Here is an X-ray of classical rheumatic mitral stenois with a mitral orifice of .8 square cm.
Why the left heart border is straight in mitral stenosis ?
It is due to 4 factors.
- Hypoplastic aorta
- LAA
- PA
- Under filled LV
Note :
- This straightening occurs only in isolated , severe forms of mitral stenosis as it requires under filling of left ventricle and Aorta.
- Significant mitral regurgitation will lift the lower end of straight line .
- In associated aortic valve lesions especially in aortic regurgitation the straightening can not occur as LV and Aorta continues to be conspicuous.
- If mitral stenosis causes severe PAH and tricuspid regurgitation , RV can become huge and form the left heart border and distort the straight line.
Dr.S.Venkatesan MD 
simple nice explanation
great sir
Thank u sir… Very useful!!
Thanks ! It is very helpful .