There are many causes of heart valve disease which range from infections to conditions that cause it to occur later in life.
Congenital Heart Disease: this means an abnormality formed in the womb and a person is born with a defect. There are several types of congenital heart defects, but related to valve, the leaflets may be improperly formed, not large enough or too big, or there may be an irregularity in the way a leaflet is attached.
Bicuspid Aortic Valve Disease: This is a condition in which a person is born with two leaflets, instead of the normal three. The two leaflets function well for a time but have a high propensity to become very stiff later in life.
Infections: Such as endocarditis or rheumatic fever.
Rheumatic fever: This can cause the valve leaflets to swell and stick together.
Endocarditis: This is a serious infection caused by germs that enter the blood stream and attack the heart valves causing leakage, stenosis, growths on the valve or holes in the leaflet.
Coronary Artery Disease: This is the condition where plaque and lipid deposits form on the inside walls of the heart arteries causing blockage to blood flow.
Cardiomyopathy: This is a general term meaning the heart is not pumping blood normally.
Aortic Aneurysms: When a blood vessel wall becomes weak, it tends to bulge or balloon outward. This is called an aneurysm. When it occurs in the aorta it can become a life threatening condition.
Connective Tissue Diseases: These are a myriad of conditions that cause the fibrous connective tissue in the body to become weak or fragile. Since the heart valves are made of this tissue, heart valves can be damaged in this condition.