There’s nothing like a good workout to see how fit you really are. You may feel like a champion in your armchair fantasies, but playing a game of tennis can tell a different story. Likewise, you don’t know how well your heart is working until you put it to the test. Almost everyone’s heart beats in the same monotonous rhythm when they are resting. But during exercise, diseased hearts and healthy hearts act very differently.
If you’re at risk for heart problems, your doctor may want to monitor your heart while you exercise. This type of test is called a stress test or exercise tolerance test. Your doctor will ask you to walk on a treadmill or ride a stationary bike for about 10 to 20 minutes. The workout will start at a slow pace and gradually become more intense. By the end, you’ll feel like you’re walking or biking up a small hill. During the test, electrodes on your chest that are connected to an electrocardiograph (ECG or EKG) machine will measure the flow of electricity in your heart. You will also have a blood pressure cuff on your arm.
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Often, a stress test is done along with other diagnostic tests, such as an echocardiogram, which uses sound waves to create a moving picture of the heart, or a nuclear stress test, which uses a harmless radioactive substance called thallium to show how well blood flows to the heart.
What can a stress test say about my heart?
First, a stress test can measure how much stress your heart can handle. If the arteries in your heart are clogged with fatty plaque, a condition called coronary heart disease, your heart will have a hard time keeping up during your workout. Your blood pressure may drop and your ECG will likely show irregular patterns. You may also feel extremely tired and out of breath.
Although the stress test correctly identifies about 75 percent of all people with coronary heart disease, people in the early stages usually pass the test without problems. In general, the test works if the arteries are already more than half clogged. So if the stress test shows your arteries are blocked, beware: Unless you and your doctor take action, a heart attack is likely on the way.
More recent research has shown that stress tests can also help doctors determine the likelihood of coronary heart disease, even for those with no signs of it. Doctors at Johns Hopkins reported in a study, published in the journal Circulation, that 90 percent of those who died of coronary heart disease and had no early signs of the disease had below-average scores 10 to 20 years earlier in stress tests. The research teams’ analysis showed that study participants who scored below average were two to four times more likely to die from coronary heart disease. More than 6,000 men and women participated in the study between 1972 and 1995.
Doctors may also prescribe light exercise tests if someone has already had a heart attack or been diagnosed with heart disease. Exercise is often done in a medically supervised setting, and the results can help doctors design a safe exercise program. The test can also be used to see if a patient is responding to treatment or how well a pacemaker is working.
If you’ve already had a heart attack, a stress test may be important to your recovery strategy. Ideally, however, most people should have a stress test BEFORE they have a heart attack. With this in mind, the American College of Cardiology recommends the test for the following groups:
- Men over 45 and women over 55, and people with diabetes, who are about to start vigorous exercise programs, especially if they have been inactive.
- Men over 45 years of age and women over 55 years of age who are involved in occupations where the disability may affect public safety, or who are at increased risk of coronary artery disease due to other conditions (eg, heart failure). chronic kidney disease).
- People with several risk factors for heart disease, including smoking, obesity, high blood pressure, diabetes, high cholesterol levels, older age, male gender, and a family history of heart problems.
- Anyone who has symptoms of coronary artery disease, especially chest pain (angina pectoris).
The procedure is quite safe. Your doctor will watch you very closely during the test. If you feel extremely tired or show any other signs of coronary artery disease, your doctor will stop the exam right away. As an added safety measure, a person trained in cardiac life support will be in the room at all times. However, it is not completely risk-free: about one patient in 2,500 has a heart attack during the test. But with proper evaluation beforehand, there should be little chance of a problem arising.
Who should not take a stress test?
Some people are not healthy enough to withstand a stress test. You should not take the test, or do any other vigorous exercise, if you have recently had a heart attack or if you have high-risk unstable angina; uncontrolled symptomatic heart failure; severe hypertension (systolic pressure greater than 200 or diastolic pressure greater than 110); inflammation of the heart (pericarditis, endocarditis, or myocarditis); acute aortic dissection; uncontrolled arrhythmia (unusual heartbeat rhythms); or blood clots in the lungs or deep veins. You may also not be able to take the test if you have severe physical disabilities or are very heavy. (Equipment generally cannot support more than 350 lbs.)
Some cases require additional caution. Patients with advanced diabetes, Parkinson’s disease, mitral valve prolapse, frequent arrhythmia, thyroid problems, or other illnesses may have trouble withstanding the test. If you have one of these conditions, your doctor will give you a complete checkup before ordering the test.
Also, many medications can make it difficult to interpret the stress test. If you are taking digoxin, antiarrhythmic drugs (such as quinidine or procainamide), blood pressure drugs, or tricyclic antidepressants, the test may be less accurate than usual.
There are alternative methods of testing your heart if, for some reason, the treadmill test cannot be performed. If a stress test isn’t right for you, your doctor may suggest cardiac catheterization, which uses a special dye and x-rays to show the inside of your arteries. Another test, a computed tomography (CT) scan, uses electron beams to find calcium deposits in the arteries of the heart, which can be an indication of heart disease.
Darrow, MD Applying for and Understanding the Exercise Stress Test. American family physician. j
ACC/AHA Guidelines for Stress Testing. Journal of the American College of Cardiology.
Johns Hopkins University. The exercise stress test helps identify the risk of coronary heart disease.
National Heart, Lung, and Blood Institute. How is coronary artery disease diagnosed?
American Heart Association. Thallium stress test.