A healthy heart follows a steady "lub-dub" rhythm. However, medical professionals often listen for variations:
The Mitral Valve and Tricuspid Valve, which sit between the upper atria and lower ventricles. the lub dub sound the heart makes is caused by
Sometimes, the two valves making the "dub" sound don't close at exactly the same time, creating a "split S2." This is often normal during deep breathing but can sometimes signal a medical issue . Summary Table: Heart Sounds at a Glance Valves Closing Cardiac Phase Characteristics Lub Mitral & Tricuspid Start of Systole Lower pitch, longer duration Dub Aortic & Pulmonary End of Systole Higher pitch, shorter duration A healthy heart follows a steady "lub-dub" rhythm
This sequence of sounds is repeated with every heartbeat, creating the characteristic lub-dub rhythm. Summary Table: Heart Sounds at a Glance Valves
the closure of the atrioventricular (AV) valves — specifically the tricuspid and mitral valves — at the beginning of ventricular systole (contraction). The "dub" (second heart sound, S2) is caused by the closure of the semilunar valves — the aortic and pulmonary valves — at the beginning of ventricular diastole (relaxation).
