Myxomatous degeneration refers to a pathological weakening of connective tissue

Connective tissue

"Connective tissue" is a fibrous tissue. It is one of the four traditional classes of tissues . Connective Tissue is found throughout the body.In fact the whole framework of the skeleton and the different specialized connective tissues from the crown of the head to the toes determine the form of...

. The term is most often used in the context of mitral valve prolapse

Mitral valve prolapse

Mitral valve prolapse is a valvular heart disease characterized by the displacement of an abnormally thickened mitral valve leaflet into the left atrium during systole. There are various types of MVP, broadly classified as classic and nonclassic. In its nonclassic form, MVP carries a low risk of...

, which is known more technically as "primary form of myxomatous degeneration of the mitral valve."

The degeneration occurs in conjunction with an accumulation of dermatan sulfate

Dermatan sulfate

Dermatan sulfate is a glycosaminoglycan found mostly in skin, but also in blood vessels, heart valves, tendons, and lungs....

, a glycosaminoglycan

Glycosaminoglycan

Glycosaminoglycans or mucopolysaccharides are long unbranched polysaccharides consisting of a repeating disaccharide unit. The repeating unit consists of a hexose or a hexuronic acid, linked to a hexosamine .-Production:Protein cores made in the rough endoplasmic reticulum are posttranslationally...

, within the connective tissue matrix of the valve. The exact mechanism is unknown.

In many cases, the degeneration is limited to the mitral valve

Mitral valve

The mitral valve is a dual-flap valve in the heart that lies between the left atrium and the left ventricle...

 and follows a benign course. When associated with systemic diseases, like Marfan syndrome

Marfan syndrome

Marfan syndrome is a genetic disorder of the connective tissue. People with Marfan's tend to be unusually tall, with long limbs and long, thin fingers....

, the degeneration is more extensive and involves other heart valves. The valves can become sufficiently distorted to cause insufficiency

Aortic insufficiency

Aortic insufficiency , also known as aortic regurgitation , is the leaking of the aortic valve of the heart that causes blood to flow in the reverse direction during ventricular diastole, from the aorta into the left ventricle....

 and regurgitation

Regurgitation (circulation)

Regurgitation is blood flow in the opposite direction from normal, as the backward flowing of blood into the heart or between heart chambers. Can be categorized by:...

. Myxomatous degeneration is, in fact, the most common cause of pure mitral valve insufficiency.