Pediatric cardiomyopathy is a rare heart condition that affects infants and children. Specifically, cardiomyopathy means disease of the heart muscle (myocardium). Several different types of cardiomyopathy exist and the specific symptoms vary from case to case. In some cases, no symptoms may be present (asymptomatic); in many cases, cardiomyopathy is a progressive condition that may result in an impaired ability of the heart to pump blood; fatigue; heart block; irregular heartbeats (tachycardia); and, potentially, heart failure and sudden cardiac death.
Cardiomyopathy may be termed ischemic or nonischemic. Ischemic cardiomyopathy refers to cases that occur due to a lack of blood flow and oxygen (ischemia) to the heart. Such cases often result from hardening of the arteries (coronary artery disease). Nonischemic cardiomyopathy refers to cases that occur due to structural damage or malfunction of the heart muscle. Nearly all cases of pediatric cardiomyopathy are nonischemic. This report deals with nonischemic pediatric cardiomyopathy.
Cardiomyopathy may also be termed primary or secondary. Primary cardiomyopathy refers to cases where cardiomyopathy occurs by itself or for unknown reasons (idiopathic). Secondary cardiomyopathy refers to cases where the disease occurs secondary to a known cause such as heart muscle inflammation (myocarditis) caused by viral or bacterial infections; exposure to certain toxins such as heavy metals or excessive alcohol use; or certain disorders that affect the heart and/or additional organs systems. According to the Pediatric Cardiomyopathy Registry, approximately 79 percent of pediatric cardiomyopathy cases occur for unknown reasons (idiopathic).
Nonischemic cardiomyopathy may be further divided into four subtypes based upon the specific changes within the heart. These subtypes are: dilated, hypertrophic, restrictive and arrhythmogenic right ventricular dysplasia.
The specific symptoms of pediatric cardiomyopathy depend upon the type of cardiomyopathy present. Some individuals with cardiomyopathy may not exhibit any symptoms (asymptomatic) throughout life. Common symptoms of cardiomyopathy that may occur include fatigue, shortness of breath (dyspnea) especially with exertion, and chest pain. Additional symptoms potentially associated with all forms of cardiomyopathy include irregular heartbeats (arrhythmias) such as abnormally fast (tachycardia) or slow (bradycardia) heartbeats; and endocarditis, a condition characterized by inflammation of the innermost layer of the heart muscle (endocardium). In some cases, cardiomyopathy may progress to cause congestive heart failure, cardiac arrest, and sudden death. In some cases, cardiomyopathy is present at birth or during childhood but no symptoms develop until adulthood.
The normal heart has four chambers. The two upper chambers, known as atria, are separated from each other by a fibrous partition known as the atrial septum. The two lower chambers are known as ventricles and are separated from each other by the ventricular septum. Valves connect the atria (left and right) to their respective ventricles. The valves allow for blood to be pumped through the chambers and prevents the flow from going backwards. Blood travels from the right ventricle through the pulmonary artery to the lungs where it receives oxygen. The blood returns to the heart through pulmonary veins and enters the left ventricle. The left ventricle sends the now oxygen-filled blood into the main artery of the body (aorta). The aorta distributes the blood throughout the body.
The various forms of nonischemic cardiomyopathy occur because of structural damage and malfunction of the heart muscle itself. Most cases of nonischemic cardiomyopathy affect the left ventricle, the main pumping chamber of the heart. However, the right ventricle and the atria may also become involved.
Dilated cardiomyopathy is characterized by abnormal enlargement or widening (dilatation) of one or ventricles because of a weakening of the heart’s pumping action, causing a limited ability to circulate blood to the lungs and the rest of the body which may result in fluid buildup in the heart, lung and various body tissues (congestive heart failure). In some cases, all four chambers of the heart may be affected. Symptoms of congestive heart failure may depend upon an affected child’s age and other factors. In young children, for example, heart failure may be manifest as fatigue and shortness of breath (dyspnea) upon exertion. Additional symptoms may include swelling of the legs and feet and, in some cases, chest pain. Initial symptoms of dilated cardiomyopathy in infants and children may include irritability, a persistent cough, shortness of breath, and poor feeding habits resulting in the failure to grow and gain weight at the expected rate (failure to thrive). Affected individuals may also experience excessive sweating, fatigue, wheezing, and paleness of the skin (pallor). More serious complications may include fainting episodes (syncope), abdominal pain, irregular heartbeats, and fluid accumulation within the lungs (pulmonary congestion) resulting in a persistent cough.
