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KEY FEATURES

ESSENTIALS OF DIAGNOSIS

  • Continuous machinery-like murmur, loudest below the left clavicle

  • Left ventricular hypertrophy

  • Pulmonary plethora, left atrial and ventricular enlargement

  • In older adults, calcification of the ductus on chest radiograph

  • Left atrial and ventricular dilatation with normal right heart chambers on echocardiography

  • Continuous high-velocity color Doppler jet with retrograde flow along lateral wall of main pulmonary artery near left branch

GENERAL CONSIDERATIONS

  • Remnant of the normal fetal circulation with a connection between the left pulmonary artery and descending aorta distal to the left subclavian artery

  • A nonrestrictive patent ductus arteriosus (large left-to-right shunt) usually causes congestive heart failure within first year of life

  • Causes volume overload and enlargement of the left heart chambers due to recirculation of blood from the aorta to pulmonary circulation and back to the left atrium

  • Usually associated with other defects, such as pulmonary or tricuspid atresia

  • In a minority of patients, pulmonary vascular disease may develop with reversal of the shunt

  • Differential cyanosis may develop when the shunt reverses and results in desaturated blood flowing into the descending aorta distal to the left subclavian artery

CLINICAL PRESENTATION

SYMPTOMS AND SIGNS

  • Usually presents in childhood

  • Rarely presents in a young adult

  • Congestive heart failure or rarely as Eisenmenger physiology

  • Adults may present with exertional dyspnea, chest pain, palpitations

PHYSICAL EXAM FINDINGS

  • Differential cyanosis

  • Sometimes clubbing and cyanosis of the lower extremities and occasionally the left hand

  • Widened pulse pressure

  • Hyperdynamic, laterally displaced apical impulse

  • Continuous, machinery-like murmur, loudest below the left clavicle

  • Murmur decreases and may disappear as pulmonary vascular resistance increases and shunt reverses

  • S3 gallop

  • Diastolic murmur across the mitral valve

DIFFERENTIAL DIAGNOSIS

  • Other causes of exertional dyspnea, chest pain, and palpitations

  • Other causes of left heart dilatation and failure

  • The characteristic continuous murmur can be mimicked by aortic stenosis with regurgitation, mitral stenosis with regurgitation, and ventricular septal defect with aortic regurgitation

DIAGNOSTIC EVALUATION

LABORATORY TESTS

  • No specific tests

ELECTROCARDIOGRAPHY

  • Normal when the shunt is small

  • Left atrial enlargement

  • Left ventricular hypertrophy

  • P pulmonale, right-axis deviation, right ventricular hypertrophy if pulmonary hypertension develops and the shunt reverses

IMAGING STUDIES

  • Chest x-ray:

    • – Normal if the shunt is small

    • – Left ventricular enlargement, pulmonary vascular plethora

    • – Enlarged pulmonary artery and peripheral pulmonary artery pruning in the presence of pulmonary hypertension

    • – Patent ductus arteriosus may be calcified in the adult

  • Echocardiography:

    • – Left atrial and left ventricular enlargement

    • – Continuous high-velocity Doppler flow in the main pulmonary artery near the left branch

    • – Right ventricular hypertrophy and high-velocity Doppler tricuspid regurgitant jet may be present if pulmonary hypertension develops

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