This is a test used to find out if the heart rate and rhythm are normal or if heart damage has occurred. It's a graphic record of the heart's electrical impulses. A Holter monitor is a 24-hour portable monitor of the electrocardiogram, used to detect heart rhythm problems, ischemia (is-KE'me-ah) or other problems. Ischemia means inadequate blood flow to the heart muscle.

What is a 12-lead electrocardiogram?

When an electrocardiogram is done, several wires, or "leads," are usually attached to the arms, legs and chest. This is called a "12-lead ECG." It allows a doctor to take 12 different recordings at the same time. Each lead records the same electrical impulse, but from a different position in relation to the heart.

What is a signal-averaged electrocardiogram (SAECG)?

This is called a high-resolution ECG or late potential study. Computers are used to amplify and enhance the ECG signal. Small electrical currents, called ventricular (ven-TRIK'u-ler) late potentials, can be recorded with a signal-averaged ECG. This test may help identify people at risk of a dangerous rhythm in the heart's lower (pumping) chambers. This is called ventricular arrhythmia (ay-RITH'me-ah) and it can lead to sudden cardiac death.

What is an echocardiogram (or echocardiography)?

This is a technique that sends sound waves (like sonar) into the chest to rebound from the heart's walls and valves. The recorded waves show the shape, texture and movement of the valves on an echocardiogram. They also show the size of the heart chambers and how well they're working. This technique doesn't hurt and poses no risk. It's done in the same way as ultrasound pictures of a fetus are taken in pregnant women.

What is stress echocardiography?

Stress echocardiography or "stress echo" is an echocardiogram done before and during or immediately after some form of physical stress (such as bicycle or treadmill exercise). It's used to help diagnose coronary heart disease.

What is transesophageal (tranz"e-sof"ah-JE'al) echocardiography (TEE)?

TEE is a special type of echocardiogram. A tube with an echocardiogram transducer on the end of it is passed down a person's throat and into the esophagus. (This is the tube connecting the mouth to the stomach.) The esophagus is right behind the heart, and images from TEE can give very clear pictures of the heart and its structures.

What other ways can doctors study heart damage?

Cardiac catheterization (KATH'eh-ter-i-ZA'shun) is also used. In it, a doctor inserts a thin plastic tube (catheter) into an artery or vein in the arm or leg. From there it can be advanced into the chambers of the heart or into the coronary arteries. This test can measure blood pressure within the heart and how much oxygen is in the blood. It's also used to get information about the pumping ability of the heart muscle. Catheters are also used to inject dye into the coronary arteries. This is called coronary angiography (an"je-OG'rah-fe) or coronary arteriography (ar-te"re-OG'rah-fe). Catheters with a balloon on the tip are used in the procedure called percutaneous transluminal coronary angioplasty (per"ku-TA'ne-us tranz-LU'min-al KOR'o-nair-e AN'je-o-plas-te) (PTCA). Catheterization is also done on infants and children to examine or treat congenital heart defects.

Some other tests, such as radionuclide (RA'de-o-NOO'klid) imaging, SPECT MRI and PET scanning, can also be used to assess damage to the heart muscle.

Related AHA publications:

• Heart and Stroke Facts
• Your Cardiac Catheterization brochure
• Printable sheets from our Answers By Heart kit on various treatments and tests

Related AHA scientific statements:
Echocardiography
Electrocardiography
Imaging
Tomography