Heart Valve Diseases

What are heart valve diseases?

The four valves in the heart function as one-way gates that open and close to allow the chambers to fill and empty at the opportune moments according to the differences in pressure on either side of the valves.  When the pressure is higher behind the valve, the valve opens to let blood flow forward until the pressure past the valve becomes higher, at which point the valve closes to prevent backflow.  The mitral valve opens to allow blood to flow from the left atrium to the left ventricle and closes to allow the contracting left ventricle to pump blood through the opened aortic valve into the aorta.  The tricuspid valve opens to allow blood to flow from the right atrium to the right ventricle and closes to allow the contracting right ventricle to pump blood through the opened pulmonary valve into the pulmonary arteries.  Two possible problems can occur with any of the four heart valves.  Stenosis is the narrowing of a valve that strains the heart because it must pump blood with greater force through a smaller hole that offers larger resistance.  Stenosis can occur when the leaflets, small flaps composing the valves that open and close in response to pressure changes on either side, become stiff, thick, or fused to one another.  Regurgitation or insufficiency occurs when one of the heart valves leaks because it does not close completely.

What causes heart valve diseases?

Two general types of heart valve problems exist based on whether they are present at birth or develop over the course of a patient’s life.  Congenital heart valve problems are present in 1 out of every 1000 live births and may be caused by an altered environment in the womb as well as by genetic factors.  If the mother has diabetes, phenylketonuria, a rubella infection, lupus, drinks, or takes lithium or some seizure medications, her infant may be more likely to be born with a heart valve problem.  Usually, the mother of a child born with a valve problem does not have one of these conditions, and did not drink, or take one of these medications; the cause of the disease is usually genetic or unknown.  The most common congenital valve problem, called a bicuspid aortic valve, occurs when the aortic valve has two instead of three leaflets.

When a patient has an acquired heart valve disease, he was born with structurally normal valves, but one or more of them became abnormal during his lifetime.  Sometimes, doctors can identify the cause of this disease as a condition such as rheumatic fever, infective endocarditis, myxomatous degeneration, calcific degeneration, syphilis, high blood pressure, arteriosclerosis, a heart attack, coronary artery disease, or some connective tissue disorders like Marfan’s syndrome.  Before antibiotics were widely used in the U.S. to treat strep throat, rheumatic fever was the most significant cause of heart valve problems.  Rheumatic fever occurs as a result of an untreated streptococcal bacterial infection and causes the body’s immune system to damage its own tissues including the heart valves.  Usually occurring in children, rheumatic fever causes rheumatic heart disease, a condition that continues throughout a patient’s life and most often lies dormant for about 20 years before causing symptoms.  Infective endocarditis is an infection of the heart’s inner lining.  In patients with this condition, microorganisms, most often streptococci or staphylococci bacteria, grow on the heart’s lining, forming bumps or holes that can distort the shape of valves and disrupt their function.  Myxomatous degeneration is most common in elderly patients and usually affects the mitral valve, which separates the left atrium and ventricle, the side of the heart that is responsible for pumping blood from the lungs out to the body.  Doctors do not know what causes myxomatous degeneration, but it is characterized by a loss of elasticity in the valve tissue that causes the valve to have problems opening and closing.  Calcific degeneration occurs most often in the elderly when their bodies deposit calcium on one of their heart valves, usually the aortic valve, causing it to harden and resulting in aortic stenosis.  A heart attack occurs when the heart muscle does not get enough blood to meet its needs.  This lack of blood scars heart muscle and can damage the papillary muscles that support the mitral and tricuspid valves leading to problems with their functioning.

What are the symptoms, dangers, and complications of heart valve diseases?

Heart valve diseases often exhibit no symptoms, cause no problems, and are discovered only when a doctor hears a murmur, an abnormal heart sound occurring when blood leaks back through a valve that failed to close properly or is turbulently squeezed through a valve that will not open completely.  Heart murmurs often do not indicate a serious problem.  In infants with severe valve disease, cyanosis (bluing of lips, fingernails, and skin) can occur along with the symptoms of heart failure like swelling and shortness of breath.  For adults, palpitations, breathlessness, chest pain, fatigue, fainting, ankle swelling, weakness, dizziness, and rapid weight gain can indicate a problem in the heart valves.  The symptoms of infective endocarditis, an inflammatory condition that can cause heart valve diseases, include fatigue, slight fever, weakness, and joint pain.  The most important danger of a valve disease is congestive heart failure.  Congestive heart failure occurs when the heart becomes weakened to the point that it cannot pump with enough strength to supply the body with blood.  Blood becomes congested in the veins and fluid may collect in the ankles to cause swelling and around the lungs to cause shortness of breath.  Malfunctioning heart valves can cause clots to form in the heart.  These clots are dangerous because they may travel to small arteries supplying the organs and block the bloodflow to those organs.  Clots traveling to the lungs (pulmonary embolism) and brain (stroke) are especially dangerous.

What are the types of heart valve diseases, and how are they different?

The aortic valve regulates blood as it passes from the left ventricle to the aorta, the artery that carries oxygenated blood to the body.  Some children are born with an aortic valve that has 2 leaflets instead of 3.  Though this congenitally bicuspid aortic valve is severely narrowed in 10% of those affected, in 90% of those with the condition, the valve is still functional to the extent that they have no symptoms in the first year of life.  Stenosis in the aortic valve increases the resistance against which the left ventricle must pump.  This increased afterload causes the left ventricle to become larger and thicker, a condition that can make the heart less able to accommodate an increase in the body’s demand for blood.  Patients with an enlarged left ventricle may not be able to sustain strenuous activities.  Additionally, a narrowed aortic valve may cause the coronary arteries, the arteries that supply the heart with oxygenated blood and exit the aorta near its beginning at the aortic valve, to have limited bloodflow.  Limited bloodflow in the coronary arteries can cause angina or a heart attack.  The aortic valve may regurgitate blood because it is unable to close sufficiently and this condition can also cause the left ventricle to enlarge.  An increase in backflow to the ventricle may cause it to increase its capacity while thinning its walls, a process called dilating.  A dilated ventricle, like an enlarged ventricle, may not be able to accommodate an increase in the body’s demand for blood. 

