4

I'm writing a paper and came across a very specific question about heart sounds.

Why is the crescendo-decrescendo systolic murmur best heard at the cardiac base? and why does it radiate to carotids?

Apparently, this question has a definitive answer. I've scoured google, but can't find a single paper that discusses the question (has answers). I'd appreciate any help or a reference that might help me find an answer.

5

It's not, unless you are using the term "base" to refer to the aortic root of the heart rather than the apex.

A systolic "crescendo-decrescendo murmur" is the classic description for the murmur resulting from aortic stenosis. The aortic valve is best auscultated at the right upper sternal border.

In the below diagram, the actual valve locations inside the heart are indicated by the colored ovals, but the location that you best HEAR the valve-related murmurs are indicated by the A P T M in circles for Aortic, Pulmonic, Tricuspid, and Mitral.

enter image description here

You hear a murmur at a different location than the valve itself because of fluid physics and acoustics. A cardiac murmur is a vibratory process occurring due to fluid mechanics; pathological murmurs are due to blood flow along abnormalities in heart structures. If you look at the course of the aorta, from the aortic valve to the carotids etc, you can see how vibration from narrowed aortic valve would easily radiate there.

Anecdotally, I've often heard it more clearly at the LUSB (left upper sternal border, which is generally the pulmonic region) than the right (RUSB), and I'm not sure why - but it was never the apex where I heard it most clearly. There must be some confusion in your sources.

References:

  • 1
    Thank you, this is very helpful! Could you please elaborate more on the patho of the radiation of the carotids? I am having a hard time analyzing that part of the question. – Artur Grigio Jan 28 at 6:41

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.