Tests and diagnosis

By Mayo Clinic Staff

To 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. The doctor may examine the veins in your neck and check for fluid buildup in your abdomen and legs. After the physical exam, your doctor may also order some of these tests:

  • 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. A blood test to check for a chemical called N-terminal pro-B-type natriuretic peptide (NT-proBNP) can help in diagnosing heart failure.
  • 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 heart failure is the echocardiogram. An echocardiogram 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. The echocardiogram also can look for valve problems or evidence of previous heart attacks, as well as some unusual causes of heart failure.
  • Ejection fraction. Your ejection fraction is measured during an echocardiogram and can also be measured by nuclear medicine tests, cardiac catheterization and cardiac MRI. 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 50 percent or higher - meaning that more than half of the blood that fills the ventricle is pumped out with each beat. But, heart failure can occur even with a normal ejection fraction. This happens if the heart muscle becomes stiff from conditions such as high blood pressure.
  • Stress test. Stress tests measure how your heart and blood vessels respond to exertion. You may walk on a treadmill or pedal a stationary bike while attached to an ECG machine. Or you may receive a drug intravenously that stimulates your heart similar to exercise. Stress tests help doctors see if you have coronary artery disease. Stress tests also determine how well your body is responding to your heart's decreased pumping effectiveness and can help guide long-term treatment decisions. If your doctor also wants to see images of your heart while you're exercising, he or she may order a nuclear stress test or a stress echocardiogram. It's similar to an exercise stress test, but it also uses imaging techniques to visualize your heart during the test.
  • Cardiac computerized tomography (CT) scan or magnetic resonance imaging (MRI). These tests can be used to diagnose heart problems, including causes of heart failure. In a cardiac CT scan, you lie on a table inside a doughnut-shaped machine. An X-ray tube inside the machine rotates around your body and collects images of your heart and chest. In a cardiac MRI, you lie on a table inside a long tube-like machine that produces a magnetic field. The magnetic field aligns atomic particles in some of your cells. When radio waves are broadcast toward these aligned particles, they produce signals that vary according to the type of tissue they are. The signals create images of your heart.
  • Coronary catheterization (angiogram). In this test, a thin, flexible tube (catheter) is inserted into a blood vessel at your groin or in your 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 heart's main pumping chamber (left ventricle) and the health of the heart valves.
  • Myocardial biopsy. In this test, your doctor inserts a small flexible biopsy cord into a vein in your neck or groin, and small pieces of the heart muscle are taken. This test is performed to diagnose certain types of heart muscle diseases that cause heart failure.

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 symptom-based scale classifies heart failure in categories from one to four. In Class I heart failure, you don't have any symptoms. In Class II heart failure, you can perform everyday activities without difficulty but become winded or fatigued when you exert yourself. With Class III, you'll have trouble completing everyday activities, and Class IV is the most severe, and you're short of breath even at rest.
  • American College of Cardiology /American Heart Association guidelines. This stage-based 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 but no signs or symptoms of heart failure is Stage A, while 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.

These scoring systems are not independent of each other. Your doctor often will use them together to help decide your best treatment options. 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.

Aug. 16, 2013