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What is Cardiomyopathy in Children?

Cardiomyopathies are diseases of the heart muscle, also known as the myocardium, in which the actual muscle cells and surrounding tissues are sick.

Cardiomyopathies can be primary, meaning the sickness mainly involves the heart.

They can also be secondary, meaning the sickness is a result of another disease or toxin and may also affect many organ systems within the body, including the heart.

Patients with cardiomyopathy will most commonly have a heart that looks normal but does not work well. 

Causes of Cardiomyopathy

The cause of cardiomyopathy in most cases is unknown, also referred to as idiopathic. Some causes of cardiomyopathy may include:

  • Changes in the genetic code or DNA, where it may run in families
  • A viral infection of the heart, or myocarditis, which weakens the heart muscle
  • Metabolic disorder as well as inherited muscle disorders
  • Problems of the coronary arteries, either present at birth or acquired

Although there is a long list of possible causes of cardiomyopathy, few are directly treatable and most therapy is aimed at treating the secondary effects on the heart.

There are other less common forms of cardiomyopathy that can be caused by hormone deficiencies, chronic medical conditions, and rhythm problems.  As part of the evaluation for cardiomyopathy, detailed medical and family histories are taken to find the cause of cardiomyopathy, but in a large number of cases, there is no other diagnosis.

Cardiomyopathy Symptoms

Dilated cardiomyopathy presents with signs and symptoms of congestive heart failure (CHF).

Infants with this disease may have:

  • Fast and heavy breathing with feedings
  • Feedings that take longer than normal
  • Sweating with feedings
  • Lethargy or inactivity
  • Poor weight gain

Common symptoms in older children and adolescents are:

  • Abdominal pain
  • Nausea
  • Vomiting
  • Trouble with exercise
  • Changes in their endurance during exercise or not able to keep up with other children their age
  • Trouble breathing
  • Cough
  • Abnormal heartbeats
  • Dizziness
  • Decreased appetite

Hypertrophic cardiomyopathy presents in a variety of ways.

Infants may have:

  • Fast and heavy breathing with feedings
  • Sweating with feedings
  • Lethargy or inactivity
  • Poor weight gain

Older children may have:

  • Trouble exercising
  • Chest pain with exercise
  • Palpitations
  • Dizziness
  • Passing out (passing out during exercise is a concern and children should be seen by a cardiologist)

Some children have no symptoms but are found to have a  murmur, usually due to the obstruction of blood flow out of the ventricle or leaking of one of the valves of the heart. Often, the murmur is absent until they reach their teenage years.

Restrictive cardiomyopathy causes trouble with breathing.

Often children may notice the following:

  • Hard to breath when they have a respiratory illness such as colds, bronchiolitis, and pneumonia
  • Passing out (also called syncope)
  • Getting tired easily
  • Enlarged belly due to high pressure on the right side of the heart which causes a large liver and fluid buildup in the belly.
  • Swelling in their face or legs

Patients with left ventricular non-compaction often have no symptoms and are found when having an echocardiogram for other reasons. Symptoms in these children are related to dilation and decreased function of the ventricle as in dilated cardiomyopathy.

Patients with arrhythmogenic right ventricular dysplasia (ARVD) often have no symptoms, and most present due to a sudden cardiac event caused by an abnormal heart rhythm or because of family history of ARVD.

Diagnosis of Cardiomyopathy

Physical Exam

For all patients thought to have cardiomyopathy, the history and physical examination are key in making the diagnosis. Signs of congestive heart failure, such as fast breathing and fast heart rate, abnormal lung and heart sounds, and an enlarged liver can help the doctor make the right diagnosis.

A murmur and abnormal chest wall impulses can be found in hypertrophic cardiomyopathy, but their absence does not rule out the diagnosis. Parents and siblings of patients with hypertrophic cardiomyopathy should see a cardiologist even if they have no signs or symptoms.

