Which heart sound is a sign of pathology in an adult and occurs early in ventricular diastole during rapid ventricular filling?

Which heart sound is a sign of pathology in an adult and occurs early in ventricular diastole during rapid ventricular filling?

• A. S1
• B. S2
• C. S3
• D. S4

Answer: (C)

S3 is the extra heart sound that appears early in diastole during rapid ventricular filling. In adults, it is usually a sign of pathology, reflecting increased ventricular volume or reduced ventricular compliance, as seen with heart failure or volume overload. It follows the second heart sound (S2) and is best heard as a soft, low-pitched gallop with the bell at the apex in the left lateral decubitus position. In contrast, S4 occurs late in diastole just before S1 and is associated with a stiff ventricle, not rapid filling. S1 and S2 are the normal first and second sounds from AV and semilunar valves, respectively. Hence, S3 fits the description of an abnormal early diastolic sound during rapid filling in adults.