Holosystolic murmurs begin at the very onset of systole, as pressure in the ventricle exceeds that in the atrium. Hence, the murmur begins with the first heart sound (S1) and continues throughout systole until the diminishing ventricular pressure equals that in the atrium. The murmur goes into and obscures the second sound (S2). The murmur is usually “flat” in intensity and blowing in pitch or timbre.
When regurgitation is of a large magnitude, diastolic blood return from the atrium to the ventricle produces a third heart sound (S3) and a diastolic flow rumble (FR).
Return to Heart Sounds Podcast Series
Updated May 2009