This document describes the four main heart sounds and how to auscultate them using a stethoscope. It explains that the first heart sound corresponds to closure of the atrioventricular valves and the R wave of an ECG. The second heart sound corresponds to closure of the semilunar valves and the T wave of an ECG. The third heart sound occurs during rapid ventricular filling between the T and P waves. The fourth heart sound corresponds to atrial contraction between the P and Q waves. It identifies the best areas over the heart to auscultate each sound using a stethoscope.

1. Physiology practical 1
(Heart sounds)
By : Osama Al-Zahrani
@OSAMA_Z96

2. 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 of ECG

3. 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 of ECG.

4. 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 of ECG.

5. 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 atrial systole.
Fourth heart sound and ECG:
• It coincides with interval between end of ‘P’ wave and onset of ‘Q’ wave in ECG.

6. Heart sounds & ECG
P
Q S
R
T

7. 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

8. Stethoscope

9. • Auscultation means in this practical : the process of listening to the heart sound .
1- Mitral or bicuspid area :
• Situated in the left 5th intercostal space.
• 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

10. 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

11. Auscultation areas

12. Auscultation areas