what is responsible for the dub of the heart beat
The Second Heart sound (S2) Dub is caused by blood slamming shut of the semilunar valves (Aortic and Pulmonic). The left side (Aortic valve) is the loud one here because the left side of the heart is the high pressure side. Just like S1, these sounds can be split. Pro Tip: In Tachycardic (fast heart rate) patients, the two sounds LUB DUB sound the same sometimes and its hard to distinguish them.