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Tests to Diagnose Heart Disease
 


Many tests can help to diagnose heart disease. The choice of which tests you have depends on your symptoms, risk factors, and history of heart problems. The types of tests used to diagnose heart disease include:
  • Cardiac Catheterization or Coronary Angiography
  • Chest X-Ray
  • Computed Tomography (CT) Scan
  • Echocardiogram
  • Electrocardiogram
  • Exercise Stress Test
  • Event Monitor
  • Holter Monitor (Ambulatory Electrocardiogram)
  • Magnetic Resonance Imaging (MRI)
  • Magnetic Resonance Angiography (MRA)
  • Multigated Graft Acquisition (MUGA) Scan
  • Positron Emission Tomography (PET) Scan
  • Signal-Averaged Electrocardiogram (SAECG)
  • Single Photon Emission Computed Tomography (SPECT) Scan
  • Radioisotope (Cardiolite or thallium) Stress Test.

Cardiac Catheterization or Coronary Angiography
Angiograms are x-ray pictures of blood vessels. Angiograms allow your health care provider to check the inside of a blood vessel to see if it is narrowed, leaking, or blocked. There are many kinds of angiograms to examine different kinds of blood vessels. Angiograms generally look at arteries. For example:
  • Carotid angiography examines the carotid arteries. These arteries travel up each side of the neck and supply blood to the brain.
  • A cerebral angiogram shows the blood vessels in the head.
  • Coronary angiography looks at the arteries that bring blood to the heart muscle.

A special dye that shows up in an x-ray is injected into a blood vessel through a thin tube called a catheter. As the dye flows in the blood vessel, a series of x-rays are taken.

Chest X-Ray
X-rays are a form of electromagnetic energy, or radiation. X-rays are able to penetrate body tissues. They are used to create pictures of body structures on film. An x-ray of your chest can show:
  • if the heart is enlarged or normal
  • signs of fluid overload
  • pneumonia or a collapsed lung
  • tumors in the lung that could mean cancer.

Computed Tomography (CT) Scan
Cardiac electron beam computed tomography is a computer-assisted x-ray scan of the heart. It may be called ultra-fast CT. It can show how much calcium is in the coronary arteries of the heart. Normal coronary arteries have very little or no calcium in them. The more calcium there is in the arteries, the higher the risk of a heart attack.

After you are positioned in an x-ray scanner, a series of x-ray pictures are taken rapidly. The whole test is painless and takes only a few minutes.

Echocardiogram
An echocardiogram makes pictures by bouncing high-frequency (ultrasound) waves off your heart. The echoes of the sound waves, translated by a computer and recorded on videotape, provide a picture of your heart as it beats. The heart valves, heart chambers, blood vessels, and the heart muscle itself can be carefully measured and examined. Ultrasound pictures of the heart are better than x-rays for outlining details of the heart. A special part of the echocardiogram called the color Doppler signal shows blood flow through your heart.

There are 2 types of echocardiograms:
  • Transthoracic. In this type of echocardiogram, the sound waves are produced by a transducer placed on your chest.
  • Transesophageal. For this type of echocardiogram, you swallow a transducer, or probe. The transducer is carefully placed in your esophagus, which is behind your heart. (The esophagus is the tube that carries food from the throat to the stomach.) Because the probe is much nearer your heart when it is inside you instead of outside on your chest, the pictures of the heart structures are much clearer.

Electrocardiogram
An electrocardiogram (ECG or EKG) is a recording of the electrical activity of the heart. (Each heartbeat starts with an electrical impulse that causes the heart to squeeze.) For this test small, sticky electrode patches are placed on your chest, wrists, and ankles. These patches are connected to a machine that records the electrical activity of your heart. The recording is printed on paper for your health care provider to interpret.

An ECG gives information about the electrical system of the heart. An echocardiogram shows the structure of the heart and its valves.

Exercise Stress Test
Many people with narrowing of the coronary arteries have symptoms only when they are active. Exercise increases the work of the heart. The heart needs more blood when it works hard. If the supply of blood to the heart cannot keep up with the amount of blood the heart needs, changes in the electrocardiogram will occur. Recording the electrocardiogram before, during, and after exercise shows these changes. The exercise test helps check for narrowing in your arteries.