Test to Help with Diagnosis Include:

  • An electrocardiogram (EKG) to evaluate the amount of enlargement as well as the rhythm of the heart is often performed during the initial evaluation.
  • An echocardiogram, or sonogram of the heart, will give a definitive diagnosis as to the type of cardiomyopathy and the degree of dysfunction of the heart muscle.
  • A chest X-ray is sometimes used to screen for cardiac disease and can show an enlarged heart and extra fluid in the lungs (also referred to as pulmonary edema).
  • cardiac catheterization may also be performed, not only to evaluate the pressures within each chamber of the heart, but also to evaluate the coronary arteries as malformations of these arteries can be a cause of cardiomyopathy. Sometimes small pieces of heart muscle are also taken during the cardiac catheterization for laboratory study. Such heart muscle biopsies are helpful in the evaluation of possible infections of the heart, as well as certain metabolic abnormalities of the heart.

Types of Cardiomyopathy

Cardiologists group cardiomyopathy into five categories:

  1. Dilated cardiomyopathy (DCM), also known as congestive cardiomyopathy: Dilated cardiomyopathy is the most common form of cardiomyopathy in children, and ischemic cardiomyopathy is the most common type of dilated cardiomyopathy. In DCM, the heart becomes enlarged and does not contract or squeezes poorly. 
  2. Hypertrophic cardiomyopathy (HCM): With hypertrophic cardiomyopathy, the heart muscle is thickened.  Another name for this is idiopathic hypertrophic subaortic stenosis (IHSS). Hypertrophy, or thickening, particularly of the left ventricle, can make it hard for blood to flow through the heart and for the left ventricle to fully relax.  Children with hypertrophic cardiomyopathy are also at increased risk for abnormal heart rhythms, or arrhythmias. 
  3. Restrictive cardiomyopathy (RCM): With restrictive cardiomyopathy, the pumping chamber or ventricle is not able to relax properly. As a result, blood gets backed up into the upper chambers of the heart, or atria, and they become enlarged or bigger, while the lower pumping chambers, the ventricles, remain normal in size. This is a rare form of cardiomyopathy in children.
  4. Left ventricular non-compaction (LVNC): On echocardiogram, the heart muscle appears coarse and marked with fingerlike projections called trabeculations.  It appears coarse and jagged instead of smooth and compact.  It may be related to  other forms of congenital heart disease but can occur on its own.  A few patients may go on to have poor function and heart failure.
  5. Arrhythmogenic right ventricular dysplasia (ARVD): The muscle of the heart is replaced by fat tissue over time and leads to dangerous heart rhythms. This form of cardiomyopathy is often hard to diagnose. It is usually first found when the patient has an abnormal rhythm. This is also sometimes referred to as arrhythmogenic right ventricular dysplasia (ARVD).

Cardiomyopathy Treatment

Dilated Cardiomyopathy

Treatment of patients with dilated cardiomyopathy may best be divided into immediate and long-term time frames.

Immediate Care

If the patient is critically ill, initial treatment can require lifesaving measures such as placement of a breathing tube and use of a mechanical ventilator. Acutely ill patients may need intravenous (IV) fluids and medicines to improve blood pressure and heart function. The sickest patients may need to have help from an artificial heart-lung machine called ECMO.

Diuretics are medicines designed to remove extra fluid from the body. Blood thinners are used when clots form within the poorly functioning heart chambers. The dilated heart may cause rhythm problems and medicines can help with these issues.

Long-Term Care

Once the patient is more stable, long-term care can involve a number of strategies. Medicines such as captopril and enalapril relax the arteries in the body, lower the  blood pressure and make it easier for the heart to pump blood to the rest of the body. Common diuretics, like Lasix and Aldactone, are used to reduce the extra fluid in the lungs. Digoxin is an oral medicine that improves the pumping function of the heart, as well as helps prevent certain types of arrhythmias.

