NBME 20 Answers : Block 3 : #12 = A 46-year-old man has dyspnea, orthopnea, and a ...

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submitted by breis(11),

Patient has Midsystolic murmur heard at the cardiac apex. there is also a LEFT ATRIAL abnormality. Echo shows LEFT ATRIUM is enlarged.

Mid systolic... enlarged left atrium...

Best choice: Mitral Regurg

hpsbwz Why is it regurg instead of stenosis? +2

minhphuongpnt07 Vague question requires a lot clinical reasoning. mitral regurgitation: holosystolic murmur( this cv: midsystolic), enlarged LA, LV Mitral stenosis: diastolic murmur, enlarged LA, normal LV. only best explanation I can think of: early stage Mitral regur, that's why the murmur is not holosystolic but midsystolic and LV still adequately handle the situation +1

dickass @hpsbwz it's regurgitation because the murmur is SYSTOLIC, when the mitral valve is not supposed to make any sound. mitral valve leaks in systole, which causes blood to back up, which causes the left atrium to work harder and eventually hypertrophy. Mitral stenosis would be a DIASTOLIC sound, which is when the left atrium normally contracts. +2