Valvular heart disease refers to several disorders and diseases of the heart valves, which are the tissue flaps that regulate the flow of blood through the chambers of the heart.
Valvular heart disease
The human heart consists of four chambers-two upper chambers (the atria) and two lower chambers (the ventricles) that are responsible for pumping blood. The heart valves are like one-way doors, which open and close with each beat of the heart, controlling the blood flow from one chamber to the next. Each of these valves is made up of a few thin folds of tissue. When functioning correctly, they keep blood from flowing backward into a chamber when closed.
The four valves function in the following manner:
- The mitral valve is located between the left atrium and the left ventricle. It is the only valve with two flaps, or cusps.
- The tricuspid valve is located on the right side of the heart, between the right atrium and right ventricle. It is made up of three cusps, each a different size.
- The aortic valve is located on the left side of the heart and opens to allow blood to leave the heart from the left ventricle into the aorta, which is the main artery of the body. It closes to prevent blood from flowing back into the left ventricle.
- The pulmonary valve is situated on the right side of the heart, between the right ventricle and pulmonary artery. It allows blood to exit the heart and enter the lungs via the pulmonary artery. It closes to prevent blood from flowing back into the right ventricle.
Patients with valvular heart disease have a malfunction of one or more of these valves. There are several types of valvular heart diseases with distinct symptoms and treatments. These are:
- Mitral valve prolapse (displacement)
- Mitral valve insufficiency (regurgitation)
- Mitral valve stenosis (narrowing)
- Aortic valve insufficiency
- Aortic valve stenosis
- Tricuspid valve insufficiency
- Tricuspid valve stenosis
- Pulmonic stenosis
- Pulmonic insufficiency
Certain types of heart disease can lead to one of the specific conditions listed above. These include rheumatic fever and infective inflammation of the heart (endocarditis). Multivalvular heart disease refers to a condition involving more than one of the heart valves.
Causes and symptoms
Problems with heart valves may occur as a result of infection, degeneration, or congenital abnormality. The most common infections are rheumatic fever and infective endocarditis.
Rheumatic fever is a condition that results from the body’s immune response to certain types of streptococcal bacteria.
Infective endocarditis is an infection and inflammation of the inner layer, or membrane, of heart tissue (endocardium). Most people with a healthy, normal heart are not at significant risk for contracting infective endocarditis. However, people who have had rheumatic fever, with its resulting scarring, or a congenital cause of heart malformation, may contract this disease when certain bacteria enter the bloodstream and become lodged in the heart. In particular, dental surgery or any surgery involving the mouth, bladder, prostate, or female pelvic organs increases risk for this infection. The disease also may occur in drug addicts who inject their veins using unsterilized needles, even if they have normal heart valves. Symptoms of infective endocarditis include fever, a new or changing heart murmur, and abnormal loss of appetite or fatigue.
Other valvular heart disease
The mitral and aortic valves may also be affected by deposits of calcium in the heart that occurs with aging. This can lead to thickening and leakage of heart valves. Heart attacks also can damage the mitral valve structures. Additionally, certain connective tissue disorders can adversely affect the heart valves, for example, Marfan’s syndrome and myxomatous degeneration.
Specific types of valvular heart disease are diagnosed using:
- Electrocardiography (ECG),
- Certain x-ray studies, and/or
- Angiography / cardiac catheterization.
The treatment of specific valvular heart diseases will vary, depending on the valve involved and the extent of damage or malfunction. Some patients will not require treatment and many will be treated with medication. Sometimes, patients need surgery. If multivalvular disease is suspected or involved, different valves may be evaluated during surgery on one of the affected valves. Women with heart valve disease who want to become pregnant should receive a thorough check-up and see a cardiologist regularly throughout their pregnancy.
The prognosis for patients with valvular heart disease varies depending on the underlying cause, age and health of the patient, and the degree of valvular damage or involvement.
Certain measures can be taken to prevent some valvular disease. However, once valvular heart disease that results from congenital abnormality occurs, it may not be prevented. Steps can be taken to prevent further complications.
The best prevention for rheumatic fever is prompt and thorough treatment of any suspected streptococcal infection, particularly strep throat in children. A physician should check any sore throat with fever that persists for more than 24 hours. The physician will probably order a throat culture. Completion of the antibiotic treatment even after symptoms diminish is important to be certain the infection is eliminated.
Anyone who was born with a defective heart valve, those with artificial (prosthetic) valves, or those who have had a valve scarred by rheumatic fever, should use prescribed antibiotics by mouth before and after a dental procedure. These patients also may need to receive injected antibiotics prior to procedures involving the bladder, prostate, and pelvic organs.
UNDER WHAT CONDITIONS VALVULAR SURGERY IS REQUIRED
Surgery is required for severe mitral valve regurgitation (MR). Surgery for MR is recommended when the symptoms of heart failure are present and when your ejection fraction drops below 60% and your left ventricle is larger than 45 mm at rest.
Surgery may be the best option under following conditions:
- Acute MR
- MR with symptoms of heart failure
- MR with or without symptoms and mild to moderate left ventricular
- dysfunction (reduced ejection fraction and an enlarged left ventricle)
Surgery may be undertaken under following conditions:
- MR with an irregular heartbeat (atrial fibrillation) present, but no symptoms and no evidence of functional damage to the left ventricle
MR with elevated blood pressure in the lungs (pulmonary hypertension), but no symptoms and no evidence of functional damage to the left ventricle
- MR with mild to severe left ventricular dysfunction, no symptoms, and a high likelihood of preserving some of the related structures of the mitral valve
Under following conditions surgery generally may not be carried out:
- Chronic MR with no symptoms and no signs of functional damage to the left ventricle even if surgical repair of the mitral valve is likely to be successful
- MR with MVP, no signs of functional damage to the left ventricle, but with recurrent ventricle arrhythmias despite treatment
WHAT TYPES OF SURGERY IS THERE FOR VALVULAR DISORDERS?
