Hypertrophy cardiomyopathy: Which murmur?

[.hematoma.]

What murmur is associated with hypertrophic cardiomyopathy? Uworld seems to suggest mitral regurgitation, but I also learned that it can cause a functional aortic stenosis.

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[appcan]

Definitely can cause mitral regurgitation. I believe that, due to the septal hypertrophy and probably some other causes, one of the mitral leaflets is pulled away during systole (see http://circ.ahajournals.org/content/circulationaha/92/7/1680/F4.large.jpg), resulting in blood going back into the left atrium. It could cause aortic stenosis, but I think that would be more likely in a patient with low preload since that means there's less blood/pressure to push the hypertrophied septum out of the way. This is why diuretics including ACEIs/ARBs are contraindicated in hypertrophy cardiomyopathy. Giving beta-blockers/non-dihydropyridine Ca2+ blockers reduces the heart rate, allowing for more filling, and providing enough preload to push the septum out of the way and minimize the aortic stenosis you were talking about. Mitral regurgitation can still occur though despite this.

 

[Instatewaiter]

Definitely can cause mitral regurgitation. I believe that, due to the septal hypertrophy and probably some other causes, one of the mitral leaflets is pulled away during systole (see http://circ.ahajournals.org/content/circulationaha/92/7/1680/F4.large.jpg), resulting in blood going back into the left atrium. It could cause aortic stenosis, but I think that would be more likely in a patient with low preload since that means there's less blood/pressure to push the hypertrophied septum out of the way. This is why diuretics including ACEIs/ARBs are contraindicated in hypertrophy cardiomyopathy. Giving beta-blockers/non-dihydropyridine Ca2+ blockers reduces the heart rate, allowing for more filling, and providing enough preload to push the septum out of the way and minimize the aortic stenosis you were talking about. Mitral regurgitation can still occur though despite this.

There are 2 murmurs common to HoCM- the first is from sub-aortic stenosis. The mitral valve moves anteriorly during systole and obstructs flow out of the aortic valve. This systolic murmur gets worse/louder with valsalva and anything that decreases preload. it gets better/softer with things that increase afterload.

The 2nd murmur is a MR murmur. However, it tends to be mid-systolic rather than pan-systolic. This occurs when the mitral valve hits the septum and the venturi forces prevent it from coapting with the posterior mitral leaflet. This tends to cause a posteriorly directed MR which does not start right when systole starts.