What Produces The Lub Dub Heart Sounds May 2026

In fact, your heart is mostly silent during the actual pump.

The chaos is the Lub-Dub. The first sound, "Lub" (clinically known as S1), marks the beginning of systole —the phase where the heart squeezes blood out . what produces the lub dub heart sounds

Why the silence between the Dub and the next Lub? That pause is —the heart’s rest and recharge phase. During this silence, the ventricles are relaxing, filling passively with blood from the atria. No valves are snapping shut. It’s the quietest part of the cycle. In fact, your heart is mostly silent during the actual pump