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Cardiac Diagnostic Testing

 

Cardiac diagnostic testing is used to evaluate both inpatients and outpatients with chest pain or shortness of breath, and pacemaker function.

Diagnostic services include:

Echocardiogram:

 

An echocardiogram provides a physician with information about the heart without using surgery or X-rays. Echocardiography uses sound waves (ultrasound) to produce an image of the heart. An echocardiogram helps determine the size of the heart, how the heart valves are working and how well the heart is pumping. An echocardiogram is usually done to detect heart or blood vessel problems (such as heart attack, leaking valves, weakened heart, heart defects, blood clots and other normal or abnormal conditions).

How does an echocardiogram work?

An echocardiogram uses sound waves (ultrasound) to record images of the heart. A transducer (a small device that looks like a microphone) is used to send silent sound waves into a person's chest. These waves "bounce back" to a receiver, producing a picture of the heart. The different parts of the heart send out different "echoes" that are recorded as pictures.

No preparation is needed for a simple echocardiogram. Patients undergoing a stress echocardiogram will be asked not to eat for three hours before the exam. They should wear comfortable clothes and take medications as usual unless otherwise instructed.

An echocardiogram takes one to two hours. Patches are placed on the chest to monitor the heart's electrical activity during the procedure. This helps the physician interpret your echocardiogram.

Patients like on their back or left side. A watery gel is applied to the skin to help transmit the ultrasound waves. A technologist or physician places the transducer on the patient's chest and moves it around to take different pictures of the heart.

During the procedure, images of the heart are displayed on a video screen or printed on paper. Patients cannot feel or hear the sound waves during the echocardiogram; however, there may be some discomfort from the pressure of the transducer on the chest. Patients also may hear the sound of blood moving through the heart.

 

There are three forms of echocardiographic pictures used to view the heart:

An M-mode echocardiogram, which is useful for measuring the size of the heart

A two-dimensional (2-D) echocardiogram, which gives a larger, two dimensional picture of the heart

A Doppler exam, which measures the speed and direction of blood flowing through the heart and its vessels

Stress Echocardiogram:

A　stress test, sometimes called a treadmill test or exercise test, helps a doctor find out how well your heart handles work. As your body works harder during the test, it requires more oxygen, so the heart must pump more blood. The test can show if the blood supply is reduced in the arteries that supply the heart. It also helps doctors know the kind and level of exercise appropriate for a patient.

For an exercise stress test, patients walk on a treadmill or pedal a bicycle to their peak exercise level. Blood pressure and the heart's electrical activity are monitored. The echocardiogram is repeated when patients reach their peak exercise levels.

A person taking the test:

Heart rate, breathing, blood pressure, electrocardiogram (e-lek"tro-KAR'de-o-gram) (ECG or EKG), and how tired you feel are monitored during the test.

Healthy people who take the test are at very little risk. It's about the same as if they walk fast or jog up a big hill. Medical professionals are present in case something unusual happens during the test.

A physician may recommend an exercise stress test to:

Diagnose coronary artery disease

Diagnose a possible heart-related cause of symptoms such as chest pain, shortness of breath or lightheadedness

Determine a safe level of exercise

Check the effectiveness of procedures done to improve coronary artery circulation in patients with coronary artery disease

Predict risk of dangerous heart-related conditions such as a heart attack.

Echocardiography uses ultrasound, which poses no known risk to the body. There is no X-ray exposure, and no surgical procedures are needed. A heart problem can occur during a stress test, but it is rare. The increased heart working during a stress test is monitored continuously to detect any problems that may arise.

Nuclear Stress Test:

If you're unable to exercise, you may be injected with a medication that increases blood flow to your heart muscle — simulating exercise — for the test

A medication is given into a vein that causes a similar effect on the heart. This medication, usually dobutamine, is given through an intravenous line (IV) in the arm. The heart rate, monitored by an electrocardiogram, gradually increases. Some people experience a slight flushing in the cheeks, a tingling scalp and a feeling that the heart is beating faster and harder. The physician compares the resting heart images with the images taken while the heart was working hard.

A nuclear stress test measures blood flow to your heart muscle at rest and during stress. It is performed similar to a routine exercise stress test but provides images in addition to electrocardiograms.

During a nuclear stress test, a radioactive substance is injected into your bloodstream. This substance mixes with your blood and travels to your heart. A special scanner — which detects the radioactive material in your heart — creates images of your heart muscle. Inadequate blood flow to any part of your heart will show up as a light spot on the images — because not as much of the radioactive substance is getting there.

There are several types of nuclear stress tests, including:

Myocardial perfusion scan. During this procedure, you exercise on a treadmill or pedal a stationary bicycle. When you reach your maximum heart rate, you're given the injection. Images are made of your heart shortly after exercise and also a few hours later. This test shows how well blood flows into the heart muscle and can detect narrowing of the coronary arteries (coronary artery disease).

Multiple gated acquisition (MUGA) scan. In this test, you receive the injection before exercising. Images are made of your heart before and after exercise. A MUGA scan shows the motion of the heart and how well it pumps out blood (ejection fraction).

Other Tests:

DMH Imaging Services Department also offers diagnostic services using state-of-the-art vascular/ultrasound machines that provide imaging and evaluation of blood flow in arteries and extremities for both inpatients and outpatients. Click on "Imaging Services" link.

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