Fontan Circulation — Adult Management

Definition

The Fontan procedure directs systemic venous blood to the pulmonary arteries without a subpulmonic ventricle, palliating single-ventricle congenital heart disease (including HLHS, tricuspid atresia, double-inlet LV, and others). Adults with Fontan circulation have obligate systemic venous hypertension and low cardiac output, creating a multisystem disease state. Fontan patients can never be classified as ACHD physiological stage A.

Key Concepts

Pathophysiology

• Passive pulmonary flow driven entirely by systemic venous pressure — no subpulmonic pump
• Chronic venous hypertension affects liver, kidneys, lymphatics, and gut
• Diverse phenotypes of Fontan circulatory failure: ventricular dysfunction, valve dysfunction, Fontan pathway obstruction, lymphatic dysfunction, noncardiac organ failure
• Aortopulmonary collaterals common → systemic venous to pulmonary arterial shunting → increased ventricular volume load and PA pressure
  sources/ACHD-AHA-2025 — very high

Routine Surveillance

Cardiac (per ACHD AP stage):

• Outpatient ACHD cardiologist: 12 months (Stage B), 6–12 months (Stage C), 3–6 months (Stage D)
• Echocardiography: 12 months (Stage B), 12 months (Stage C), 6–12 months (Stage D)
• ECG: 12 months (Stage B), 6–12 months (Stage C)

Annual laboratory evaluation (COR 1, C-EO): Renal function (cystatin C preferred), LFTs, albumin (protein-losing enteropathy), iron studies, hematologic indices (thrombocytopenia, erythrocytosis, lymphopenia), NT-proBNP, alpha-fetoprotein

Fontan-associated liver disease (FALD) surveillance:

• Annual hepatic imaging + AFP for HCC and progressive FALD (COR 1, C-LD) — new 2025 recommendation
• Liver MR preferred: characterises nodules, quantifies fibrosis without radiation; elastography overestimates fibrosis due to venous hypertension
• Cirrhosis on imaging → imaging every 6 months at minimum
• Hepatologist consultation (COR 2a, C-EO) — new; for interpretation, portal hypertension management, and transplantation timing decisions
• Liver biopsy before transplantation consideration (COR 2a, C-LD): gold standard for fibrosis; guides decision for combined heart-liver transplantation
  sources/ACHD-AHA-2025 — very high

Haemodynamic Investigations

• New or progressive symptoms, hypoxemia, declining functional status, or noncardiac organ dysfunction → cardiac catheterization (COR 1, C-EO)
• New progressive severe hypoxemia or hypotension → advanced imaging (CMR, CT, TOE) to exclude thrombus or emboli (COR 1, C-EO)
• CT angiography protocols must use dual injection (upper + lower extremity) or multiple phases to avoid streaming artefact false positives/negatives (COR 1, C-EO)
• Before catheter placement → consider imaging to exclude Fontan thrombus (COR 2b, C-LD)
• Before Fontan completion or conversion → cardiac catheterization for haemodynamic assessment (COR 1, C-EO)
  sources/ACHD-AHA-2025 — very high

Antithrombotic Therapy

Low-risk Fontan (no high-risk features, no bleeding contraindications):

• Aspirin or anticoagulation recommended to reduce thromboembolic risk (COR 1, B-NR) — upgraded from COR 2b in 2018; no evidence of superiority between aspirin and anticoagulant for primary prevention

High-risk features (any of the following):

• History of thromboembolism
• Sustained atrial flutter or fibrillation
• Atriopulmonary Fontan type
  → Anticoagulation required unless contraindicated

Before cardioversion (any duration of arrhythmia): TOE to exclude thrombus — mandatory given high thrombus prevalence in Fontan
sources/ACHD-AHA-2025 — very high

Arrhythmia Management

• Atrial arrhythmias in >60% of adults with Fontan — major source of morbidity and mortality
• New-onset AFL/AF → timely cardioversion (pharmacological or electrical) to prevent clinical decompensation (COR 1, C-LD)
• New/worsening atrial tachyarrhythmias → evaluate for haemodynamic contributors and Fontan pathway thrombosis (COR 1, C-EO)
• Recurrent SVT → catheter ablation by ACHD EP specialist (COR 2a, C-LD); challenging due to multiple circuits, difficult access, atrial scarring, high conduction system injury risk
• Atriopulmonary Fontan + refractory atrial arrhythmias → Fontan conversion surgery may be considered (COR 2b, C-LD)
• Rhythm control preferred over rate control in complex ACHD including Fontan
  sources/ACHD-AHA-2025 — very high

