A healthy heart is defined as much by silence as by sound. In a standard healthy individual, there is silence between the "Lub" and the "Dub" (during systole), and silence between the "Dub" and the next "Lub" (during diastole).
The lub-dub sound is an essential indicator of cardiovascular health. A normal lub-dub sound is a sign of a healthy heart, while abnormal sounds can indicate potential problems. For example: what is lub dub sound in heart
Mechanism: Semilunar Valve Closure