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Wednesday, 20 September 2017
Valvular Heart Diseases

 Valvular Heart Disease – The heart valves

 

The heart has four chambers two of which collect blood called the atria and the other two namely the ventricles pump the collected blood out. There are four valves within your heart two of them, the mitral on the left and the tricuspid valve on the right connect the collecting chambers (the atria) to the pumping chambers( the ventricles) while the other two, the aortic on the left and pulmonary on the right are placed between the ventricles and the great arteries. The valves open in the forward direction and act as trapdoors making sure that blood flows in only one direction through the heart. Any change in this function can cause a strain on the heart and result in valvular heart disease.The valves are made of thin leaflets which can be two in the case of the mitral valve and three in the rest of them. These leaflets are thin and made of elastic connective tissue. They can be damaged by diseases and altered flow patterns. The leaflets are supported in their function by thin strands of tissue that hold the valve to the heart muscle, these are called the chords. Any shortening or lengthening in them can lead to improper functioning of the valves and leaks.

 

 Types and causes

 

The valves of our heart are god’s gift to us. They are unparalleled in their longevity if we take good care of them. The valves can be affected by multiple conditions starting from birth defects to acquired infections. Each one of these conditions affects them in multiple ways in this section we strive to give the reader a better understanding of what causes this damage.

 

 What is heart valve disease?

 

Valvular heart disease occurs when your heart's valves do not work correctly. Valvular heart disease can be caused by valvular stenosis or valvular insufficiency.

 

Valvular Stenosis

 

Valvular stenosis means obstruction, the tissues forming the valve leaflets become stiffer, narrowing the valve opening and reducing the amount of blood that can flow through it. The grade of stenosis or obstruction determines how much blood flows out. This affects us in two ways

  1. There is less output from the heart
  2. The heart has to pump that much harder to get blood out of the chambers and in course of time it gets tired and that what the doctors call Heart failure.

 

Valvular Insufficiency

 

Valvular insufficiency or "leaky valve", this occurs when the leaflets do not close completely, letting blood leak freely across the valve. The quantum of leak determines the extent of damage to the heart. This can happen as follows

  1. Less forward output as most blood is returning back to the heart
  2. The heart is not used to this return blood and the excess volume eventually causes dilatation or ballooning of the heart.This weakens the heart and results in heart failure.

 

 

Some patients may have a combination of both valvular stenosis and insufficiency in one or more valves. The valves are important for the proper functioning of our heart and to protect the lung circulation from increased pressures. Correction of any valvular defect early improves long term survival and reduces morbidity.

 

 What causes heart valve disease?

 

There are many types of valve disease. Valve disease can be congenital(present at birth) or may be acquired later in life. Sometimes the cause of valve disease may be unknown.

 

Congenital valve disease

 

Congenital valve disease is an abnormality that develops before birth. It may be related to improper valve size, malformed leaflets, or an irregularity in the way the leaflets are attached. This most often affects the aortic, mitral and pulmonic valve.

 

Bicuspid aortic valve disease

 

Bicuspid aortic valve disease is a congenital valve disease that affects the aortic valve. Instead of the normal three leaflets or cusps, the bicuspid aortic valve has only Bi meaning two leaflets. Without the third leaflet, the valve may be:

  • Stenotic - stiff valve leaflets that can not open or close properly
  • Leaky - not able close tightly
  • Is damaged more easily from the turbulence of blood flow
  • Symptoms presents in the third or fourth decade of life commonly
  • Frequently associated with enlargement of the aorta above it which in some cases may necessitate treatment of the aorta.

This occurs more frequently in some family members. Bicuspid aortic valve disease affects about 2 percent of the population.

Congenital Pulmonic valve stenosis

 

The pulmonary valve can get narrowed or stenotic at early childhood or infancy. When this narrowing is severe and not permitting sufficient flow across the valve it causes breathing difficulties and fatigability. When it occurs in isolation it can be easily dealt with by percutaneous intervention techniques and the results are very gratifying.

 

Acquired valve disease

 

Acquired valve disease includes problems that develop with valves that were once normal. These may involve changes in the structure of your valve or infection.

 

 Infection

 

Infective endocarditis and rheumatic fever are the two causes of acquired valve disease.
Rheumatic fever is a common cause of valvular heart disease and is also known as rheumatic heart disease.

It causes:

  • The heart valve leaflets to become inflamed
  • May cause the leaflets to become scarred, rigid, thickened and shortened
  • May cause one or more of the valves (most commonly the mitral valve) to become stenotic (narrowed) or leaky
  • Usually caused by an untreated streptococcal infection.
  • Occurs most often in young children aged five to fifteen.
  • Presents in the second or third decade of life.

