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Case 010: Fontan Patient with Edema - Protein-Losing Enteropathy

Presentation

A 12-year-old boy with history of hypoplastic left heart syndrome (HLHS), status post staged palliation (Norwood, Glenn, Fontan at age 3) presents with 2 weeks of progressive abdominal distension and lower extremity edema. He also reports loose stools.

Vital Signs: - Heart rate: 90 bpm - Blood pressure: 95/60 mmHg - SpO2: 92% on room air (his baseline) - Respiratory rate: 20

Exam: - Comfortable, thin-appearing - No JVD (difficult to assess in Fontan) - Distant heart sounds - Distended abdomen with fluid wave - 2+ pitting edema to knees bilaterally

Initial Workup

Labs: - Albumin: 1.8 g/dL (LOW) - Total protein: 4.2 g/dL (LOW) - IgG: 320 mg/dL (LOW) - Lymphocyte count: 800/μL (LOW) - Stool alpha-1 antitrypsin: ELEVATED

Echocardiogram: - Fontan pathway patent without obstruction - Systemic RV function mildly reduced (TAPSE 12mm) - Moderate systemic AV valve regurgitation - No fenestration visible

Clinical Reasoning

Question 1: What is the diagnosis?

Answer **Protein-Losing Enteropathy (PLE)** A Fontan-associated complication characterized by: - Enteric protein loss - Hypoalbuminemia - Hypogammaglobulinemia - Lymphopenia - Edema/ascites **Confirmed by:** Elevated stool alpha-1 antitrypsin (measures protein loss into gut)

Question 2: What causes PLE in Fontan patients?

Answer **Pathophysiology:** Fontan circulation → chronically elevated CVP → - Intestinal lymphatic congestion - Protein-rich lymph loss into gut lumen - Also lose immunoglobulins and lymphocytes **Risk factors:** - High CVP/Fontan pressures - Systemic ventricular dysfunction - AV valve regurgitation - Arrhythmias - Fontan pathway obstruction **Prevalence:** 5-15% of Fontan patients

Question 3: What workup is needed to identify reversible causes?

Answer **Complete Fontan evaluation:** 1. **Echo** - already done - Fontan pathway obstruction? - Ventricular function? - AV valve function? - Fenestration patency? 2. **Cardiac catheterization** - Fontan pressures - Pulmonary artery pressures - Rule out pathway obstruction - Assess for intervention targets 3. **Cardiac MRI** - Detailed Fontan pathway anatomy - Flow quantification - Ventricular function 4. **Holter/event monitor** - Arrhythmias can worsen hemodynamics 5. **Liver assessment** - FALD (Fontan-associated liver disease) common - Ultrasound, elastography, labs

Catheterization Results

Findings: - Fontan pressure: 18 mmHg (elevated) - No pathway obstruction - Transpulmonary gradient: 8 mmHg - No fenestration present (closed at prior cath) - LVEDP equivalent: 12 mmHg

Question 4: What medical therapies are used for PLE?

Answer **Supportive:** - High protein diet - IV albumin (temporary effect) - Diuretics (spironolactone + furosemide) - Medium-chain triglyceride (MCT) diet - absorbed without lymphatics **Specific therapies:** 1. **Sildenafil** - pulmonary vasodilation, may reduce Fontan pressures 2. **Budesonide** (enteric-coated steroid) - reduces gut inflammation 3. **Heparin** (subcutaneous unfractionated or LMWH) - unclear mechanism but often effective 4. **Octreotide** - reduces splanchnic blood flow **Interventional:** - Fenestration creation (if closed) - "pops off" Fontan pressure - Treat any obstruction - Treat arrhythmias aggressively **Advanced:** - Heart transplantation - definitive but limited by organ availability

Question 5: What is the prognosis?

Answer **PLE is a serious complication:** - 5-year survival after PLE diagnosis: 50-80% - Indicates Fontan circulation is failing - May be indication for transplant evaluation **Poor prognostic factors:** - Lack of response to medical therapy - Persistent hypoalbuminemia - Recurrent infections (hypogammaglobulinemia) - Associated liver disease **Consider transplant evaluation** for: - Refractory PLE - Progressive symptoms despite maximal therapy - Significant ventricular dysfunction

Management Plan

Question 6: What is your comprehensive management approach?

Answer **Immediate:** 1. IV albumin infusion (temporary, to reduce edema) 2. Diuretics (spironolactone 1 mg/kg BID, furosemide 1 mg/kg BID) 3. Start budesonide 9 mg daily 4. Start sildenafil 5. Dietary: High protein, MCT oil supplementation **Consider adding:** - Heparin therapy (subcutaneous) - If recurrent infections: IVIG replacement **Interventional consideration:** - Fenestration creation to reduce Fontan pressures **Long-term:** - Close monitoring of albumin, weight - Multidisciplinary Fontan care (hepatology, GI, nutrition) - Transplant evaluation given severity

Teaching Points

  1. PLE = protein loss into gut from elevated CVP in Fontan
  2. Stool alpha-1 antitrypsin confirms diagnosis
  3. Evaluate for reversible causes (obstruction, arrhythmia, ventricular dysfunction)
  4. Multiple medical therapies available - budesonide, heparin, sildenafil, diuretics
  5. PLE indicates Fontan failure - consider transplant evaluation
  6. 5-year survival ~50-80% after PLE diagnosis