Children's Cardiomyopathy Foundation
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ABOUT THE DISEASE

EVALUATION & DIAGNOSIS

If a child is suspected to have cardiomyopathy, an evaluation usually begins with a visit to a pediatric cardiologist for a complete history review and physical examination. The evaluation starts with a discussion of a child's medical history, symptoms, prior tests and any family history. As part of the examination, the physician may evaluate the child's blood pressure, take pulses in various locations and use a stethoscope to listen to the patient's lungs, a heart murmur or unusual heartbeat. The doctor will also check the child's skin color and whether there is any swelling in the limbs or organs. Various cardiac tests may follow. This is done to determine the heart size, thickening and whether there is any obstruction or valve leakage.

Echocardiograms have been the most widely used method of diagnosis but some cardiomyopathies are being further defined by special genetic testing. Some of the procedures below may be performed to confirm a diagnosis and to determine a treatment plan.

Noninvasive Procedures

Chest Radiography, Computed Tomography (CT Scan)
or Magnetic Resonance Imaging (MRI)

This is a radiation based imaging procedure that looks at the size, shape and structure of the heart. It also evaluates the lungs for any abnormalities. When dilated cardiomyopathy is suspected, this test is done first to check if the heart is enlarged and to see whether there is any fluid accumulation in the lungs (referred to as pulmonary edema). Sometimes a CAT scan or MRI will be done if the doctor wants to see a 3 dimensional image of the heart. A CAT scan or MRI procedure allows for multiple x-rays to be taken.

Electrocardiogram (EKG)

Electrodes are placed on the child's limbs and chest wall, which then generates a graphic record of the heart's electrical activity. It can evaluate the amount of heart enlargement, reveal any abnormal heart rhythm and indirectly provide information about the size of the heart. Some children who have a normal echocardiogram may have an abnormal EKG that may indicate that they are a carrier of the cardiomyopathy gene and may develop the disease later in life.

Holter Monitor

An external device is worn for 24-72 hours and continuously records the heart rhythm. It can identify any irregular heart rhythms commonly associated with dilated, hypertrophic or restrictive cardiomyopathy.

Echocardiogram & Doppler

This is the most informative noninvasive test for diagnosing the type of cardiomyopathy and the degree of dysfunction in the heart muscle. Patients with cardiomyopathy generally require regular echocardiograms to assess the progress of the disease.

High frequency sound waves are used to produce moving images of the beating heart on a video screen. These cross-sectional views of the heart allow the cardiologist to measure the muscle thickness, size, pumping ability, degree of obstruction, chamber size, and valve movement. Pressures inside the heart chambers and major vessels can also be determined. A doppler ultrasound includes color-coded images of blood flow within the heart. Besides evaluating cardiac blood flow, it checks for any obstruction or valve leakage (from mitral regurgitation).

Genetic Studies

This step is often overlooked but is crucial in understanding the cause of cardiomyopathy. Since cardiomyopathy can be a symptom of another genetic disorder, certain biochemical, genetic, and enzyme deficiency tests (i.e. mitochondrial, fatty acid oxidation, glycogen storage diseases) should be requested before determining the most appropriate medical therapy. These tests typically involve submitting blood, urine and/or tissue samples to specialized laboratories. Obtaining these test results are important not only for a child's management but also for family planning because some genetic conditions have a 25-50% inheritance risk.

If cardiomyopathy is detected in a child under 4 years old, it is especially important to get metabolic screening. With certain metabolic disorders where cardiomyopathy is a common symptom, a change in diet, specific drug therapy (i.e. carnitine) or bone marrow transplant can greatly reduce or reverse the progression of cardiomyopathy.

Invasive Procedures

These tests involve anesthesia and are done to determine the severity of the cardiomyopathy. In the case of arrhythmogenic right ventrivular cardiomyopathy, diagnosis can only be confirmed by certain invasive tests.

Radionuclide Ventriculogram

Low-dose radioactive material, comparable to the amount in a set of chest x-rays, is injected into a vein that flows to the heart. Pictures are taken by a special camera to show how well the heart is functioning. It is used to assess contraction and filling of the ventricles at rest and with exertion. Recent studies have indicated that this may be the best way to diagnose ARVD.

Cardiac Catheterization

Under fluoroscopic control, thin, flexible plastic tubes (catheters) are inserted into a blood vessel from the groin area to the heart. A dye is then injected to measure blood pressures and flows inside the heart and check for any blockages in the arteries. Several other procedures may also be done at the same time. An x-ray of the heart (angiograms) may be taken to determine the function of the heart and the extent of "leakiness" in the mitral valve and to check whether the coronary arteries are diseased.

The doctor may also perform a heart muscle biopsy where a few tiny pieces of heart tissue are taken for laboratory study. Such heart muscle biopsies are helpful in evaluating possible infections of the heart and certain metabolic abnormalities of the heart, in distinguishing cardiomyopathy from other diseases, or in verifying whether there is fat in the muscle wall or ventricular structural damage for an ARVD diagnosis.

Electrophysiology Study (EP study)

Similar in approach to a heart catheterization, tubes (catheters) with fine wires are inserted through veins in the groin area to the heart. Electrical stimuli are applied to these wires to induce a very fast heart rhythm and map out the heart's electrical system. It also tests for abnormal conduction pathways, susceptibility to arrhythmias, the effectiveness of anti-arrhythmic drugs and the need for an implantable cardioverter defibrillator.

For more detailed information on various cardiac testing in children.

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