An electrocardiogram (EKG) detects and records electrical impulses created by your heart each time it beats. An echocardiogram provides an ultrasound image of the heart's size and movements in addition to measuring electrical impulses. Performing these tests before, during and after physical stress allows a doctor to:
- Identify heart-related causes of symptoms such as dizziness, fainting, or palpitations that occur during stress.
- Screen for coronary artery disease (CAD) in people without symptoms but with risk factors for the disease, such as smoking, high cholesterol, high blood pressure, diabetes, or a family history of heart disease at a young age.
- Investigate unexplained chest pain when CAD is suspected.
- Determine the heart's ability to tolerate stress following a heart attack or surgery.
- Monitor the effectiveness of medication, surgery, or other therapy.
- Recommend an appropriate level of exercise for someone who is over 40, has led an inactive lifestyle, and wishes to begin an exercise program.
Treadmill stress test (stress EKG)
This test is performed at three-minute intervals before, during, and after you exercise on a treadmill. It records the electrical impulses produced by your heart each time it beats.
What to expect: The technician will place electrodes on several areas of your arms, legs, and chest. The electrodes transmit your heart's activity through wires to the EKG machine, where it will be displayed on a monitor and traced onto paper or stored in a computer. A blood pressure cuff on your upper arm will take blood pressure readings every few minutes during the test.
Your resting vital signs and a resting EKG are first taken as a precaution to ensure there are no signs that the test is unsafe for your heart. You will begin by walking on the treadmill, and gradually increase the intensity of your exercise with speed and incline. After exercising, you will be asked to rest for 5 to 10 minutes as recovery EKG and blood pressure measurements are taken. This procedure lasts about 15 to 30 minutes.
Stress echocardiogram (stress echo):
This test is like Stress EKG, with the addition of visual imagery. It is done before and during or immediately after physical exercise on a treadmill. It allows a physician to see the motion of the heart walls and pumping action when the heart is stressed.
What to expect: Several electrodes will be attached to your chest for the EKG reading. Your oxygen levels will also be monitored. Ultrasound images of your heart's resting function are taken prior to exercise.
Your resting vital signs and a resting EKG are first taken as a precaution to ensure there are no signs that the test is unsafe for your heart. Next you will run or walk on a treadmill to elevate your heart rate. As you exercise, your heart's electrical activity is recorded and displayed by the EKG machine. Every few minutes a cuff on your upper arm will measure your blood pressure. After exercising, you will be asked to rest for 5 to 10 minutes as recovery EKG and blood pressure measurements are taken. This procedure lasts about 30 to 60 minutes.
Dobutamine stress test
The purpose of a Dobutamine stress echocardiogram is to view the heart's movement under stress. It is particularly useful for those who have difficulty engaging in physical activity. Instead of having the patient exercise on a treadmill, a medication is given that causes the heart to react as if it were exercising.
What to expect: The test is done in two parts, resting and stress. The first part is done after an intravenous (IV) is started in your arm and nuclear imaging material is injected into your vein. The nuclear material will circulate while you rest. Following a circulation time of about 30 minutes, the first scan is completed. You will be asked to lie still with your left arm above your head for each scan while the camera rotates around your chest. Shortly after completing this scan, the second part of the test will begin. You cannot eat or drink anything between the two parts of a Dobutamine stress test.
Before the second part of the test begins, you will lie on a bed or stretcher and have several electrodes (small sticky patches) placed on your chest using a gel-like substance. While resting on the bed, the medication Dobutamine is slowly dripped through the intravenous (IV) for about 20 minutes. As the Dobutamine drips, the heart muscle squeezes faster and harder. When the physician has obtained enough information, the nuclear imaging material will be injected again and the Dobutamine will be stopped. Once again, the nuclear material will be allowed to circulate for 30 minutes while you rest and then the final scan will be done under the same camera.
You will be allowed to eat and drink during the scan waiting period, which takes about 15 minutes. The two scans help to determine if any defects or blockages are temporary or permanent as a result of earlier heart damage.
Patient preparation for stress tests
Before your test, inform your doctor of all medications you are taking, especially heart medications or treatment for erectile dysfunction, as these can alter your results. Discuss any physical limitations, including joint problems in your legs or hips, that may limit your ability to exercise. If you have diabetes, ask your doctor for further instructions. On the day of your test, follow these instructions, unless your physician instructs you otherwise:
- Do not eat, drink or smoke for four hours prior to your test.
- Do not take any medication the day of your test unless you have recently had cardiac surgery or experienced a heart attack, in which case you should take your medications as usual.
- Bring a list of your current medications to the appointment.