Stress Test

Stress test

Definition

There are different forms of stress tests. Two components are required for a stress test. The stress itself (such as exercise) and some form of evaluation (EKG or images obtained from your heart). An exercise stress test is particularly useful because it is used to obtain information about how your heart functions with physical activity. An exercise stress test makes your heart work much harder than your normal everyday activities, and may be used to discover problems with your heart that might not be noticeable under non-exertional activities.

Most commonly, an exercise stress test involves walking on a treadmill (rarely a stationary bike is used). While you are exercising, your heart rhythm, blood pressure, pulse, and breathing are monitored.

Your doctor should order an exercise stress test if possible before choosing any other stress test. Exercise should be the principal modality of stress unless you are unable to exercise or have certain abnormality on your EKG.

Why Performed

A stress test is a functional study that is ordered when a doctor is concerned that a patient may suffer from limiting coronary artery disease or suffering from an irregular heart rhythm (arrhythmia). Sometimes an exercise stress test may be used to guide treatment in a patient with a known and diagnosed heart condition.

A stress test is often ordered for any of the following:

  • To diagnose obstructive coronary artery disease. Coronary arteries supply the heart with blood, oxygen, and nutrients. Coronary artery disease develops when arteries become diseased. The usual disease process involves plaque deposits containing cholesterol. Symptoms such as shortness of breath or chest pain are common causes for undergoing a stress test. Results from your test are used to determine if further testing is needed, such as a coronary angiogram.
  • To diagnose heart rhythm disturbances (arrhythmias). Arrhythmias are electrical disturbances of the heart. When functioning normally, the impulses generated from the heart’s pacemaker center is well coordinated throughout the rest of the heart. Abnormalities in heart rhythms may cause your heart to to beat too fast, too slow, or irregularly. Symptoms may are usually referred as “palpitations”, “racing heart, or “skipped beats”. Sometimes, patients may experience dizziness or frankly pass out without warning. An exercise stress test is monitored by a health care professional and sometimes used to see if stress on the heart precipitates a difficult to assess arrhythmia.
  • Assess treatment of heart disease. If a patient carries a diagnosis of heart disease, a stress test may be used to diagnose arrhythmias or evaluate response to treatment. Most commonly, a stress test is used to assess for significant coronary disease that may causing symptoms. The test may be used to assess severity of valvular heart disease or effectiveness of treatment of other heart conditions. It also may be used to guide therapy or goal of treatment.

Risks

Stress tests are considered be generally safe. Complications may occur, but are rare.

Potential complications include:

  • Low blood pressure. Your blood pressure may suffer a transient fall during the stress portion of the your test and cause dizziness.
  • Arrhythmia. Abnormal heart rhythms may be precipitated by the stress portion of your exam. It may relieve on its own or require medicine to terminate the disturbance.
  • Heart attack. Myocardial infarction is when your heart suffers damage. It is very rare for this to occur during a stress test, but it has been reported and possible.
  • Chest Pain. During the stress portion of your exam (chemical or exercise) you may experience chest pain. There is no relationship between heart disease and chest pain during a chemical stress (usually), but there is for an exercise stress test.

**Note: with chemical stress tests, there is a higher propensity of experiencing chest pain, nausea, and shortness of breath.

Preparation

Food and drink should be withheld for at least 2 hours prior to a stress test. There are certain medicines your doctor may ask you to not take prior to a stress, but in general, most medicines are continued as normally prescribed. Some exceptions may be beta blockers (i.e. metoprolol, atenolol, carvedilol) or diabetic medicines. In addition, if you are undergoing a chemical stress such as adenosine or regadenoson (Lexiscan), you should hold caffeine at least 12 hours prior to the test (some labs advocate 24 hours).

Asthmatics and patients with emphysema should bring their inhalers to the test. You should notify your doctor and persons conducting the stress that you use inhalers.

Bring comfortable exercise clothes with you for your stress test. Remember to wear shoes that allow you to walk/jog for an exercise stress test.

Expectation

During the procedure

  1. You will have electrodes placed on your chest, legs and arms (very similar to EKG). This is to monitor your heart during exercise. The electrocardiogram measures and displays the electrical impulses that during heartbeats. Your blood pressure will be monitored before, during, and after the test. An IV may be inserted depending on the type of stress you undergo.
  1. Depending on the type of stress:
    • For an exercise stress test, you will walk on a treadmill (or ride a stationary bike). The treadmill difficulty will increase usually every three minutes unless you physician adjusts the intensity. There may be rails in front or on the side of the treadmill. Try not to hold on to the rails and walk normally. The object is to continue exercising until your symptom limits any further exercise. Your EKG, blood pressure, and heart rate will be monitored throughout and after the test.
    • For an exercise nuclear stress: same as above, but you will have a radiotracer (such as Tc-sestamibi/Cardiolite) injected usually towards the end of your exercise. You should allow some time before your peak to allow the technician to inject the radiotracer (injection usually 1-2 minutes is sufficient)
    • For a chemical stress test: You will lay down. The IV is flushed and checked. A chemical (adenosine, regadenoson, or dobutamine) will be injected in the IV. Adenosine usually is infused for 6 minutes, but some labs advocate 4 minutes is sufficient. For regadenoson (Lexiscan), it is injected as a one time dose (test lasts for 2-3 minutes). For Dobutamine, it is infused in the IV over a period of time with incremental concentration every 3 minutes (test usually runs for 15-20 minuntes).

