Electronics in Medicine and Biomedical Instrumentation by Jog Nandini K

Author:Jog, Nandini K. [Jog, Nandini K.]
Language: eng
Format: epub
ISBN: 9788120347243
Publisher: PHI Learning
Published: 2013-05-31T16:00:00+00:00

4.6.1 Phonocardiography

Phonocardiography is a record of heart sounds. Heart sounds are picked up as vibrations and transformed into a varying electric current by a piezoelectric microphone. The signal is amplified and recorded as a graph. This is a non-invasive technique, and is useful for detecting heart murmurs or unusual heart sounds such as gallops.

Heart Murmurs

During a cardiac cycle, the normal heart produces repeatable sounds. However, under certain abnormal conditions, such as heart valve disease or ventricular septal defects, there is turbulent flow of blood which leads to the production of additional sounds called murmurs. Karotkoff identified 17 sounds out of which only 4 sounds are of significance.

The 1st sound is due to the closure of the mitral and tricuspid valves.

The 2nd sound is that of the closure of aortic and pulmonary valves.

The 3rd sound is rapid ventricular filling in early diastole.

The 4th sound is ventricular filling due to atrial contraction.

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