distinguishing S3 and mitral stenosis

[yoyohomieg5432]

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how are you supposed to tell these apart from auscultation? Both are diastolic sounds. both can be associated dyspnea, paroxysmal nocturnal dyspnea , etc

where is S3 "best heard"?

 

[slz1900]

MS will cause an opening snap followed by a late diastolic rumbling murmur. S3 will have a diastolic sound as well but there is no murmur. Both are heard over the apex.

 

[Phloston]

Slz1900 is right about the sounds.

However I'd normally consider an S3 to be a murmur. There's only no murmur if it's S1/2 + nil. I'm not a cardiologist so maybe I'm wrong, but if there's a reputable source saying S3/4 aren't murmurs I'd be keen to see it.

Apart from that, the vignettes will differ substantially. S3 is normally seen in someone with heart failure with reduced ejection fraction/systolic dysfunction. The heart will be dilated on CXR and apex beat displaced laterally. Yes, you can get S3 in pregnancy and in young athletes, but for the sake of the USMLE, heart failure is lightyears more common.

MS is seen in adults with history of rheumatic fever. 99% of MS is due to prior RF. RF causes MS acutely, but it becomes MS over time. The <1% of MS is Libman-Sacks endocarditis seen in SLE (increased if + lupus anticoagulant). So for MS they'll mention an immigrant most often, or someone who had MR as a kid after an infection. MS can also appear acutely during pregnancy (as does S3), but MS will present as acute dyspnea in pregnancy due to pulmonary oedema from sudden increase in preload; the S3 in preggers is most often incidental.

 

[slz1900]

Slz1900 is right about the sounds.

However I'd normally consider an S3 to be a murmur. There's only no murmur if it's S1/2 + nil. I'm not a cardiologist so maybe I'm wrong, but if there's a reputable source saying S3/4 aren't murmurs I'd be keen to see it.

Apart from that, the vignettes will differ substantially. S3 is normally seen in someone with heart failure with reduced ejection fraction/systolic dysfunction. The heart will be dilated on CXR and apex beat displaced laterally. Yes, you can get S3 in pregnancy and in young athletes, but for the sake of the USMLE, heart failure is lightyears more common.

MS is seen in adults with history of rheumatic fever. 99% of MS is due to prior RF. RF causes MS acutely, but it becomes MS over time. The <1% of MS is Libman-Sacks endocarditis seen in SLE (increased if + lupus anticoagulant). So for MS they'll mention an immigrant most often, or someone who had MR as a kid after an infection. MS can also appear acutely during pregnancy (as does S3), but MS will present as acute dyspnea in pregnancy due to pulmonary oedema from sudden increase in preload; the S3 in preggers is most often incidental.

I've always thought that murmurs were related to turbulent flow through valves and therefore had a certain duration, while sounds were not related to valvular flow and therefore just produced a single sound . Hence, a diastolic plop with a myxoma would be a sound and not a murmur. This medscape article also draws that distinction, but I am also not sure if there really is a formal distinction.

 

[Phloston]

I've always thought that murmurs were related to turbulent flow through valves and therefore had a certain duration, while sounds were not related to valvular flow and therefore just produced a single sound . Hence, a diastolic plop with a myxoma would be a sound and not a murmur. This medscape article also draws that distinction, but I am also not sure if there really is a formal distinction.

I think you might be right. And by all means, it's not uncommon to hear, "S1/2, no murmurs, no added sounds." And I notice Wiki has them under different headings as well. I really appreciate it mate!