Hypertrophic cardiomyopathy is characterized by abnormal thickening of the walls of the heart potentially resulting in obstruction of blood flow in and out of the heart. In most cases, the left ventricle is affected. The symptoms of hypertrophic cardiomyopathy vary widely among affected individuals. In many cases, affected individuals have no symptoms. Affected infants and children may experience shortness of breath upon exertion, fatigue, excessive sweating, and poor appetite and weight gain resulting in growth failure. As affected children age, they may experience chest pain or discomfort, irregular heartbeats, dizziness or fainting episodes (syncope) usually upon heavy exertion, and, eventually, congestive heart failure and fluid accumulation within the lungs. In some cases, affected individuals may experience sudden cardiac arrest and, potentially, sudden death.
Restrictive cardiomyopathy is extremely rare in children. In this form of cardiomyopathy, the muscular walls of the heart become stiff and rigid preventing proper blood flow through the heart. Symptoms associated with restrictive cardiomyopathy in infants and children include shortness of breath, fatigue, chest pain, and poor appetite and weight gain, resulting in growth failure. Additional symptoms may include fluid collection in the abdomen (ascites) and feet due to accumulation of fluid, congestion of the lungs, and an abnormally large liver (hepatomegaly). Irregular heartbeats, the formation of blood clots and heart block may also occur. Restrictive cardiomyopathy may progress to cause congestive heart failure and sudden death.
Arrhythmogenic Right Ventricular Dysplasia
Arrhythmogenic right ventricular dysplasia (ARVD) is a rare form of nonischemic cardiomyopathy in which the normal muscular tissue of the right ventricle is replaced by fatty tissue and may also occasionally affect the right ventricle. The symptoms of ARVD vary greatly. Symptoms may develop during childhood, but in most cases do not appear until the 30s or 40s. Symptoms associated with ARVD may include irregular heartbeats (arrhythmias), shortness of breath, swollen neck veins, abdominal discomfort, and fainting episodes (syncope). In some cases, no symptoms are apparent until an affected individual goes into cardiac arrest and possibly sudden death.
Most cases of pediatric cardiomyopathy occur for unknown reasons (idiopathic). Pediatric cardiomyopathy may be inherited or acquired. In recent years, investigators have determined that many cases of pediatric cardiomyopathy may be caused by disruption or changes (mutations) of certain genes. Researchers have discovered more than 300 different genetic mutations that may play a role in the development of different forms of cardiomyopathy.
In most cases, the cause of dilated cardiomyopathy is unknown (idiopathic). However, dilated cardiomyopathy may be acquired or inherited. The development of dilated cardiomyopathy has been linked to excessive alcohol use, viral or bacterial infections that result in inflammation of the heart muscle (myocarditis), autoimmune disease, and metabolic deficiencies. Exposure to certain toxins including heavy metals (e.g., cobalt or lead) and certain chemotherapy drugs may lead to the development of the disorder. Dilated cardiomyopathy may also occur as part of certain endocrine, blood (hematological), and collagen vascular disorders.
Dilated cardiomyopathy may also occur secondary to a generalized genetic disorder such as one of the muscular dystrophies, certain metabolic disorders, or a rare genetic disorder such as Barth syndrome. In some cases, dilated cardiomyopathy may be inherited as an isolated genetic condition (familial dilated cardiomyopathy). It has been estimated that genetic factors play a role in more than 30 percent of cases of dilated cardiomyopathy. Most cases are inherited as an autosomal dominant trait. Cases of autosomal recessive or X-linked inheritance have also been reported.
Genetic diseases are determined by two genes, one received from the father and one from the mother. Dominant genetic disorders occur when only a single copy of an abnormal gene is necessary for the appearance of the disease. The abnormal gene can be inherited from either parent, or can be the result of a new mutation (gene change) in the affected individual. The risk of passing the abnormal gene from affected parent to offspring is 50% for each pregnancy regardless of the sex of the resulting child.
