Fourth Sound

The next extremely important finding is a fourth heart sound. Filling sounds are very, very important. A patient comes to your office, describes distress in the chest and you suspect angina, you listen to the patient carefully, examine them entirely, but at the apex you listen with light pressure on the bell and you can enhance this, again, if the patient is in the left lateral decubitus position, light pressure… For our purposes, to time systole we’ll put a cotton swab on the carotid vessel and everyone listen together. [sounds]

And what did we hear? We heard [sounds], a low-frequency sound just before the first heart sound. You do it, mimic it. [sounds] You know, sometimes you can even feel that movement on the chest wall, because it is low-frequency and can move the chest wall. [sounds] You mimic It. Now, what does that mean? This is a patient with angina, that ischemic myocardium is less compliant and as the atrium in late diastole goes to push that extra bit of blood into the ventricle, that ventricle is less giving, less compliant, the blood decelerates more rapidly and you hear [sounds]. A very, very important finding.

Fourth Heart Sound

The other important filling sound that may be heard at the apex is the fourth heart sound. It occurs in late diastole, when atrial contraction causes rapid blood flow into the ventricle. If the ventricle is less compliant than normal, rapid deceleration of blood occurs and causes low frequency vibrations analogous to those occurring with a third heart sound.

S4 Heart Animation

This is a graphic example of the heart in a patient with hypertension with a fourth heart sound at the apex. In the animation that follows, we can appreciate that the fourth heart sound is generated during late diastole, and it is associated with left atrial contraction.

Volume Curve - Filling Sound S4

This is a graphic example of an S4 filling sound. By simultaneosly viewing the ventricular volume curve, one can appreciate that the fourth sound occurs in late diastole, at the time of rapid flow due to atrial contraction. Let us listen together.