Cardiomyopathy Diagnosis

  • Diagnosis

    Cardiomyopathy is a serious condition in which the heart muscle becomes damaged and cannot pump blood adequately. While serious, cardiomyopathy is relatively rare, affecting approximately 50,000 Americans. Usually symptoms do not appear until the disease has progressed. When they occur, symptoms include shortness of breath, fatigue, and heartbeat abnormalities.

    There are three major forms of cardiomyopathy Figure 01.

    • Dilated (congestive) cardiomyopathy. This is the most common type of cardiomyopathy. In this type, one or more of the chambers of the heart stretches out of shape and becomes larger and weaker. This form occurs most often in middle-aged men, although it also affects women, children, and older people.
    • Hypertrophic cardiomyopathy. This is the second most common type of cardiomyopathy, and yet it occurs in only around 0.2% of the US population. In this form, the muscular walls of the heart thicken so that the main pumping chamber (the left ventricle) becomes smaller, and its pumping action is limited.
    • Restrictive cardiomyopathy. This third form occurs even less often than the second type. In this rare disease, extra tissue grows in the heart, causing the chamber walls to stiffen and lose their ability to pump blood.

    Click to enlarge: Types of Cardiomyopathy

    Figure 01. Types of Cardiomyopathy

    Dilated cardiomyopathy can occur as a result of infections, as a complication of pregnancy, and as a result of abusing certain drugs or alcohol. However, in approximately 80% of cases the cause remains a mystery.

    • Infections. Some cases are caused by bacterial or viral infections that inflame the heart muscle (myocarditis).
    • Pregnancy. Dilated cardiomyopathy sometimes occurs in women during the last three months of pregnancy, or within six months after delivery. The group most at risk is African-American women who have had several children already, and who are older than 30 years of age.
    • Medications. Some powerful medications given to treat cancer (particularly doxorubicin and daunorubicin) can also cause the heart muscle to stretch and weaken. Cocaine and alcohol abuse can also cause the disease.
    • Nutrition and hormones. Nutritional deficiencies such as a lack of vitamin B1 or potassium, and hormonal imbalances caused by metabolic diseases such as diabetes and thyroid problems can also lead to dilated cardiomyopathy.
    • Other diseases. About 8% of patients with HIV develop dilated cardiomyopathy. A family history of dilated cardiomyopathy, suggesting a genetic cause, occurs in up to 30% of cases of this disease.

    Genes seem to be responsible for the heart thickening of hypertrophic cardiomyopathy. An abnormal gene may be inherited from a parent, or a normal gene may mutate later in life. Researchers have identified at least four genes that may be involved in hypertrophic cardiomyopathy.

    Restrictive cardiomyopathy is usually caused by one of three rare conditions.

    • Amyloidosis causes abnormal protein fibers to accumulate in the heart muscle.
    • Sarcoidosis produces lumps (called granulomas) in organs, including the heart.
    • Hemochromotosis is a genetic condition that causes iron to build up in the heart and other parts of the body.

    Symptoms, including shortness of breath, fatigue, and heartbeat abnormalities, usually do not show up until cardiomyopathy is well-established. People with cardiomyopathy may feel winded or tired after any amount of exertion, or may experience a pounding heart during physical activity. In some cases, the heart is so weak that the blood that cannot be pumped forward effectively backs up in the lungs, abdomen, or hands and feet. Some patients experience heart rhythm disturbances and feel dizzy or faint. Others may have chest pains or a severe cough. When an infection is present, fever and flu-like symptoms occur.

    Symptoms of Cardiomyopathy

    • Chest pain
    • Cough
    • Dizziness
    • Faintness
    • Fatigue
    • Heart palpitations
    • Shortness of breath
    • Swelling in the hands and feet or abdomen

    Lifestyle factors and existing health problems can put you at risk for cardiomyopathy. Risk is higher among smokers and people who are obese, and those with a family history of cardiomyopathy. Years of excessive alcohol intake can also increase a person’s risk for developing the problem. Anyone with a family history of cardiomyopathy should discuss safe forms of exercise with a doctor.

