Four heart valves control how blood flows in and out of your heart. The valves are like one-way doors that keep blood flowing in the right direction.
Your mitral valve separates your left atrium and left ventricle. This valve opens to let blood from your lungs out of your left atrium and into the left ventricle. The valve closes to keep blood from running back into your left atrium.
In mitral valve prolapse, the mitral valve bulges back into the left atrium when your left ventricle contracts. If that bulge also causes blood to leak backward into the left atrium, that's called mitral regurgitation.
(See also Overview of Heart Valve Disorders.)
Most people with mitral valve prolapse have no symptoms.
But some people may have:
Awareness of heartbeats
Severe headaches called migraines
Feeling tired and weak all over
A drop in blood pressure when they stand up
Doctors suspect mitral valve prolapse when they hear a clicking sound while listening to your heart with a stethoscope. Doctors use echocardiography (an ultrasound of your heart) to confirm the diagnosis and see if the valve is leaking.