You will be asked not to eat for about 2 hours before the test. Small, sticky patches are placed on your back and chest for the electrocardiogram. Blood pressure and the electrocardiogram are recorded while you are resting. You then start a slow walk on the treadmill or peddle a bicycle. You will walk faster or peddle harder every couple of minutes. The electrocardiogram and blood pressure continue to be recorded while you exercise and just after the test.

Event Monitor and Holter Monitor (Ambulatory Electrocardiograms)
Ambulatory electrocardiographic monitoring (AEM) is a way to record a continuous electrocardiogram.

Event recorders come in many shapes. They are small devices that you keep with you. When you have symptoms or feel like your heart rhythm is not normal, your place the device on your chest and it records your heart activity at that time. You then transmit your recordings over the telephone. These recordings are sent to your health care provider. You may be asked to keep the recorder for up to a month.

Holter monitors record the electrical activity of your heart on a tape cassette. Several sticky patches are placed on your chest. Small plastic wires are snapped on to these patches and connected to a monitor. You will keep this device on for 24 to 48 hours. You also may need to keep a diary of your symptoms and activities.

AEM is mostly used for 2 purposes:
  • to observe and record heart rhythm and any abnormality that might occur
  • to look for times when the heart muscle is not getting enough blood flow through the coronary arteries.

Magnetic Resonance Imaging (MRI)
Magnetic resonance imaging (MRI) produces very detailed pictures of body tissues and organs. If you have a pacemaker or implantable cardiac defibrillator (ICD), you cannot have an MRI.

You lie on a special table inside the opening of the MRI unit. Radio waves in a strong magnetic field create 2-D or 3-D images that may be viewed from any direction. The MRI is painless. MRI images are very sharp and detailed. They show even tiny changes from the normal pattern.

Magnetic Resonance Angiography (MRA)
MR angiography (MRA) is an MRI study of the blood vessels. It uses MR technology to detect, diagnose, and aid the treatment of heart disorders, stroke, and blood vessel diseases.

Multigated Graft Acquisition (MUGA) Scan
MUGA scans show how well the heart is pumping. They measure the amount of blood that is pumped with each heartbeat, and the flow of blood into the pumping chamber. MUGA scans also provide information about the size of the pumping chambers of the heart and the strength of the heart muscle. This test is also called a "radionuclide ventriculogram (RVG) or a gated blood pool scan.

An injection of a radioactive chemical temporarily highlights your red blood cells. A camera linked to a computer follows the blood moving through the heart. Information from several hundred heartbeats are collected and analyzed.

Positron Emission Tomography (PET) Scan
PET scans measures chemical changes that occur before signs of disease can be seen on CT and MRI images.

PET scans use a small amount of a radioactive chemical that is attached to a substance that is used by heart cells. The radioactive substance is injected into a vein. A special camera is then used to take the pictures of the heart. The PET scan shows how different parts of the heart use the substance. It can identify decreased blood flow and problems with the heart muscle.

Signal-Averaged Electrocardiogram (SAECG)
The signal-averaged electrocardiogram (SAECG) is a special type of electrocardiogram. The SAECG records very low electrical power signals of the heart. It provides information about your heart's electrical system and if you are at risk for fast heart rhythms.

The SAECG requires a special ECG machine that includes a computer. A regular ECG is taken, for at least 15 to 20 minutes. A computer quickly analyzes the results when enough heartbeats have been collected. About 1,000 heartbeats in a row are needed.

Radioisotope Stress Test
A radioisotope stress test uses radioactive tracers that allow blood flow patterns to be seen on a camera. These tracers are not harmful to you. This test is done along with an exercise stress test on a treadmill or bicycle. An echocardiogram (ultrasound images of the beating heart) is done just before and just after exercise. Sometimes the stress is provided by medicine instead of by exercise.

If there is good blood flow through the arteries, the pictures will show heart muscle that picks up the tracer. If there is decreased or no blood flow though an artery, the pictures will show heart muscle that is not picking up the tracer.




Disclaimer: This content is reviewed periodically and is subject to change as new health information becomes available. The information provided is intended to be informative and educational and is not a replacement for professional medical evaluation, advice, diagnosis or treatment by a healthcare professional.

HIA File CRD3652F.HTM Release 9.0/2006. Copyright © 2006 McKesson Corporation and/or one of its subdiaries. All Rights Reserved.


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