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NBME 23 Answers

nbme23/Block 3/Question#12

A 39-year-old man comes to the physician for a ...

β-Myosin

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submitted by yotsubato(520),

Murmur that is louder with reduced venous return => Hypertrophic cardiomyopathy

HOCM is due to mutations encoding sarcomeres such as myosin binding protein C and beta myosin heavy chain.

btl_nyc  So I thought this was Marfan's because the murmur from HOCM is at the left sternal border, but Marfan's is a defect in fibrillin, not in collagen. +1  
arcanumm  To help rule out Marfran's, it is stated that there are "no history of major medical illness," which I wouldn't expect them to put if there was a syndrome going on. (they also tend to give body habitus descriptors at least) +  




 +1  upvote downvote
submitted by krewfoo99(40),

Wouldnt the HCOM murmur be best heard in the aortic area?

krewfoo99  Correction: Shouldnt it be heard best in the left upper sternal border? +  
usmlehulk  In FA 2018 page 303. patients with HOCM presents with MItral regurgitation due to impared mitral valve closure. Hence this explains the murmur. +  




FA 19, pg. 305 - May see Mitral regurgitation due to impaired mitral valve closure.

I always find it important to remember that once you get pathology somewhere in the heart, you can expect pathology everywhere behind it, over time.

So in this case you start with HCM -> Mitral regurg -> LA dilation -> A.fib -> LA/LV failure -> Pulm edema -> RHF -> etc.

It's always a matter of time.

mario  wrong q bro @ maxillarythirdmolar +