Heart Valve Diseases
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The heart consists of four chambers, two atria (upper chambers) and two ventricles (lower chambers). There is a valve through which blood passes before leaving each chamber of the heart. The valves prevent the backward flow of blood. These valves are actual flaps that are located on each end of the two ventricles (lower chambers of the heart). They act as one-way inlets of blood on one side of a ventricle and one-way outlets of blood on the other side of a ventricle. Normal valves have three flaps, except the mitral valve, which has two flaps. The four heart valves include the following:
- tricuspid valve - located between the right atrium and the right ventricle
- pulmonary valve - located between the right ventricle and the pulmonary artery
- mitral valve - located between the left atrium and the left ventricle
- aortic valve - located between the left ventricle and the aorta
As the heart muscle contracts and relaxes, the valves open and close, letting blood flow into the ventricles and out to the body at alternate times. The following is a step-by-step illustration of how the valves function normally in the left ventricle:
- After the left ventricle contracts, the aortic valve closes and the mitral valve opens, to allow blood to flow from the left atrium into the left ventricle.
- The left atrium contracts and more blood flows into the left ventricle.
- When the left ventricle contracts, the mitral valve closes and the aortic valve opens, so blood flows into the aorta and the systemic circulation.
Heart valves can have one of two malfunctions:
The valve(s) does not close completely, causing the blood to flow backward instead of forward through the valve.
The valve(s) opening becomes narrowed or valves become damaged or scarred (stiff), inhibiting the flow of blood out of the ventricles or atria. The heart is forced to pump blood with increased force in order to move blood through the narrowed or stiff (stenotic) valve(s).
Heart valves can have both malfunctions at the same time (regurgitation and stenosis). Also, more than one heart valve can be affected at the same time. When heart valves fail to open and close properly, the implications for the heart can be serious, possibly hampering the heart's ability to pump blood adequately through the body. Heart valve problems are one cause of heart failure.
Mild heart valve disease may not cause any symptoms. The following are the most common symptoms of heart valve disease. However, each individual may experience symptoms differently. Symptoms may vary depending on the type of heart valve disease present and may include:
- chest pain
- palpitations caused by irregular heartbeats
- migraine headaches
- low or high blood pressure, depending on which valve disease is present
- shortness of breath
- abdominal pain due to an enlarged liver (if there is tricuspid valve malfunction)
Symptoms of heart valve disease may resemble other medical conditions and problems. Always consult your physician for a diagnosis.
The causes of heart valve damage vary depending on the type of disease present, and may include the following:
- a history of rheumatic fever (now a rare disease in north America due to effective antibiotic treatment) - a condition characterized by painful fever, inflammation, and swelling of the joints.
- damage resulting from a heart attack
- damage resulting from an infection
- changes in the heart valve structure due to the aging process
- congenital birth defect
- syphilis (now a rare sexually transmitted disease in North American due to effective treatment) - a disease characterized by progressive symptoms if not treated. Symptoms may include small, painless sores that disappear, followed by a skin rash, enlarged lymph nodes, headache, aching bones, appetite loss, fever, and fatigue.
- myxomatous degeneration - an inherited connective tissue disorder that weakens the heart valve tissue.
The mitral and aortic valves are most often affected by heart valve disease. Some of the more common heart valve diseases include:
|Heart Valve Disease
||Symptoms and Causes
Bicuspid aortic valve
|This congenital birth defect is characterized by an aortic valve that only has two flaps (a normal aortic valve has three flaps). If the valve becomes narrowed, it is more difficult for the blood to flow through, and often the blood leaks backward. Symptoms usually do not develop during childhood, but are often detected during the adult years.
|When Ebstein's anomaly is present, there is a downward displacement of the tricuspid valve (located between the upper and lower chambers on the right side of the heart) into the right bottom chamber of the heart (or right ventricle). This condition is usually associated with an atrial septal defect, an opening between the two upper chambers of the heart.
|When tricuspid atresia is present, there is no tricuspid valve, therefore, no blood flows from the right atrium to the right ventricle. Tricuspid atresia defect is characterized by a small right ventricle, a large left ventricle or only one ventricle, diminished pulmonary circulation, and cyanosis (insufficient oxygen in the blood, which can cause the skin, gums, and lips to be pale or appear blue or gray in color). An atrial septal defect is present to allow blood to enter the circulatory system from the right side.
