Your doctor will diagnose coronary heart disease (CHD) based on your medical and family histories, your risk factors, a physical exam, and the results from tests and procedures.
No single test can diagnose CHD, but, if your doctor thinks you have CHD, they may recommend a stress test.
During stress testing, you exercise to make your heart work hard and beat fast while heart tests are done. If you can't exercise, you may be given medicines to increase your heart rate.
Doctors usually use stress testing to help diagnose
coronary heart disease (CHD). They also use stress testing to find out the severity of CHD.
CHD is a disease in which a waxy substance called plaque builds up in the coronary arteries. These arteries supply oxygen-rich blood to your heart.
Plaque narrows the arteries and reduces blood flow to your heart muscle. The buildup of plaque also makes it more likely that blood clots will form in your arteries. Blood clots can mostly or completely block blood flow through an artery. This can lead to chest pain called angina or a heart attack.
You may not have any signs or symptoms of CHD when your heart is at rest. But when your heart has to work harder during exercise, it needs more blood and oxygen. Narrow arteries can't supply enough blood for your heart to work well. As a result, signs and symptoms of CHD may occur only during exercise.
A stress test can detect the following problems, which may suggest that your heart isn't getting enough blood during exercise:
During a stress test, if you can't exercise for as long as what is considered normal for someone your age, it may be a sign that not enough blood is flowing to your heart. However, other factors besides CHD can prevent you from exercising long enough (for example, lung disease, anemia, or poor general fitness).
Doctors also may use stress testing to assess other problems, such as
heart valve disease or
Stress testing is done in a doctor's office or at a medical center or hospital. You should wear shoes and clothes in which you can exercise comfortably. Sometimes you're given a gown to wear during the test.
Your doctor might ask you to fast (not eat or drink anything but water) for a short time before the test. If you're diabetic, ask your doctor whether you need to adjust your medicines on the day of the test.
For some stress test, you can't drink coffee or other caffeinated drinks for a day before the test. Certain over-the-counter or prescription medicines also may interfere with some stress tests. Ask your doctor whether you need to avoid certain drinks or food or change how you take your medicine before the test.
If you use an inhaler for asthma or other breathing problems, bring it to the test. Make sure you let the doctor know that you use it.
During all types of stress testing, a doctor, nurse, or technician will always be with you to closely check your health status.
Before you start the "stress" part of a stress test, the nurse will put sticky patches called electrodes on the skin of your chest, arms, and legs. To help an electrode stick to the skin, the nurse may have to shave a patch of hair where the electrode will be attached.
The electrodes will be connected to an EKG (electrocardiogram) machine. This machine records your heart's electrical activity. It shows how fast your heart is beating and the heart's rhythm (steady or irregular). An EKG also records the strength and timing of electrical signals as they pass through your heart.
The nurse will put a blood pressure cuff on your arm to check your blood pressure during the stress test. (The cuff will feel tight on your arm when it expands every few minutes.) Also, you might have to breathe into a special tube so the gases you breathe out can be measured.
Next, you'll exercise on a treadmill or stationary bike. If such exercise poses a problem for you, you might turn a crank with your arms instead. During the test, the exercise level will get harder. You can stop whenever you feel the exercise is too much for you.
The medicine may make you flushed and anxious, but the effects go away as soon as the test is over. The medicine also may give you a headache.
While you're exercising or getting medicine to make your heart work harder, the nurse will ask you how you're feeling. You should tell them if you feel chest pain, shortness of breath, or dizzy.
The exercise or medication infusion will continue until you reach a target heart rate, or until you:
The nurse will continue to check your heart functions and blood pressure after the test until they return to normal levels.
The "stress" part of a stress test (when your heart is working hard) usually lasts about 15 minutes or less.
However, there's prep time before the test and monitoring time afterward. Both extend the total test time to about an hour for a standard stress test, and up to three hours or more for some imaging stress tests.
For an exercise stress echocardiogram (echo) test, the nurse will take pictures of your heart using echocardiography before you exercise and as soon as you finish.
A sonographer (a person who specializes in using ultrasound techniques) will apply gel to your chest. The, they will briefly put a transducer (a wand-like device) against your chest and move it around.
The transducer sends and receives high-pitched sounds that you probably won't hear. The echoes from the sound waves are converted into moving pictures of your heart on a screen.
You might be asked to lie on your side on an exam table for this test. Some stress echo tests also use dye to improve imaging. The dye is injected into your bloodstream while the test occurs.
For sestamibi stress test or other imaging stress test that uses radioactive dye, the nurse will inject a small amount of dye into your bloodstream. This is done through a needle placed in a vein in your arm or hand.
You'll get the dye about a half-hour before you start exercising or take medicine to make your heart work hard. The amount of radiation in the dye is considered safe for you and those around you. However, if you're pregnant, you shouldn't have this test because of risk it might pose to your unborn child.
Pictures will be taken of your heart at least two times: when it's at rest and when it's working its hardest. You'll lie down on a table, and a special camera or scanner that can detect the dye in your bloodstream will take pictures of your heart.
Some pictures may not be taken until you lie quietly for a few hours after the stress test. Some patients may even be asked to return in a day or so for more pictures.
After stress testing, you'll be able to return to your normal activities. If you had a test that involved radioactive dye, your doctor may ask you to drink plenty of fluids to flush it out of your body. You shouldn't have certain other imaging tests until the dye is no longer in your body. Your doctor can advise you further.
Stress testing shows how your heart works during physical stress (exercise) and how healthy your heart is.
A standard exercise stress test uses an EKG (electrocardiogram) to monitor changes in your heart's electrical activity. Imaging stress tests take pictures of blood flow throughout your heart. They also show your heart valves and the movement of your heart muscle.
Doctors use both types of stress tests to look for signs that your heart isn't getting enough blood flow during exercise. Abnormal test results may be due to coronary heart disease (CHD) or other factors, such as poor physical fitness.
If you have a standard exercise stress test and the results are normal, you may not need further testing or treatment. But if your test results are abnormal, or if you're physically unable to exercise, your doctor may want you to have an imaging stress test or other tests.
Even if your standard exercise stress test results are normal, your doctor may want you to have an imaging stress test if you continue having symptoms (such as shortness of breath or chest pain).
Imaging stress tests are more accurate than standard exercise stress tests, but they're much more expensive.
Imaging stress test show how well blood is flowing in the heart muscle and reveal parts of the heart that aren't contracting strongly. They also can show the parts of the heart that aren't getting enough blood, as well as dead tissue in the heart, where no blood flows. (A heart attack can cause heart tissue to die.)
If your imaging stress test suggests significant CHD, your doctor may want you to have more testing and treatment.
Source: National Heart, Lung, and Blood Institute; National Institutes of Health; U.S. Department of Health and Human Services.
Cardiac and vascular imaging specialists on the medical staff of Baylor Scott & White The Heart Hospital – Plano use advanced technologies to diagnose and manage a wide range of cardiac and vascular disorders.
Physicians should call 469.814.3480 to schedule patients for cardiac imaging.In some cases, these tests and procedures are provided on an outpatient basis in The Heart Hospital's Outpatient Services facility.
Physicians are members of the medical staff at one of Baylor Health Care System's subsidiary, community or affiliated medical centers and are neither employees nor agents of those medical centers, Baylor Scott & White The Heart Hospital – Plano or Baylor Health Care System.