Cardiovascular: mitral stenosis opening snap: practice question

A Physiology question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Physiology · Cardiovascular: mitral stenosis opening snap

Sample item

In two patients with rheumatic mitral stenosis, the interval from the aortic component of the second sound (A2) to the opening snap is 0.06 s in one and 0.12 s in the other. What does the shorter interval indicate?

AA lower left atrial pressure and milder stenosisBA prolonged isovolumetric relaxation time from a stiff ventricleCMitral regurgitation of greater severityDA higher left atrial pressure and more severe stenosis

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

D. A higher left atrial pressure and more severe stenosis

The opening snap occurs when the stenotic valve opens as left ventricular pressure falls below left atrial pressure. If left atrial pressure is higher because of tighter stenosis, the valve opens earlier in diastole, so A2 to opening snap is shorter. An interval under about 0.08 s suggests severe stenosis.

Option by option

A. A lower left atrial pressure and milder stenosis
A lower atrial pressure needs a longer fall in ventricular pressure, so the interval would be longer.
B. A prolonged isovolumetric relaxation time from a stiff ventricle
A stiff ventricle would not shorten the A2 to opening snap interval in this way.
C. Mitral regurgitation of greater severity
Regurgitation is not what determines the interval; the snap arises from the stenotic valve doming open.
D. A higher left atrial pressure and more severe stenosis (correct)
Correct. A high left atrial pressure forces the valve open early, shortening the interval.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

Questions about this Physiology question

What is the answer to this Physiology question?

The best answer is D, A higher left atrial pressure and more severe stenosis. The opening snap occurs when the stenotic valve opens as left ventricular pressure falls below left atrial pressure.

Why is "A lower left atrial pressure and milder stenosis" not the answer?

A lower atrial pressure needs a longer fall in ventricular pressure, so the interval would be longer.

Why is "A prolonged isovolumetric relaxation time from a stiff ventricle" not the answer?

A stiff ventricle would not shorten the A2 to opening snap interval in this way.

Why is "Mitral regurgitation of greater severity" not the answer?

Regurgitation is not what determines the interval; the snap arises from the stenotic valve doming open.

What concept does this question test?

It tests Cardiovascular: mitral stenosis opening snap in Physiology. If left atrial pressure is higher because of tighter stenosis, the valve opens earlier in diastole, so A2 to opening snap is shorter. An interval under about 0.08 s suggests severe stenosis.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Cardiovascular: mitral stenosis opening snap?

For each system, sketch the key graph (pressure–volume loop, oxygen dissociation curve, nephron handling) and explain it aloud. Then use the flashcards and the other Physiology questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.