What are Heart Sounds:
Heart sounds are the sounds produced by mechanical activities of heart during each cardiac cycle. Heart sounds are produced by:
1. Flow of blood through cardiac chambers
2. Contraction of cardiac muscle
3. Closure of valves of the heart.
Heart sounds are heard by placing the ear over the chest or by using a stethoscope or microphone. These sounds are also recorded graphically.
There are 4 sounds produced in heart per beat.
There are 4 sounds produced in heart per beat.
The Four Heart Sounds
Four heart sounds are produced during each cardiac cycle:
- First heart sound
- Second heart sound
- Third heart sound
- Fourth heart sound.
First and second heart sounds are called classical heart sounds and are heard by using the stethoscope. These two sounds are more prominent and resemble the spoken words ‘LUB, (or LUBB) and ‘DUBB’ (or DUP), respectively. Third heart sound is a mild sound and it is not heard by using stethoscope in normal conditions. But it can be heard by using a microphone. Fourth heart sound is an inaudible sound. It becomes audible in pathological conditions only. This sound is studied only by graphic registration, i.e. the phonocardiogram.
Major cause for first heart sound is the sudden and synchronous (simultaneous) closure of atrioventricular valves. Second heart sound is produced due to the sudden and synchronous closure of the semilunar valves.
First and second heart sounds are heard on the auscultation areas, by using the stethoscope. The chest piece of the stethoscope is placed over four areas on the chest, which are called auscultation areas.
Heart Sounds Locations (Positions Where Heart Sounds are audible:
i. Mitral area (Bicuspid area)
Mitral area is in the left 5th intercostal space, about 10 cm away from the midline (midclavicular line). Soundproduced by the closure of mitral valve (first heart sound) is transmitted well into this area. It is also called apex beat area because apex beat is felt in this area. Apex beat Apex beat is the thrust of the apex of ventricles, against the chest wall during systole.
ii. Tricuspid area
Tricuspid area is on the xiphoid process. Sound produced by the closure of tricuspid valve (first heart-sound) is transmitted well into this area.
iii. Pulmonary area
Pulmonary area is on the left 2nd intercostal space, close to sternum. Sound produced by the closure of pulmonary valve (second heart sound) is heard well on this area.
iv. Aortic area
Aortic area is over the right 2nd intercostal space, close to the sternum. On this area, the sound produced by the closure of aortic valve (second heart sound) is heard well.
First heart sound is best heard in mitral and tricuspid Location. However, it is heard in other areas also but the intensity is less. Similarly, the second heart sound is best heard in pulmonary and aortic areas. It is also heard in other areas with less intensity.Demonstration Of Heart Sounds:
Requirements:
Subject, Stethoscope, chair
Procedure:
- Put the
chest piece over the auscultatory areas on the chest and concentrate on
the areas from where the sounds are heard most clearly.
- Listen to
the heart sounds several times but at least three times in order to accustom
your ears with the quality of first and second heart sound.
- After
becoming familiar with the first and second heart sounds note and search
for any other heart sounds.
Precautions:
- The
Subject should be in relax condition.
- Procedure
should be performed in quiet room.
