When taking an apical pulse, how is the "lub-dub" sound counted?

The correct approach to counting the "lub-dub" sound when taking an apical pulse is to consider it as one beat. The "lub" sound, known as S1, results from the closure of the atrioventricular valves at the beginning of ventricular contraction. The "dub" sound, or S2, occurs from the closure of the semilunar valves at the end of ventricular contraction. Together, these two sounds indicate one complete heartbeat as they reflect the cyclical process of heart activity.

Understanding this is crucial for accurately assessing heart rate and rhythm since each heartbeat involves both valve closures. Therefore, when conducting a precise count of the pulse, health professionals recognize the "lub-dub" as one coherent event rather than separate beats, which is vital in both clinical practice and documentation. This knowledge reinforces the importance of listening attentively to heart sounds during evaluations.