Recessive genetic disorders occur when an individual inherits the same abnormal gene for the same trait from each parent. If an individual receives one normal gene and one gene for the disease, the person will be a carrier for the disease, but usually will not show symptoms. The risk for two carrier parents to both pass the defective gene and, therefore, have an affected child is 25% with each pregnancy. The risk to have a child who is a carrier like the parents is 50% with each pregnancy. The chance for a child to receive normal genes from both parents and be genetically normal for that particular trait is 25%.
X-linked recessive genetic disorders are conditions caused by an abnormal gene on the X chromosome. Females have two X chromosomes but one of the X chromosomes is “turned off” and all of the genes on that chromosome are inactivated. Females who have a disease gene present on one of their X chromosomes are carriers for that disorder. Carrier females usually do not display symptoms of the disorder because it is usually the X chromosome with the abnormal gene that is “turned off”. Males have one X chromosome and if they inherit an X chromosome that contains a disease gene, they will develop the disease. Males with X-linked disorders pass the disease gene to all of their daughters, who will be carriers. Males cannot pass an X-linked gene to their sons because males always pass their Y chromosome instead of their X chromosome to male offspring. Female carriers of an X-linked disorder have a 25% chance with each pregnancy to have a carrier daughter like themselves, a 25% chance to have a non-carrier daughter, a 25% to have a son affected with the disease, and a 25% chance to have an unaffected son.
Hypertrophic cardiomyopathy is inherited as an autosomal dominant trait in more than 50 percent of cases. In some cases, there is no apparent family history of the disorder. In some of these cases, hypertrophic cardiomyopathy may be caused by new genetic changes (mutations) that occur spontaneously for unknown reasons (sporadically). These mutations may be passed onto future generations as an autosomal dominant trait. Non-genetic factors, in combination with genetic factors, may play a role in determining who develops hypertrophic cardiomyopathy. In other cases, the cause of hypertrophic cardiomyopathy is unknown (idiopathic).
In most cases, restrictive cardiomyopathy occurs secondary to a systemic disorder such as amyloidosis, sarcoidosis or hemochromatosis. In amyloidosis, specific proteins (amyloids) abnormally accumulate in the heart resulting in stiffening of the ventricles, which prevents proper blood flow through the heart. In sarcoidosis, certain white blood cells abnormally accumulate in the heart. In hemochromatosis, iron accumulates in the heart. Some cases of restrictive cardiomyopathy occur secondary to certain connective tissue diseases.
Restrictive cardiomyopathy may also occur as a result of scarring from open-heart surgery or exposure of the chest to radiation. In a rare subset of cases, restrictive cardiomyopathy has run in families suggesting that hereditary (genetic) factors may play a role in the development of the disorder in rare cases. In children, the cause of restrictive cardiomyopathy is unknown in more than 90% of those affected.
Genetic factors play a role in most cases of ARVD. In many cases, the disorder is inherited as an autosomal dominant trait. Some cases of ARVD may result from infection of the heart muscle.
The exact prevalence of pediatric cardiomyopathy in the general population is unknown and estimates vary within the medical literature. However, because asymptomatic cases often go unrecognized, pediatric cardiomyopathy is under-diagnosed, making it difficult to determine the true frequency of these disorders in the pediatric population.
According to the national Pediatric Cardiomyopathy Registry, 1 in every 100,000 children in the United States under the age of 18 is diagnosed with primary cardiomyopathy.
This estimate, however, excludes children affected by secondary cardiomyopathy and potentially undiagnosed asymptomatic cases. Within the pediatric population, cardiomyopathy as a whole occurs in approximately 12 children out of every million. Approximately 1,000 to 5,000 new cases are diagnosed each year.
The estimated incidence of dilated cardiomyopathy is 36.5 per 100,000 children. According to the Pediatric Cardiomyopathy Registry, the estimated incidence of hypertrophic cardiomyopathy is 5 per 1 million children. The overall prevalence of hypertrophic cardiomyopathy is estimated to be less than .2 percent of the general population. The prevalence of restrictive cardiomyopathy is unknown. According to one estimate, ARVD occurs in 1 out of 5,000 people in the general population.
