1. Valvular Heart Disease

Valvular heart disease is characterized by damage to or a defect in one of the four heart valves: the mitral, aortic, tricuspid or pulmonary. These conditions occur largely as a result of ageing. Most people are in their late 50s when diagnosed, and more than one in ten people over 75 have it. According to Professor Ben Bridgewater, consultant cardiac surgeon at University Hospital of South Manchester, ‘If the disease is picked up early, the outcomes from surgery are very good. Life expectancy goes back to match that of healthy people the same age.

2. The normal functions that would be affected by the disease.

Normally functioning valves ensure that blood flows with proper force in the proper direction at the proper time. In valvular heart disease, the valves become too narrow and hardened to open fully, or are unable to close completely.
Many of the symptoms are similar to those associated with congestive heart failure, such as shortness of breath and wheezing after limited physical exertion and swelling of the feet, ankles, hands or abdomen. Other symptoms include: * Palpitations, chest pain (may be mild). * Fatigue. * Dizziness or fainting (with aortic stenosis). * Fever (with bacterial endocarditis). * Rapid weight gain.

3. Changes in function caused by the disease
There are many different types of valve disease; some types can be present at birth (congenital), while others may be acquired later in life.
Congenital valve disease. Most often affects the aortic or pulmonic valve. Valves may be the wrong size, have malformed leaflets, or have leaflets that are not attached to the annulus correctly.
Bicuspid aortic valve disease is a congenital valve disease that affects the aortic valve. Instead of the normal three leaflets or cusps, the bicuspid aortic valve has only two. Without the third leaflet, the valve may be stiff (unable to open or close properly) or leaky (not able close tightly).

Acquired valve disease. This includes problems that develop with valves that were once normal. These may involve changes in the structure or your valve due to a variety of diseases or infections, including rheumatic fever or endocarditis. * Rheumatic fever is caused by an untreated bacterial infection (usually strep. throat). Luckily, the introduction of antibiotics to treat this infection has dramatically reduced the numbers of this infection. The initial infection usually occurs in children, but the heart problems associated with the infection may not be seen until 20-40 years later. At that time, the heart valves become inflamed, the leaflets stick together and become scarred, rigid, thickened and shortened. This leads to mitral regurgitation. * Endocarditis occurs when germs, especially bacteria, enter the bloodstream and attack the heart valves, causing growths and holes in the valves and scarring. This can lead to leaky valves. The germs that cause endocarditis enter the blood during dental procedures, surgery, IV drug use, or with severe infections. People with valve disease (except mitral valve prolapse without thickening or regurgitation/leaking) are at increased risk for developing this life-threatening infection.
There are many changes that can occur to the valves of the heart. The chordae tendinea or papillary muscles can stretch or tear; the annulus of the valve can dilate (become wide); or the valve leaflets can become fibrotic (stiff) and calcified.
Mitral valve prolapse (MVP) is a very common condition, affecting 1 to 2 percent of the population. MVP causes the leaflets of the mitral valve to flop back into the left atrium during the heart's contraction. MVP also causes the tissues of the valve to become abnormal and stretchy, causing the valve to leak. The condition rarely causes symptoms and usually doesn't require treatment.

4. Sources Used

* http://www.medicinenet.com/heart_valve_disease/page2.htm#what_causes_valvular_heart_disease

* http://www.hopkinsmedicine.org/heart_vascular_institute/conditions_treatments/conditions/valvular_heart_disease.html

* http://en.wikipedia.org/wiki/Valvular_heart_disease