‘Opening Snap’ in Mitral Stenosis
‘Opening Snap’ in Mitral Stenosis
High-pitched early diastolic sound due to sudden tensing of the valve leaflets and subvalvular apparatus at the end of the opening excursion.
- Opening snap is a high-pitched sound in early diastole
- Coincides with the opening of the mitral valve.
How to differentiate – Opening snap vs S3
- Opening snap -Because of its higher pitch, Opening snap can be heard over a wider area over the precordium than mid-diastolic rumble and S3
- Opening snap – is a much higher pitched sound than S3
- S3 – localised to the apex only
- Opening snap -can be heard at the left sternal border and even at the base of the heart.
How to differentiate – Opening snap vs P2
- Loud P2 may simulate the OS
- Normally P2 is not heard at the aortic area unless there is severe pulmonary hypertension.
A crisp OS suggests a pliable valve and hence is probably suitable for balloon mitral valvuloplasty.
Opening snap – occurs closer to S2 than the pericardial knock and the S3 gallop.
Opening snap – Best heard in the “supramammary area” – just above and slightly to the left of the nipple (or between the apex and the left sternal border).
- The OS occurs 40-120 milliseconds after A2.
- A2-OS interval is inversely proportional to the height of the left atrial (LA)-LV diastolic pressure gradient.
Mitral Stenosis severity – A2-OS interval varies inversely with the severity of mitral stenosis.
- Mild MS – A2-OS interval of more than 100 milliseconds usually indicates mild MS
- Moderate MS – A2-OS interval 70 -100 milliseconds usually suggests Moderate MS
- Severe MS – A2-OS interval less than 70 milliseconds usually suggests severe MS