Biatrial enlargement on Chest X-ray

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Biatrial enlargement on Chest X-rayBiatrial enlargement on CXR

Biatrial enlargement on CXR: Right atrial enlargement is manifest as a shift of the right atrial contour to the right side and left atrial enlargement is manifest as a double atrial contour within the right atrial shadow. Straightening of the left border and elevation of left bronchus are other features of left atrial enlargement on chest X-ray. Upper lobe vessels are prominent, suggesting a redistribution of pulmonary blood flow (also known as cephalisation and antler sign). Horizontal lines near the cardiophrenic angles due to thickened alveolar septa are known as Kerley B lines. Prominent descending aortic shadow can be seen behind the cardiac shadow to the left of the spine.

Chest X-ray showing Kerley’s A, B, and C lines as been illustrated in an article in the New England Journal of Medicine [1]. It was in a middle aged lady who presented with severe hypertension, diabetic nephropathy and sudden onset of breathlessness after discontinuing medications. She had features of gross congestive heart failure. Though there was peribronchial cuffing and cardiomegaly, typical features of biatrial enlargement on CXR were not visible.


  1. Koga T, Fujimoto K. Images in clinical medicine. Kerley’s A, B, and C lines. N Engl J Med 2009; 360:1539.