A midsystolic click followed by a late systolic murmur is most characteristic of which condition?

• A. Mitral stenosis
• B. Aortic regurgitation
• C. Tricuspid stenosis
• D. Mitral valve prolapse

Answer: (D)

Midsystolic click with a late systolic murmur is classic for mitral valve prolapse. This happens when the mitral valve leaflets are abnormally floppy and billow back into the left atrium during systole due to myxomatous degeneration. The click comes from the sudden tensing of the chordae as prolapse begins, and the murmur follows later in systole from turbulent flow once the leaflets are prolapsing. It’s best heard at the apex and often radiates toward the axilla, with the exact timing and loudness changing with loading conditions: standing or Valsalva (which reduce LV volume) makes the click occur earlier and shortens the murmur, while squatting (increases LV volume) delays the click and lengthens the murmur. Other valvular diseases produce different timing or diastolic sounds, so this specific pattern points to mitral valve prolapse.