Normal Heart Sounds Lesson #633

patient thorax when auscultating by stethoscope

patient position during auscultation
The patient was supine during auscultation.


The closure of the mitral and tricuspid valves creates the first heart sound. The mitral valve usually closes first, immediately followed by the tricuspid valve. Closure of the aortic and pulmonic valves creates the second heart sound.

This recording is a normal first and second heart sound with a rate of sixty beats per minute. The stethoscope's diaphragm is positioned at the Apex (mitral valve area). Usually, the first heart sound is somewhat louder than the second heart sound when auscultating at the Apex. Sound intensity will vary with the chestpiece's position as well as with the patient's anatomy.

In addition to sound intensity, the first heart sound (S1) can be identified by its timing. At moderate heartbeat rates, the first heart sound follows the longer pause.



Normal Heart Sounds

The first heart sound is produced by the closing of the mitral and tricuspid valve leaflets. The second heart sound is produced by the closing of the aortic and pulmonic valve leaflets.
Authors and Sources

Authors and Reviewers


? v:3 | onAr:0 | onPs:2 | tLb:0 | pv:1
uStat: False | db:0 | cc: | tar: False
| cDbLookup # 0

An error has occurred. This application may no longer respond until reloaded. Reload 🗙