present in 42.3% of patients before and in 32% after the procedure (P = 0.08); splenomegaly (spleen size > 13 cm) was present in 58.3% and 58.8% (P = 0.57), respectively. Liver fibrosis (aspartate transaminase to platelet ratio index and Fibrosis-4) scores were unchanged after the procedure compared with baseline.

CONCLUSIONS

Percutaneous stenting in adults is safe and effective in relieving Fontan obstruction, resulting in subjective improvement in functional capacity in some. A subset of patients demonstrated improvement in markers of portal hypertension, suggesting that Fontan stenting could improve Fontan-associated liver disease in select individuals.

Exercise Pathophysiology and Testing in Individuals With a Fontan Circulation

The Fontan circulation, a surgical palliation for single-ventricle congenital heart disease, profoundly impacts the cardiopulmonary response to exercise. Reliant on passive pulmonary blood flow, the Fontan circulation has limited capacity to augment cardiac output as necessary to supply working muscles during exercise. Cardiopulmonary exercise testing (CPET) objectively assesses cardiorespiratory fitness and provides insight into the etiology of exercise intolerance. Furthermore, CPET variables, such as peak oxygen consumption and submaximal variables, have prognostic value and may be used as meaningful endpoints in research studies. CPET is also useful in clinical research applications to assess the effect of pharmacologic or other interventions. Medical therapies to improve exercise tolerance in individuals with a Fontan circulation, such as pulmonary vasodilators, may modestly improve peak oxygen consumption. Exercise training focused on aerobic fitness and lower extremity strength may have a more consistent and larger impact on these measures of aerobic fitness. CPET is a valuable diagnostic and prognostic tool for those with a Fontan circulation. Newer ancillary assessments, such as noninvasive peripheral venous pressure monitoring and cardiac output measurements, hold promise to provide a more nuanced insight into the underlying pathophysiology.

Successful complex percutaneous intervention in patient with Fontan circulation and severe heart failure: A case report

We report the case of a successful complex percutaneous intervention in a patient with Fontan circulation and severe heart failure. The patient presented with cyanosis; Fontan conduit stenosis was detected, and the fenestration was patent. The complex interventional procedure allowed for a long-term stabilization of the patient's condition.