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KEY FEATURES

ESSENTIALS OF DIAGNOSIS

  • Young adult with history of multiple staged interventions and surgeries in infancy

  • Physical findings of:

    • – Low-amplitude waveform on jugular venous pulse

    • – Single S2 (may be quite loud if presence of transposed great vessels)

    • – Prominent liver edge (as patients may develop Fontan-associated liver disease)

    • – Evidence of multiple sternal scars +/– thoracotomies

  • Echocardiographic findings reveal a single dominant ventricle of either right or left ventricular morphology

GENERAL CONSIDERATIONS

  • True prevalence of univentricular hearts is unknown. It is estimated to be ~0.05–0.1 per 1000 live births

  • Final common pathway for a variety of lesions that exhibit a single ventricular physiology or in which a biventricular repair could not be performed. Most common lesions are tricuspid atresia, hypoplastic left heart syndrome, double inlet left ventricle, unbalanced atrioventricular (AV) septal defects, and double outlet right ventricle

  • Deoxygenated blood from the superior and inferior vena cava is redirected passively to the pulmonary artery

  • Atriopulmonary Fontan, lateral tunnel Fontan, and extracardiac total cavopulmonary connections are the various forms of palliative repairs seen in patients with the Fontan circulation

  • Features of the "failing Fontan" should be monitored. Patients can present with:

    • – Arrhythmias, heart failure, venous thromboembolism, lymphatic obstruction, protein-losing enteropathy, plastic bronchitis, and liver disease

CLINICAL PRESENTATION

SYMPTOMS AND SIGNS

  • Dyspnea

  • Diminished exercise tolerance

  • Chest pain

  • Palpitations

  • Symptoms more common after the third decade of life

  • Signs and symptoms of volume overload due to either heart failure, liver failure, or hypoproteinemia

PHYSICAL EXAM FINDINGS

  • Blunting of the jugular venous pressure waveform

  • Single S2 (maybe loud in the presence of transposed great vessels)

  • Holosystolic murmurs in the presence of significant AV valve regurgitation

  • Mild cyanosis (due to either a Fontan fenestration or venovenous collaterals)

  • Palpable liver edge

  • Sternotomy scars

  • Cyanosis in patients with

DIFFERENTIAL DIAGNOSIS

  • Differential is based on the initial anatomy of the congenital lesion

  • However, different phenotypes of Fontan failure include:

    • – Fontan failure with reduced ejection fraction

    • – Fontan failure with normal ejection fraction

    • – Fontan failure with normal pressures and hemodynamics but portovenous outflow obstruction, ascites, and cirrhosis

DIAGNOSTIC EVALUATION

LABORATORY TEST

  • Liver functions tests, CBC, N-terminal pro-B-type natriuretic peptide, alpha1-antitrypsin

  • Incomplete right bundle branch block in 90% of cases

  • Absence of right-sided forces in tricuspid atresia

  • Sinus node dysfunction requiring a pacing device and atrial pacing

  • Atrial arrhythmias (atrial fibrillation, flutter, and intra-atrial reentrant tachycardia)

  • Sequential AV pacing

IMAGING STUDIES

  • Chest radiograph: may be used if pulmonary edema is suspected in single ventricular dysfunction

  • Transthoracic echocardiography (preferred initial imaging modality):

    • – Dominant single ventricle with an adjacent smaller rudimentary chamber

    • – Presence of a large ventricular septal defect or ...

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