Cardiomyopathy

What is cardiomyopathy?

Cardiomyopathy is any disease or condition that changes the structure of or weakens the heart muscle.  “Cardio” refers to the heart, “myo” refers to muscle, and “pathy” refers to disease.  The heart muscle can either be enlarged, abnormally thick, rigid, or replaced with scar tissue.  Often, the result of cardiomyopathy is heart failure, a condition in which a modified heart muscle is unable to pump an adequate amount of blood to the rest of the body.

What is dilated cardiomyopathy?

Doctors classify cardiomyopathies based on what causes them and what changes occur in the heart muscle structure.  Dilated cardiomyopathy, the most common form, usually initiates in the lower area of the left ventricle in the heart.  The left ventricle is the largest, strongest chamber of the heart because it pumps oxygenated blood out to the body.  When the body does not get enough blood, the heart muscle may respond by dilating.  The inside area of this ventricle enlarges as the muscle surrounding it stretches and thins (dilates).  A dilated ventricle pumps with less force than a healthy ventricle.  Often, the heart muscle will continue to stretch in an effort to compensate for the reduced pumping action.  Thus, the atria and right ventricle may also dilate as this disease progresses.

What causes dilated cardiomyopathy?

Dilated and other cardiomyopathies are classified by what causes them in addition to what changes occur in the heart.  Idiopathic or primary cardiomyopathies have no identifiable cause and compose the majority of cases in children.  Secondary cardiomyopathies have an identifiable cause such as a disease, condition, or substance.  About one half of the cases of dilated cardiomyopathy are called familial dilated cardiomyopathy because they are inherited or caused by an inherited condition.  Barth syndrome is a rare genetically linked disease affecting male children during their first year of life.  Along with skeletal muscle changes, short stature, metabolic abnormalities, and a low number of white blood cells (this condition is known as neutropenia), Barth syndrome can cause dilated cardiomyopathy.  Coronary artery disease and heart attacks cause ischemic cardiomyopathy.  Scars in the heart muscle from heart attacks leave areas of the heart which are unable to contribute to the pumping.  The larger a scar is, the more likely it is to develop cardiomyopathy.  Alcohol abuse can cause alcoholic cardiomyopathy, especially when the abuse is sustained over a period of at least ten years and/or is combined with a poor diet.  The good news about alcoholic cardiomyopathy is that sometimes when a person has damaged their heart with excessive alcohol, he may recover completely when he stops drinking.  Peripartum cardiomyopathy is related to pregnancy and occurs during the last month of pregnancy or the five months following birth.  Cobalt and other toxins can cause dilated cardiomyopathy along with drugs like cocaine, amphetamines, and some medicines used to treat cancer like doxorubicin and daunorubicin.  Metabolic disorders like thyroid disease and diabetes can also cause dilated cardiomyopathy.

What is hypertrophic cardiomyopathy?

Hypertrophic cardiomyopathy describes an abnormal thickening of the heart muscle, usually in the left ventricle, without any obvious cause.  The thickening is characterized by a disorganized arrangement of muscle cells called myocardial disarray.  Because the thickened muscle makes the inside volume of the ventricle smaller, hypertrophic cardiomyopathy decreases the pumping volume of the heart.  As the muscle thickens, it may also become stiff and cause the ventricle not to relax and fill properly in between contractions resulting in increased pressure in vessels of the lungs and the ventricles themselves.  When the wall that divides the left and right sides of the heart thickens and bulges into the left ventricle blocking blood flow, doctors refer to this as hypertrophic obstructive cardiomyopathy (HOCM), asymmetric septal hypertrophy (ASH), or idiopathic hypertrophic subaortic stenosis (IHSS).  The obstruction causes the ventricle to work harder and the body to receive an insufficient amount of blood.  Obstructive hypertrophic cardiomyopathy may also distort a leaflet of the mitral valve in the heart and cause blood to leak through the valve when it cannot close completely.  When the thickened muscle does not obstruct the blood flow out of the ventricle, the hypertrophy is considered nonobstructive.  Apical hypertrophy, in which only the bottom of the heart is thickened, and symmetrical hypertrophy, in which the entire ventricle is thickened, are both forms of nonobstructive hypertrophic cardiomyopathy. 

What causes hypertrophic cardiomyopathy?

When hypertrophic cardiomyopathy is not inherited, the cause may be unknown or the disease may be attributed to aging or sustained high blood pressure.

