What is mitral valve regurgitation?Mitral valve regurgitation is also called "MR". MR happens when some of the blood in your heart leaks from the left ventricle into the left atrium. This causes health problems because the blood flows backward through the mitral valve instead of forward.
The heart has 4 chambers (rooms). The two upper chambers are called atria and the two lower chambers are called ventricles (VEN-trik-ulls). When the heart "beats", the atria push blood into the ventricles. The ventricles then push blood out of the heart. The right ventricle pushes blood into the pulmonary artery, then into the lungs to get oxygen. The left ventricle pushes blood with oxygen into the aorta and out to the body.
There are valves (doors) between the chambers that open and close to direct blood flow through the heart. The mitral valve is made up of two leaflets that come from the front and back of the valve and meet in the middle. As your heart beats, the mitral valve opens to let blood go from the left atrium to the left ventricle. The mitral valve closes when your heart rests between beats. The closed mitral valve should prevent backflow of blood from the ventricle to the atrium.
The mitral valve functions as a one-way valve, allowing oxygen-rich blood that has returned from the lungs to flow from the left atrium into the left ventricle. This occurs while the left ventricle is in its relaxed, uncontracted phase of the heart cycle. When the left ventricle contracts, the mitral valve closes, preventing blood from being pumped back into the left atrium. This ensures that all blood is pumped across the aortic valve into the aorta. If the mitral valve is not functioning properly, due to injury or disease, blood leaks back into the left atrium (regurgitates) when the left ventricle contracts and, simply put, backs up into the lungs.
Because some of the blood being pumped by the left ventricle flows back (regurgitates) into the left atrium, less blood is pumped into the aorta and, ultimately, throughout the body. The heart compensates for this by increasing the size of the left ventricle to increase the amount of blood it is pumping and to maintain an adequate forward flow of blood throughout the body. Unfortunately, compensation eventually leads to impairment of the left ventricle's ability to contract (decompensate), which leads to further back-up of blood into the lungs.