Question

Following is true regarding opening snap:

• A. It is a high-pitched diastolic sound.
• B. It is due to opening of stenosed aortic valve.
• C. It indicates pulmonary arterial hypertension.
• D. It precedes the aortic component of second heart sound.

Hint:

The opening snap comes from a stenotic mitral valve snapping open, right after S2, not before it.

Answer 1

The Correct Option is A

The opening snap is a well-known extra sound in cardiology, tied closely to one specific valve lesion, so this question is really about knowing exactly where it comes from and when it occurs.

1. It is a high-pitched diastolic sound: correct. In mitral stenosis, the fused but still mobile leaflets snap taut as they dome open under the pressure from the left atrium, producing a crisp, high-pitched sound right at the start of diastole.
2. It is due to opening of stenosed aortic valve: wrong. The opening snap is generated by the mitral valve, not the aortic valve; the aortic valve has no equivalent "snap" sound in aortic stenosis.
3. It indicates pulmonary arterial hypertension: wrong. The opening snap signals mitral stenosis. Pulmonary hypertension may coexist as a complication of severe mitral stenosis, but the snap itself does not indicate it.
4. It precedes the aortic component of second heart sound: wrong. The sequence is actually S1, then S2 (with its aortic component A2), and only after that the opening snap. Clinicians even measure the A2 to opening snap gap, since a shorter gap means tighter, more severe stenosis.

Only the first statement matches the true nature of the opening snap.

Let's summarize:

• The opening snap is a high-pitched sound from a stenotic mitral valve snapping open in early diastole.
• It always comes after S2, and a short A2-OS gap suggests severe mitral stenosis.

So the correct statement is that it is a high-pitched diastolic sound.