American Association of Critical-Care Nurses (AACN) Certification Practice Test

Which heart sound is generally considered abnormal?

1. S3 heart sound

2. Both S3 and S4 heart sounds

3. S4 heart sound

4. Normal heart sound

The correct answer is: S4 heart sound

The S4 heart sound is typically associated with abnormal cardiac conditions. It is caused by the vibration of the ventricular wall during the rapid filling phase of the ventricle. This sound is often heard in patients with conditions that lead to increased stiffness of the ventricular wall, such as hypertensive heart disease or aortic stenosis. Unlike the S3 sound, which can be heard in some healthy individuals—especially in those who are younger or athletes—the S4 is more commonly linked with underlying pathology, making it significant when assessing cardiac function. In a clinical setting, the presence of an S4 heart sound can indicate left ventricular hypertrophy or reduced ventricular compliance, which are conditions typically concerning for clinicians. Understanding the implications of heart sounds helps in identifying possible cardiac issues and determining the necessity for further investigation or intervention.