Cardiomyopathy is any disease of the heart muscle in which the heart loses its ability to pump blood effectively. In some instances, the heart rhythm is disturbed, leading to irregular heartbeats, called arrhythmias or dysrhythmia. There are multiple causes of cardiomyopathy, including viral infections. Sometimes, the exact cause of the muscle disease is never found.
Why is cardiomyopathy a concern?
Cardiomyopathy can prevent the heart muscle from pumping enough blood to meet the body’s needs, a condition called congestive heart failure. It can also cause blood pressure in the lungs to become higher than normal, a condition called pulmonary hypertension. Cardiomyopathy can be progressive and sometimes worsen quickly. Cardiomyopathy is a leading diagnosis that results in heart transplantation.
What causes cardiomyopathy?
Viral infections that infect the heart are a major cause of cardiomyopathy. In some instances, cardiomyopathy is a result of another disease or its treatment, such as complex congenital heart disease, nutritional deficiencies, fast heart rhythms, or certain types of chemotherapy for childhood cancers. Sometimes, cardiomyopathy can be linked to a genetic abnormality. Other times, the cause is unknown.
What types of cardiomyopathy commonly affect children?
The following is information on two types of cardiomyopathy that affect children:
Dilated (congestive) Cardiomyopathy (DCM) – This is the most common form of cardiomyopathy. The heart muscle is enlarged and stretched, causing the heart to become weak and pump inefficiently. Other problems that may occur with dilated cardiomyopathy include the following:
- irregular heart rhythms (arrhythmia or dysrhythmia)
- risk of blood clots
- congestive heart failure
Various infections (including viral) that lead to an inflammation of the heart muscle (myocarditis) can cause this type of cardiomyopathy.
Contact with toxins or very powerful therapeutic drugs, such as certain types of chemotherapy given to fight cancer, have been known to cause dilated cardiomyopathy. Heredity also can be a factor. Twenty percent of people with dilated cardiomyopathy have a parent or sibling with the disease. In many cases, a specific cause for this type of the disease is never identified.
Because the heart muscle is weak and unable to pump enough blood to meet the body’s demands, the body tries to preserve blood flow to essential organs such as the brain and kidneys by reducing blood flow to other areas of the body, such as the skin and muscles.
The following are the most common symptoms of dilated cardiomyopathy. Each child may experience symptoms differently. Symptoms may include pale skin color, sweaty skin, rapid heart rate, rapid breathing rates, shortness of breath, fatigue, irritability, chest pain, poor appetite, slow growth, vomiting and/or abdominal pain.
Your child’s physician may recommend medications to accomplish the following:
- help the heart beat more effectively
- decrease the workload of the heart
- decrease the oxygen requirements of the heart
- prevent clots from forming
- decrease inflammation of the heart
- regulate irregular heartbeats
In some cases, dilated cardiomyopathy that is due to viral causes improves. In other cases, the condition worsens and transplantation of the heart may be considered. Consult your child’s physician for more information regarding the specific outlook for your child.
Hypertrophic Cardiomyopathy (HCM) – (also known as hypertrophic obstructive cardiomyopathy, HOCM; asymmetric septal hypertrophy, ASH; or idiopathic hypertrophic subaortic stenosis, IHSS) – In this type of cardiomyopathy, the muscle mass of the left ventricle of the heart is larger than normal, or the wall between the two ventricles (septum) becomes enlarged. These abnormalities may obstruct the blood flow from the left ventricle.
The thickened muscle or septal wall also can affect one of the leaflets of the mitral valve, which separates the left atrium and the left ventricle. The valve becomes leaky, allowing blood to move backward from the left ventricle into the left atrium, instead of forward to the body.
Hypertrophic cardiomyopathy is often hereditary. Half of children with the disease have a parent or sibling with varying degrees of left ventricular muscle or ventricular wall enlargement, although relatives may or may not have symptoms.
Children with hypertrophic cardiomyopathy may have symptoms that increase with exertion, or symptoms may be unpredictable. The following are the most common symptoms of hypertrophic cardiomyopathy. Each child may experience symptoms differently. Symptoms may include dizziness, fainting, chest pain and/or abnormal heart rhythms.
Your child’s physician may recommend medications to accomplish the following:
- decrease the workload of the heart
- decrease the oxygen requirements of the heart
- regulate irregular heartbeats
Surgical treatments may include:
- removal of part of the enlarged muscle
- artificial pacemaker
- heart transplantation
Other types of Cardiomyopathy include:
Left Ventricular Non-Compaction – a heart muscle condition in which the muscular wall of the main pumping chamber of the heart (the left ventricle) appears to be spongy and “non-compacted”, consisting of a meshwork of numerous muscle bands (trabeculations). Its cause, development, clinical course and treatment are fields of ongoing research.
Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC) – an inherited heart muscle disorder where damaged heart muscle is gradually replaced by scar tissue and fat. A recognized cause of sudden death in the young, ARVC may cause abnormal electrical heart rhythms and weakening of the pumping action of the heart. In many cases, the disease does not limit the quality or duration of life. However, a proportion of people with ARVC develop complications, all of which are treatable. Evaluation and follow-up by a cardiologist is therefore recommended.
Restrictive Cardiomyopathy (RCM) – a disorder of the heart muscle in which the walls of the ventricles become stiff, but not necessarily thickened, so they resist normal filling with blood. There is no cure. Treatment aims to relieve symptoms caused by the backup of blood into the lungs and veins of the neck and liver.
The least common of the cardiomyopathies, restrictive cardiomyopathy can be idiopathic (its cause is unknown) or secondary to a number of rare cardiac and systemic disorders such as endomyocardial fibrosis (tropical, hypereosinophic syndrome), infiltrative disorders (amyloidosis, sarcoidosis), and rare metabolic disorders (Gaucher’s disease, Mucopolysaccharidoses, Fabry’s disease, carcinoid syndrome).
Restrictive cardiomyopathy is also described following radiation therapy for some types of cancer.
Patients with the idiopathic form may have a family history of cardiomyopathy. Recent evidence suggests that the disease may be caused by the same genetic abnormalities that result in the more common hypertrophic cardiomyopathy (HCM).
Patients with RCM have signs and/or symptoms of heart failure such as fatigue, shortness of breath, tissue swelling and abdominal enlargement. Up to a third of patients may have an embolic complication, such as a blood clot. Abnormal heart rhythms and palpitations are common whatever the underlying cause of the disease.
As the onset of symptoms in RCM is often very subtle, the diagnosis of RCM may be made late in the course of the disease. There is no specific treatment for RCM, and the aims of medical therapy are to improve symptoms of heart failure, treat cardiac rhythm disturbance and to prevent blood clots. Pacemakers are indicated for patients with slow heart rates or ‘heart block’. Severe cases may require a heart transplant.
Source: Wikipedia, Children’s Hospital Boston, and Cardiomyopathy Association
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