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Cardiac Electrophysiology Consultants of South Texas, P.A.

Medical Center Tower I
7950 Floyd Curl Drive
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San Antonio, TX 78229
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General information about the heart for patients, their family members, and concerned laymen

  Valvular Disorders Section Contents
Overview of the Valves of the Heart
     The purpose of the valves in the heart is very simple: they make sure that blood flows only one way. That is, they make sure that when the heart squeezes, blood flows in the way that it is supposed to flow. Remember that when the heart squeezes and relaxes with each heart beat, the squeezing only raises and lowers the pressure inside the heart. How the blood moves under those changes in pressure is determined by how well the valves work and how easily blood can flow into and out of the heart.

There are four valves in the heart, corresponding to the four chambers in the heart:

  • the tricuspid valve divides the right atrium from the right ventricle. The right atrium receives blood returning from the body through the superior and inferior vena cavae, and pushes that blood into the right ventricle. The right atrium is a low-pressure pump, and serves mainly to push a little extra blood with each heart beat into the more powerful right ventricle.

  • the pulmonic valve divides the right ventricle from the pulmonary artery. The right ventricle receives blood from the right atrium and pushes it into the pulmonary arteries, whence it goes to the lungs to soak up oxygen.

  • the mitral valve divides the left atrium from the left ventricle. The left atrium receives oxygenated blood from the lungs and pushes it into the left ventricle. The left atrium is a low-pressure pump, and serves mainly to push a little extra blood with each heart beat into the powerful left ventricle.

  • the aortic valve divides the left ventricle from the aorta. The left ventricle receives blood from the left atrium and pushes it into the aorta, whence it travels to the rest of the body to supply oxygen. The left ventricle is the most powerful of the four chambers, and generates the blood pressure that pushes blood all throughout the body and back to the right atrium.
There are two categories of problems that can occur with heart valves: they can be too leaky ("regurgitation"), so that blood flows backwards; or they can be too tight ("stenosis"), so that blood cannot pass easily along its proper path. Both categories of problems can be so severe that the diseased valve should be replaced. The following sections provide more information about the common valvular disorders and then some not-so-common disorders.

It is important to remember that any person with an artificial (prosthetic) heart valve should consult a physician about whether to take antibiotics before dental procedures and certain other medical procedures in order to prevent infection of the heart valve. This practice is known as prophylactic antibiotics to prevent infective endocarditis.

The remainder of this section deals with echocardiography, which (like ultrasonography of pregnant women) provides anatomic information at little or no risk to the person; and prosthetic (artificial) heart valves and the risks and problems associated with them. A related subject is anticoagulation, or "blood thinning", which is a treatment prescribed for some people with diseased or artificial heart valves.

Aortic Regurgitation
     Aortic regurgitation is a condition in which the aortic valve is too leaky. 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. This section discusses 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 certain autoimmune diseases.

If this condition is mild, there is a minimal effect on the overall health of the person (except for the question of prophylactic antibiotics). If the condition is moderate or severe, however, the left ventricle must enlarge in order to maintain its high pumping volume (high "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 ( diuretics, digoxin) 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.

The proper timing of aortic valve replacement in aortic regurgitation is relatively easy to determine in the person who has symptoms, such as shortness of breath, due to enlargement of the left ventricle. Determining when to replace the aortic valve in people who have no symptoms is more controversial because early surgery increases the risk of long-term complications (see prosthetic valves) while late surgery may prove to be too late. Often, people with this condition are seen by a cardiologist every six to 12 months and undergo echocardiography to measure the size and function of the left ventricle every six to 12 months, depending on how severe the regurgitation is.

Aortic Stenosis
     Aortic stenosis is a condition in which the aortic valve is too tight. 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 ill effects on the person (except for the question of prophylactic antibiotics). When the condition is severe, however, it can be life-threatening.

The aortic valve can become stenotic in three circumstances: bicuspid aortic valve (up to 2% of infants are born with two instead of three leaflets in their aortic valves), rheumatic valvular disease, and age-related calcification of the previously normal aortic valve. The first two circumstances are more common in people younger than 65 years, while the lastis more common in older people.

The aortic valve must be replaced if aortic stenosis causes angina pectoris, 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, even octagenarians who are otherwise in good health. 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 tight valves (e.g., valve area less than or equal to 0.7 square centimeters). Not all experts agree on when to do valve replacement surgery in people with aortic stenosis who have no symptoms. The rationale for doing so it that the first symptom of aortic stenosis can be sudden death.

Mitral Regurgitation
     Mitral regurgitation is a condition in which the mitral valve is too leaky, resulting in flow of blood back from the left ventricle into the left atrium. 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. This section discusses chronic mitral regurgitation.

