ASD

51 yrs female-

Small aortic knuckle( yellow) and large pulmonary conus(red)

Plain film (CXR) findings in ASD

can be normal in early stages +/- when the ASD is small
signs of increased pulmonary flow (shunt vascularity)
enlarged pulmonary vessels
upper zone vascular prominence
vessels visible to the periphery of the film
eventual signs of pulmonary arterial hypertension

chamber enlargement 
right atrium
right ventricle
note: left atrium is normal in size
note: aortic arch is small to normal