Causes of Acquired Valve Disease

The most common causes of heart valve disease include rheumatic fever, age-related changes, infections and other heart conditions and disorders. All these factors can change the shape and flexibility of the once normal valves. The following is a description of each one of the factors:

Heart Conditions

Certain heart conditions can lead to the distortion of the heart valves. They include:

• Heart attack or heart injury can create scar tissue which can either lead to stenosis or insufficiency of a heart valve.
• High blood pressure - Overtime, high blood pressure can lead to heart failure which causes the heart to enlarge. This may result in insufficiency of the heart valves as the valve openings are stretched.
• Atherosclerosis - Generalized atherosclerotic processes have a strong positive correlation with valvular atherosclerotic changes. Valvular atherosclerosis causes the valve flaps to thicken and stiffen which limits the blood flow through the valve. Atherosclerotic changes most commonly affect the aortic valve.  

Age-related Changes

Elderly men and women tend to have calcium deposits develop on their heart valves. These deposits are quite similar to plaque caused by atherosclerosis. Just like atherosclerosis, this process primarily affects the aortic valve resulting in stenosis.

Rheumatic fever

Rheumatic fever is an inflammatory disease which usually follows streptococcal pharyngitis, or following other diseases which were caused by Streptococcus pyogenes. This disease causes the immune system to become sensitized to the body’s own proteins located in the heart, skin, joints, and brain. The antibodies that form to combat Streptococcus pyogenes can also cross react with heart muscle glycogen, cardiac myofiber protein (myosin), and smooth muscle cells. This can greatly damage the heart valves, causing the leaflets to thicken and fuse together (which may lead to valve stenosis). Rheumatic fever also affects tendinous cords by shortening and thickening them, which can result in valve insufficiency.

Roughly half of the patients with rheumatic fever also develop rheumatic valvulitis, which may lead to stenosis or insufficiency.

Infections

Bacteremia caused by an inflammatory process in some part of the body (usually gums) may lead to a serious complication known as infective endocarditis. Aortic and mitral valves are most commonly affected by infective endocarditis. However, people who acquire infective endocarditis as a result of using dirty needles, may also have right-sided endocarditis affecting the tricuspid valve.

Not only does infective endocarditis cause damage to the valves, the damaged valves themselves are a major risk factor for developing infective endocarditis.

Other conditions linked to heart valve disease

• Autoimmune disorders (including lupus) can affect the heart valves.
• Radiation therapy focused on the chest area can damage the heart valves. Usually, the person doesn’t develop symptoms until years after the therapy.
• Carcinoid syndrome - Digestive tract tumors can spread through the venous system and affect the pulmonary and tricuspid valves.
• Diet medicines - Diet pills that contain phentermine and fenfluramine have been linked to heart valve disease, and is the reason the production of fenfluramine was discontinued in 1997. In clinical trials these drugs resulted in thickening of the leaflets and chordae tendineae, and sometimes led to pulmonary hypertension.

Risk Factors

Risk factors include:

• Old age – The leaflets of heart valves become thicker and stiffer with age. As people live much longer now, heart valve disease is becoming more common.
• History of infective endocarditis, heart attack and heart failure.
• Abuse of intravenous drugs.
• Risk factors that promote atherosclerosis include: smoking, high blood pressure, high blood cholesterol, diabetes, insulin resistance, lack of physical activity, obesity and familial history of early cardiovascular diseases.

 Next Chapter: Symptoms of acquired valve disease