The S3 ventricular gallop is a transient sound, sometimes only heard in a certain position or phase of respiration. Both experience and knowledge improve detection of the S3, making this truly part of the art of physical diagnosis (Marcus GM Arch Int Med 2006). It is not sensitive for CHF, and most patients are not going to show it. However, in the elderly population it is specific, so when it is there, we would like to recognize it. (In the younger population and in athletes there can be a physiologic third heart sound that is normal).
The S3 gallop represents the sound of excess blood flowing into the ventricle during early diastole. The cadence has been described as “Kentucky” but even better is “SLOSH-ING-in.” Notice the lack of capitalization of the last bit. The S3 can be subtle. Steven McGee in Evidence-Based Physical Diagnosis recommends onomatopoeia for classifying auscultatory findings and describes this as “lub du bub, lub du bub.”
The original description is credited to Potain in 1880: “This sound is dull, much more so than the normal sound . It is a shock, a perceptible elevation ; it is hardly a sound… In addition to the two normal sounds, this bruit completes the triple rhythm of the heart. It thus produces a rhythm of three sounds unequally distinct, and occasionally unequally distant, a rhythm which the ear seizes with extreme facility, provided that it had once perceived it distinctly. This is the bruit de galop.”
The best way to recognize the S3 gallop is to listen to examples, which are widely available online. A recommended resource would be the accompanying sounds to W. Proctor Harvey’s final work, Clinical Heart Disease.
Maneuvers to improve detection of the S3 gallop include quieting the ED (not easy to do), turning the patient to left lateral decubitus (easier) and paying particular attention to expiration. A left-sided S3 is accentuated during expiration. W Proctor Harvey points out in Cardiac Pearls that it is sometimes only heard every third or fourth beat. He also points out that if you press too hard with the bell of the diaphragm, it will disappear. It is also reportedly accentuated with exercise and hand-grip. Press the stethoscope into your ear to prevent air leak (and do the same thing with your headphones when listening to audio examples). If you have trouble with the timing, move the stethoscope to the aortic area and listen for S2, then use that as your anchor for timing as you inch back down to the apex of the heart.
The bottom line is that S3 ventricular gallops can be heard in the ED, and in certain populations they are specific for CHF. Familiarize yourself with the sound through audio recordings. If we know what we are looking for, we are more likely to find it. The next time an S3 presents itself, you will hear it.