Rheumatic fever is caused by a group of bacteria called streptococci and presents commonly with throat infection hence the name “strep throat”. When left untreated or poorly treated it can damage the valves and heart alike. Antibodies developed by the body to fight the infection react with the heart valves, causing inflammation and eventual scarring. It can also cause joint pains, nose bleeds, neurological symptoms (chorea) and kidney infections. Penicillin is the antibiotic of choice. Rheumatic fever is the most common cause of valvular heart disease in developing nations such as India and south East Asia.

 

 

Endocarditis is a major infection of the heart and can be life-threatening. It occurs when germs (especially bacteria) enter your blood stream and attach to the surface of your heart valves.

  • Germs attack the heart valve, damaging the valve, by eroding the valve itself and causing holes or scarring of the valve tissue
  • May cause the valve to leak or become narrowed.

The germs can enter your blood stream during:

  • Dental procedures
  • Surgery
  • Intravenous (IV) drug use
  • Severe infections

Other causes of valve disease include: coronary artery disease, cardiomyopathy (heart muscle disease) , syphilis, hypertension, aortic aneurysms, connective tissue diseases, and less commonly, tumors, some types of drugs and radiation.

 

 Mitral valve disease

 

The mitral valve is found on the left side of the heart. It connects the collecting chamber or the left atrium to the pumping chamber or the left ventricle. This is commonly affected by rheumatic heart disease in the Asian subcontinent and by degenerative disease in the western world.


The mitral valve is made of two leaflets that are well supported in their structure and function by chords and papillary muscles of the heart. The normal area of opening is 3.5 sq.cm when this is area is less than 0.8sq.cm then the valve is said to critically stenosed and requires urgent attention. Any malfunction of the mitral valve can cause a back pressure on the blood vessels of the lungs resulting in increased pressures in the lungs and eventually right heart failure. This is one of the reasons early treatment of mitral valve disease has better results and lesser morbidity.

 

Rheumatic mitral valve disease

 

Frequent episodes of rheumatic activity triggered by strep throats can cause an inflammation of the mitral valve leaflets leading to

  • Thickening or stiffening of the leaflets
  • Shrinkage of the chords that hold the leaflets and their thickening

The above mentioned two processes can cause stenosis of the valve leading to back pressure in the left atrium and transmitting the pressure into the lungs.

They can also cause the leaflets to be pulled apart and make the valve leaky. This will cause the heart to enlarge and eventually lead to heart failure. This is easily repairable and the earlier one does it the lesser the risk and greater the benefit.

 

Degenerative mitral valve disease

 

The degeneration of the connective tissue framework of the valve results in the leaflets becoming loose and floppy. The floppy leaflets have poor approximation and result in a leaky valve.

Mitral valve prolapse (MVP) is a type of myxomatous valve disease. MVP causes the leaflets of the mitral valve to flop back into the left atrium during the heart's contraction. MVP also causes the tissues of the valve to become abnormal and stretchy, causing the valve to leak.

MVP occurs in about 1 to 2 percent of the population, equally in men and women. Most often it is not a cause for concern. Only 1 in 10 patients with MVP eventually require surgery. If the prolapse becomes severe or is associated with torn chordae or flail (floppy, lacking support) leaflets, the leak may be greater, requiring surgical intervention.

 

Ischemic Mitral valve disease

 

The mitral valve is supported in its function by chordae tendinae which are thin strands that connect it to the papillary muscles which are outpouchings from the left ventricle muscle and together these go to play an important part in the mechanics of the mitral valve. When one of these is damaged the valve is pulled apart and can leak profusely. These can be damaged by Ischemia or heart attack or trauma.

If the chordae become torn or papillary muscles become stretched or torn, the leaflets may flop backward when the ventricles contract (flail leaflet), causing a leaky valve.

 

 Aortic Valve disease

 

The aortic valve sits between the pumping chamber (the ventricle) and the aorta (main blood pipe out of the heart). This is very important to us as any defect will cause a significant decrease in blood going out of the heart. The valve can be affected in two ways

 

A. Stenosis

 

Stenosis is a narrowing of the valve causing a decrease in blood flowing out of the heart as a result the body is starving for good oxygenated blood. The heart has to pump harder to push blood against the resistance and over a period of time it becomes enlarged from increase in the muscle thickness quite similar to lifting weights in gym the more the resistance the greater the muscle bulk. The valve is narrowed by many causes such as

  1. congenital aortic stenosis
  2. Rheumatic aortic valve disease – stenosis or a combination of leak and stenosis
  3. bicuspid aortic valve
  4. Cacific Aortic stenosis: Fibro-calcific degeneration most commonly affects the aortic valve. It most often occurs in adults over the age of 65. This condition can be compared to atheroma in coronary artery disease. The valve leaflets become fibrotic (thickened) and calcified (hardened), producing a narrowed valve opening. Risk factors for this type of valve disease include:
                       Increased age
                       Low body weight
                       High blood pressure