Mitral valve prolapse (also known as click-murmur syndrome, Barlow's syndrome, balloon mitral valve, or floppy valve syndrome)
|This disease is characterized by the bulging of one or both of the mitral valve flaps during the contraction of the heart. One or both of the flaps may not close properly, allowing the blood to leak backward. This may result in a mitral regurgitation murmur.
Mitral valve stenosis
|Often caused by a past history of rheumatic fever, this condition is characterized by a narrowing of the mitral valve opening, increasing resistance to blood flow from the left atrium to the left ventricle.
Aortic valve stenosis
|This type of valve disease mainly occurs in the elderly and is characterized by a narrowing of the aortic valve opening, increasing resistance to blood flow from the left ventricle to the aorta.
|This condition is characterized by a pulmonary valve that does not open sufficiently, causing the right ventricle to pump harder and enlarge.
Heart valve disease may be suspected if the heart sounds heard through a stethoscope are abnormal. This is usually the first step in diagnosing a heart valve disease. A characteristic heart murmur (abnormal sounds in the heart due to turbulent blood flow across the valve) can often indicate valve regurgitation or stenosis. To further define the type of valve disease and extent of the valve damage, physicians may use any of the following diagnostic procedures:
- electrocardiogram (ECG or EKG) - a test that records the electrical activity of the heart, shows abnormal rhythms (arrhythmias or dysrhythmias), and detects heart muscle damage.
- chest x-ray - a diagnostic test which uses invisible electromagnetic energy beams to produce images of internal tissues, bones, and organs onto film. An x-ray can show enlargement in any area of the heart.
- cardiac catheterization - this diagnostic procedure involves a tiny, hollow tube (catheter) being inserted into an artery leading to the heart in order to image the heart and blood vessels. This procedure is helpful in determining the type and extent of valve blockage.
- transesophageal echo (TEE) - TEE is a diagnostic test that is used to measure the sound waves that bounce off the heart, creating a graphic image of the movement of the heart structures.
- radionuclide scans - these scans use radioactive imaging to view blood flow, internal organ structure, and organ function.
- magnetic resonance imaging (MRI) - a diagnostic procedure that uses a combination of large magnets, radiofrequencies, and a computer to produce detailed images of organs and structures within the body.
In some cases, the only treatment for heart valve disease may be careful medical supervision. However, other treatment options may include medication, surgery to repair the valve, or surgery to replace the valve. Specific treatment will be determined by your physician based on:
- your age, overall health, and medical history
- extent of the disease
- the location of the valve
- your signs and symptoms
- your tolerance for specific medications, procedures, or therapies
- expectations for the course of the disease
- your opinion or preference
Treatment varies, depending on the type of heart valve disease, and may include one, or a combination of, the following:
In some cases, medication alone is successful in the treatment of heart valve disease, and may include:
- Medications such as beta-blockers, digoxin, and calcium channel blockers reduce symptoms of heart valve disease by controlling the heart rate and atrial fibrillation.
- Medications to control blood pressure, such as diuretics (medications that remove excess water from the body by increasing urine output) or vasodilators (medications which relax the blood vessels, decreasing the force against which the heart must pump).
Surgery may be necessary to repair or replace the malfunctioning valve(s). Surgery may include:
- Heart valve repair: In some cases, surgery on the malfunctioning valve can help alleviate symptoms. Examples of heart valve repair surgery include cutting scarred flaps so they open more easily; remodeling valve tissue that has enlarged; or inserting prosthetic rings to help narrow a dilated valve. In many cases, heart valve repair is preferable, because a person's own tissues are used.
- Heart valve replacement: When heart valves are severely malformed or destroyed, they may need to be replaced with a new mechanism. Replacement valve mechanisms fall into two categories: tissue (biologic) valves, which include animal valves and donated human aortic valves, and mechanical valves, which can be metal, plastic, or another artificial material.
Another treatment option that is less invasive than valve repair/replacement surgery is balloon valvuloplasty, a non-surgical procedure in which a special catheter (hollow tube) is threaded into a blood vessel in the groin and guided into the heart. The catheter, which contains a deflated balloon, is inserted into the narrowed heart valve and the inflated balloon is stretching the valve open. The balloon is then removed. This procedure is often used to treat pulmonary stenosis and, in some cases, aortic stenosis.
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