a u s c u l t a t i o n    t u t o r
S3 Gallop

Gallops (are low-pitched sounds) easily missed unless specifically listened for in a quiet room. Listen for
triple heart sounds: couplets alternating with single sounds resembling a horse’s gallop. The couplet may
be either a normalS2 followed closely by an audible S3 or an audible S4 preceding a normal S1.
Differentiating S3 from S4 requires accurate identification of S1 and S2. The gallop rhythm will become
most evident at rates > 100 bpm and some would reserve the term “gallop” for the presence of an S3
and/or S4 and a rate >100 bpm. At very fast rates, S3 and S4 fuse creating a summation gallop in the
middle of diastole.

S3 occurs at the transition from the rapid phase of ventricular filling to the slow-filling phase, as the walls
reach the limits of early diastolic excursion. The resulting reverberations of ventricular muscle and blood
mass cause the sound (Fig. 8–20, page 325 and 8–38). An audible S3 closely follows S2 in early diastole.
It has the cadence of Kentucky: ken. . . . TUCK..eh. By whispering “ken . . . .TUCK..eh” to yourself as you
listen, timing “ken” to S1 and “TUCK” to S2 you can train your ear to listen for the low pitched S3 coincident
with “eh.” If the S3 is from the left ventricle, it is best heard at the apex with the patient lying 45 degrees to
the left side; if from the right ventricle it is best heart near the lower left sternal border. S3 are best heard in
expiration and are accentuated by exercise, abdominal pressure, or flexing the knees on the abdomen, all
of which increase venous return. An S3 is normal in children, young adults and with pregnancy. After the
third decade, it may indicate myocardial systolic dysfunction, with increased LV end-diastolic pressure and
elevated left atrial pressure. It is also seen, although of less concern, when caused by a hyperkinetic
circulatory state as with fever, anemia, hyperthyroidism, or by excessively rapid ventricular filling from mitral
regurgitation or a large left to right shunt due to a VSD.
t h e     h e a r t
Normal Cardiac Cycle
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