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KEY FEATURES

ESSENTIALS OF DIAGNOSIS

  • Infant with congestive heart failure

  • Physical findings include primum atrial septal defect (ASD) plus mitral (left-sided atrioventricular [AV] valve) regurgitation

  • Cardiac imaging shows a common AV valve annulus, 1 or more abnormal AV valves, and defects at the atrial or the ventricular level that can be detected in utero

GENERAL CONSIDERATIONS

  • Also called endocardial cushion defect

  • AV canal defect is a spectrum of lesions associated with maldevelopment of the AV septum and adjoining AV valves

  • A partial AV canal defect has a cleft mitral valve along with a defect in the inferior portion of the AV septum

  • Complete AV canal defect is a complex combination of:

    • – An ASD

    • – A nonrestrictive ventricular septal defect

    • – Complex morphology of a common AV valve

  • The condition is associated with other congenital anomalies such as:

    • – Patent ductus arteriosus

    • – Tetralogy of Fallot

    • – Double-outlet right ventricle

    • – Transposition of the great arteries

    • – Unroofed coronary sinus with left superior vena cava

    • – Asplenia or polysplenia syndromes

  • Very common in Down’s syndrome (approximately 20%)

  • Large defects are usually repaired in the first 3–6 months of life

CLINICAL PRESENTATION

SYMPTOMS AND SIGNS

  • Complete AV canal defects:

    • – Presentation under age 1 year with a history of frequent respiratory infections and poor weight gain

    • – Heart failure in infancy common

  • Partial AV canal defects:

    • – Presentation may be later, with dyspnea and signs and symptoms of right ventricular (RV) failure due to right-sided volume overload

  • Patients with persistent complete AV canal defects > age 2 years invariably develop pulmonary vascular disease and possibly Eisenmenger’s syndrome

  • Arrhythmias

PHYSICAL EXAM FINDINGS

  • Findings similar to patients with ASDs but may include the following:

    • – Holosystolic apical murmur of mitral regurgitation

    • – Holosystolic lower left sternal border murmur of interventricular communication

DIFFERENTIAL DIAGNOSIS

  • Secundum ASD with mitral regurgitation due to rheumatic disease or prolapse

  • Ventricular septal defect

  • Other causes of heart failure

DIAGNOSTIC EVALUATION

ELECTROCARDIOGRAPH

  • First-degree AV block

  • Complete right bundle branch block

  • Left anterior fascicular block

  • RV hypertrophy

IMAGING STUDIES

  • Chest x-ray:

    • – Right atrial and ventricular cardiomegaly

    • – Prominent RV outflow tract

    • – Increased pulmonary vascular markings

  • Echocardiographic features of a partial AV canal defect:

    • – Right atrial and ventricular enlargement

    • – Increased pulmonary artery flow velocity

    • – A defect in the inferior portion of the interatrial septum immediately adjacent to the AV valves, either of which may be deformed and incompetent

    • – The mitral valve is often cleft and sometimes has a double orifice

    • – Doppler findings of pulmonary hypertension may be present with or without RV dysfunction

  • Echocardiographic features of a complete AV canal defect in addition to the ...

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