When S4 is present, it indicates which type of heart dysfunction?

The presence of an S4 heart sound, also known as an "atrial gallop," is specifically associated with diastolic dysfunction. This sound occurs when the left atrium contracts to push blood into a stiff or hypertrophied left ventricle. The vibration created by the forceful entry of blood into the ventricle contributes to the S4 sound.

Diastolic dysfunction refers to the impaired ability of the heart to relax and fill adequately during the diastole phase of the cardiac cycle. Conditions such as hypertension, left ventricular hypertrophy, or ischemic heart disease can lead to changes in ventricular compliance, which is reflected in the presence of an S4 sound. This is significant as it often suggests an underlying issue with how well the heart can fill with blood, rather than how well it contracts or ejects blood, which would be implied by a systolic dysfunction.

Understanding the relationship between S4 and diastolic dysfunction assists clinicians in diagnosing conditions that affect heart function, specifically those involving impaired filling rather than impaired contraction.