Public Safety Training Facility
Monroe Community College
Rochester, New York
The Third Heart Sound
Examine the illustration and play the WAV file multiple times. It is more important to learn the cadence (pattern / timing) than the quality of the sounds at this point.
Remember and review the cardiac events as you listen. S3 is a low intensity, low pitch sound that is best heart with the bell of your stethoscope pressed lightly on the apex area of the heart. S3 is created when the ventricles relax and pressure from the filling blood rapidly distends the ventricle. When the stiff, non-complient ventricular wall reaches its physical limits, it suddenly tenses, and the S3 sound is created. In children an S3 is common and normal. After age 40, it almost always indicates the failing heart in congestive heart failure. Note this illustration is at a slow rate to facilitate learning. Most patients in failure will have rapid hearts. Learning the cadence is your first task. Once you are very comfortable with the cadence, turn the volume down to a point where you can just hear the S3. This will be a more realistic representation of the S3 gallop. We will soon be providing examples of these heart sounds at different rates.
Often a patient with a failing heart has a tachycardia to attempt to meet the bodies needs. Here is an S3 gallop with a tachycardia.
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Updated: August 12, 1998