Heart Sounds and Heart Murmurs, Animation.

When a healthy heart beats, it makes a “lub-dub” sound. The first heart sound “lub”, also known as S1, is caused by the closing of the AV valves after the atria have pumped blood into the ventricles. The second heart sound “dub”, or S2, originates from the closing of the aortic and pulmonary valves, right…