Heart valve disorders
There are various kinds of heart valve disorders. Five major ones are mitralvalve insufficiency, mitral valve prolapse, mitral valve stenosis, tricuspidvalve insufficiency, and tricuspid valve stenosis.
Mitral valve insufficiency is a term used when the valve between the upper left chamber of the heart (atrium) and the lower left chamber (ventricle) doesn't close well enough to prevent back flow of blood when the ventricle contracts. Mitral valve insufficiency is also known as mitral valve regurgitation ormitral valve incompetence.
Mitral valve prolapse (MVP) is a ballooning of the support structures of themitral heart valve into the left upper collection chamber of the heart.
The term stenosis means an abnormal narrowing of an opening. Mitral valve stenosis refers to a condition in the heart in which one of the valve openings has become narrow and restricts the flow of blood from the upper left chamber(left atrium) to the lower left chamber (left ventricle).
Tricuspid valve insufficiency occurs when a tricuspid valve does not close tightly enough to prevent leakage. This condition is also called tricuspid valve regurgitation and tricuspid incompetence.
Tricuspid valve stenosis is a narrowing or stiffening of the opening in the valve. This stenosis causes increased resistance to blood flow through the valve.
Normally, blood enters the left atrium of the heart from the lungs and is pumped through the mitral valve into the left ventricle. The left ventricle contracts to pump the blood forward into the aorta. The aorta is a large artery that sends oxygenated blood through the circulatory system to all of the tissues in the body. If the mitral valve is leaky due to mitral valve insufficiency, it allows some blood to get pushed back into the atrium. This extra bloodcreates an increase in pressure in the atrium, which then increases blood pressure in the vessels that bring the blood from the lungs to the heart. Increased pressure in these vessels can result in increased fluid buildup in the lungs.
When these structures weaken or lengthen abnormally, the valve may balloon into the left atrium. Sometimes this can cause the mitral valve to leak blood backward.
This condition may be inherited and occurs in approximately 10% of the population. It affects more women than men and often peaks after the age of 40.
If the mitral valve is abnormally narrow, due to disease or birth defect, blood flow from the atrium to the ventricle is restricted. This restricted flowleads to an increase in the pressure of blood in the left atrium. Over a period of time, this back pressure causes fluid to leak into the lungs. It can also lead to an abnormal heart rhythm (atrial fibrillation), which further decreases the efficiency of the pumping action of the heart.
The tricuspid valve is located between the right atrium and the right ventricle of the heart. When the right ventricle contracts, it is supposed to pump blood forward into the lungs. If the tricuspid valve does not close tightly, some of that blood leaks back into the right atrium. When the atrium receivesits usual quantity of blood from veins leading to the heart, plus the leakingblood, the pressure inside the atrium increases. This higher pressure creates resistance to the flow of blood in the veins that enter the atrium from thebody. In addition, this increase in pressure causes the right atrium to enlarge over time. Congestion from fluid buildup occurs, particularly in the liver and legs.
The tricuspid valve is the largest of the four valves in the heart. When it is narrowed or stiffened, it decreases the amount of blood that can flow through it. This decrease raises the pressure in the right atrium and causes the atrium to enlarge. It also causes the right ventricle to shrink, and lowers the cardiac output.
In the past, rheumatic fever was the most common cause of mitral valve insufficiency. However, the increased use of antibiotics for strep throat has maderheumatic fever rare in developed countries. In these countries, mitral valveinsufficiency caused by rheumatic fever is seen mostly in the elderly. In countries with less developed health care, rheumatic fever is still common andis often a cause of mitral valve insufficiency.
Heart attacks that damage the structures that support the mitral valve are acommon cause of mitral valve insufficiency. Myxomatous degeneration can causea "floppy" mitral valve that leaks. In other cases, the valve simply deteriorates with age and becomes less efficient.
People with mitral valve insufficiency may not have any symptoms at all. It is often discovered during a doctor's visit when the doctor listens to the heart sounds.
Both the left atrium and left ventricle tend to get a little bigger when themitral valve does not work properly. The ventricle has to pump more blood soit gets bigger to increase the force of each beat. The atrium gets bigger tohold the extra blood. An enlarged ventricle can cause palpitations. An enlarged atrium can develop an erratic rhythm (atrial fibrillation), which reducesits efficiency and can lead to blood clots forming in the atrium.
MVP may occur due to rheumatic heart disease but is usually found in healthypeople. Changes that occur in the valve are caused by rapid multiplication ofcells in the middle layer that presses on the outer layer. The outer layer weakens, causing a prolapse of the valve toward the left atrium.
Most persons do not have symptoms. Those that do may experience sharp, left-sided chest pain. Some complain of fatigue, or a pounding feeling in the chest. Others can have an irregular heart beat and even pass out. Some persons mayexperience difficulty breathing, ankle swelling, and fluid in the lungs. Other symptoms may include anxiety, headaches, morning tiredness, and constantlycold hands and feet. Death from this condition is rare.
