by Sr Anne PONNATTIL

1. Physiology of Heart sounds
Sr. Anne ponnattil

2. Dfinition
The mechanical activities of the heart during each cardiac cycle
produces some sounds, which are called heart sounds
The first and second heart sounds can be heard by using a
stethescope. The third heart sound can be heard by using a
microphone. Can be heard with Stethescope in children and
athletes. The fourth heart sound is inaudible. Studied with
graphic registration-- phonocardiogram
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3. 1st heart sound
• It is produced during isometric contraction and earlier part of
ejection period.
• It resembles spoken word ‘LUB’ of"lub-dub"
Characteristics:
• It is long, soft, low pitched sound.
• Duration of this sound is 0.10 – 0.17 sec
Causes:
• It mainly occurs due to sudden closure of atrioventricular valves.
First heart sound and ECG:
• It coincides with peak of ‘R’ wave ofECG

4. 2nd heart sound
• It produces during the onset of diastole.
• It resembles the spoken word ‘DUB’ of"lub-dub"
Characteristics:
• It is short, sharp and high pitched sound.
• Duration of this sound is 0.10 – 0.14 seconds.
Causes:
• It mainly produces during sudden closure of the semilunar valves :
(aortic & pulmonary valves).
Second heart sound and ECG:
• It coincides with the ‘T’ wave ofECG.

5. 3rd heart sound
• It is produced during rapid filling period of the cardiac cycle.
Characteristics:
• It is short and low pitched sound.
• Duration of this sound is 0.07 – 0.10 seconds.
Causes:
•It is produced due to the vibrations which set up in ventricular wall,
due to rushing of blood in to ventricles during rapid filling phase.
Third heart sound and ECG:
• It appears between ‘T’ and ‘P’ waves ofECG.

6. 4th heart sound
• It is produced during atrial systole and considered as physiologic heart sound.
Characteristics:
• It is short and low pitched sound.
• Duration of the sound is 0.02 – 0.04 seconds.
Causes:
• It occurs due to vibrations which set up in atrial musculature during atrialsystole.
Fourth heart sound and ECG:
• It coincides with interval between end of ‘P’ wave and onset of ‘Q’ wave in ECG.

7. Heart sounds & ECG
P
Q S
R
T

8. Stethoscope
- Stethoscope :
Is a medical device for auscultation & measure.
- Main part of Stethoscope :
1- Diaphragm (Use for high frequency sounds).
2-Bell (Use for low frequency sounds).
3 drum.
4 Tubing.
5 Ear tips.
- Uses of Stethoscope :
Measure heart rate & heart sound
Measure respiratory rate & respiratory sound

9. Stethoscope

10. • Auscultation means in this practical : the process of listening to the heart sound .
1- Mitral or bicuspid area :
• Situated in the left 5th intercostalspace.
• This is the area of apex beat.
• Mitral valve sound best heart near this region.
2- Tricuspid area :
• Present over xiphoid process.
• Tricuspid valve sound best heart near this region.
(1st heart sound is best heard in this areas)
Auscultation areas
Xiphoid process

11. 3- Pulmonary area :
• Present over the left 2nd intercostal space close to the sternum.
• Semilunar valve sounds are best heard near this region.
4- Aortic area :
• Situated over right 2nd intercostal space near to the sternum.
• Semilunar valve sounds are best heard near this region.
(2nd heart sound is best heard in this areas)
Auscultation areas

12. Auscultation areas

13. Auscultation areas