A third heart sound can be a valuable clinical finding but hearing it may take some skill. The sound occurs when there is a sudden check of the left ventricular wall after rapid filling.


Requirements for hearing a third heart sound:

(1) very quiet environment

(2) fully exposed thorax (not buried in clothing)

(3) fully attentive physician with an unhurried demeanor

(4) high quality stethoscope

(5) bell of the stethoscope applied lightly to the chest

(6) optimizing the patient posture (place the patient on his or her left side if the third sound is not heard when supine)

(7) optimizing placement of the stethoscope:

(7a) over the apical impulse

(7b) if a recumbent posture cannot be maintained then listen over the xyphoid with the patient sitting up and leaning forward)

(8) sustained listening through several heart beats and several breaths

(9) maneuvers to increase ventricular filling and stroke volume (holding up the lower extremities for a few minutes or light exercise)


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