Murmurs at left sternal border?

[britesky89]

Hey, I have a question about the location of heart murmurs.

The tricuspid area and the area for aortic/pulmonic regurg are both along the left sternal border. The tricuspid is the lower left sternal border, while aortic regurg is upper left sternal border.

So when they describe a left sternal murmur in a question stem, how do you know which one they're referring to? This always gets me! When ever I get a question that says "left sternal border" I get stuck!

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[Transposony]

Associated symptoms/findings usually helps since AR is quite unique.

 

[theTruth_97]

you bring up a good point. today on Uworld I saw a question where it said that the HOCM murmur was best heard at left lower sternal border, but according to First Aid it's best heard at Left Upper Sternal border so idk which one to "believe"

 

[Transposony]

Murmurs are best heard in the direction of the blood flow at an area closest to the chest wall.
So, it makes sense that the HOCM murmur is best heard at left upper sternal border (being a LV outflow obstruction). However, it is also associated with SAM (systolic anterior motion of the mitral valve) and therefore a murmur at left lower sternal border (similar to an MR murmur).

 

[theTruth_97]

thanks so much transposony!.....but one more question- I though MR is best heard at the apex of the heart?

 

[Jabbed]

Hey, I have a question about the location of heart murmurs.

The tricuspid area and the area for aortic/pulmonic regurg are both along the left sternal border. The tricuspid is the lower left sternal border, while aortic regurg is upper left sternal border.

So when they describe a left sternal murmur in a question stem, how do you know which one they're referring to? This always gets me! When ever I get a question that says "left sternal border" I get stuck!

I feel like the "upper sternal border" is generally described as the left 2nd intercostal space and "lower left sternal border" is interchangeable with "left sternal border". If you've isolated the timing of the murmur to systole vs diastole though and have a general description of its sound it should be fairly obvious anyways.

 

[Jabbed]

...

 

[Transposony]

thanks so much transposony!.....but one more question- I though MR is best heard at the apex of the heart?

You are absolutely correct. MR murmur is best heard at the apex of the heart.
HOCM murmur is a complex murmur and the site where it is best heard will depend on the other factors.
For example, when it is pure LV outflow obstruction it will be best heard at left upper sternal border.
When it is associated with SAM it will be best heard at left lower sternal border.
When it is associated with MR it will be best heard between an area from left lower sternal border till the apex of the heart.

I don't think they will ask about this on Step 1 since they have many more specific things to ask on HOCM.

 

[theTruth_97]

thanks again! really appreciate you taking the time to answer!

 

[britesky89]

You are absolutely correct. MR murmur is best heard at the apex of the heart.
HOCM murmur is a complex murmur and the site where it is best heard will depend on the other factors.
For example, when it is pure LV outflow obstruction it will be best heard at left upper sternal border.
When it is associated with SAM it will be best heard at left lower sternal border.
When it is associated with MR it will be best heard between an area from left lower sternal border till the apex of the heart.

I don't think they will ask about this on Step 1 since they have many more specific things to ask on HOCM.

Hi, just want to make sure I'm understanding correctly. About HOCM, when it's associated with SAM, it would be heard at lower sternal border because that is close to the location of the mitral valve, right?

Whereas, when it is purely a LV outflow obstruction the murmur is only due to the flowing of blood against the obstruction so it will be heard loudest as the blood flows out of the heart, i.e. upper left sternal border as blood is gushing out, right?

Thanks for taking the time answer my question!

 

[Transposony]

Hi, just want to make sure I'm understanding correctly. About HOCM, when it's associated with SAM, it would be heard at lower sternal border because that is close to the location of the mitral valve, right?

Whereas, when it is purely a LV outflow obstruction the murmur is only due to the flowing of blood against the obstruction so it will be heard loudest as the blood flows out of the heart, i.e. upper left sternal border as blood is gushing out, right?

Thanks for taking the time answer my question!

Yes, that is my understanding.
However, you can hear HOCM murmur anywhere from between left upper sternal border till apex depending on the associated dysfunction.

 

[Instatewaiter]

Murmurs are best heard in the direction of the blood flow at an area closest to the chest wall.
So, it makes sense that the HOCM murmur is best heard at left upper sternal border (being a LV outflow obstruction). However, it is also associated with SAM (systolic anterior motion of the mitral valve) and therefore a murmur at left lower sternal border (similar to an MR murmur).

Hi, just want to make sure I'm understanding correctly. About HOCM, when it's associated with SAM, it would be heard at lower sternal border because that is close to the location of the mitral valve, right?

