Lub-dub-by cadence similar to "Kentucky“ SLOSH’-ing-in
It can be thought of as a sound which is generated when the ventricle is forced to dilate beyond its normal range because the atrium has overloaded volume. As seen in congestive heart failure, which is the most common cause of a S3.
May be normal physiological finding in patients less than age 30.
S3 is low frequency and thus best heard with the bell of the stethoscope at the apex while the patient is in the left lateral decubitus position. .
Caused by the beating of the heart against an inflamed pericardium or lung pleura, which itself has a wide variety of etiologies.
This sound is usually continuous, and heard diffusely over the chest.
If the rub completely disappears when the patient holds his breath it is more likely due to pleural, not pericardial, origin.
Intensity of Murmurs Murmur Grades Grade Volume Thrill 1/6 very faint, only heard with optimal conditions no 2/6 loud enough to be obvious no 3/6 louder than grade 2 no 4/6 louder than grade 3 yes 5/6 heard with the stethoscope partially off the chest yes 6/6 heard with the stethoscope completely off the chest yes