The Cardiac Exam: Auscultation

S3

S3 occurs at the end of the rapid filling period of the ventricle during the beginning of (ventricular) diastole.  An S3, if heard should occur 120-170 msec after S2. A patient could have a left sided S3 (best heard with the bell of the stethoscope at the apex of heart while the patient is in the left lateral decubitus position), a right sided S3 (best heard with the bell of the stethoscope in the tricuspid region with the patient in the supine position during inspiration) or both.

An S3 can either be physiological or pathological.
A normal S3 is common in:

• children
• young adults (sometimes up to age 35-40)
• third trimester of pregnancy

An abnormal S3 (an S3 heard in anyone above 40) (also known as a ventricular gallop) is associated with:

• decreased myocardial contraction
• myocardial failure
• volume overload of a ventricle (such as from mitral or tricuspid regurgitation)

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(16 October 2006)
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