How Is Cardiomyopathy Diagnosed?
If cardiomyopathy is suspected, the diagnosis is
based on a person's:
- Symptoms and medical history
- Family history of cardiomyopathy,
heart
failure, or sudden cardiac arrest
- Physical exam
- Results on diagnostic tests and procedures
The physical exam will identify a number of findings
in patients with cardiomyopathy. The doctor will use a stethoscope to listen to
the person's heart and lungs for sounds that may suggest the presence of
cardiomyopathy. These sounds may even indicate a certain type of
cardiomyopathy. For example, the loudness, timing, and location of a
heart
murmur may suggest that a person has hypertrophic obstructive
cardiomyopathy. A "crackling" sound in the lungs may be a sign of heart
failure, which often develops in the later stages of cardiomyopathy.
Physical signs also help the doctor diagnose
cardiomyopathy. Swelling of the abdomen, legs, or feet may indicate excess
fluid, which is a sign of heart failure.
Sometimes, doctors discover cardiomyopathy during a
routine exam if they hear a heart murmur or if the patient has an abnormal
electrocardiogram (see Diagnostic Tests and Procedures below).
Specialists Involved
Often a cardiologist or pediatric cardiologist is
involved in the care of a patient with cardiomyopathy. A cardiologist is a
doctor who specializes in heart diseases. A pediatric cardiologist specializes
in children's heart diseases.
Diagnostic Tests and Procedures
Doctors may order one or more tests to diagnose
cardiomyopathy, including:
- EKG
(electrocardiogram). This test measures the rate and regularity of the
heartbeat and can detect
arrhythmias.
- Holter monitor (ambulatory EKG/ECG). This test records the EKG
readings for a continuous 24-hour period. It can detect arrhythmias that occur
only rarely throughout the day. A small monitoring device is attached to
patches (electrodes) that are placed on the patient's chest. The device is
carried in a pouch around the neck or attached to a belt.
- Echocardiogram. This test uses sound waves to create a moving
picture of your heart. Echocardiogram provides information about the size and
shape of your heart and how well your heart chambers and valves are
functioning. The test also can identify areas of poor blood flow to the heart,
areas of heart muscle that are not contracting normally, and previous injury to
the heart muscle caused by poor blood flow.
- There are several different
types of echocardiograms, including a stress echocardiogram. During this test,
an echocardiogram is done both before and after your heart is stressed either
by having you exercise or by injecting a medicine into your bloodstream that
makes your heart beat faster and work harder. A stress echocardiogram is
usually done to find out if you have decreased blood flow to your heart (coronary
artery disease). Echocardiogram is a good way to diagnose hypertrophic
cardiomyopathy because it shows the thickened walls of the heart.
- Transesophageal (tranz-ih-sof-uh-JEE-ul)
echocardiography (TEE). In this test, the doctor inserts an ultrasound probe
into the throat after the patient is sedated. TEE provides a view of the back
of the heart.
- Stress Test. Some heart problems are easier to
diagnose when your heart is working harder and beating faster than when
its at rest. During stress testing, you exercise (or are given medicine
if you are unable to exercise) to make your heart work harder and beat faster
while heart tests are performed.
- During exercise stress testing,
your blood pressure and EKG readings are monitored while you walk or run on a
treadmill or pedal a bicycle. Other heart tests, such as nuclear heart scanning
or echocardiography, also can be done at the same time. These would be ordered
if your doctor needs more information than the exercise stress test can provide
about how well your heart is working.
- If you are unable to exercise, a
medicine can be injected through an intravenous line (IV) into your bloodstream
to make your heart work harder and beat faster, as if you are exercising on a
treadmill or bicycle. Nuclear heart scanning or echocardiography is then
usually done.
- During nuclear heart scanning,
radioactive tracer is injected into your bloodstream, and a special camera
shows the flow of blood through your heart and arteries. Echocardiography uses
sound waves to show blood flow through the chambers and valves of your heart
and to show the strength of your heart muscle.
- Your doctor also may order two
newer tests along with stress testing if more information is needed about how
well your heart works. These new tests are magnetic resonance imaging (MRI) and
positron emission tomography (PET) scanning of the heart. MRI shows detailed
images of the structures and beating of your heart, which may help your doctor
better assess if parts of your heart are weak or damaged. PET scanning shows
the level of chemical activity in different areas of your heart. This can help
your doctor determine if enough blood is flowing to the areas of your heart. A
PET scan can show decreased blood flow caused by disease or damaged muscles
that may not be detected by other scanning methods.
- Chest x ray. A chest x ray takes a picture of the organs and
structures inside the chest, including the heart, lungs, and blood vessels.
This test can show whether the heart is enlarged or whether fluid is building
up in the lungs.
- Blood tests, such as complete blood count, blood
chemistries, and cardiac enzymes. These tests are done to provide information
on the condition of the heart and to rule out other conditions.
The doctor may order additional tests to confirm the
diagnosis or if surgery is planned. These tests may include:
- Cardiac
catheterization. With this test doctors can check the pressure and blood
flow in the heart's chambers, collect blood samples from the heart, and examine
the arteries of the heart using x ray. A thin, flexible tube (catheter) is
passed through an artery in the upper thigh (groin) or in the arm to reach the
coronary arteries. This allows the doctor to study the inside of the arteries
to look for blockages.
- Coronary angiography. This test is usually performed along
with cardiac catheterization. Angiography enables the doctor to see the flow of
blood to the heart muscle. A dye that can be seen on an x ray image is injected
into the coronary arteries. Dye also can be injected into the chambers to
evaluate the pumping function of the heart.
- Myocardial biopsy. In this test, the doctor removes a piece of
heart muscle to look at under a microscope. The biopsy can be done during a
cardiac catheterization and is useful in diagnosing some types of
cardiomyopathy.
Because some types of cardiomyopathy run in
families, the doctor may recommend looking for the disease in the parents,
brothers and sisters, and children of people with cardiomyopathy.
Genetic counseling may be recommended. Genetic
counseling is useful to help define and explain how the disease runs in
families and to determine the chances of parents passing it on to their
children. |