Generally, surgery for mitral valve prolapse (MVP) is only done when mitral valve regurgitation is present. The two types of surgery available to treat these conditions are:
- Valve repair or
- Valve replacement
In both cases it is an open heart surgery.
WHAT IS THE PROCEDURE FOR VALVULAR SURGERY?
You are given general anesthesia and placed on a heart-lung machine during the surgery, which usually lasts about 3 to 5 hours. During valve surgery, the doctor makes a large incision in the chest. Blood is circulated outside of the body to add oxygen to it (cardiopulmonary bypass or heart-lung machine). The heart may be cooled to slow or stop the heartbeat; this protects the heart muscle from damage during surgery to replace the heart valve. The damaged mitral valve is either repaired or removed and replaced with an artificial (prosthetic) heart valve.
The decision between repairing or replacing the valve depends on the type of damage to the mitral valve. For instance, repair is more successful if there is limited damage to certain areas of the mitral valve flaps (leaflets) or to the tough fibers that control movement of the mitral valve leaflets (chordae tendineae). Replacement, however, is usually preferred for people who have a hard, calcified mitral valve ring (annulus) or widespread damage to the valve and surrounding tissue.
For heart valve repair, one of the following procedures is done:
- Reshaping of the valve by removing excess valve tissue
- Adding support to the valve ring by adding tissue or a collarlike structure around the base of the valve
- Attaching the valve to nearby heart cordlike tissues (chordal transposition)
Heart valve replacement surgery involves the removal of the badly damaged valve. The valve is replaced with a plastic or metal mechanical valve, or a bioprosthetic valve, usually made from pig tissue. The damaged valve is cut out, and the new valve is sewn into place.
People who receive a mechanical heart valve are more likely than those who receive a bioprosthetic heart valve to develop blood clots in the heart that may break loose, travel to the brain, and cause a stroke. Therefore, if you have received a mechanical heart valve to treat severe MR, you will need to take medication to prevent clots from forming (anticoagulant medication) for the rest of your life.
In some cases, a plastic or metal valve may be preferred if you are already are taking long-term anticoagulants for other reasons.
WHAT HAPPENS AFTER SURGERY?
Recovery from heart valve surgery usually involves a few days in an intensive care unit (ICU) of a hospital. Full recovery from heart valve surgery can take several months. Recovery includes healing of the surgical incision, gradual building of physical endurance, and exercise. An exercise program under the direction of a physical therapist is usually recommended.
Once you have an artificial valve, your heart function and your life will largely return to normal. You should feel better than before you had the surgery if your condition was symptomatic; for example, you should no longer experience shortness of breath and fatigue. However, if your heart was already severely affected before your surgery, you may continue to experience complications of heart disease.
You should be able to resume most of your normal activities, although you will have to continue to monitor your condition. You need to watch out for blood clots and infections.
Artificial valves need to be replaced after a period of time, so it is important that you see your doctor regularly.
WHAT ARE THE RESULTS OF VALVULAR SURGERY?
If mitral valve repair is done before the heart is severely damaged by the faulty valve, most people have excellent short- and long-term results.
The outcome of mitral valve replacement depends upon a person’s overall health, including other underlying conditions.
- Mechanical valves, which are made of metal or plastic, tend to cause more clotting than those made of animal tissue. However, mechanical valves generally do not have to be replaced and usually do not require additional surgery. A plastic or metal valve may be preferred if you are already taking long-term anticoagulants for other reasons.
- Bioprosthetic valves cause less blood clotting, but they tend to wear out in 8 to 10 years and thus may require repeat operations.
WHAT ARE THE RISKS OF VALVULAR SURGERY?
The exact risks of mitral valve surgery vary depending on the person’s specific condition and general health prior to surgery. In general, the risks include:
- Effects from the operation itself (such as bleeding, infection, and risks associated with anesthesia). These risks are low.
- Blood clotting caused by the new valve. Replacement with a mechanical valve requires lifelong treatment with medication to prevent blood clots (anticoagulant).
- Infection in the new valve. Infection is more common with valve replacement than with valve repair.
- Failure of the new valve. Valve failure is more common with valve replacement than with valve repair. Pig valves tend to fail after about 8 to 10 years.
SHOULD I GO FOR VALVE REPAIR OR REPLACEMENT?
Repair of the heart valve usually is the preferred and more common type of surgery for MVP because it is a simpler surgical procedure and has a lower risk of infection.
When the mitral valve is seriously damaged, heart valve replacement may be recommended. Examples of serious damage or complicated conditions that might lead to mitral valve replacement include:
- Extensive ballooning of the mitral valve (rather than one isolated flap puffing up).
- Severe hardening (calcification) of the valve.
- Prolapse of the valve at an unusual location.
- Damage to the valve from infection (endocarditis).
The decision regarding whether to repair or to replace a valve is based on many factors, including the person’s general health, the condition of the damaged valve, the presence of other health conditions, and the expected benefits of surgery. In some cases, the decision clearly may be in favor of repair or replacement.