First Heart Sounds

First Heart Sound - Decreased Intensity Sounds

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A decreased intensity first heart sound can be produced by various heart abnormalities, such as a viral infection of the heart called a cardiomyopathy.

Other conditions include a previous heart attack and decreased thyroid function.

The decreased intensity first heart sound is due to a decrease in the vigor of contraction of the left ventricle. See the anatomy tab.

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The recommended auscultation position for the stethoscope is the Mitral position. For this sound, use stethoscope's Diaphragm.

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The recommended patient position is Supine

Phonocardiogram

This waveform plots sound amplitude on the vertical axis against time on the horizontal axis.

Heart Animation

Lessons

1	First Heart Sound - Loud
2	First Heart Sound (Minimally Split)
3	First Heart Sound (Markedly Split)
4	First Heart Sound - Decreased Intensity
5	Fourth Heart Sound Plus First Heart Sound
6	First Heart Sound plus Aortic Ejection Click

Practice Drill

Listening Tips
A synopsis of important sound features and timing for this abnormality.
S1: Reduced intensity.

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