As part of your child's initial visit, the pediatric cardiologist will perform several diagnostic tests to determine the type of cardiomyopathy and its severity. Tests will be recommended based on your child's disease features. An echocardiogram is the most informative, non-invasive test for distinguishing the type of cardiomyopathy and assessing the degree of dysfunction in the heart muscle.
The following non-invasive tests allow your child to be awake during the evaluation:
Also known as chest radiograph, chest X-rays use a small amount of ionizing radiation to generate film images of the chest and lungs. Chest X-rays show the size and shape of the heart, major blood vessels and bones in the chest, and the presence of any fluid and abnormalities in the lungs. This is primarily used to determine if the heart is enlarged and to see if there is congestive heart failure. X-rays take about 30 minutes to complete.
Computed Tomography (CT scan or CAT scan)
This is an X-ray procedure that combines multiple X-ray images, with the aid of a computer, to generate two or three-dimensional, cross-sectional images of internal organs. It helps to reveal how well the heart is working by providing information about the structure and function of the heart and blood vessels.
Echocardiogram & Doppler Ultrasound
An echocardiogram (echo) uses high frequency sound waves to produce moving images of the beating heart on a video screen. These cross-sectional views of the heart allow the cardiologist to measure muscle thickness, chamber size, pumping ability (contractile force and filling of blood), and valve movement. Pressures inside the heart chambers and major vessels can also be estimated.
A Doppler ultrasound, performed as part of the echocardiogram, shows color-coded images of blood flow within the heart. The images are used to evaluate cardiac blood flow, measure how well the heart is contracting, and determine if there is obstruction or a leaky valve. The echocardiogram and Doppler ultrasound together usually take about one hour.
Through an echo, HCM can be distinguished from other potential causes of abnormal wall thickening such as aortic valve stenosis, coarctation of the aorta, high blood pressure. The echocardiogram can be used to estimate blood pressure in the lungs (pulmonary artery pressure) in advanced stages of RCM, and it also can be used to confirm a diagnosis of LVNC by revealing the deep crevices or trabeculations in the heart walls of the left ventricle.
This test records the heart's electrical activity through electrode patches placed on the child's limbs and chest wall. The EKG records the heart rate and rhythm and can indicate whether the heart is enlarged, thickened or there are abnormal heartbeats. Some children who have a normal echocardiogram may have an abnormal EKG, which may indicate they are a carrier of the cardiomyopathy gene and may develop the disease later in life. This test usually takes 10 to 15 minutes.
Exercise Stress Test
This test is usually performed in older children (beyond age 5-7 years) to estimate the risk for developing abnormal heart rhythms when the heart is under exertion. An exercise stress test can show if the heart is pumping enough blood to meet the body's increased need for oxygen. While the child is exercising – walking on a treadmill or pedaling a stationary bike – the child's blood pressure, heart rhythm and breathing are measured during different degrees of exertion. This test helps to determine the kind and level of exercise a child can tolerate. In cases where children do not respond adequately to medication, a stress test can help predict the need for heart transplantation.
A Holter is an external device that records the heartbeat continuously for 24 to 72 hours through electrode patches placed on your child's skin. The data that is recorded on a tape cassette is used to identify any irregular and life-threatening heart rhythms commonly associated with cardiomyopathy. The device can be worn at home and taken off 24, 48 or 72 hours later, depending on the length of time determined by the cardiologist. There are options for extended monitoring for up to 21 days if needed.
Magnetic Resonance Imaging (MRI)
This is a radiation-based imaging procedure that looks at the size, shape and structure of the heart and checks for any lung abnormalities. The test uses radio waves inside a large magnet to generate a three-dimensional image. This allows doctors to evaluate heart and blood vessel anatomy, function and flow dynamics. In ARVC cases, MRI is used to differentiate fatty deposits from muscle tissue within the heart walls of the right ventricle since an echocardiogram and angiogram may fail to identify any heart abnormality.
Multiple Gated Acquisition (MUGA) Scan
Also known as radionuclide ventriculogram, this test is similar to an echocardiogram, but more accurately measures how much blood the heart pumps or "ejects" with each contraction and how quickly that blood is ejected. Its advantage is in detecting subtle, early changes in a patient's cardiac function over time. A low-dose of radioactive substance (equal to that in a set of chest x-rays) is injected into a vein that flows to the heart. This substance labels or "tags" red blood cells with a tiny bit of radioactivity so that the blood cells can be clearly seen in pictures taken with a special camera. By counting the "tagged" red blood cells over the course of many heartbeats, a moving image of the beating heart is produced. This provides a detailed picture of the heart's chambers and its functioning.
Myocardial Perfusion Test
Following an exercise stress test for older children, a small amount of radioactive substance can be injected into the bloodstream through an intravenous (IV) line and then tracked by a special perfusion-scanning camera to generate images of blood flow to the heart. The test is then repeated after rest for comparison. This procedure allows doctors to see how blood flows through the heart while working hard and during rest. It also reveals areas of the heart that are not receiving an adequate supply of blood. Because the test consists of two sections, the entire test may take up to five hours.
Pulmonary Function Test (PFT)
In advanced stages of cardiomyopathy, lung circulation may be affected and this test measures lung function. A child breathes into a mouthpiece that is connected to a measuring device called a spirometer. The spirometer records the amount and the rate of air that the child breathes in and out over a period of time.