    Gender and race can be risk factors for cardiomyopathy. While the reason is unknown, restrictive cardiomyopathy occurs more frequently in tropical and subtropical Africa.

    Dilated cardiomyopathy is most common among middle-aged African-American men. African-American women over 30 years of age are at increased risk for cardiomyopathy associated with childbirth.

    To determine what is causing your symptoms, your doctor will start with a medical history and do a physical examination. In addition to asking you about chest pain, fatigue, shortness of breath, and any other symptoms you may be experiencing, your doctor will listen to your heart through a stethoscope for abnormal rhythms and sounds. Cardiomyopathy may cause the heart to beat too quickly or too slowly, or in an uncoordinated manner. Sometimes cardiomyopathy interferes with the ability of the heart valves to open and close properly, and a murmur can be heard. Listening to your breathing can reveal fluid in your lungs -- another indication that you might have cardiomyopathy. Your doctor will also take your blood pressure, which may be elevated because of hypertension, or lowered because of heart muscle weakness.

    Your doctor will run several tests to study your heart before making a diagnosis.

    • Chest x-ray. An x-ray of the chest can show any enlargement of your heart or an accumulation of fluid in your lungs.
    • Electrocardiogram (EKG). An electrocardiogram (EKG) is a simple, painless test in which electrodes are placed on your skin (arms, legs, chest) to record the electrical impulses that control your heartbeat. An EKG can reveal numerous heart problems, including irregular heartbeats, inadequate blood supply to the heart, and a thickening of the heart muscle.
    • Holter monitor. A Holter monitor is a portable device that can be worn over a long period of time to record the electrical impulses of the heart. Whereas an EKG can only record these impulses for a limited amount of time, a Holter monitor can provide a more in-depth and longer-term record of your heart’s activity.
    • Echocardiogram. An echocardiogram is a test that uses an ultrasound probe and a video screen for viewing sound-wave pictures of the structure and movements of your heart. This is particularly useful for showing any thickening in the heart walls and for checking the strength of the heart’s pumping action. Echocardiograms are painless, and are done by moving the ultrasound probe over the surface of the skin. If the echocardiogram does not provide satisfactory pictures of the heart, other tests may be needed.

    Your doctor may wish to have a specialist perform a procedure called cardiac catheterization. For this procedure, a long thin tube called a catheter will be inserted through an artery or vein (usually in an arm or leg) and threaded through a major vessel to your heart. Dye is then injected, and x-rays are taken to show the structure of the heart. This test is useful for looking for blockages in the arteries supplying the heart muscle, verifying the strength or weakness of the heart muscle, measuring pressures in the heart, and occasionally for collecting tissue samples (biopsies).

    Genetic tests are useful for identifying patients with hypertrophic cardiomyopathy. If you have a family history of cardiomyopathy, your doctor may recommend genetic testing. A small sample of your tissue will be sent to a laboratory to see if you have inherited an abnormal gene.

    If anyone in your family has had cardiomyopathy or has died suddenly from heart disease, talk to your doctor about what tests you should have to check for the condition.

    If you have a family history of hypertrophic cardiomyopathy, avoid exercising too much and avoid competitive sports. Your doctor will tell you what types of physical activities are safe.

    Women who have had cardiomyopathy associated with pregnancy should discuss the risk of future childbearing with their doctor.

  • Prevention and Screening

    If anyone in your family has had cardiomyopathy or has died suddenly from heart disease, talk to your doctor about what tests you should have to check for the condition.

    If you have a family history of hypertrophic cardiomyopathy, avoid exercising too much and avoid competitive sports. Your doctor will tell you what types of physical activities are safe.

    Women who have had cardiomyopathy associated with pregnancy should discuss the risk of future childbearing with their doctor.

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