What is restrictive cardiomyopathy?

Restrictive cardiomyopathy, the least common form of the disease, occurs when the ventricle muscles in the heart become stiff but are not necessarily thickened.  The stiffened muscles make it difficult for the chambers to expand and fill with blood in between contractions.  When the ventricles do not fill properly, the atria become enlarged in an effort to compensate.

What causes restrictive cardiomyopathy?

Restrictive cardiomyopathy can be idiopathic (occurring for no known reason), or may be the result of a specific disease process or condition occurring in another part of the body.  Hemochromatosis is a hereditary disorder that can cause restrictive cardiomyopathy when the body absorbs too much iron from food.  This disorder can damage the heart and other organs because the body stores the excess iron in their tissues.  Cells in the bone marrow of individuals with amyloidosis produce abnormal proteins.  The body may deposit these proteins in heart tissue and cause restrictive cardiomyopathy.  Amyloidosis may begin in the bone marrow due to some unknown cause, be the result of a chronic inflammatory or infectious condition, or be inherited.  Sarcoidosis is an inflammatory condition that begins in the lungs and can spread to other organs including the heart where it can cause restrictive cardiomyopathy.  Certain connective tissue disorders can also cause restrictive cardiomyopathy.

What is arrhythmogenic right ventricular dysplasia?

Arrythmogenic right ventricular dysplasia (ARVD) is a rare, genetic cardiomyopathy in which fat and fibrous scar tissue replaces the muscle tissue in the right ventricle.  An affected person’s heart has patches of abnormal tissue surrounded by areas of healthy muscle tissue.  This disorganized heart structure interferes with the heart’s electrical activity and causes abnormal heart rhythms (arrythmias).  ARVD is an important cause of sudden cardiac death in young patients.

What are the symptoms of cardiomyopathy?

Some cardiomyopathy patients never have symptoms, but most eventually develop symptoms because as the disease progresses, the heart weakens and begins to fail.  The symptoms of heart failure and cardiomyopathy include the following:  arrhythmias; chest or heart pain; decreased alertness; decreasing ability to tolerate physical exertion; dizziness; fainting; heart murmurs; lightheadedness; low daytime urine production; heart palpitations; high nighttime urine production; high blood pressure; shortness of breath; swelling in the abdomen, ankles, feet, or legs; tiredness; and weakness.

What are the dangers of cardiomyopathy?

All types of cardiomyopathy can cause heart failure.Heart failure does not mean that the heart has stopped beating or working, instead, it describes the condition where the heart is unable to pump enough blood through the body.Heart failure causes fluid to accumulate in the lungs, feet, ankles, and legs; it also causes tiredness and shortness of breath.Arrhythmias, abnormal heart rates or rhythms, may occur as cardiomyopathy interferes with the heart’s electrical signaling system.Arrhythmias may result in the loss of a heart beat (cardiac arrest).  Endocarditis, the inflammation of the heart’s inner lining, may occur in rare cases of cardiomyopathy.  Heart failure, blood clots, arrhythmias, glomerulonephritis, severe heart valve damage, stroke, brain abscess, brain or nervous system changes, and jaundice can all occur with endocarditis.  With dilated cardiomyopathy, the enlarged heart serves as a slow pool in which blood clots can develop.  A clot or piece of a clot may break free and block blood flow somewhere else in the body.

What are the risk factors for cardiomyopathy?

Cardiomyopathy occurs in both sexes, and in all age and ethnic groups.  African Americans, people from 20 to 60 years of age, males, and patients with a positive family history are most likely to get dilated cardiomyopathy.  Patients with a family history of hypertrophic cardiomyopathy are at risk for the disease; in up to 70% of hypertrophic cardiomyopathy cases, the patient has a positive family history.  People afflicted with a disease that is known to cause restrictive cardiomyopathy may be at risk for developing the disease.  Having one or more of the following may mean that you are at risk for cardiomyopathy:  alcoholism; amyloidosis; coronary artery disease; diabetes or other metabolic diseases; hemochromatosis; hypertension; myocarditis; a positive family history of cardiomyopathy, heart failure, or sudden cardiac death; a previous heart attack; or sarcoidosis.

How do doctors find and diagnose cardiomyopathy?

