The frontal chest x-ray shows cardiomegaly (the cardio thoracic ratio more than 0.5). The right heart border is bulging, indicative of right atrial enlargement. The left hear border appears straightened with cardiac apex displaced up, suggesting possible bi ventricular enlargement.

The lateral chest x-ray reveals obliteration of the retrosternal clear space, indicating right ventricular enlargement.

The patient went on to have an echocardiogram which showed severe pulmonary hypertension, There was also severe right atrial and right ventricular enlargement. The left cardiac chambers were normal.

Cardiac chamber enlargement on chest x-ray:

• Left atrium – widened carinal angle, double right heart border.
• Right atrium – prominent bulge on the right heart border to the right of the spine (more than 5.5 cm from the midline).
• Left ventricle – elongated left heart border with apex pointing down.
• Right ventricle – obliterated retrosternal clear space.

Echocardiogram is the best modality to assess cardiac chamber enlargement as chest x-ray is insensitive and findings may not manifest until late.

Reference: Fundamentals of Diagnostic Radiology by Brant & Helms.