Auscultation: Heart Sounds


Heart Sounds

Closure of the heart valves is responsible for normal heart sounds.

S1 = Pressure from the contracting left ventricle, exceeds left atrial pressure closing the mitral valve.

Early Systolic Ejection click: may be present in some pathologic conditions with the closing of the aortic valve.

S2 = The aortic valve shutting results in the second heart sound. The valve closes as the left ventricle pressure drops below the aortic pressure.

O.S = Opening Snap = mitral stenosis, as the mitral valve opens as the left ventricle relaxes and its pressure falls below that of the left atrial pressure.

S3 = 3rd heart sound = May occur in children and young adults, Marked by a period of rapid ventricular filling as blood flows early in diastole from left atrium to left ventricle.

S4 = 4th heart sound = Not often heard in normal adults. Marks atrial contraction. It immediatly preceeds S1 of the next beat.

Bates, Barbara. 1974. A Guide to Physical Examination. J.B. Lippincott Company, Toronto.


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