Valvular Heart Disease
The heart consists of four chambers. The two upper chambers, or atria, pump blood into the lower chambers, or ventricles. The right ventricle pumps blood through the lungs, and the blood then returns with oxygen to the left ventricle. The left ventricle pumps blood to the rest of the body and the veins return blood to the right atria. The valves between the atria and ventricle are the tricuspid valve (right) and the mitral valve (left). The valves out of the heart are the pulmonary valve (right) and the aortic valve (left). These prevent blood from going backwards, optimizing pumping efficiency. There are two possible malfunctions with any valve. The valves can become stenotic, or tight, and cause a flow obstruction, or the valves can become loose or floppy and allow backward flow, or insufficiency. Most valve disease in adults involves the mitral valve or the aortic valve. Rheumatic fever is probably the most common cause of valvular heart disease worldwide. Caused by untreated streptococcal infections, rheumatic fever can cause either stenosis or insufficiency. This is much less common where antibiotics are widely available. The aortic and the mitral valve are also prone to calcification, or thickening, and stenosis with aging.
Mild-to-moderate mitral insufficiency does not require any surgical intervention, but if the insufficiency becomes severe, or if there are signs of worsening heart failure, then repair or replacement of the mitral valve may be necessary. If the mitral valve is too tight, it can cause CHF. This is diagnosed by an echocardiogram. Mitral stenosis can be repaired either by surgery or with a balloon (valvuloplasty). The balloon prevents the need for invasive surgery but may result in some mitral insufficiency. If a patient is not a good candidate for open heart surgery, a valvuloplasty is an attractive option.
Artificial valves are either tissue or metal. Tissue valves are frequently used on older patients because they do not require anticoagulation and cause less risk of stroke, but they tend to wear out within ten to fifteen years. Metal or mechanical valves require special blood thinners (e.g., warfarin) to prevent the valve from clotting up and blocking, and to prevent strokes. These blood thinners do increase the risk of bleeding and require regular monitoring.
The aortic valve occasionally shows significant leaking. If this is mild or moderate, it can be treated with medication. Nifedipine has been shown to reduce the progression and the need for surgery. If regurgitation is severe, valve replacement may be necessary. Aortic stenosis causes an increased strain on the pumping action of the heart. This can lead to angina, CHF, or loss of consciousness (syncope). Surgery is the only definitive treatment with severe aortic stenosis.
The risks of valvular surgery is increased in elderly patients, including an increased rate of perioperative mortality, increased postoperative infection, stroke and renal failure, prolonged hospital stay, and postoperative disability. Operative risks also depend on other comorbidities. Surgical consideration must be individualized for each patient and a balanced discussion of all reasonable risks and benefits is necessary for making the right decision.
Patients with valvular heart disease or artificial heart valves are at increased risk for developing endocarditis—an infection on the heart valve. Antibiotics are needed to prevent such infections when undergoing surgery and dental work.