Cardiomyopathy is a disorder affecting the heart muscle that usually results in the heart being unable to pump effectively,
a condition known as heart failure. It can be caused by a number of factors, including infections, conditions affecting the
body’s metabolism, and genetics. It affects about 3 in 10,000 children.
There are 3 major types of cardiomyopathy: dilated, hypertrophic, and restrictive. There are also 2 more rare forms: arrhythmogenic
right ventricular dysplasia (ARVD) and noncompaction.
What is dilated cardiomyopathy?
Dilated cardiomyopathy is the most common kind of cardiomyopathy in both children and adults. It may be underreported because
it is often not detected. The muscle in the heart becomes stretched, increasing the size of the ventricular chamber. This
reduces the ability of the heart to contract, which in severe cases, results in not enough blood circulating to the body.
When the ventricles don’t squeeze the blood out of the heart, some blood can back up into the lungs.
Sometimes cardiomyopathy causes abnormal heart rhythms (arrhythmias) because the heart’s electrical impulse isn’t conducted
properly through the stretched muscle.
When dilated cardiomyopathy occurs through many generations in a family, it’s called familial dilated cardiomyopathy. About 30% to 40% of cases are traced to genes. The condition occurs more often in females than males, and in blacks more often
than whites.
Symptoms are those typical of congestive heart failure — shortness of breath, tiring easily, difficulty tolerating physical
exertion, fainting, sweating at rest, and sudden death. The heart will increase in size and the liver can enlarge.
Children with dilated cardiomyopathy need intensive therapy. Symptoms can be challenging to treat. Children will usually need
diuretics and digoxin. Recently, however, improvements in drug therapies such as the use of angiotensin-converting enzyme
(ACE) inhibitors and beta-blockers are making longer survival a reality, as are other procedures like implantable cardiac
defibrillators (ICD) and ventricular assist devices which helps support cardiac output until transplant. This condition may
require a heart transplant.
| Dilated Cardiomyopathy |
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| With this condition, the heart muscle becomes stretched, increasing the size of the ventricular chamber. The heart muscle
weakens, and it becomes difficult for the heart to contract and pump blood to the body.
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What is hypertrophic cardiomyopathy?
Hypertrophic cardiomyopathy is less common in infants and children and more often diagnosed during adolescence. It occurs
in 1 in every 500 people. With this condition, the muscle in the heart, usually in the ventricles, is unusually thick. This
is known as hypertrophy. This can reduce the size of the left ventricle or make the walls of the ventricle stiffer, which
affects the ability of the heart to pump and relax effectively and send blood to the body.
When the thick muscle prevents blood from being squeezed from the heart, it’s called hypertrophic obstructive cardiomyopathy
(HOCM). This affects the blood being pumped to the lungs and/or the body. The altered arrangement of muscle fibres can cause
abnormal heart rhythms, which are potentially fatal. Implantable cardiac defibrillators (ICD) are recommended when the heart
thickness reaches a certain size, even in the absence of arrhythmias. ICDs may reduce the risk of significant arrhythmias
in certain types of hypertrophic cardiomyopathy patients. Many children will be on beta-blocker medicine to ease the workload
of the heart. This condition may require a heart transplant.
While it can occur spontaneously, hypertrophic cardiomyopathy is usually passed along through families.
This condition is also sometimes called idiopathic hypertrophic subaortic stenosis (IHSS) or asymmetric septal hypertrophy
(ASH).
| Hypertrophic Cardiomyopathy |
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| With this condition, the muscle in the heart is unusually thick. This can reduce the size of the left ventricle or make the
walls of the ventricle stiffer, which affects the ability of the heart to pump and relax effectively and send blood to the
body.
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What is restrictive cardiomyopathy?
Restrictive cardiomyopathy is also rare but is the most serious type of cardiomyopathy, with the fewest treatment options
of all the cardiomyopathies. The heart muscle becomes very stiff, so it doesn’t stretch in the relaxation phase when it needs
to fill with blood. Although the heart keeps pumping, it doesn’t pump enough blood to meet the body’s needs. Children with
this problem will have symptoms of congestive heart failure. This condition is difficult to treat with medications. It may
require a heart transplant.
| Restrictive Cardiomyopathy |
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| With this condition, the heart muscle becomes very stiff, so it doesn't stretch in the relaxation phase when it needs to fill
with blood. The atria become severely enlarged and because the ventricles are stiff, blood backs up into the atria. As a result,
not enough blood is pumped to meet the body's needs.
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What is arrhythmogenic right ventricular dysplasia (ARVD)?
“Arrhythmogenic” means causing an arrhythmia. “Dysplasia” means an abnormality of the structure (in this case, the right ventricle).
With arrhythmogenic right ventricular dysplasia, the muscle of the right ventricle is replaced by fat and fibrosis tissue.
The electrical signal that keeps the heart beating regularly cannot pass through the abnormal fibrotic tissue, resulting in
abnormal heart rhythms. Treatment often involves medicine and/or placement of a pacemaker or an implantable cardiac defibrillator
(ICD) to help control the heart’s rhythm. ARVD can be passed through families.
| Arrhythmogenic Right Ventricular Dysplasia |
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| With this condition, the muscle of the right ventricle is replaced by fat and fibrosis tissue. Abnormal electrical signals
may start within this fibrous tissue, resulting in abnormal heart rhythms.
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Are there other kinds of cardiomyopathy?
There are some other cardiomyopathies that are connected to the chemistry of the heart muscle. A problem with an enzyme may
cause the heart not to have the normal reactions it should have. These types of cardiomyopathy can occur with some inherited
diseases such as Pompe’s disease, Friedreich's Ataxia, congenital lactic acidosis, and carnitine deficiency.
Other types of cardiomyopathy can occur when the body doesn’t get the nutrients it needs through diet. This is usually only
seen in developing countries and is preventable through good nutrition.
What is the treatment for cardiomyopathy?
There are several medicines that can be used to help the heart pump more effectively. Diuretics help the body get rid of extra
fluid, while digoxin helps the heart pump more strongly. Angiotensin-convering enzymes (ACE) inhibitors or beta-blockers help
relax the blood vessels so the heart has an easier time pumping.
When the heart isn’t pumping well, the blood flow may be slower than normal, so blood thinners may be used to prevent blood
clots from developing in the heart chamber. A pacemaker or defibrillator may be required.
What is the outlook for children with cardiomyopathy?
The outlook is variable depending on the type of cardiomyopathy and its severity. Many children will live normal lives. Some
children will need to take medication for the rest of their lives. In more severe cases, if the medication is unable to help
the heart function better, some children may require a heart transplant.
