Definition of Mitral regurgitation - chronic:

Chronic mitral regurgitation is a long-term disorder in which the heart's mitral valve does not close properly, causing blood to flow backward (leak) into the upper heart chamber when the left lower heart chamber contracts. The condition is progressive, which means it gradually gets worse.

See also: Acute mitral regurgitation

Causes, incidence, and risk factors:

Mitral regurgitation is the most common type of heart valve insufficiency. After age 55, some degree of mitral regurgitation is found in almost 20% of men and women who have an echocardiogram.

Blood that flows between different chambers of your heart must flow through a valve. The valve between the two chambers on the left side of your heart is called the mitral valve.

Regurgitation refers to leaking from a valve that doesn't close all the way. Diseases that weaken or damage the valve or the heart tissue around the valve cause mitral regurgitation.

When the mitral valve doesn't close all the way, blood flows backward into the upper heart chamber (atrium). This leads to a decrease in blood flow to the rest of the body. As a result, the heart may try to pump harder. This may lead to congestive heart failure.

Mitral regurgitation may begin suddenly, most often after a heart attack. When the regurgitation does not go away, it becomes chronic (long-term).

Mitral valve prolapse (MVP) is a relatively common cause of chronic mitral regurgitation. However, most patients with MVP do not develop severe mitral regurgitation.

One out of three cases of chronic mitral regurgitation are caused by rheumatic heart disease, a complication of untreated strep throat that is becoming less common.

Congenital (present from birth) mitral regurgitation is most often part of a more complex heart defect or syndrome.

Common causes of chronic mitral regurgitation include:

• Coronary artery disease and heart attacks
• Endocarditis
• Heart tumors
• High blood pressure
• Marfan syndrome
• Swelling of the left lower heart chamber
• Untreated syphilis (rare)

Risk factors include an individual or family history of any of the disorders mentioned above and use of fenfluramine or dexfenfluramine (appetite suppressants banned by the FDA) for 4 or more months.