Mitral valve prolapse and other valvular disorders
Mitral valve prolapse
Mitral valve prolapse is a relatively common disorder, and affects from 2% to 10% of the general population, depending on the study. Although it usually causes no trouble at all, it is associated with bothersome symptoms in some people and serious problems in about one in 10 persons with the disorder.
Mitral regurgitation
Mitral regurgitation is a condition in which the mitral valve allows blood to flow back from the left ventricle into the left atrium during systolic contraction. The left ventricle generates the highest pressure of any of the four chambers in the heart, while the left atrium normally experiences only normal pressures.
Acute mitral regurgitation is a medical emergency that requires in-hospital treatment under the care of one or more specialists. Chronic mitral regurgitation is far more common. The mitral valve can become regurgitant for many reasons, including:
- Age-related degeneration
- Rheumatic valvular disease (a complication of rheumatic fever)
- Previous infection of the valve (Endocarditis)
- Chest trauma
- Left ventricular enlargement due to previous myocardial infarction (heart attack) or some other cause
If chronic mitral regurgitation is mild, there is a minimal effect on the overall health of the person (except for the need for prophylactic antibiotics). Many patients who have left ventricular enlargement from causes such as damage to heart muscle from heart attacks will have mild to moderate mitral regurgitation.
If the condition is moderate to severe, the left atrium will enlarge ("dilate") to compensate for the extra volume it faces; not only must it hold the blood returning from the lungs between heart beats, but it must also hold the extra blood that leaks backward when the left ventricle contracts.
The left ventricle also, over time, can enlarge because it too must handle the extra volume of blood that returns from the left atrium. Enlargement of the left atrium can cause several types of symptoms: fatigue, pulmonary edema (fluid accumulation in the lungs), atrial fibrillation (heartbeat that is completely irregular) and atrial flutter (a very fast, steady heartbeat), and left atrial thrombi (clots) that can cause strokes. Enlargement of the left ventricle can cause both forward and backward congestive heart failure, either of which can be fatal.
Mitral stenosis
Mitral stenosis is a condition in which the mitral valve is narrowed and/or non-compliant, so that blood cannot flow easily from the left atrium to the left ventricle. In response, the left atrium will enlarge ("dilate") to develop the extra pressure it needs to push blood into the left atrium. The pressure in the left atrium rises above normal, leading to shortness of breath. This happens because the blood from the lungs drains into the left atrium. The amount of blood in the blood vessels of the lungs increases if flow into the left atrium is slowed by increased left atrial pressure. This extra blood in the lungs then leaks into the air spaces of the lungs, causing shortness of breath. Often, the symptom of shortness of breath ("dyspnea") is worsened by exertion or by lying down for several hours.
The enlargement can, and often does, lead to atrial fibrillation, which can lead to stroke.
Read more about arrhythmias.
If mitral stenosis is mild, there is a minimal effect on the overall health of the person (except for the need for prophylactic antibiotics). If the condition is moderate to severe, the person develops symptoms that can be difficult to control, including dyspnea, swelling of the legs and abdomen, and even syncope (fainting) and chest pain. Dangerous problems with thrombus formation in the left atrium can lead to stroke, heart attack, or infarction in other parts of the body such as the arm, kidney or spleen.
Aortic regurgitation
Aortic regurgitation is a condition in which the aortic valve allows blood to flow back into the left ventricle from the aorta. Some of the blood that should be flowing to the body from the heart instead flows back into the left ventricle as soon as the heart stops squeezing. As a result, the left ventricle has to pump more blood than normal in order to deliver the normal blood flow to the body. Acute aortic regurgitation is a medical emergency that requires in-hospital treatment under the care of one or more specialists. Most patients have chronic aortic regurgitation.
Chronic aortic regurgitation can be caused by a number of diseases, such as chronic hypertension that dilates the aortic root, rheumatic valvular disease, chest trauma, infection of the heart valve (endocarditis), certain congenital disorders, and autoimmune diseases.
If this condition is mild, there is a minimal effect on overall health. If the condition is moderate or severe, however, the left ventricle must enlarge in order to maintain its high pumping volume or cardiac output. If the enlargement process goes too far, permanent damage can occur and replacement of the valve can become dangerous.
People with chronic aortic regurgitation can do well for many years when they follow a low salt diet and take drug therapy that controls the symptoms of congestive heart failure and helps reduce the amount of blood that flows back into the heart after each heart beat (afterload reducing agents). It is important to replace the valve before irreversible damage to the left ventricle occurs, however.
Aortic stenosis
Aortic stenosis is a condition in which the aortic valve is stiff and the aperture is narrowed. This means that the opening through which blood must flow is too small, so that the left ventricle must generate higher pressure in order to maintain normal blood flow. When the condition is mild, there are usually no discernible ill effects. When the condition is severe, however, it can be life threatening.
The aortic valve can become stenotic in three situations:
- Bicuspid aortic valve (up to 2% of infants are born with two instead of three leaflets in their aortic valves)
- Rheumatic valvular disease, a complication of rheumatic fever
- Age-related calcification of the previously normal aortic valve, also called aortic valve sclerosis, which refers to the build-up of calcium deposits on the valve
The first two circumstances are more common in people younger than 65 years, while the last is more common in ages 65 and older.
The aortic valve is usually replaced if aortic stenosis causes angina pectoris (heart-related chest pain), syncope (fainting), or congestive heart failure. People who suffer these symptoms because of aortic stenosis often die within two to five years, sometimes suddenly. The stenotic aortic valve can be replaced safely in almost all patients who are otherwise healthy. Decreased left ventricular function, which can prevent surgery in other conditions, is not a reason to avoid surgery in aortic stenosis. This is true because the left ventricle is straining against a tight valve, and almost always recovers when the tight valve is replaced with an artificial one.
Replacement of the stenotic aortic valve is sometimes recommended in patients who have not yet developed symptoms but who have very narrow. Not all physicians agree on when to do valve replacement surgery in people with aortic stenosis who have no symptoms. The rationale for doing so is that the first symptom of aortic stenosis can be sudden death.
Tricuspid regurgitation
Tricuspid regurgitation is a condition in which the tricuspid valve is too leaky, so that blood flows backward from the right ventricle to the right atrium. It occurs in two settings: by itself, and in combination with a disease process that elevates right ventricular pressure. It is relatively uncommon.
Tricuspid stenosis
Tricuspid stenosis is a condition in which the tricuspid valve is too tight. This is almost always due to rheumatic valvular disease (a condition in which heart valves are damaged by rheumatic fever), and is usually associated with damage to the mitral and/or the aortic valves.
Pulmonic regurgitation
Pulmonic regurgitation is a condition in which the pulmonic valve allows blood to flow back into the right ventricle from the pulmonary artery. It is quite rare. In the unusual case of severe pulmonic regurgitation associated with right heart failure, despite administration of digoxin, valve replacement should be considered.
Pulmonic stenosis
Pulmonic stenosis is a condition in which the pulmonic valve is narrow. It is also relatively rare. In severe cases, correction of the stenosis can often be accomplished with balloon valvuloplasty. If that is not possible, surgical valvulotomy without valve replacement usually suffices. Replacement of the stenotic pulmonic valve is rare.
Source: National Heart, Lung and Blood Institute