 

B. Regurgitation

 

Also known as leaky valve. The blood flows to and fro freely across the valve which leads to enlargement of the heart due to the excess volume that it holds. . the causes of leaky valves are

  1. Rheumatic heart disease- the leaflets are stiffened and pulled apart or the edges may get rolled up thereby resulting in non coaptation or lack of a meeting point of the leaflets.
  2. Infective endocarditis: A severe bloodstream infection can seed the valve and damage it by causing a hole in the leaflets of by causing an infective vegetation to sit on the valve and prevent proper closure of the valve.
  3. Syphilis; this infection is less common these days and causes disease of the aorta leading to dilatation or widening of the aortic annulus (ring that hold the leaflets) leading to a leak in the valve.
  4. Marfans syndrome: It is a connective tissue disorder that cause weakening of the leaflets making them more floppy and in addition it can weaken the aortic annulus adding a component of annular dilatation. These lead to noncoaptation of the valve and significant leaks.
  5. Degenerative: just as atherosclerosis can cause aortic stenosis it can also cause a combination of stenosis and leak by the same mechanism.
  6. Connective tissue disorders: the human body has a fair amount of elastic tissue when this tissue is present in excess it can cause floppy valves and lead to leaks.
  7. Aortic disease- aortic dissection or aortic aneurysm.
  8. Dilatation of the valve annulus is a widening or stretching of the annulus. This causes the leaflets to lack support and not close tightly. Dilatation may occur when the heart muscle is damaged due to:
    • A heart attack (heart muscle injury)
    • Cardiomyopathy (weakened heart muscle)
    • Heart failure
    • Advanced stages of high blood pressure
    • Syphilis
    • Inherited disorders (such as Marfan syndrome)

 

 Tricuspid valve Disease

 

The tricuspid valve is located on the right side of the heart between the right atrium or collecting chamber and the right ventricle or pumping chamber. This side collects the deoxygenated blood and sends it to the lungs to get oxygenated. The right side of the heart is usually a low pressure system.
The tricuspid valve can get damaged in two ways

  1. Regurgitation or leak; the valve most commonly develops a leak when the annulus or ring holding the leaflets gets dilated due to an increase volume load to the right ventricle. The other cause of leak is infection of the valve which is seen in intravenous drug abusers. Sometimes infected pacemaker leads can also damage the valve.
  2. Stenosis: this is rare condition which is caused by rheumatic heart disease and is commonly associated with other valve lesions.
    Treatment: The tricuspid valve is a very repair friendly valve and in most cases it can be repaired. Rarely in infective endocarditis it may be damaged beyond repair and needs to be replaced.

 Pulmonary Valve disease

 

This valve is commonly affected by congenital disorders. This may occur in isolation or as a component of multiple disorders. The valve is mainly narrowed or stenosed leading to decreased flow of blood from the right heart to the lungs. Rarely the valve may be absent.

 

For isolated pulmonary valvar stenosis the treatment of choice is Balloon pulmonary valvotomy. When it is part of a complex congenital defect it is repaired surgically.

 

 How is valve disease diagnosed?

 

A detailed medical history and physical examination are the precursors to evaluating valvular heart disease. This can present in multiple ways such as

  • Difficulty in breathing worsened by exercise or stress and eventually even at rest.
  • Difficulty in lying down flat.
  • Heart murmur
  • Palpitations or abnormal heart rhythms
  • Dizziness and sometimes even fainting
  • Chest pain
  • Swelling of feet
  • Early morning puffiness of face
  • Distension of the abdomen

This is followed by a series of investigations that will confirm the diagnosis and also determine the extent of the disease. These are

  • Electrocardiogram (EKG or ECG) - electrical activity of the heart recorded on graph paper, using small electrode patches attached to the skin. The ECG can give us a clue to enlargement of the different chambers of the heart, if there are any rhythm disturbances present and any associated defects.
  • Echocardiogram (ultrasound of the heart) - a moving image of the heart’s valves and chambers using sound waves from a hand-held wand placed on your chest or passed down your throat (Trans esophageal echocardiogram).Using echocardioraphy we can assess the degree of damage to the valve, extent of narrowing or leak, and on most occasions a clue to the probable cause of the damage. When trans thoracic echocardiography is not clear as in obese individuals the acoustic windows may be poor, in them we use transesophageal echocardiography to get better visualization of the cardiac anatomy.

