The mitral valve controls the flow of blood into the left ventricle. Normally, when the left ventricle contracts the mitral valve closes and the blood flows out through the aortic valve.

In mitral valve prolapse, the shape or dimensions of the leaflets of the valve are not ideal - they may be too large and fail to close properly or balloon out - hence the term "prolapse."

Although, in general, healthy hearts are structurally similar, like other parts of the body, there are individual variations....