According to two studies published in the April 24th, 2003 issue of the New England Journal of Medicine, children are much more likely to develop cardiomyopathy early in life than previously thought. In fact, children are 10 times more likely to develop cardiomyopathy before the age of one than between ages two through 18 combined. In one of the studies, the overall incidence rate of cardiomyopathy was 1.13 per 100,000 children.
Dilated and restrictive cardiomyopathies affect males and females in equal numbers. Hypertrophic cardiomyopathy is slightly more common in males. ARVD affects more males than females. Cardiomyopathy continues to be the leading reason for heart transplants in children.
Pediatric cardiomyopathy may be diagnosed based upon a thorough clinical evaluation, identification of characteristic physical findings, a complete patient and family history, and a variety of specialized tests. Such tests may include x-ray studies (e.g., computed tomography), electrocardiography (EKG), or echocardiography. An EKG, which records the electrical activities of heart muscle, may reveal abnormal electrical patterns (e.g., resulting in arrhythmias). During an echocardiogram, sound waves are bounced off the heart (echoes), enabling physicians to study cardiac function and motion.
Three additional tests that may be performed for evaluation of heart disease are cardiac catheterization, cardiac magnetic resonance imaging (MRI) and radionuclide ventriculogram. During the cardiac catheterization, a small hollow tube (catheter) is inserted into a large vein and threaded through the blood vessels leading to the heart. Cardiac catheterization may enable physicians to withdraw blood to assess oxygen content, measure blood pressure in the heart, evaluate heart function, obtain small samples of myocardial tissue for microscopic evaluation, or thoroughly identify certain anatomical abnormalities. Cardiac MRI generates images of the heart similar to echocardiography but uses magnetic waves instead of sound waves. During radionuclide ventriculogram, tiny amounts of low-dose radioactive materials (tracers) are injected into to a vein and travel into the heart. Tracers release energy that is used by special cameras to produce pictures of the heart.
Because certain forms of cardiomyopathy may occur as part of a larger genetic disorder, infants and young children with a diagnosis of cardiomyopathy should receive specific tests to rule out any potentially associated disorders such as metabolic disorders.
The treatment of pediatric cardiomyopathy is directed toward the specific symptoms that are apparent in each individual. Such treatment may require the coordinated efforts of a team of medical professionals, such as pediatricians; physicians who specialize in childhood heart disease (pediatric cardiologists); specialists in the study of the blood and blood-forming tissues (hematologists); pediatric cardiothoracic surgeons; physical therapists; occupational therapists; and/or other health care professionals. Individuals with pediatric cardiomyopathy may be treated by lifestyle changes, dietary restrictions, various medications, and surgery.
It is important to note that many drug therapies and surgical techniques used to treat cardiomyopathy have predominantly been used and tested in adults. Only limited information exists detailing the effectiveness of such therapies in children with cardiomyopathy. More research is necessary to determine the long-term safety and effectiveness of such therapies in the pediatric population.
Specific therapeutic procedures and interventions may vary, depending upon numerous factors such the specific type of cardiomyopathy present; the progression of the disease upon diagnosis; an affected individual's age; associated health conditions; an individual's tolerance to certain medications; and additional factors.
Individuals with dilated cardiomyopathy may be treated with a variety of medications including drugs that reduce abnormal fluid retention by promoting the production and excretion of urine (diuretics); drugs that reduce the workload of the heart by blocking certain substances from binding to structures within the heart (beta blockers); and digitalis medications such as digoxin, which increase the efficiency of heart muscle contractions and produce a more regular heartbeat. Another type of medication used to treat individuals with dilated cardiomyopathy are vasodilators, which relax blood vessels, thereby lowering the blood pressure and minimizing the effort needed by the heart to pump blood throughout the body. Angiotensin-converting enzyme (ACE) inhibitors are a type of vasodilator.