The most recent addition to our armamentarium is 3-D/4-D echocardiography which is very useful studying the anatomy of the defect and deciding on whether we can repair the valve if yes then what repair would be ideal. This preoperative information makes planning for the procedure easier.

 

  • Cardiac catheterization (angiogram) - x ray movies of the coronary arteries, heart chambers, and heart valves produced by contrast dye injected into a catheter in your arm or leg.
  • Magnetic resonance imaging (MRI) – Visualisation of the cardiac anatomy with the help of magnetic fields. The images are real time and one can calculate the exact volume of blood regurgitating back into the heart.

Additional test, such as the exercise stress echocardiogram, radionuclide scans, may also be used. By repeating tests over time, your doctor can see the progress of your valve disease and help make decisions about your treatment.

 

Valvular heart disease can be approached in a multidisciplinary manner. The treatment is broadly classified into three divisions

 Medical Treatment

 

This involves the following

  • Treatment of causative factors
  • Symptomatic treatment
  • Prophylactic treatment
  • Percutaneous treatment
  • Surgical treatment
    • Repairs
    • Replacement
    • Types of valves

Not all valvular heart disease requires intervention. If picked up at an early stage some of the diseases can be nipped in the bud or one can certainly extend the time to intervention. The medical management of valve diseases is subdivided into

 

Treatment of causative factors:

  • Rheumatic: The mainstay is antibiotics during an acute episode. In addition in case of active carditis we use steroids and anti-inflammatory agents.
  • Ischemic: Coronary artery disease can cause damage to the heart muscle and in turn the supporting apparatus. The treatment here is dircted more towards relief of the ischemia medically with anti anginals a\or by intervention be it percutaneous or surgical.
  • Infective: Antibiotics is the mainstay.
  • Heart failure: Any disease causing enlargement of the heart can cause valvar leaks due to non coaptation. Treatment is primarily directed towards control of failure.

Symptomatic treatment

 

Involves treatment with

  • Diuretics: Agents that increase urine output) to reduce lung congestion and peripheral edema.
  • Vasodilators : These drugs reduce the strain on the heart and increase the cardiac output. These drugs can buy precious time before one has to intervene and in some cases can delay the need for intervention in total.

Prophylactic treatment

 

The commonest cause of valve disease in the developing nations is still rheumatic which is a sequel of frequent “strep throats”. Penicillin is the drug of choice for this disease. Good prophylaxis can nip the disease in the bud and prevent rheumatic heart disease. Patients with underlying structural heart disease will need antibiotic cover during any surgical procedure such as dental extraction.

 

Percutaneous Treatment

 

Percutaneous mitral valvotomy: This is the procedure of choice for those patients who present with mitral valve stenosis or obstruction where the leaflets are still pliable and not very thickened. It is performed in the angiogram suite, the average length of hospital stay is around 2-3 days.

 

Percutaneous balloon aortic valve dilatation; This is the treatment of choice for congenital aortic stenosis and can also be used in adults if the valve anatomy is suitable for dilatation. This buys the patient a significant length of time before they need a valve replacement.

 

Balloon pulmonary valvotomyPulmonary valvar stenosis is condition that causes a narrowing of the pulmonary valve and can result in debilitating symptoms. This can occur in isolation or as a part of complex congenital heart disease. If it is stand alone then Balloon pulmonary valvotomy is the treatment of choice. The recovery is quick and results are gratifying.

 

Percutaneous valve repair/ replacement;The state of the art in the treatment of valve disease. Percutaneous technology is now available to repair leaking mitral valves from different causes. The choice of who is a good candidate is made by your doctor. Aortic valve disease in poor risk patients was until recently an inoperable condition, with the advent of percutaneous technology this is now feasible and has rigid criteria that need to be satisfied to deploy the valve. These are all in the early stages of use, time will tell us the long term benefits

 

Surgery
Mitral valve surgery:

 

In the years gone by most surgeons would replace the mitral valve for most disease and this scenario has changed dramatically. With better understanding of the mitral valve mainly due to some pioneering work by Prof. Carpenteiur from France and his classification of mitral valve disease. The era of mitral valve repair started. Now most surgeons repair the mitral valve as far as possible . the surgeon decides who is a good candidate for repair. The advantages of mitral valve repair are

 

1. Retains native valve
2. No need for long term anticoagulation
3. Retains heart function and improves it.

 

Aortic valve repair:

 

This is a technically difficult operation that can be used in small subset of patients. Young patients with aortic valve leak due to prolapsing or floppy leaflets are good candidates. The other group is patients with bicuspid aortic valve disease In some cases repair is not possible or has failed these patients will require a mitral valve replacement with either mechanical valves or bioprosthetic tissue valves. The choice of the valve is based on patient factors and your doctor will advise you accordingly.

 

 
 

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