Atrial gallop occurs in which stage of the cardiac cycle?

An atrial gallop, also known as a third heart sound or S4, occurs late in diastole. During this phase of the cardiac cycle, the heart is preparing to fill with blood, and the atria contract to push blood into the ventricles. When there is increased resistance to ventricular filling, which can happen due to conditions such as hypertension or left ventricular hypertrophy, the contraction of the atria can create vibrations that result in the S4 sound.

The presence of this sound can indicate that the heart is working harder to fill the ventricles, making it an important indicator of potential cardiac issues. Understanding the timing of this sound in relation to the cardiac cycle helps in assessing a patient's cardiovascular health.