Left atrial enlargement – while echocardiography has emerged as the preferred tool for assessing cardiac chamber size, recognising the features of left atrial enlargement on chest radiography remains worthwhile.
Direct signs
- The double density sign (left image) occurs when the right side of the dilated left atrium is visible next to the normal right heart border (right atrium). It may even extend out beyond the right heart border, an appearance known as atrial escape.
- Oblique measurement of greater than 7cm (right image, blue arrow).
- Convex left atrial appendage – normally it is flat or concave.
Indirect signs
- Splaying of the carina to greater than a 90 degree angle (right image, yellow lines).
- Posterior displacement of the left main stem bronchus on lateral radiographs forming an upside down ‘V’ known as the walking man sign.
from our tumblr blog
http://radiologysigns.tumblr.com/