Pacing Strategy

• Sinus node dysfunction with pacemaker required → atrial-based pacing, programme to minimise ventricular pacing (COR 1, C-LD)
• AV block with high ventricular pacing burden (>40%) → apical site pacing preferred over nonapical sites to improve transplant-free survival (COR 2a, B-NR)
• Ventricular pacing associated with decline in ventricular function and adverse outcomes
  sources/ACHD-AHA-2025 — very high

Catheter-Based and Surgical Interventions

• Fontan pathway stenosis + haemodynamically significant → catheter-based stenting (COR 2a, C-EO); threshold: ≥1 mmHg pull-back gradient or ≥25% internal diameter reduction
• Aortopulmonary collaterals with ventricular volume overload → closure (COR 2a, C-EO)
• Pulmonary vasodilators: may be considered to improve exercise capacity, particularly exercise at anaerobic threshold (COR 2b, B-R); effect on FALD progression unclear
• Atriopulmonary Fontan → lateral tunnel/extracardiac conversion: reserved for refractory arrhythmias not amenable to medical/catheter therapy (COR 2b, C-LD)
  sources/ACHD-AHA-2025 — very high

Exercise and Rehabilitation

• Formal exercise programs / cardiac rehabilitation: beneficial for improving functional capacity (COR 2a, B-NR) — new
• Lower extremity resistance training facilitates increased muscle mass and venous return
• Many Fontan patients are sedentary due to prior instructions limiting activity; clinician-directed supervised programs are particularly beneficial
  sources/ACHD-AHA-2025 — very high

Heart Transplantation

• Fontan circulatory failure → formal HF/transplant evaluation by program experienced in adult Fontan transplantation (COR 1, B-NR)
• Pre-transplantation multidisciplinary committee review (COR 1, C-EO) — broad representation including ACHD, HF/transplant, congenital surgery, hepatology, social work, psychiatry
• Outcomes worse with additional time to referral after onset of progressive circulatory failure/multiorgan dysfunction — early referral recommended
• Combined heart-liver transplantation: high complication rates; consider in cirrhosis with portal hypertension (varices, ascites, splenomegaly); decision centre-specific
• ACHD patients accredited at high-volume ACHD centres have equal or superior long-term survival despite high early posttransplant mortality
  sources/ACHD-AHA-2025 — very high

HLHS/Norwood Subgroup

• Unique risks: systemic morphological RV, single systemic tricuspid valve, neoaortic dilation, Norwood anastomosis obstruction, coronary ischemia
• Routine 3D imaging of neoaorta (COR 2a, C-EO) — echocardiography insufficient for distal ascending aorta
• Higher risk for early Fontan failure, ventricular and AV valve dysfunction, neurocognitive dysfunction
  sources/ACHD-AHA-2025 — very high

Contradictions / Open Questions

• Combined heart-liver vs heart-only transplantation: limited prospective data; trajectory of FALD after heart-only transplantation unknown
• Optimal timing of transplantation referral and listing criteria remain undefined; no single accepted definition of Fontan circulatory failure
• Pulmonary vasodilator therapy data largely from paediatric populations; long-term impact on FALD and non-exercise outcomes unclear
• Role of routine liver biopsy for FALD surveillance (outside transplantation planning) remains controversial — lack of correlation between fibrosis grade and clinical outcomes in published studies
  sources/ACHD-AHA-2025 — very high

Connections

• Related to concepts/ACHD-AP-Classification — Fontan is Class III; cannot be Stage A
• Related to entities/Pulmonary-Hypertension — PVR assessment before Fontan; pulmonary vasodilators in Fontan
• Related to entities/Heart-Failure — Fontan circulatory failure management; MCS and transplantation
• Related to entities/Atrial-Fibrillation — AF/AFL in Fontan; antithrombotic therapy; rhythm control preferred
• Related to concepts/Conduction-System-Pacing — pacing strategy in Fontan (minimise ventricular pacing; apical preferred if high burden)

Sources

• sources/ACHD-AHA-2025