The mitral valve can become regurgitant for many reasons, including age-related degeneration, rheumatic valvular disease, previous infection of the valve (endocarditis), chest trauma, and left ventricular enlargement due, for example, to previous myocardial infarction.

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, atrial fibrillation and atrial flutter, and left atrial thrombi that can cause strokes. Enlargement of the left ventricle can cause both forward and backward congestive heart failure, either of which can be fatal.

All patients with mitral regurgitation should receive prophylactic antibiotics before dental manipulations or surgical procedures. Anticoagulation should be used if atrial fibrillation develops, in addition to the usual medications for control of the atrial fibrillation. Following a low salt diet and taking medications to treat congestive heart failure, including diuretics, digoxin, and afterload reducing agents, often relieve symptoms. However, mere relief of symptoms may not be a reason to delay valve repair or replacement surgery.

Mitral valve surgery can be either a "repair" or a "replacement". In the surgical "repair", the components of the valve are fixed so that the valve is no longer leaky. This procedure can include "plastic surgery" on the valve apparatus, and/or insertion of a metal ring around the valve ring to help it hold its shape. In the surgical "replacement", the diseased valve is cut out and is replaced with a prosthetic heart valve.

The timing of surgery in mitral regurgitation is sometimes difficult to determine, as with aortic regurgitation, but the consequences of waiting too long are worse. If the left ventricle enlarges too much, repair or replacement of the mitral valve can actually cause it to function worse than it did before the valve surgery. This happens because leakiness ("regurgitation") of the mitral valve actually makes the job of the left ventricle easier from beat to beat. If the muscle of the left ventricle is weakened by enlargement, it may not be strong enough to deal with the harder task of working with a repaired or artificial valve. Unfortunately, there is no iron-clad rule that lets doctors tell exactly when to repair or replace a leaky mitral valve, so they have to use their best judgement. One rule of thumb in the absence of symptoms is to wait until the first sign of enlargement of the left ventricle, and to operate then. In the presence of symptoms, one should be careful not to delay even if the left ventricle appears normal.

Mitral Stenosis
     Mitral stenosis is a condition in which the mitral valve is too tight, 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. Like a stopped-up toilet, 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, causings shortness of breath. Often, the symptom of shortness of breath (dyspnea") is worsened by exertion or by lying down for several hours (e.g., at night during sleep).

The enlargement can, and often does, lead to atrial fibrillation, which can lead to stroke.

If this condition 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 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.

Most doctors agree that the stenotic mitral valve should be repaired or replaced if a person has more than mild symptoms due to mitral stenosis on medications. It is important to remember that people who have the combination of atrial fibrillation and mitral stenosis have a very high rate of stroke, on the order of 5 per cent per year.

The choices of surgical therapy for the stenotic mitral valve include repair with balloon valvuloplasty or mitral commissurotomy and replacement with a prosthetic valve. The two methods for repair are not permanent: the valve will become stenotic again in 5 to 15 years. The mechanical prosthetic valves all require chronic anticoagulation; the bioprosthetic valves degenerate rapidly in persons under 35 years of age. For these reasons, many doctors prefer to repair the stenotic mitral valve in younger patients, knowing that the repair will be temporary, so that the eventual valve replacement will be delayed until the person is old enough to tolerate the prosthetic valve well.

Mitral Valve Prolapse
     Mitral valve prolapse is a very common disorder, and affects 5 to 10 percent of the general population. Although it usually causes no trouble at all, it is associated with bothersome symptoms in some people and serious problems in about one in ten persons with the disorder. More information is available from a patient support group and from another medical information site, as well as many other sites on the Web.
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.

When tricuspid regurgitation occurs by itself due to, for example, subacute bacterial endocarditis, the person usually does not have problems due to the regurgitation. When it occurs with other conditions, such as mitral stenosis, lung disease, or right ventricular infarction, however, the person can have fatigue, abdominal discomfort and nausea, and swelling of the legs and feet.

If this condition is associated with another cardiac process that requires surgery, repair or replacement of the tricuspid valve can be performed if assessment after the planned surgery indicates that fixing the tricuspid valve would be helpful. Otherwise, medical treatment with low-salt diet, diuretics, and digoxin is preferable.

Tricuspid Stenosis
     Tricuspid stenosis is a condition in which the tricuspid valve is too tight. This is almost always due to rheumatic valvular disease, and is usually associated with rheumatic damage to the mitral and/or the aortic valves.

While the condition is mild, the person should receive prophylactic antibiotics prior to surgical procedures and dental manipulation. Symptoms due to tricuspid stenosis include fatigue, abdominal discomfort and nausea, and swelling of the legs and feet.

