Heart sounds


Normal heart sound consist of two sounds. -First heart sound and second heart sound. Both are best heard in the apex. The apex of the heart is usually at the left 5th intercostal space just medial to the midclavicular line.

Physiology of heart sounds
First heart sound is caused by the closure of the tricuspid and mitral valves and normally lasts for 0.15 seconds with a frequency of about 25-45Hz. The second sound is shorter and lasts for 0.12 seconds with a frequency of about 50Hz. It is caused by closure of aortic and pulmonary valves at the end of ventricular systole. It may be split physiologically between the aortic and pulmonary valves.


Auscultation is the art of listening to the body sounds with the aid of a stethoscope or a machine device. There are normal heart sounds and  abnormal ones and there are also normal breath sounds,  which are said to be vesicular, and abnormal ones.

To listen to breath sounds follow the same points of percussion in auscultation. To listen to heart sounds try to follow the areas where the valves of the heart can be best heard. Also take note of the principles of korotkoff sound.



















Heart sounds  


1 isovolumetric contraction 2 ejection 3 isovolumetric relaxation 4 rapid inflow 5 diastasis 6 atrial systole  



















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Creator: Oluwole Ogunranti