In more serious cases of dilated cardiomyopathy a device that helps maintain normal heart rhythm through electrical stimulation (pacemakers or defibrillators) may be implanted. If drug therapy fails some individuals may require a heart transplant (see below).
Individuals with hypertrophic cardiomyopathy may be treated with a variety of drugs including beta-blockers, calcium channel blockers, and drugs that regulate irregular heartbeats (anti-arrhythmics). If drug therapy does not work, a permanent pacemaker or defibrillator may be implanted to help control irregular heartbeats. In some cases where drug therapy does not work, the blockage that causes the enlargement of the heart and restricts blood flow that characterizes hypertrophic cardiomyopathy may be treated with surgery. Surgical techniques may include septal myectomy or alcohol ablation.
Septal myectomy is a type of open-heart surgery, in which a portion of the abnormally thick and stiff ventricular septum (the partition that separates the left and right ventricles) is removed. This procedure allows for improved blood flow and reduces the symptoms associated with severe hypertrophic cardiomyopathy. Alcohol ablation is a new catheterization procedure in which alcohol is used to destroy certain heart cells, thereby shrinking the heart muscle and resulting in improved blood flow. In some cases of hypertrophic cardiomyopathy, a heart transplant may ultimately be necessary (see below).
Restrictive cardiomyopathy may be treated with diuretics and drugs that prevent blood clotting (anticoagulants). A pacemaker or defibrillator may be implanted to help control irregular heartbeats. In most cases, heart transplantation will be necessary. Some physicians recommend that affected children be listed for transplant as soon as the diagnosis is made.
ARVD may be treated by avoidance of severe physical and emotional stress, drugs that help regulate heart rhythms, and/or the implantation of a defibrillator.
In many cases of pediatric cardiomyopathy, the disorder progresses to the point where medications and surgical treatment options are ineffective. In such cases, affected children may require a heart transplant, a form of open-heart surgery in which a severely diseased heart is replaced with a healthy donor heart. Pediatric cardiomyopathy is the leading cause of heart transplantation in children. A heart transplant is considered a last resort for individuals with end-stage heart failure. Drawbacks of heart transplantation include the potential for rejections and the limited availability of a suitable donor.
Genetic counseling may be of benefit for affected individuals and their families. Other treatment is symptomatic and supportive.
Numerous clinical studies related to pediatric cardiomyopathy are in progress. These studies are focused on improving diagnostic techniques, improving existing treatments options and developing new ones, and learning about various genetic aspects of cardiomyopathy such as locating disease genes. For more information on clinical trials dealing with cardiomyopathy, contact the Children’s Cardiomyopathy Foundation listed in the Resources section of this report or the National Institutes of Health (NIH) clinical trials web site: http://www.clinicaltrials.gov/
The Pediatric Cardiomyopathy Registry was established to describe the epidemiologic features and clinical course of selected cardiomyopathies in individuals aged 18 years or younger and to promote the development of etiology-specific treatments. The registry is funded by the National Heart, Lung and Blood Institute. For more information on the Pediatric Cardiomyopathy Registry, please contact JJ McGill at 617-923-7747 x231.
In 1993, Ray Hershberger, MD founded the Familial Dilated Cardiomyopathy (FDC) Project at Oregon Health & Science University (OHSU). This study was moved to the University of Miami in 2007. The goals of the project are to identify and characterize families with FDC, and to identify the gene or genes that cause or predispose an individual to dilated cardiomyopathy and heart failure. An NIH research grant was received in mid-1998 to fund these activities, and was renewed in 2002 and 2008. For more information on the FDC Project, contact:
Familial Dilated Cardiomyopathy Research Project
University of Miami, Miller School of Medicine
CRB C-205 Rm 1136, 1120 NW 14th St., Miami, FL 33136
(Toll free) 877-800-3430
Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.
For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:
Tollfree: (800) 411-1222
TTY: (866) 411-1010
For information about clinical trials sponsored by private sources, contact:
For information about clinical trials conducted in Europe, contact:
Contact for additional information about pediatric cardiomyopathy:
Steven D. Colan, MD
Associate Chiefof Cardiology
Boston Children’s Hospital
300 Longwood Avenue
Boston MA 02115
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