In a patient with rheumatic mitral stenosis in sinus rhythm, auscultation reveals a loud first heart sound, an opening snap, and a mid-diastolic rumble with presystolic accentuation. The interval between the second heart sound and the opening snap measures 60 milliseconds. This short interval indicates:

• A Severe mitral stenosis ✓
• B Mild mitral stenosis
• C Associated severe mitral regurgitation
• D Predominant tricuspid stenosis

Explanation

The B2 to opening snap interval inversely tracks left atrial pressure. Higher left atrial pressure causes earlier snapping open of the stenotic mitral valve after aortic closure, so an interval under about 70 ms signifies severe stenosis, while intervals above 100 ms suggest mild disease. Severe mitral regurgitation would soften S1 and tend to lengthen the interval by lowering late diastolic gradient contribution.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

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