Information on the Carinal Angle in a Chest Xray
Carinal angle- It is the angle formed by the carina. It measures 50-70 degrees.
You should remember 2 conditions where it is increased, one is Left atrial enlargement and another is Enlarged subcarinal lymph node.
Remember that the posterior border of the heart is formed by the left atrium, which lies just inferior to the carina. So the carinal angle is increased when there is an increased left atrium.
Image showing a normal carinal angle.
Case of Left atrial enlargement. Note the increased carinal angle. Also, mitral valve calcifications can be seen.