In most cases, the diagnosis of “cardiomyopathy” in a child elicits concern in both the child (if old enough to understand) and the parent. Much of this concern is because the disease is relatively rare in children and not as well publicized. Fortunately, our understanding of how the heart works under normal and abnormal conditions is increasing each year. Hopefully, armed with this knowledge, you and your child will be less fearful of this diagnosis as you move forward with your child’s physician toward a treatment plan.

What is cardiomyopathy?

The term “cardiomyopathy” refers to a diseased state of the heart involving abnormalities of the muscle fibers, which contract with each heartbeat. It is considered a primary problem when it occurs because the muscle cells themselves are abnormal (usually due to a gene mutation). It is a secondary problem when the muscle cells were normal but are affected by other diseases that have secondary damaging effects on the heart and its function such as certain infections, low blood flow to the heart, low blood oxygen or high blood pressure. According to the Pediatric Cardiomyopathy Registry, one in every 100,000 children in the U.S. under the age of 18 is diagnosed with cardiomyopathy. The majority of diagnosed children are under 12 months followed by children 12 to 18 years old. Because the clinical features and therapies differ, it is best to separate this disease into four broad types:

Dilated Cardiomyopathy (DCM)
Dilated or congestive cardiomyopathy is diagnosed when the heart is enlarged (dilated) and the pumping chambers contract poorly (usually left side worse than right). For more detailed info, click here.

Hypertrophic Cardiomyopathy (HCM)
Most often diagnosed during infancy or adolescence, hypertrophic cardiomyopathy is the second most common form of heart muscle disease, is usually genetically transmitted, and comprises about 35–40% of cardiomyopathies in children. For more detailed info, click here.

Restrictive Cardiomyopathy (RCM)
Restrictive cardiomyopathy is a rare form of heart muscle disease that is characterized by restrictive filling of the ventricles. In this disease, the contractile function (squeeze) of the heart and wall thicknesses are usually normal, but the relaxation or filling phase of the heart is very abnormal. For more detailed info, click here.

Miscellaneous (Rare) Cardiomyopathies – There are other forms of cardiomyopathy which comprise only a very small percentage of the total (2–3%) number of cardiomyopathies in children. These cardiomyopathies may have overlapping features with any of the previous types described and include arrhythmogenic right ventricular dysplasia (ARVD), mitochondrial and left ventricular non-compaction cardiomyopathies (LVNC). For more detailed info on ARVD, click here. For more detailed info on LVNC, click here.

    For info on a rare form of cardiomyopathy called Danon Disease, click here.

    General Complications From Cardiomyopathy

    Several complications can occur with cardiomyopathies such as arrhythmias, heart block, blood clots, endocarditis, congestive heart failure and premature or sudden death. The most likely complications to occur in diagnosed children are arrhythmias and congestive heart failure.

    Arrhythmias
    Many cardiomyopathies affect the heart’s normal electrical impulses generating irregular heartbeats. With prolonged arrhythmias, the heartbeat may become either too fast (tachycardia) or too slow (bradycardia) and can occur in either the heart ventricles or atrial. If tachycardias are not treated they can become fibrillations which can be life threatening.

    Ventricular fibrillation is the most common arrhythmia associated with cardiomyopathy in children. With fibrillations, the regular rhythm of the heartbeat is lost and replaced by a chaotic, rapid heartbeat. This abrupt loss of organized heart function leads to insufficient blood being pumped to the body.

    A very slow heart rate (bradycardia) can also occur when there is a problem in transmitting the electrical signal to contract the heart. If the heart’s pumping ability is severely reduced, an artificial pacemaker may be needed.

    About 10% of patients with hypertrophic cardiomyopathy develop arrhythmias. Patients with arrhythmogenic right ventricular and dilated cardiomyopathy are also susceptible but to a lesser degree. Early identification of high-risk patients allows for early treatment with anti-arrhymic medications or an implantable pacemaker/defibrillator to prevent sudden cardiac arrest.

    Heart Block
    If the normal electrical system within the heart fails to function properly, the heart’s conduction is disrupted and the heartbeat may become too slow. If this occurs, a pacemaker needs to be implanted.

    Blood Clots
    With dilated cardiomyopathy, the blood flow through the heart is abnormal which may cause blood clots to form within the heart (thromboembolism). Blood clots can damage other organs including the lungs and brain.

    Endocarditis
    Children with cardiomyopathies or who have had heart surgery are more susceptible to endocarditis. This is an infection of the heart walls, valves or blood vessels caused by bacteria entering the blood stream. It typically occurs after a dental procedure or surgical procedures involving the gastrointestinal or urinary tract. Infection can lead to serious illness, additional heart damage and even death in rare instances. Taking prophylactic antibiotics (amoxicillin, erythromycin) before any dental or surgical procedures can help prevent endocarditis.

    Congestive Heart Failure
    This is a common feature of all late stage cardiomyopathies when the muscles of the heart become too weak to pump enough blood to the body for normal function. When this happens, fluid can build up in the lungs or in the rest of the body, causing difficulties in breathing, swelling, poor appetite, exercise intolerance and gastro-intestinal distress.

    Premature Or Sudden Death
    Sudden death is not as common in children with dilated cardiomyopathy. On the other hand, children with hypertrophic or restrictive cardiomyopathy are at a great risk of cardiac arrest occurring with little or no warning. Sudden death can be caused by several factors related to arrhythmia (i.e. ventricular tachycardia), myocardial ischemia, outflow obstruction, and intense physical activity.

    Source: AHA, Children’s Cardiomyopathy Foundation