Seeing is believing - the S3 heart sound

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Identifying extra heart sounds while auscultating is very challenging. Especially in relation to the third (S3) and fourth (S4) heart sounds.

The third heart sound is very common in children and even in people under 40, but later in life it is an indication of serious problems, like heart failure, and only appears when the problem is relatively far advanced. In some cases the third heart sound may never be heard, due to chest size, obesity or lung sounds, or due to hearing constraints of the listener. Therefore, the absence of a third heart sound does not exclude ventricular dysfunction or volume overload.

The low intensity, very low frequency and small audible area challenge clinicians auscultation skills and in most cases the third heart sound falls outside the human ear’s audio range.

The ability to detect and monitor third heart sounds in older patients is very important as this is associated with heart failure.

Hearing skills of trained cardiologists were recently compared with Sensi. Results confirmed that Sensi detected and indicated the third heart sound in cases where the human ear could not detect it, as well as in cases where the human ear detected the sound. This confirmed the importance of having a tool to assist in identifying extra, impossible-to-hear, heart sounds.

The next two figures show heart sounds recorded at the APEX. Figure 1 shows the presence of a very subtle S3 sound while Figure 2 indicates a prominent S3 sound. In both cases Sensi was used to visually confirm the presence of an S3 sound. S1, S2 and S3 annotation were added by hand.



Figure 1: Subtle S3 sound.

Although very small, a S3 sound pulse is present in the consecutive heart beats shown in Figure 1.


Figure 2: Prominent S3 sound.

  The amplitude of the S3 sound in Figure 2 is of the same magnitude as the S2 sound pulse. In this case the S3 sound could be mistaken for a widely split S2.

Reference: Nirav J. Mehta, Ijaz A. Khan, Third heart sound: genesis and clinical importance, International Journal of Cardiology, Volume 97, Issue 2, Pages 183–186, November 2004.

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