Doctors may hear suspicious heart and lung sounds with a stethoscope or observe swelling of the abdomen, legs, or feet during a physical exam.  If doctors detect a heart murmur or inspect an abnormal electrocardiogram, they may be able to determine that the patient has cardiomyopathy.  These tests may indicate the presence and type of cardiomyopathy: electrocardiogram (EKG or ECG), holter monitor, echocardiogram, exercise stress test, positron emission tomography (PET) scanning, magnetic resonance imaging (MRI), transesophageal echocardiography (TEE), chest x-ray, blood tests, cardiac catheterization, coronary angiography, and myocardial biopsy.

What medicines and behavioral changes help with cardiomyopathy treatment?

There is often no cure for cardiomyopathy, but treatment of the cardiomyopathy or underlying cause may allow patients to live normal lives.  The treatment options for cardiomyopathy include certain drugs, behavioral changes, procedures, and devices.  A doctor may prescribe angiotensin-converting enzyme (ACE) inhibitors which dilate blood vessels to lower blood pressure and make pumping easier for the heart.  Diuretics help patients with heart failure because they expel excess fluids to help the heart pump and lower blood pressure.  Beta-andrenergic blocking drugs (beta-blockers) slow nerve impulses through the heart so that it can relax and use less blood and oxygen.  Calcium channel blockers relax blood vessels, lower blood pressure, and give the heart more blood and oxygen.  Digoxin slows the heart rate and makes the heart pump with more force.  Anticoagulents are used for dilated cardiomyopathy to help prevent forming new blood clots or enlarging existing ones.  Antiarrhythmic drugs can help return a heart that is beating too fast or irregularly to normal rhythm.  Antibiotics can prevent infection of heart tissues.  A doctor may recommend that a patient do the following to help treat or prevent aggravating cardiomyopathy: avoid illegal drugs, eat a low-salt diet, exercise, lose weight, quit smoking, and quit drinking alcohol.

What devices and procedures are available for cardiomyopathy treatment?

In addition to medicines and behavioral changes, doctors use surgery, a special procedure, and surgically implanted devices to treat cardiomyopathy.  Sometimes, with severe congestive heart failure, a heart transplant is the ultimate treatment. 

What are septal myectomy and alcohol septal ablation?

Septal myectomy is an open heart surgery that can be used for patients with severe symptoms of hypertrophic obstructive cardiomyopathy.  The purpose of the surgery is to remove part of the wall dividing the left and right sides of the heart (septum) and repair the mitral valve, if necessary, in order to restore normal blood flow in the heart.  This procedure has low mortality rates (1 to 2%) and high five, ten, and fifteen year survival rates (98, 96, and 83%).  Alcohol septal ablation is a newer, less invasive procedure used to restore normal blood flow through the hearts of patients with hypertrophic obstructive cardiomyopathy.  During the procedure, a doctor inserts a catheter into the groin, guides it to the heart, isolates a vein and injects alcohol.  The goal of the procedure is to kill cells in the thickened tissue so that it will shrink for several weeks after the ablation and blood will flow freely through the left ventricle.  Alcohol septal ablation has only been performed since 1994, and some issues about the advantages and disadvantages of this procedure and septal myectomy remain unresolved. 

What surgically implanted devices help with cardiomyopathy treatment?

Sometimes surgeons will implant permanent devices to help the heart keep a steady, controlled, effective rhythm.  A pacemaker is an electronic device that functionally replaces a patient’s natural pacemaker or overrides a patient’s faulty atrioventricular node in order to maintain a normal heart rate and rhythm.  A biventricular pacemaker makes sure that the left and right ventricles contract at the same time.  A left ventricular assist device (LVAD) is a mechanical device that helps the left ventricle pump oxygenated blood through the body.  A patient awaiting a heart transplant may use an LVAD to temporarily assist a failing heart, a patient who cannot get a heart transplant may use the device as a long term treatment, or a patient who is recovering from open heart surgery may use an LVAD until they have recovered.  Patients with a history of arrhythmias or certain heart diseases like hypertrophic cardiomyopathy use an implantable cardioverter defibrillator to monitor their heart rate and rhythm and deliver a restoring shock if necessary to prevent dangerous arrhythmias.

What is a heart transplant?

Patients with cardiomyopathy are at risk for heart failure.  Sometimes, the only effective treatment option for a person with heart failure is a heart transplant.  During a heart transplant, a surgeon uses an artificial pump to maintain circulation while he removes a patient’s diseased heart and replaces it with a donor’s healthy heart.