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Third Heart Sound Gallop

Virtual Auscultation

patient torso with stethoscope chestpiece
patient position during auscultation

The patient's position should be supine.


The third heart sound (S3) is a low-frequency sound best heard with the stethoscope bell, pressed lightly on the skin. A third heart sound occurs early in diastole. In the presence of S3, the first heart sound has diminished loudness. The second heart sound becomes louder.

Sudden deceleration of blood flow into the left ventricle from the left atrium causes the third heart sound. Observe the dilated, thin-walled left ventricle with generalized decreased contraction vigor in the cardiac animation video.

In young people and athletes, it is a normal phenomenon. In older people, S3 indicates congestive heart failure.


Heart Sounds Video

Authors and Reviewers

Authored by Dr. Jonathan Keroes, MD and David Lieberman, Developer, Virtual Cardiac Patient. Medically reviewed by Dr. Barbara Erickson, PhD, RN, CCRN. Last Update: 11/28/2021

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