Electrocardiography Typical electrocardiographic findings include an RSR
pattern and partial right bundle branch block, often with right-axis deviation.
Chest Radiography (Fig. 1 and 2) A prominent pulmonary artery, right ventricular enlargement, and pulmonary plethora are found on chest radiographs. Left atrial enlargement does not typically occur unless the patient is older than 40 years or has atrial fibrillation. If left atrial enlargement is present in a young person with an ASD in sinus rhythm, consider a primum ASD in the differential diagnosis or coincidental mitral valve disease.