Whereas, when it is purely a LV outflow obstruction the murmur is only due to the flowing of blood against the obstruction so it will be heard loudest as the blood flows out of the heart, i.e. upper left sternal border as blood is gushing out, right?

Thanks for taking the time answer my question!

HoCM always has SAM. This is one of the things that gives the O in HoCM (ie for obstruction). The anterior mitral leaflet moves in systole (Systolic Anterior Motion) toward the septum causing theobstruction of the LV outflow tract that defines HoCM. There is often concomitant mitral regurgitation in HoCM however which can explain the apical murmurs but isnt the HoCM murmur.

The HoCM murmur is along the sternal border. They will give you more information on the test (usually valsalva increasing the murmur or a young guy with a familial cardiomyopathy) to help you distinguish between the other murmurs it could be.

Other Murmurs along the sternal border-
AI is diastolic. It is one of the few diastolic murmurs along the sternal border (PI and TS are not only rare but near impossible to hear).

Other things at the sternal border- PDA, VSD, TR.

The exact location (upper/lower) doesn't really matter in clinical practice.

 

[Instatewaiter]

Without SAM- HoCM is just hypertrophic cardiomyopathy (ie HCM). The distinction is of vital clinical importance- it has major implications for prognosis and treatment.

 

[Transposony]

Approximately one-third of symptomatic patients demonstrate a resting intraventricular gradient that impedes outflow during systole and is exacerbated by increased contractility. This was previously termed hypertrophic obstructive cardiomyopathy (HOCM), as distinguished from nonobstructive hypertrophic cardiomyopathy. Other terms that have been used include asymmetric septal hypertrophy (ASH) and idiopathic hypertrophic subaortic stenosis (IHSS). However, the accepted terminology is now hypertrophic cardiomyopathy with or without an obstructive gradient.
MR in HOCM occurs as a consequence of anterior papillary muscle displacement and systolic anterior motion of the anterior mitral valve leaflet into the narrowed LV outflow tract.

---Harrison's Cardiovascular Medicine

 

[Jabbed]

Pretty sure that he's a cards fellow.

 

[Transposony]

The obstructive form of hypertrophic cardiomyopathy (HOCM) is associated with a mid-systolic murmur that is usually loudest along the left sternal border or between the left lower sternal border and the apex. The murmur is produced by both dynamic left ventricular outflow tract obstruction and MR, and thus, its configuration is a hybrid between ejection and regurgitant phenomena.

---Harrison's Cardiovascular Medicine

 

[Instatewaiter]

Thanks for telling me how it is based on a textbook. I have seen and examined a HoCM patient or two

 

[Instatewaiter]

HoCM is not a single disease process so the murmurs will change based on the cause of the obstruction...

It can be related to how the pap muscles insert and can be related to obstruction from a large or strange geometrical configuration of the pap-muscle/septum interaction . It can be for a floppy anterior leaflet and can even be due to a reduntant posterior leaflet in rare cases. Or can be the 'normal' SAM of the anterior leaflet. Each of these things will have different characters of murmurs as they interact the flow through the mitral valve, the degree of MR and the degree of LVOT obstruction

 

[Transposony]

I have seen more HoCM patients that you have seen patients young man... at a heart hospital that is a major leader in HoCM care and does more surgeries for HoCM than anywhere else in the world... but thanks for telling me how it is based on a text book.

I don't want to enter into a pissing contest with you but remember that assuming things about a person on the internet is probably not a very wise move.
That's the first thing they teach about internet now-a-days in Elementary school.
And I am not telling you anything, I only posted the quotes from textbook so that people on this Step 1 subforum can decide for themselves what peer reviewed experts have to say and how much of that is relevant for Step 1.
If I wanted to tell you something I would have quoted your post.

 

[Instatewaiter]

I don't want to enter into a pissing contest with you but remember that assuming things about a person on the internet is probably not a very wise move.
That's the first thing they teach about internet now-a-days in Elementary school.
And I am not telling you anything, I only posted the quotes from textbook so that people on this Step 1 subforum can decide for themselves what peer reviewed experts have to say and how much of that is relevant for Step 1.
If I wanted to tell you something I would have quoted your post.

Ah... playing the old mysterious card... but the internet is a great thing. For instance, I can figure out when you took step 1 and 2 and figure out that you're at the point where you're either an intern or a 2nd year resident. So at this point perhaps you have run into 1 or 2 HoCM patients ever - assuming you went into IM. If you went into something else, you've probably never actually examined a HoCM patient... again, thanks for telling me what HoCM is and sounds like from a textbook.