The mitral valve regulates blood as it passes from the left atrium to the left ventricle.  Mitral valve prolapse is the most common valve disease and involves a mitral valve in which one or both of the leaflets bulge backwards into the left atrium.   Mitral valve prolapse is thought to affect 5-10% of the U.S. population, but is usually mild, causes no symptoms, and needs no treatment.  Mitral valve prolapse, however, can be serious in some patients and result in mitral regurgitation as well as an increased risk for infective endocarditis.  Congenital mitral valve stenosis is rare, but when it occurs, it can be serious and life-threatening.  The most important cause of acquired mitral valve stenosis is rheumatic fever.  When the resistance between the left atrium and ventricle increases due to a narrowed mitral valve, pressure builds up in the pulmonary veins, the veins that carry blood from the lungs back to the heart.  High pressure in the blood vessels of the lungs causes them to become congested and results in shortness of breath.  When mitral valve stenosis is severe, the result is congestive heart failure.  Mitral regurgitation can also be serious if the valve is significantly leaky.

The tricuspid valve regulates blood as it passes from the right atrium to the right ventricle.  Problems with the tricuspid valve rarely occur separate from problems with the other valves.  Tricuspid stenosis and regurgitation may cause leg swelling and fatigue.

The pulmonary valve regulates blood as it passes from the right ventricle to the pulmonary veins.  Problems with this valve are rare and usually congenital.  If a child has severe pulmonary stenosis, he will often develop heart failure and subsequent cyanosis as his lips, fingernails, and skin turns blue because of an inadequate blood supply.  High blood pressure in the lung’s blood vessels (pulmonary hypertension) due to chronic obstructive pulmonary disease can damage the pulmonary valve causing pulmonary valve stenosis or regurgitation.

How do doctors diagnose heart valve diseases?

Doctors can detect many heart valve conditions by listening to a patient’s heart with a stethoscope because of the abnormal sounds (murmurs) usually accompanying them.  An electrocardiogram (EKG or ECG), chest X-ray, blood tests, echocardiogram, Doppler echocardiogram, or cardiac catheterization may help doctors identify and accurately diagnose a valve condition.  Doctors usually begin with less invasive tests like ECGs, chest X-rays, and echocardiograms before performing a cardiac catheterization for a more definitive diagnosis.

What are the treatment options for heart valve diseases?

Many heart valve conditions are not serious and require no treatment.  While some drugs can help alleviate the symptoms of valve conditions, prevent further complications, and reduce the strain on the heart, a surgery or a catheter-based procedure may be able to treat the conditions entirely or substantially alleviate complications.  Digitalis medications can help a failing heart by increasing its pumping efficiency and maintaining the heart in proper rhythm.  Antiarrhythmics like quinidine and procainamide can also help maintain a patient’s heart in proper rhythm.  Vasodilator medications like ACE inhibitors, nitroglycerin, and Minipress can be helpful because they make blood vessels expand to decrease the pressure against which the heart must pump.  Diuretics like Lasix and Hydrodiuril can help by reducing total blood volume, when it has increased as a result of congestive heart failure.  Anticoagulants like Coumadin can prevent clots from forming in the heart.  These medications may be able to sufficiently manage a valve problem such that a major intervention will be unnecessary or allow a patient to delay an operation until the condition becomes more threatening. 

Final treatment of a severe problem involves repair or replacement of the diseased valve.  Percutaneous balloon valvoplasty is a catheter-based procedure doctors use to repair a narrowed heart valve.  A physician inserts a tiny catheter with a deflated balloon on it into a patient’s blood vessel and pushes it through the vessel, into the patient’s heart to the narrowed valve.  At the narrowed point, the doctor inflates the balloon to widen the valve opening.  Doctors may decide to use a more invasive open surgery to repair a diseased valve.  An open surgery valvotomy is a more invasive method doctors can use to fix a stenotic valve.  In this procedure the doctor uses open heart surgery to separate valve leaflets that are fused together.  A surgeon may also open up the valve by surgically stretching it.  If a valve is leaking, a surgeon may try to suture tears or tighten the leaflets.  Sometimes, a surgeon can fix a leaking valve by pulling its base closer together in order to facilitate tighter closing and eliminate any gaps. 

Some severely stenotic or regurgitating valves must be replaced instead of repaired.  Valve replacement surgery involves opening the heart and removing a damaged valve while replacing it with a biological or mechanical valve.  Biological valves come from pigs, cows, or deceased human donors.  There are two main designs for mechanical valves, both of which are more durable and last longer than their biological counterparts.  A caged ball design involves a small cage containing a ball that blows up off of a hole when blood is being force through, but settles back on top of the hole to prevent backflow when greater pressure exists on the other side of the valve.  Another design is called a tilting disk valve and involves a round disk that is allowed to tilt inside of a ring.  When blood is being forced through the valve, the ring spins 90 degrees from the horizontal to the vertical position so that it does not cover the hole.  When, however, greater pressure exists past the valve, the ring spins back 90 degrees to be horizontal and fit over a hole to seal it and prevent backflow.  Both mechanical and biological valves can promote blood clots, with mechanical valves tending to do so to a greater extent.  For this reason, patients who undergo valve replacement surgeries must take anticoagulants (blood thinners).