Lub-dub Sound

| Feature | S1 ("Lub") | S2 ("Dub") | | :--- | :--- | :--- | | | Closure of Mitral & Tricuspid valves | Closure of Aortic & Pulmonic valves | | Phase | Marks onset of Systole | Marks onset of Diastole | | Sound Quality | Lower pitch, longer duration | Higher pitch, shorter, sharper | | Best Heard At | Cardiac Apex (5th ICS, MCL) | Cardiac Base (2nd ICS, RSB) |

The lub-dub is not just a cute onomatopoeia – it’s a precise acoustic event from valve closures. Mimic it correctly, and you’re speaking the language of cardiology. lub-dub sound

The "Lub-Dub" is the heartbeat's punctuation mark. signals the ventricles are squeezing (systole), and S2 signals they are relaxing (diastole). Mastering the distinction between these two sounds is the prerequisite for identifying valve pathologies, murmurs, and gallops. | Feature | S1 ("Lub") | S2 ("Dub")