Lub — the start, the spark. Dub — the echo in the dark. Dub — the unexpected mark.
The second normal sound. It happens when the aortic and pulmonary valves close after the heart has finished pumping blood out to the body and lungs. lub dub dub heart sound
The "lub dub" sound is the rhythmic signature of a healthy heart, but an extra beat—creating a "lub dub dub" pattern—often signals something more complex. This three-beat rhythm, known medically as a , can be a normal occurrence in specific groups or a critical warning sign of heart failure. The Anatomy of "Lub Dub" (S1 and S2) Lub — the start, the spark