This presentation deals with significance and causes of third heart sound.

1. ‫الرحیم‬ ‫الرحمن‬ ‫هللا‬ ‫بسم‬

2. Third Heart Sound
SIGNIFICANCE

3. S3
 Third heart sound (S3) is produced in the ventricle due to
abnormal filling pattern. It is a low-pitched sound heard at
the end of rapid filling phase (early diastole). It occurs 0.14---
-0.22 seconds after the second heart sound.
 A third heart sound arising from the left ventricle is known as
"left-sided third heart sound" and the one arising from right
ventricle as "right-sided third heart sound".

4. S3
 S3 is best heard with the bell of stethoscope.
 Left-sided S3 is best heard during expiration with the patient
in the left lateral position.
 Right-sided S3 is best heard during inspiration.
 Left-sided S3 may be physiological or pathological. Right-
sided S3 is always pathological.

5. Causes of Third Heart Sound
Physiological S3 Hyper dynamic
States
Pathological left-
sided S3
Pathological right-
sided S3
• Children
• Under 40 years
• Athletes
• Pregnancy
• AV fistula
• Thyrotoxicosis
• Left ventricular
failure
• Aortic
regurgitation
• Mitral
regurgitation
• lschaemic heart
disease
• Cardiomyopathy
• Right ventricular
failure