Detecting the gallop: the third heart sound and its significance
Good technique and a reflective approach assist clinicians to identify an easily missed indicator of ventricular dysfunction
The term “gallop rhythm” was first coined in 1847 by Jean-Baptiste Bouillaud to describe the cadence of three heart sounds occurring in rapid succession. It was further described by his pupil Pierre Potain as follows:
One distinguishes therein three sounds, namely: two normal sounds of the heart and a superadded sound… It is a shock, a perceptible elevation; it is hardly a sound. If one applies the ear to the chest it is affected by a tactile sensation, perhaps more so than an auditory one… In addition to the two normal sounds, this bruit completes the triple rhythm of the heart… This is the bruit de gallop.1
Third heart sound (S3) and fourth heart sound gallops are indicators of underlying ventricular dysfunction; however, the term gallop is only used when the sounds are pathological.
The S3 is a mid-diastolic, low pitched sound (Box 1). In early diastole, the ventricular pressure falls below atrial pressure, and the atrioventricular valves open initiating rapid ventricular filling. Filling slows as the ventricles reach the limit of their elasticity. It is thought that the S3 occurs in the presence of volume overload or ventricular…