‘Opening Snap’ in Mitral Stenosis

‘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.

  1. Opening snap is a high-pitched sound in early diastole
  2. Coincides with the opening of the mitral valve.

How to differentiate – Opening snap vs S3

  1. 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
  2. Opening snap – is a much higher pitched sound than S3
  3. S3 – localised to the apex only
  4. 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

  1. Loud P2 may simulate the OS
  2. 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

‘Opening Snap’ in Mitral Stenosis

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