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By Mayo Clinic staffTo diagnose heart failure, your doctor will take a careful medical history and perform a physical examination. Your doctor will also check for the presence of risk factors such as high blood pressure. Using a stethoscope, your doctor can listen to your lungs for signs of congestion. The stethoscope also picks up abnormal heart sounds that may suggest heart failure. After the physical exam, your doctor may do blood tests and a chest X-ray followed by an echocardiogram.
- Blood tests. Your doctor may take a sample of your blood to check your kidney and thyroid function and to look for indicators of other diseases that affect the heart. In addition, your doctor may check your blood for specific chemical markers of heart failure, such as a hormone called brain natriuretic peptide (BNP). Although first identified in the brain, BNP is secreted by the heart at high levels when it's injured or overworked.
- Chest X-ray. X-ray images help your doctor see the condition of your lungs and heart. In heart failure, your heart may appear enlarged and fluid buildup may be visible in your lungs. Your doctor can also use an X-ray to diagnose conditions other than heart failure that may explain your signs and symptoms.
- Electrocardiogram (ECG). This test records the electrical activity of your heart through electrodes attached to your skin. Impulses are recorded as waves and displayed on a monitor or printed on paper. This test helps your doctor diagnose heart rhythm problems and damage to your heart from a heart attack that may be underlying heart failure.
- Echocardiogram. An important test for diagnosing and monitoring heart failure is the echocardiogram. An echocardiogram also helps distinguish systolic heart failure from diastolic heart failure, in which the heart is stiff and can't fill properly. An echocardiogram uses sound waves to produce a video image of your heart. This image can help doctors determine how well your heart is pumping by measuring the percentage of blood pumped out of your heart's main pumping chamber (the left ventricle) with each heartbeat. This measurement is called the ejection fraction.
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Ejection fraction. Your ejection fraction is measured during an echocardiogram. An ejection fraction is an important measurement of how well your heart is pumping and is used to help classify heart failure and guide treatment. In a healthy heart, the ejection fraction is about 60 percent — meaning 60 percent of the blood that fills the ventricle is pumped out with each beat.
Other imaging tests may be used to measure ejection fraction, including cardiac catheterization, multiple gated acquisition (MUGA) scanning of the heart, magnetic resonance imaging (MRI) and computerized tomography (CT).
Other tests
In addition to the physical examination, blood tests, chest X-ray and echocardiogram, your doctor may recommend one or more tests to help diagnose heart failure, determine its underlying cause and guide treatment decisions. You may have tests such as:
- Stress test. You may have one of a variety of stress tests either using an exercise bike or treadmill or medications that stress the heart. In some stress tests, pictures are taken of your heart with either nuclear medicine or echocardiographic techniques to try and determine if you have blockages in your heart arteries as a cause for your heart failure. You may also have an oxygen uptake stress test which helps your doctor know how well your body is compensating for your condition.
- Cardiac CT or MRI scan. These tests are now being used with increased frequency for people with heart failure, not only to measure ejection fraction but to check the heart arteries and valves, determine if you have had a heart attack, and look for unusual causes of heart failure.
- Coronary catheterization (angiogram). In this test, a thin, flexible tube (catheter) is inserted into a blood vessel at your groin or arm and guided through the aorta into your coronary arteries. A dye injected through the catheter makes the arteries supplying your heart visible on an X-ray. This test helps doctors identify narrowed arteries to your heart (coronary artery disease) that can be a cause of heart failure. The test may include a ventriculogram — a procedure to determine the strength of the left ventricle (the heart's main pumping chamber) and the health of the heart valves.
Classifying heart failure
Results of these tests help doctors determine the cause of your signs and symptoms and develop a program to treat your heart. To determine the best course of treatment, doctors may classify heart failure using two scales:
- New York Heart Association scale. This scale classifies heart failure in categories from one to four. In Class I heart failure, the mildest form, you can perform everyday activities and not feel winded or fatigued. Class IV is the most severe, and you're short of breath even at rest.
- American College of Cardiology scale. This newer classification system uses letters A to D. The system includes a category for people who are at risk of developing heart failure. For example, a person who has several risk factors for heart failure is Stage A, but a person with end-stage heart failure requiring hospice care is Stage D. Doctors use this classification system to identify your risk factors and begin early, more aggressive treatment to help prevent or delay heart failure.
Ask your doctor about your score if you're interested in determining the severity of your heart failure. Your doctor can help you interpret your score and plan your treatment based on your condition.