Lub-dub Sound Of Heart Is Caused By [top] Page

The human heart is often compared to a tirelessly working pump, but it is perhaps better described as a rhythmic percussion instrument. Every minute of every day, it produces a signature "lub-dub" sound that clinicians use as a primary indicator of cardiovascular health.

The "lub" occurs at the beginning of —the phase where the heart's lower chambers (ventricles) contract to push blood out to the body and lungs. As the ventricles squeeze, the pressure inside them rises sharply. To prevent blood from flowing backward into the upper chambers (atria), two valves snap shut: The Mitral Valve: Located on the left side. The Tricuspid Valve: Located on the right side. lub-dub sound of heart is caused by

The "dub" occurs at the beginning of —the phase where the ventricles relax to refill with blood. Once the ventricles have finished pumping blood into the aorta and the pulmonary artery, the pressure in those major vessels becomes higher than the pressure inside the relaxing ventricles. To prevent blood from falling back into the heart, two more valves snap shut: The Aortic Valve: Leading to the rest of the body. The Pulmonary Valve: Leading to the lungs. The human heart is often compared to a