Exercise stress test

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Stress tests provide information about how the heart works during physical stress. Some heart problems are easier to diagnose when the heart is overloaded and its beatings are accelerated.

During exercise stress test, there will be a strenuous exercise (walking on the treadmill or pedaling a stationary bicycle). Heart activity will be assessed while the patient will support physical activity.

There are situations in which a person may show arthritis or other medical problem that could prevent him to make the appropriate exercise during stress test. In this case, the doctor will administer medications to aggravate heart activity, in a manner similar to that of exercise. This is called a pharmacological stress test.


1. Overview
2. Usefulness of the exercise stress test
3. Types of stress tests
4. How does exercise stress test runs?
5. Stress echocardiography
6. Sestamibi stress echocardiogram
7. What can’t stress tests detect?
8. Risks during exercise stress test

Usefulness of the exercise stress test

Doctors usually use stress tests to aid in the diagnosis of coronary artery disease and to determine the severity of this type of condition.

Coronary heart disease is a condition characterized by the accumulation of plaque in coronary arteries. These arteries supply the heart with oxygen-rich blood, while the plaque narrows the arteries and reduce blood flow to the heart muscle. These deposits also cause blood clots in the arteries.

Blood clots can partially or completely block blood flow in the arteries and the result could be angina or a heart attack. Signs and symptoms of coronary heart disease does not occur when the heart is at rest, but occur when the heart has to pump more blood and oxygen during exercise. Narrowed arteries can’t supply enough blood to the heart and it will not work correctly.

A stress test can detect these problems that may suggest that the heart does not get enough blood during exercise:
- Abnormal changes in heart rate or blood pressure
- Symptoms such as shortness of breath or chest pain, especially if they occur in minor effort
- Changes in heart rate or abnormal electrical activity

During a stress test, the patient should be able to sustain the effort considered normal for a person of his age; if this won’t happen, it could be a sign that not enough blood reaches the heart.

There may be other factors, except for coronary heart disease that prevents prolonged effort (eg anemia, lung disease or poor stamina). Doctors can use stress tests to assess other types of problems such as heart failure or heart valve disease.

Types of stress tests

The two main types of stress tests are: standard exercise stress tests and stress imaging tests.

- Standard exercise stress test involves using EKG to detect and record the electrical activity of the heart. An EKG shows how fast the heart beats and its rate. It records the intensity and tempo of electrical signals passing through the heart.

During a standard stress test blood pressure will be checked. Patient may be asked to breathe through a special tube during the test, allowing the physician to observe how well he breathes and measure the quantity of gas exhaled.

After a standard stress test the doctor can see the changes in electrical activity of the heart. Also, he can see if the heart is good enough supplied with blood during exercise.

- Stress imaging test involves obtaining images when the heart is overloaded both during exercise and when it rests. Thanks to stress imaging tests the doctor can see how well blood flows through the heart and how blood is pumped by the heart.

This test involves performing stress echocardiography and uses sound waves to create a moving picture of the heart. Following this investigation the doctor can see how well work the heart chambers and heart valves when it is subjected to physical stress.

Exercise stress echocardiography may reveal areas of the heart where blood flow is poor, cardiac muscle tissue and necrotic heart muscle wall areas that are not properly contracted. These areas could be damaged during a heart attack or there may be insufficient blood supply.

There are other stress imaging tests that use dye (contrast substance) to create the image for viewing blood flow route to the heart. Thanks to these pictures the doctor can see how much dye came in different parts of the heart during exercise or rest.

Some tests that use contrast substance include electrocardiographic stress test with thallium or sestamibi and positron emission tomography (PET). The amount of radiation from the contrast substance is considered harmless both for the patient and for others. However, pregnant women should not take this test because of the risks that may occur in the fetus.

Imaging stress tests detect better coronary problems compared to standard stress tests and may predict future risk of heart attack or premature death. A stress imaging test may be conducted if:
- A person can’t sustain enough physical activity to overload heart (because of other health problems such as arthritis, plaque buildup in the arteries, etc.).
- Are present abnormal heartbeat or other problems that affect the correct results of a standard exercise stress
- If the patient has undergone surgery in the past, such as coronary artery bypass, angioplasty and stent placement

Other synonyms for the exercise stress test are nuclear stress test, PET stress test, sestamibi stress test, EKG or ECG stress test.

