When do you typically hear an S4 Atrial Gallop?

An S4 heart sound, also known as an atrial gallop, occurs during atrial contraction before the first heart sound (S1). This sound is typically associated with conditions that lead to a stiff or hypertrophied ventricle, where the atrial contraction forces blood into the already filled ventricle. Since the ventricle is non-compliant, this additional flow causes a vibration that produces the S4 sound.

The timing of the S4 sound is crucial; it is heard just prior to the first heart sound (S1) as the atria contract to push blood into the ventricles. This indicates that it occurs in late diastole, but it is specifically related to the action of atrial contraction, making it a key indicator of this phase of the cardiac cycle. The clinical significance of the S4 sound is that it frequently signifies underlying cardiovascular problems, such as left ventricular hypertrophy or decreased ventricular compliance.

Understanding that S4 is linked to atrial contraction helps in identifying the heart's mechanical function, especially in cases like hypertensive heart disease or aortic stenosis, where the ventricles struggle to accommodate the volume from the atria during contraction. Since the other options do not accurately describe when S4 occurs