Double atrial shadow and prominent upper lobe vessels
X-ray chest PA view showing prominent double atrial shadow (double atrial contour, shadow in shadow, double density [1,2]) to the right of the spine, suggestive of left atrial enlargement. Here the left atrium contributes to the upper part of the right heart border. It may be noted that normally right atrium forms the right heart border and left atrium does not reach the right heart border. It reaches the right border when it is significantly enlarged. Grossly enlarged left atrium when it is aneurysmal, may even bulge further beyond the right atrium on the right heart border in anteroposterior view. Another sign of left atrial enlargement on chest X-ray is elevation of left bronchus with widening of the tracheal bifurcation carinal angle .
Right border of the heart is significantly shifted to the right, indicating associated right atrial enlargement. Left atrial appendage is seen as a bulge along the middle region of left heart border (third mogul sign) . Upper lobe vessels are quite prominent (inverted moustache sign, antler sign, cephalization), indicating pulmonary venous hypertension. All together the findings on the chest X-ray indicate severe mitral stenosis.