The exercise stress test is necessary for the people who have chest pain, shortness of breath or symptoms of low blood flow to the heart.

How does exercise stress test runs?

Before starting the investigation, the nurse will apply some electrodes on the patient’s skin. The electrodes are connected to an ECG machine which will record the electrical activity of the heart.

ECG shows how fast the heart beats and what is its rate. An EKG records the intensity and tempo of the electrical signals that pass through the heart. Nurse will check blood pressure during stress test. It may be necessary for the patient to breathe into a special tube to measure expired gases.

Then the patient will exercise using a stationary bike or treadmill. Exercise will become increasingly difficult, but the patient may stop when the exercise becomes too difficult. If the patient can’t complete the exercise, the nurse will inject a drug that increases blood flow through the coronary arteries and accelerate heartbeat, for the hear effort to be similar to the effort during stress test.

The drug can cause anxiety and headache, but the effects disappear immediately after testing. During exercise or after taking this medicine, the nurse will supervise the patient’s condition, will be interested to see if there are chest pain, shortness of breath or dizziness.

Exercise or drug for effort stress will continue until heart reaches a target rate or until:
- Will feel the moderate or severe intensity pain in chest
- Breathing is too accelerated
- Blood pressure is abnormally high, low or appear arrhythmias (irregular heartbeats)
- Patient feels dizzy

Nurse will continue to check heart function and blood pressure after test until they are back to normal. Exercise stress test takes about 15 minutes or less. However, it may take longer if they are included periods of training and its evaluation (an hour or more if stress imaging tests).

Stress echocardiography

During specific exercise for stress echocardiography, the specialist will obtain images of the heart using echocardiography before and after exercise.

On the chest will apply a special gel over which a transducer device will be moved (specifically device, ultrasound probe, rods shaped) and the nearby chest.

Sestamibi stress echocardiogram

This procedure involves injecting contrast substance and will be done about half an hour before the start of the stress test or involving administration of drugs for overloading cardiac activity.

Will obtain images both when the patient is resting and when he is making effort. It will be lying on a table and a special camera or scanner will detect the contrast substance in the blood and will capture the images of the heart.

What can’t stress tests detect?

Through stress testing effort can be seen how the heart works during exercise and if it is healthy or not. A standard exercise test uses the electrocardiogram to monitor changes in the electrical activity of the heart.

Stress imaging tests capture images of blood flow to the heart. With their help, heart valves and heart muscle movements become viewable. Doctors use two types of stress tests in their quest to discover if the heart is getting enough blood during exercise. Abnormal test results can be caused by coronary heart disease or other factors, such as poor stamina.

If a person’s exercise stress test results are normal, the person may not need further tests or treatment, but if the test results are abnormal or if they are unable to exercise, the doctor will ask to perform other types of exercise stress if the patient continues to show some symptoms such as shortness of breath or chest pain.

Imaging stress tests are more accurate than standard effort stress testing but are more expensive. Stress imaging tests show how well the heart muscle is irrigated with blood and emphasize the parts of the heart that are not so strongly contracted.

With these tests can be seen parts of the heart not receiving enough blood and necrotic tissue of the heart (resulting from a heart attack, for example). If imaging stress test suggests the presence of severe coronary artery disease, the doctor will recommend implementation of several tests and recommend treatment.

Risks during exercise stress test

Exercise stress tests pose very few serious risks. Risk that these tests to cause a heart attack or death is about 1 in 5000. Common side effects (less severe) of exercise stress test are:

- Arrhythmias – irregular heartbeat – arrhythmias often disappear once the person ceases to make effort and is at rest. If the arrhythmia persists, it may be necessary monitoring or treatment in hospital.

- Low blood pressure can cause dizziness or fainting. This problem will disappear after heart will not be overloaded and usually does not require treatment.

- Discomfort caused by taking medicines that overload cardiac activity (used when the exercises are not possible due to diverse problems).

These side effects disappear soon after stopping physical activity or medication. Sometimes, symptoms may last up to several hours. Some of the medicines used in pharmacologic stress tests may cause difficulty breathing or wheezing and other symptoms similar to those of asthma. In some cases, these symptoms are severe and require treatment.



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