If the stenosis worsens, the person should follow a low salt diet and take diuretics to shed excess fluid. If atrial fibrillation develops, digoxin will slow the ventricular response (heart) rate. If symptoms persist on medical treatment, valve repair with balloon valvuloplasty or surgery, or valve replacement, are indicated. Because the risk of thrombus on the valve is higher in the tricuspid position than in the mitral position, bioprosthetic valves are better than mechanical valves despite their limitations.

Pulmonic Regurgitation
     Pulmonic regurgitation is a condition in which the pulmonic valve is too If this condition is mild to moderate, there is a minimal effect on the overall health of the person (except for the need for prophylactic antibiotics). If the regurgitation results from another condition, such as mitral stenosis or chronic obstructive lung disease, the prognosis depends on the causative condition. Otherwise, the prognosis is good.

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 too tight If this condition is mild to moderate, there is a minimal effect on the overall health of the person (except for the question of prophylactic antibiotics).

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.

     What is It?
Echocardiography is a method for obtaining images, or pictures, of the heart inside of the body. Based on reflection of sound waves by body tissues, it has no known harmful side effects. In fact, it is the same as the "ultrasound" used to look at fetuses inside pregnant women.
For What is It Best Used?
The echocardiogram, which is the set of images that are obtained by echocardiography, some things well but not other things.
  • It shows the valves of the heart, and how the blood moves through them. Using a method based on the Doppler principle, it can show the direction and speed of the blood flow inside the heart. These data can be used to detect back flow (regurgitation) and high velocity forward flow (through stenosis) of the heart valves.
  • It shows the walls of the heart, including how thick or thin they are and how well each part of them moves. It is useful for estimating the overall ability of the left ventricle to pump blood, known as the left ventricular ejection fraction.
  • It does not show the coronary arteries in enough detail to be useful for assessing blood flow to the heart directly. However, when echocardiography is combined with a form of cardiac stress in cardiac stress testing, it can show the effect of stress on a person's heart by revealing how well the various parts of the heart pump during stress compared with rest.
  • It can also show the lining around the heart, the "pericardium". This is useful when there is a possibility of accumulation of fluid around the heart and therefore inside the lining (pericardial tamponnade) or when there is the possibility of excessive thickening of the lining itself (constrictive pericarditis).
Prosthetic (Artificial) Valves
     Replacement of diseased natural heart valves with artificial ones has been life saving. However, as in so much of medicine today, the replacements valves are never as good as undiseased natural ones. Prosthetic (artificial) heart valves have been used for the past several decades. During that time, we have learned much about what to do and what not to do.

The manufacture of prosthetic heart valves has been studied so intensively that valves are considered successful when they have performed well for 20 years and more. There are two general types of valves: mechanical and bioprosthetic (usually taken from pigs). The mechanical valves last longer but require the person to take blood thinners ((anticoagulants). The Starr-Edwards valve has a caged-ball design and has performed well since 1965. The Bjork-Shiley, has a tilting-disk design, and has been in use since about 1970 The newer St. Jude, and Medtronic-Hall valves also have a tilting-disk design. Of the tilting-disk designs, the St. Jude appears to have the most favorable properties especially in children and small adults.

The bioprosthetic valves do not require long-term anticoagulation, but frequently must be replaced after only about 10 years or so in adults. They are often selected by women who wish to become pregnant and by elderly people. They often need to replaced much more quickly in children and in people with diseased kidney function who are on hemodialysis.

The major risk of prosthetic heart valves is stroke, which can occur in several each year out of each 100 people who have certain artificial valves. The reason seems to be that, despite considerable engineering research and development, the flow of blood across the prosthetic valve is turbulent, not smooth. This leads to formation of blood clots ("thrombi", technically, since they form inside the body), which can float into the brain. When they reach the brain, they float into smaller and smaller arteries until they reach arteries that are thinner than they are. They plug up these arteries, which prevents oxygen from reaching the part of the brain supplied by those arteries, which in turn causes a stroke.

In general, the risk of stroke is higher for mitral valve replacement than for aortic valve replacement, perhaps because blood flows more slowly across the mitral valve and therefore has more time to form thrombi.

There are only two good thoughts about stroke due to prosthetic valves. First, the body has its own defense system against thrombi, and this system often breaks them down down either before they reach the brain or quickly enough after they reach the brain that little or no damage results. The second is that people with prosthetic heart valves who take anticoagulation regularly have a much lower, but not a zero rate, of stroke.

There are other problems that can occur with prosthetic valves, but they occur much less frequently. Each person should consult with her or his physician as needed.

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