Heart Failure: Testing
Many tests help to evaluate CHF (congestive heart failure). Your doctor may order several of these tests for you. The tests include:
- Echocardiogram (echo)
- Multiple-gated acquisition scan (MUGA)
- Heart catheterization (pronounced kath-eh-te-re-ZAY-shun)
- Exercise test
- Endomyocardial biopsy
The echocardiogram, or echo, is an ultrasound image of your heart. It is used to check your heart structure and function. First, a gel is applied to your chest. A device called a transducer (trans-DOO-sir) is moved over the surface of your chest. The transducer picks up the sound waves from your heart. The sound waves are transmitted to a monitor to display a picture. This test evaluates the heart size, pumping function (sometimes called ejection fraction), and the structure and function of the cardiac valves.
There is no preparation for this test. It does not expose you to radiation. The test takes approximately 30 to 60 minutes to complete.
The MUGA scan is a video image of your beating heart. You will be given an IV (intravenous) injection of a radioactive tracer. This is a substance that attaches to your red blood cells. From this test, your doctor will be able to tell how well your heart pumps. This measure is called the ejection fraction. The normal ejection fraction is 55 to 60 percent. Generally, either the echocardiogram or the MUGA scan is done.
There are no special instructions to prepare for this test. The tracer does expose you to a small amount of radiation, so it is important to tell your doctor if you are or may be pregnant, or if you are breast-feeding. This test takes about 30 to 60 minutes to complete.
Exercise testing helps to detect the presence of coronary artery disease or to evaluate your exercise tolerance. Various tests may be used.
Exercise thallium test
During this test, you will walk on a treadmill while your heart rate and blood pressure are monitored. You will have an IV inserted before you exercise. You will be asked to walk as long as possible. When you are a minute away from quitting, thallium (a radioactive substance) will be injected into your IV.
After you have finished exercising, you will lie down. Images will be taken of your heart. A second set of images usually is taken 4 to 6 hours later. A third set of images may be needed after 24 hours for some patients. This test shows if blood flow to certain areas of the heart is reduced during exercise.
Oxygen consumption exercise test (MVO2)
During an oxygen consumption exercise test, you will walk on a treadmill while your heart rate and blood pressure are monitored. You will wear a mouthpiece (similar to a snorkel) or a mask, and you will breathe in and out through it during exercise. You will be asked to exercise as long as you can. This test measures how much oxygen your body is using during exercise. This is an important indicator of how well your heart is working.
Right heart catheterization
During a right heart catheterization, a long, thin tube called a catheter is placed in a vein in your neck or groin. A small wire is threaded through the catheter to the right side of your heart under x-ray guidance. Pressure measurements are made inside the right-sided chambers of your heart. Then the amount of blood your heart is pumping is evaluated.
Left heart catheterization
During a left heart catheterization, a catheter is placed in your groin. A small wire is threaded up to your heart under x-ray guidance. Pressures inside the aorta (the major artery thatarises from the heart) and the left ventricle are measured. Dye is injected, and pictures are taken of your left ventricle and coronary arteries. Your doctor will be able to tell if there are any blockages in your coronary arteries.
During an endomyocardial (pronounced en-doh-my-oh-KAR-dee-ul) biopsy, a special wire is placed in a vein in your neck. The wire is threaded to the right side of your heart under x-ray guidance. Samples of the heart muscle are removed carefully, so that the physician can study them under a microscope. This procedure is done only in special circumstances.