Lub Dub Sound Heart [patched]

The second sound, the "dub" (medically termed S2), is sharper, shorter, and higher in pitch. It marks the end of systole and the beginning of diastole, the phase where the heart muscle relaxes and refills with blood. After the ventricles have emptied their contents into the pulmonary artery and the aorta, the pressure within these vessels becomes higher than the pressure inside the relaxing ventricles. Gravity and fluid dynamics attempt to force the blood back into the heart, but two semilunar valves—the pulmonary valve and the aortic valve—snap shut to block this return. The collision of blood against these closed valves creates the "dub" sound. This signifies that the heart is taking a split-second pause to refill before the next contraction.

Bilal Hasdemir * The 'lub-dub' sound of a healthy heart is more than just a beat. It's a key to understanding heart health. ... * ... Liv Hospital Heart Murmurs | The Texas Heart Institute® Heart Murmurs. ... Normal heart sounds come in pairs. The sounds are often described as a constant “lub-dub, lub-dub.” The first “... The Texas Heart Institute Heart Murmurs | The Texas Heart Institute® Normal heart sounds come in pairs. The sounds are often described as a constant “lub-dub, lub-dub.” The first “lub-dub” is the sou... The Texas Heart Institute 17.4C: Heart Sounds - Medicine LibreTexts Oct 14, 2025 — lub dub sound heart

The cardiac cycle is divided into two primary phases: (contraction) and diastole (relaxation). Each phase is punctuated by a specific sound, known medically as S1 and S2. The second sound, the "dub" (medically termed S2),