Mitral valve prolapse is a heart problem where the mitral valve does not work normally.

The mitral valve is between the left upper chamber (left atrium) and left lower chamber (left ventricle) of the heart. This valve has two leaflets, or flaps, that open when the heart relaxes and close when it contracts. The base of each leaflet is attached to the heart muscle by strong, flexible cords called the chordae tendineae, which control the opening and closing of the mitral valve. These cords are thin and white. They look like the strings of a parachute.

In a normal heart, the two mitral valve flaps close completely, and stay closed, when blood is pumped out of the heart to the body.

When you have mitral valve prolapse, the valve closes after blood flows through. But the valve flaps bulge backward a little when blood is pumped out of the heart. When the valve bulges, it looks like a tiny parachute or balloon.