Normal Heart Sounds

Third Heart Sound - Physiologic Sounds

The third heart sound is heard early in diastole. Along with the first and second heart sounds, this extra sound creates a gallop cadence and sounds like "Kentucky."

In this auscultation example the second heart sound is unsplit to make it easier for you to distinguish the third heart sound.

The third heart sound is very low frequency (between 25 hz and 50 hz). Listen with the bell of the stethoscope at the cardiac apex. Asking the patient to lie on his left side will frequently increase the intensity of the third heart sound.

A third heart sound is heard on occasion in normal individuals with no cardiac pathology.

play
pause

The recommended auscultation position for the stethoscope is the Mitral position. For this sound, use stethoscope's bell.

maneuver

The recommended patient position is Supine

Phonocardiogram

This waveform plots sound amplitude on the vertical axis against time on the horizontal axis.

Heart Animation

Lessons

1	First and Second Heart Sounds - Normal and Unsplit
2	First Heart Sound (Minimally Split)
3	Second Heart Sound - Physiologically Split #1
4	Third Heart Sound - Physiologic
5	Innocent Murmur
6	Exercise - Heart Rate 120

Practice Drill

Listening Tips
A synopsis of important sound features and timing for this abnormality.
S2: Unsplit.
Diastole: S3 in early diastole. Low pitch. Galloping (S1,S2,S3) or intermittent sound.

CaseID	35
CourseID	22
CourseCaseOrder	4
ID	18