Mitral valve stenosis is also almost always caused by rheumatic fever. As a result of rheumatic fever, the leaflets that form the opening of the valve arepartially fused together. Mitral valve stenosis can also be present at birth. Babies born with this problem usually require surgery if they are to survive. Sometimes, growths or tumors can block the mitral valve, mimicking mitralvalve stenosis.
If the restriction is severe, the increased blood pressure can lead to heartfailure. The first symptoms of heart failure, which are fatigue and shortnessof breath, usually appear only during physical activity. As the condition gets worse, symptoms may also be felt even during rest. A person may also develop a deep red coloring in the cheeks.
Tricuspid valve insufficiency usually produces vague symptoms, such as general weakness and fatigue. As the conditions worsens, a person experiences painin the upper right part of the abdomen, caused by a congested and enlarged liver. The legs may also swell (edema).
Tricuspid valve stenosis, again, is most often the result of rheumatic fever.On rare occasions, it is caused by a tumor or disease of the connective tissue. The rarest cause is a birth defect.
A person with tricuspid valve stenosis may experience generalized weakness and fatigue. Many people have palpitations and can feel fluttering in their neck. Over time, there may be pain in the upper right abdomen, due to increasedcongestion and enlargement of the liver.
When the doctor listens to the heart sounds, mitral valve insufficiency is generally recognized by the sound the blood makes as it leaks backward. It sounds like a regurgitant murmur. The next step is generally a chest x ray and anelectrocardiogram (ECG) to see if the heart is enlarged. The most definitivenoninvasive test is echocardiography, a test that uses sound waves to make an image of the heart. This test gives a picture of the valve in action and shows the severity of the problem.
The diagnosis of MVP is based on symptoms and physical exam. During the exam,the physician may hear a click and/or heart murmur with a stethoscope. The best diagnostic test for MVP is the echocardiogram.
Mitral valve stenosis is usually detected by a physician listening to heart sounds. Normal heart valves open silently to permit the flow of blood. A stenotic valve makes a snapping sound followed by a "rumbling" murmur. The condition can be confirmed with a chest x ray and an electrocardiogram, both of which will show an enlarged atrium. If surgery is necessary, cardiac catheterization may be done to fully evaluate the heart before the operation.
A severely impaired valve needs to be repaired or replaced. Either option will require surgery. Repairing the valve can fix the problem completely or reduce it enough to make it bearable and prevent damage to the heart. Valves canbe replaced with either a mechanical valve or one that is partly mechanical and partly from a pig's heart.
Mechanical valves are effective but can increase the incidence of blood clots. To prevent blood clots from forming, the patient will need to take drugs that prevent abnormal blood clotting (anticoagulants). The valves made partly from a pigs heart don't have as great a risk of blood clots, but they don't last as long as fully mechanical valves. If a valve wears out, it must be replaced again.
Repair can be accomplished in two ways. In the first method, balloon valvuloplasty, the doctor will try to stretch the valve opening by threading a thin tube (catheter) with a balloon tip through a vein and into the heart. Once thecatheter is positioned in the valve, the balloon is inflated, separating thefused areas. The second method involves opening the heart and surgically separating the fused areas.
Damaged heart valves are easily infected. Anytime a procedure is contemplatedthat might allow infectious organisms to enter the blood, the person with mitral valve insufficiency should take antibiotics to prevent possible infection.
Persons who experience certain types of an irregular heartbeat with MVP should be treated. Propranolol (Inderal) or other beta blockers or digoxin (Lanoxin) are often helpful. Persons who develop moderate to severe symptoms with aleaky mitral valve may require repair or replacement of the mitral valve withan artificial heart valve. Persons with MVP and a leaky valve need to protect themselves from heart or heart valve infections. Antibiotics should be taken before any surgical, dental or oral procedures according to the American Heart Association recommendations.
Tricuspid valve insufficiency itself usually does not require treatment, since a tiny leakage occurs in most normal people. In certain cases, however, ifthere is underlying pulmonary valve disease or lung disease, those conditionsshould be treated.
If irregular heart rhythms or heart failure are present, they are usually treated independently of the valve insufficiency.
Since a person with known tricuspid valve insufficiency is at risk for infections of the heart, antibiotics should be taken before and after oral or dental surgery, or urologic procedures.
Tricuspid valve stenosis itself usually doesn't require treatment. However, if there is damage to other valves in the heart as well, then surgical repairor replacement must be considered.
The only possible way to prevent mitral valve insufficiency and stenosis, aswell as tricuspid valve stenosis, is to prevent rheumatic fever. This can bedone by evaluating sore throats for the presence of the bacteria that causesstrep throat. Strep throat is easily treated with antibiotics.
In general, tricuspid valve insufficiency cannot be prevented.