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Important Tests and Screenings

A number of exams are used to diagnose a potential heart problem. To help you understand these exams and why they are used, LifeBeat Online explains several common and talked-about tests. We also tell you what to expect if you need to have one of these tests. For your specific health needs, consult your doctor.

Blood Tests

Blood tests are essential to the treatment of most medical conditions. They enable doctors to measure the levels of important substances in the blood. If the levels are abnormal, doctors can often use this information to diagnose a condition and help manage it. For a suspected heart problem, a number of substances — like proteins, electrolytes, and enzymes — offer clues to what may be wrong. In general, analyzing these substances can help:

Identify problems that can lead to heart disease
Determine if a heart attack has occurred
Gauge the extent of heart damage

One potential screener, which has become more frequently used in testing for risk of heart disease, is the C-reactive protein (CRP) test. It measures the levels of CRP, a protein produced by the body when there is inflammation. A high level of CRP does not necessarily mean that you are at risk for heart attack or stroke. But it can be a useful predictor of heart disease when used with other information.

What To Expect. Blood is usually taken from a vein. An elastic band is placed around the upper arm. A needle-tipped syringe is then inserted into a vein at the inside of the elbow or at the back of the hand. The blood is drawn into an empty test tube at the bottom of the syringe. The test should take only about 5 minutes. For the best accuracy, you may also be asked to not eat or drink for a certain number of hours before the test.

Chest X-rays

The chest x-ray is a general screening tool for evaluating a patient's overall health. It is also effective in diagnosing heart or lung disease. A chest x-ray is often taken when a patient is feeling congested or has chest pain. Among other benefits, a chest x-ray can help:

Determine size and shape of the heart, lungs, and large blood vessels
Detect calcium deposits in the lungs that can indicate disease
Diagnose various lung disorders like pneumonia

What To Expect. You will most likely be asked to undress from the waist up and wear an exam gown. You will also need to remove any jewelry. Typically, you are standing during the test, as the x-ray camera takes an image from the front and the side. The x-ray technician will leave the room before each x-ray, and you will have to hold your breath for a few seconds while each image is taken. No preparation is needed and the test is painless. If you are pregnant, be sure to tell your doctor before having a chest x-ray.

Electrocardiogram (ECG or EKG)

An ECG measures the tiny electrical signals created by a heartbeat. Each set of signals provides a different view of the heart. Beverly Lorell, MD, professor of medicine at Harvard University, explains, "an ECG is typically the first tool used in diagnosing a heart attack." An ECG can:

Measure heart rate and heart rhythm
Identify enlargement of the heart's chambers
Help diagnose whether you've had a heart attack

What To Expect. You will need to remove all clothes from the waist up. You will lie on your back as small sticky pads are placed on your neck, chest, legs, and arms. Wires connect the pads to a machine that receives the signals. The data, shown as waves, are recorded on graph paper or a monitor. An ECG is painless, takes a few minutes, and can be done in a doctor's office.

Echocardiogram

An echocardiogram, also known as an "echo" or "cardiac ultrasound," uses sound waves to build images of the heart. For Dr. Lorell, "It's hard to imagine how we practiced cardiology before the echocardiogram." An echo can:

Evaluate heart muscle function
Check for abnormalities in the heart wall, valves, and chambers
Identify blood clots

One key measurement taken from an echocardiogram is the ejection fraction (EF). The ejection fraction is the percentage of blood that's pumped out of the left ventricle with each heartbeat. A typical EF is between 50% and 75%. An EF below 35% may indicate the heart is not working at full capacity. The EF is a powerful tool that helps doctors decide the best treatment.

What To Expect. You will most likely be asked to undress from the waist up and wear an exam gown. A gel is applied to your chest. The doctor or technician then passes a hand-held device called a transducer over your chest. Images of your heart will appear on a video monitor. An echo can be done in the doctor's office or at a patient's bedside in the hospital. It's a painless test that can be done lying down or while exercising. The test takes 30 to 90 minutes.

Cardiac MRI

Like an echo exam, a cardiac MRI (magnetic resonance imaging) test can be used to test heart muscle function and look closely at the heart's structure. However, a cardiac MRI uses radio waves, not sound waves. MRIs can create precise 3-D images — either still or moving images — of the heart. "These images are so accurate," Dr. Lorell says, "it's as if the heart is right in front of you." Recently, specialists have even used the MRI to create movie-like images of the beating heart. MRIs can also measure the ejection fraction.

What To Expect. The test takes 30 to 90 minutes. You will probably lie on a table that slides into the MRI machine. Although your body is inside the large tube-like machine, you can look out the top end. (Some MRI machines are fully open on one or more sides.) You may be required to lie still for up to an hour during the test, but you will be able to communicate with the MRI technicians the whole time. The machine may make loud noises while it is scanning. Many facilities also provide headphones so you can listen to relaxing music. If you are pregnant or have a pacemaker or defibrillator, you typically should avoid an MRI.

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