Research in adults has shown that the use of a group of blood pressure medicines called beta-blockers (propranolol, atenolol, carvedilol) has some long-term benefit, and these are sometimes used in children.

Hypertrophic Cardiomyopathy

Immediate Care

Patients with hypertrophic cardiomyopathy may have trouble with abnormal, fast heart rates.  They may need medicines to slow their heart rate (beta-blockers) or even electrical shock to stop these abnormal rhythms. These patients may also need some of the same life-saving treatments mentioned above.

In patients who have had a life-threatening arrhythmia, which can be caused by the thickened ventricle, or have risk factors for such arrhythmias, surgically placed devices can “shock” a patient instantly at the time of a life-threatening event. Such devices are called ICDs (internal cardioverter / defibrillator).

Long-Term Care

The more chronic treatment options for hypertrophic cardiomyopathy address both the problems of arrhythmia and obstruction to flow by the thickened heart muscle. Treatment for outflow obstruction can include medicines such as beta-blockers (atenolol, metoprolol) and calcium channel blockers (verapamil), designed to slow the heart rate and “relax” the heart, thereby decreasing the obstruction. Diuretics and digoxin are not usually used in this type of cardiomyopathy as it can worsen the obstruction of blood flow out of the heart. There is some controversy as to whether surgically removing some of the thickened muscle is of any benefit. Sometimes surgery on the mitral valve, if it is involved in the obstruction, is performed, although this too is controversial. 

Restrictive Cardiomyopathy

Immediate and Long-Term Care

Patients with restrictive cardiomyopathy are at high risk for blood clots within the heart, particularly the enlarged upper chambers. Blood thinners such as aspirin, Coumadin (warfarin) or Lovenox may be needed. Gentle use of diuretics can also help some patients. ICDs are also used because these patients are at risk for sudden cardiac arrest related to fast or slow rhythms.


Immediate and Long-Term Care

Patients with ARVD can benefit from treatment with medicines to limit abnormal rhythms. Treatment also consists of placement of an ICD to protect against sudden cardiac events such as an arrest. In certain cases, a catheter-based procedure to eliminate the abnormal rhythm can be performed.

Long-Term Outlook

Dilated cardiomyopathy (DCM) is a serious disease. However, like most diseases, dilated cardiomyopathy occurs with a spectrum of severity and outcomes.

For patients with DCM and heart failure from viral illnesses or myocarditis,  about one-third have persistent poor heart function, one-third improve but are left with some heart dysfunction, and one-third recover completely. It is hard to predict into which category an individual patient will fall. This is why frequent cardiology follow-up is important. Patients who have irreversible damage and persistent poor function may go on to require a heart transplant.

The exact number of patients with hypertrophic cardiomyopathy is unknown, as some patients have no symptoms. The chance of premature death is estimated to be less than 1 percent. Risk factors for sudden death include episodes of passing out, diagnosis at a young age, family history of sudden death, marked heart thickening on echocardiogram, and fast heart rhythms seen on monitoring. In less than 5 percent of patients, late complications can include enlargement of the left ventricle and decreased pumping function.

As restrictive cardiomyopathy accounts for only 5 percent of patients with cardiomyopathy, the total number of patients with this disease is small and the overall outcome data is limited. Unfortunately, the available information indicates that prognosis is generally poor. Only 45 percent to 50 percent of patients with this type of cardiomyopathy are estimated to survive two years after the diagnosis. These patients are typically referred early to heart transplant, before they get other symptoms from their heart disease.

Left ventricular non-compaction can present in different ways and some patients never go on to develop heart disease.  Family history in these cases is important to find those patients at risk of developing heart disease but most patients are found in isolation. Regular visits to a cardiologist are necessary to find any changes in heart function.

The outcome for ARVD is hard to assess due to its relatively rare nature and generally late diagnosis. How the patient initially presents, for example after a cardiac arrest or due to family history, can influence the course of the disease.

Last Updated 07/2019

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