While auscultating a client's heart sounds, the nurse hears an extra heart sound immediately after the second heart sound (S2). An audible S3 would be considered an expected finding in what client?

A third heart sound (S3) occurs early in diastole immediately after S2, during the rapid ventricular filling phase. In younger people — typically those under 40 years of age — an S3 can be a normal physiological finding because a compliant, healthy ventricle rapidly filling with blood creates this low-frequency sound. It is sometimes called a physiological or benign S3 in this population. Therefore, hearing an S3 in a 20-year-old patient is considered an expected, normal finding and does not necessarily indicate pathology. In older adults, an S3 is generally considered abnormal and is associated with conditions such as heart failure, dilated cardiomyopathy, or volume overload; the aging myocardium is less compliant and an S3 in this population suggests impaired ventricular function. A client taking a beta-adrenergic blocker would not be expected to have an S3 as a routine finding; beta blockers slow the heart rate and reduce myocardial contractility but do not produce an S3. A client who has undergone valve replacement would have altered heart sounds, but an S3 in this context would suggest a pathological process such as ventricular dysfunction rather than a normal finding. The young adult remains the one population where an audible S3 is considered physiologically normal.