What are the key clinical and echocardiography (echo) parameters to assess after a Fontan repair?

Assessment of Fontan Repair: Clinical and Echocardiographic Parameters

All patients with prior Fontan repair should have periodic echocardiographic examinations performed by staff with expertise in adult congenital heart disease (ACHD), as echocardiography is the cornerstone of postoperative evaluation. 1

Clinical Examination Parameters

Cardiac Auscultation

• Most patients have no murmurs and a single second heart sound after successful Fontan operation 1
• The absence of murmurs is the expected finding and indicates satisfactory hemodynamics 1

Jugular Venous Assessment

• Mild jugular venous distention (usually nonpulsatile) is common and normal even without heart failure 1
• Significant jugular venous distension with hepatomegaly raises suspicion for Fontan obstruction 1
• Critical pitfall: In patients with prior Glenn procedure, jugular venous pressure does not reflect right atrial pressure, and Fontan obstruction may be missed 1

Cyanosis Assessment

• Mild cyanosis accentuated with aerobic activity suggests Fontan obstruction 1
• Oxygen saturation ≤90% at rest that decreases with exercise warrants investigation for shunts, fenestrations, or pulmonary arteriovenous malformations 1

Hepatic Assessment

• Hepatomegaly indicates potential Fontan obstruction or hepatic congestion 1
• Elevated alkaline phosphatase suggests hepatic dysfunction from chronic venous congestion 2

Electrocardiogram Parameters

• ECG features mirror the unoperated patient, but atrial arrhythmias are more common postoperatively 1
• Atrial arrhythmias are particularly common in patients with direct atriopulmonary connections 1

Chest X-Ray Parameters

• Normal heart size indicates satisfactory hemodynamics 1
• Normal pulmonary vascularity is expected 1
• Pleural effusions mandate workup for hemodynamic abnormalities or protein-losing enteropathy (PLE) 1

Comprehensive Echocardiographic Parameters

Fontan Pathway Assessment

• Image the entire Fontan pathway (lateral tunnel, extracardiac conduit, or atriopulmonary connection) 1
• Transesophageal echocardiography (TEE) is often necessary to completely visualize the Fontan circuit 1
• Spontaneous contrast in the Fontan circuit represents slow flow and is commonly seen 1
• Any degree of obstruction in the nonpulsatile Fontan circuit is hemodynamically significant 1, 3

Fenestration Evaluation

• Identify presence or absence of Fontan fenestration 1
• Measure gradient across fenestration if present 1
• Persistent fenestration can cause right-to-left shunting and cyanosis 1, 3

Thrombus Detection

• TEE is required to rule out right atrial thrombus, particularly in patients with direct atriopulmonary connections 1
• Thrombus formation is especially common in older-style direct atrium-to-pulmonary artery connections 1, 4

Ventricular Function Assessment

• Assess systemic ventricular systolic function (ejection fraction) 1, 3
• Evaluate diastolic function and ventricular filling pressures 1, 3
• Systemic ventricular ejection fraction is typically reduced compared to normal (median ~55%) 5
• Pulsed-wave Doppler E velocity >75 cm/s has 88% sensitivity and 86% specificity for elevated filling pressures 5
• E/A ratio >1.7 has 100% sensitivity for elevated filling pressures (PAWP >12 mmHg) 5
• Deceleration time <135 ms has 88% sensitivity and 83% specificity for elevated filling pressures 5

Atrioventricular Valve Assessment

• Evaluate systemic atrioventricular valve regurgitation severity 1, 3
• TEE provides superior assessment of AV valve regurgitation compared to transthoracic echo 4

Pulmonary Artery and Venous Flow

• Pulsed Doppler interrogation of pulmonary artery and pulmonary vein flow patterns allows detailed evaluation of Fontan circulation 4
• Assess branch pulmonary artery anatomy and flow 1, 3

Shunt Detection

• Search for atrial right-to-left shunts 1
• Identify systemic venous-to-pulmonary venous collaterals 1, 3
• Detect pulmonary arteriovenous malformations 1, 3
• Contrast echocardiography assists in identifying shunts 1, 3

Additional Diagnostic Modalities

Cardiac Catheterization Indications

Catheterization should be performed at regional centers with ACHD expertise and is indicated for: 1, 3

• Unexplained volume retention, fatigue, or exercise limitation 1, 3
• Atrial arrhythmias 1, 3
• Cyanosis and hemoptysis 1, 3
• Protein-losing enteropathy evaluation 1, 3

Hemodynamic Parameters During Catheterization

• Fontan pathway pressure (normal >10 mmHg; ≥20 mmHg indicates major hemodynamic disturbance) 3
• Pulmonary vascular resistance (critical as Fontan circulation cannot compensate for elevated PVR) 1, 3
• Cardiac output and cardiac index (typically 80% of normal at rest) 3
• Ventricular end-diastolic pressure (>15 mmHg indicates major hemodynamic disturbance) 3
• Oxygen saturation throughout circuit 3

Laboratory Markers

• N-terminal pro-brain natriuretic peptide (NT-proBNP) elevation indicates ventricular dysfunction 2
• Elevated alkaline phosphatase suggests hepatic congestion 2

Long-Term Complications to Monitor

The ACC/AHA guidelines emphasize that long-term problems include: 1

• Atrial arrhythmias (especially with direct atriopulmonary connections)
• Right atrial thrombus formation
• Ventricular dysfunction and edema
• Hepatic congestion and dysfunction
• Protein-losing enteropathy (reduces 5-year survival to ~50%)
• Single ventricle failure

Ten-year survival after Fontan operation is 90%, with late deaths primarily from single ventricle failure, arrhythmias, reoperation, and PLE. 1