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First Heart Sound (Minimally Split) Reference Guide

First Heart Sound (Minimally Split)

On occasion the first heart sound can be made up of two separate sounds separated by a very small interval (20-30 milliseconds). The Mitral component (caused by closure of the Mitral valve) comes first and is louder than the Tricuspid component (caused by closure of the Tricuspid valve). A minimally split first heart sound is a normal variation of the first heart sound.

Auscultation Sound From Lesson

auscultation sound from lesson

Patient Recording

patient heart or lung sound
First Heart Sound (Minimally Split)

Patient Recording - Half Speed Playback

patient heart or lung sound
First Heart Sound (Minimally Split)


Patient position
The patient's position should be supine.

Listening Tips

S1:Minimal splitting

Waveform (Phonocardiogram)

Observe Cardiac Animation

First Heart Sound (Minimally Split) | Description, Audio and Animations | #39

Authors and Reviewers

Authored by Dr. Jonathan Keroes, MD and Diane Wrigley, PA.
Medically reviewed by Dr. Barbara Erickson, PhD, RN, CCRN.
Last Update: 12/06/2021



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