Case study: Symptoms in adult Fontan patient looked like a heart complication

Adult patient presented with protein-losing enteropathy symptoms suggestive of Fontan failure, but specialized adult congenital heart care pointed to something different.

Author: rton Children’s

Published: November 7, 2025

The patient

A 33-year-old female presented with progressive exertional intolerance, peripheral edema, nausea and vomiting. Cardiac history included tricuspid atresia with normally related great vessels with severe pulmonic stenosis (single ventricle heart disease). She underwent staged surgical palliations with a left modified Blalock-Taussig shunt procedure in infancy followed by bilateral, bidirectional Glenn procedure, and finally a modified, nonfenestrated lateral tunnel Fontan procedure. Labs were concerning for protein-losing enteropathy.

The challenge

Development of protein-losing enteropathy (PLE) is a significant risk factor for mortality in the Fontan population and requires a high index of suspicion when a Fontan patient presents with symptoms of Fontan failure and gastrointestinal disturbance. Medical treatment can help stabilize disease, but often the curative next step is heart transplant.

Laboratory evaluation showed elevated erythrocyte sedimentation rate (ESR) and elevated stool alpha-1 antitrypsin level, concerning for possible PLE. Albumin levels fluctuated between 2.9 to 4.3 grams per deciliter in the preceding two years.

With concerns for Fontan failure causing PLE, the patient underwent cardiac catheterization. Findings included mildly elevated heart pressures, no Fontan obstruction by angiography and no significant collaterals. Two years prior, she had similar findings.

Graph showing serum albumin level trends over time

Cardiac catheterization images showing no obstruction within the Fontan circuit.

The solution

Medical therapy was initiated, including furosemide, spironolactone and ambrisentan. Because the findings were unchanged from two years prior, this suggested that the etiology of the PLE was noncardiac.

Referrals included heart failure/transplant evaluation; rheumatology, due to elevated ESR; and finally, gastroenterology, where laboratory evaluation and colonoscopy showed celiac disease.

The result

A gluten-free diet resolved nausea and vomiting, along with improved appetite. The case demonstrated that common association of PLE in Fontan patients may leave other etiologies overlooked.

Multisystem evaluation is important when objective cardiovascular data appears reassuring in the face of active PLE.

Subspecialty cardiology care is needed in patients with complex congenital heart disease to discern cardiac versus noncardiac etiologies of symptoms.

Successful treatment of the underlying etiology of PLE can resolve symptoms and, in this particular case, avoided the pursuit of unnecessary and risky therapies such as heart transplant.