Mitral regurgitation (MR) and tricuspid regurgitation (TR) are two conditions involving backward leakage of blood through a heart valve when a ventricle contracts. People may experience either or both of these conditions.

More than one-third of people with MR also experience TR. Both conditions involve leaking heart valves. Valve regurgitation happens when the valves do not seal properly as the heart beats, allowing blood to leak in the wrong direction.

MR and TR can range in severity from trace regurgitation, which requires no treatment, to severe regurgitation, which may lead to serious complications.

This article looks at the causes, symptoms, diagnosis, and treatment for MR and TR. It also discusses the outlook for the conditions.

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MR occurs when blood flows backward through the mitral valve on the left side of the heart.

The mitral valve opens and closes as the heart beats. As it opens, blood flows from the top left chamber of the heart, called the left atrium, to the bottom left chamber of the heart, the left ventricle.

As the mitral valve seals with each heartbeat, blood flow between the chambers pauses to prevent blood from traveling backward from the atrium to the ventricle.

If the mitral valve cannot fully close, blood can leak from the ventricle back through the mitral valve and into the left atrium. If the leak is significant or prolonged, MR can cause a strain on the heart, which may lead to complications.

MR can be primary or secondary.

In primary MR, the condition may occur due to structural damage or deformity of the valve flaps (leaflets) or the muscles (chords) that control the movements of the leaflets.

In secondary MR, the valve structure is normal, but changes to the left ventricle or left atrium are responsible for the regurgitation.

Learn more about heart valves.

In TR, blood leaks backward from the bottom right chamber of the heart, called the right ventricle, into the top right chamber, the right atrium.

As the right ventricle contracts to pump blood toward the lungs, blood may leak back into the bottom right chamber. As blood gathers in the atrium, the chamber can enlarge, affecting the pressure of nearby blood vessels. This can lead to various complications.

TR can be primary or secondary.

Abnormalities in the tricuspid valve are the cause of primary TR. In secondary TR, the valve is normal, and dilation of the heart chamber causes the regurgitation.

Learn about the symptoms of leaky heart valves.

There are various potential causes of heart valve regurgitation.

Mitral regurgitation causes

The causes of MR can differ depending on whether the condition is primary or secondary.

Causes of primary MR include:

  • Mitral valve prolapse (MVP): Aging and connective tissue diseases, such as systemic lupus erythematosus and Marfan syndrome, can cause the mitral valve to degenerate, resulting in a prolapse. In MVP, the valve flops into the left atrium, which can prevent it from sealing correctly, allowing blood to leak backward through the valve.
  • Papillary muscle rupture: This is a rare and life threatening occurrence in which one of the papillary muscles that attach to the mitral valve leaflets ruptures. It may happen as a complication of a heart attack.
  • Congenital conditions: A person may develop MR due to structural issues in the mitral valve that are present from birth.
  • Rheumatic heart disease (RHD): RHD is a severe and potentially life threatening disease. Inflammation in the heart tissues related to streptococcal infection damages the heart valves.
  • Infective endocarditis: This condition involves inflammation of the endocardium — the heart’s inner lining — and the heart valves. It can lead to MR.

Causes of secondary MR include:

  • Ischemic MR: This condition causes displacement of the papillary muscles and changes the positioning of the leaflets. This can affect how the leaflets function, leading to MR.
  • Congestive heart failure (CHF): In CHF, the heart cannot pump blood around the body effectively. This may cause the heart to dilate, or enlarge, and can lead to MR.
  • Hypertrophic cardiomyopathy (HCM): In HCM, the anterior mitral valve leaflet is pulled toward the septum, which can lead to MR.

Tricuspid regurgitation causes

An enlarged right ventricle is a common cause of TR. Other causes of TR include:

  • Rheumatoid arthritis (RA): RA causes inflammation, which may damage the heart valves.
  • Infective endocarditis: Endocarditis is a condition that causes inflammation in the heart.
  • Myxomatous degeneration: This condition affects the valve’s structure and function.
  • Marfan syndrome: This condition affects the body’s connective tissues and can damage the heart valves.
  • Phentermine (Fen-Phen) use: Phentermine is an appetite suppressant drug that stimulates the brain and spinal cord. The drug has strong links to valvular heart disease and other heart conditions, including TR.

The treatment for a leaking heart valve can depend on the severity of the condition. In some cases, treatment may not be necessary. However, more severe cases may require surgical repair or replacement using one of the following methods:

Doctors may prescribe medications to treat underlying causes and complications of valvular heart disease, such as arrhythmias and heart failure. Possible medications include:

Read about types of surgery for heart valve replacement.

The outlook and death rates for MR vary greatly depending on the condition’s severity and the presence of other health conditions.

In general, the outlook for secondary MR is worse because it is often a complication of heart failure or coronary artery disease.

The outlook for TR also varies greatly. People with mild or trace TR generally have better outcomes. Severe symptomatic TR is associated with unfavorable outcomes.

Having both MR and TR may affect a person’s outlook. One 2021 study found that the 5-year survival rate of people with both MR and TR was 59.4%. This statistic relates to people with moderate to severe MR and TR.

Mitral regurgitation (MR) is backward leakage of blood from the heart’s left ventricle to the left atrium. Tricuspid regurgitation (TR) is backward leakage of blood from the right ventricle to the right atrium.

These valve leakages may occur individually or together. They may be minor, causing no symptoms, or they may be severe and lead to serious health complications.

MR and TR have various potential causes, which may relate to structural abnormalities in the heart or underlying health conditions.

Doctors may treat MR and TR with surgery to repair or replace the necessary valve or valves.