What is mitral valve regurgitation?

Backflow: The mitral valve is the between the left atrium and the left ventricle. As the left ventricle fills with blood, the blood in the left ventricle starts pushing on the mitral valve like the leaflets floating and when the ventricle squeezes, the mitral leaflets don't appose enough and allow some blood to flow back to the atrium instead of forward to the aorta.

Leaky: Your heart valves are supposed to be one way doors. Blood is supposed to be pushed out in one direction with the valve (door) closing behind. If the door doesn't close completely and or some blood leaks backward it is called regurgitation. A little bit is not a problem, a large amount can make the heart need to work too hard.