The length of your stay will depend on the type of stress you perform, your symptoms after the test, and if you need imaging of your heart after the stress portion is completed.

Typical scenarios:

  1. Exercise stress: EKG leads are placed; walk on treadmill; EKG, blood pressure, heart rate are monitored; treadmill increasing in intensity and speed periodically; treadmill stopped when you reach functional limitation (shortness of breath, chest pain, dizziness, leg pain, etc); you are monitored for 5-10minutes after test. Total approximate time = 30min-1hour.
  2. Exercise nuclear stress: EKG leads are placed; walk on treadmill; EKG, blood pressure, and heart rate are monitored; a radiotracer (such as Tc-sestamibi/Cardiolite) is injected IV at peak exercise; the treadmill continues for 1-2 minutes; treadmill stopped when you reach functional limitation (shortness of breath, chest pain, dizziness, leg pain, etc) you are monitored for 5-10 minutes after test. In 20 min-1 hour, you are placed under a camera to analyze your heart. You will have a second set of pictures either before or after the stress portion (usually performed before; radiotracer (such as Tc-sestamibi/Cardiolite) is injected IV and 20min-1hour later you are placed under a camera to analyze your heart at ‘rest’ which functions as a baseline).
    Total approximate time = 2-3 hours.
  3. Adenosine nuclear stress: EKG leads are placed; you lay under a camera to obtain baseline pictures of your heart; you may or may not walk slowly on treadmill while adenosine (chemical stress agent) is infused via IV for 4-6 minutes; EKG, blood pressure, heart rate are monitored; a radiotracer agent is injected in your IV after 2-4 minutes; adenosine infusion is terminated. Between 20 minutes and 1 hour, you will lay under a camera to obtain images of your heart. Total approximate time = 2-3 hours.
  4. Regadenoson (Lexiscan) stress test: EKG leads are placed; a radiotracer is injected via IV; after 20 min – 1 hour you lay under a camera to obtain baseline pictures of your heart; regadenoson (stress agent) is injected via IV; 15-30 seconds after regadenoson is administered, a radiotracer agent (such as Tc-sestamibi/Cardiolite), is injected in your IV; EKG, blood pressure, and heart rate are monitored. In 20min-1hour, you will need to lay under a camera to obtain images of your heart. Total approximate time =2-3 hours.
  5. Dobutamine Nuclear Stress : EKG leads are placed; a radiotracer agent (such as Tc-sestamibi/Cardiolite) is injected in your IV; 20 min-1 hour later you lay under a camera to obtain baseline pictures of your heart; Dobutamine (chemical stress agent) is infused via IV for 3-30 minutes; EKG, blood pressure, heart rate are monitored; a radiotracer agent (such as Tc-sestamibi/Cardiolite), is injected via IV at target heart rate; Dobutamine infusion is terminated. After 20 minutes and 1 hour, you will lay under a camera to obtain images of your heart. Total approximate time = 2-3 hours.
  6. Dobutamine Stress Echo: EKG leads are placed; a baseline echocardiogram is performed to obtain baseline pictures of your heart; Dobutamine (chemical stress agent) is infused via IV for 3-30 minutes; EKG, blood pressure, heart rate are monitored; an echocardiogram is performed while your heart rate is at target; Dobutamine infusion is terminated. Total approximate time = 1-2 hours.
  7. Exercise Echocardiogram: EKG leads are placed; a baseline echocardiogram is obtained; walk on treadmill; EKG, blood pressure, and heart rate are monitored; treadmill stopped when you reach functional limitation (shortness of breath, chest pain, dizziness, leg pain, etc) or your target heart rate; an echocardiogram is obtained quickly before your heart rate decreases; you are monitored for 5-10minutes after test. Total approximate time = 1-2 hours.

After the procedure

After your stress test, you will be monitored between 5-20 minutes depending on your symptoms, EKG findings, blood pressure, and heart rate readings. There is usually not much of a recovery period. Most of the time will be able to go home the same day, unless your doctor finds a very critical finding on your test. There are no physical restrictions after your test.

If you plan to fly, please obtain a certification from the stress lab stating you had a stress test and possible traces of radio-active isotope material may be still present when you fly. Some airports have security scans which detect radio-active material and you may be detained unnecessarily.

Typically, a stress test lasts about 10 minutes for exercise or chemical stress, and 15-20 minutes per each set of pictures you may need to further evaluate the heart (echocardiogram or Nuclear images).

Results

Results are usually available in 1-2 days. Tests are usually interpreted by a cardiologist and/or a radiologist. We recommend a cardiologist to read your test because they have more knowledge of your condition and may be looking for something in particular. Your results will usually be comprised of any abnormalities on the imaging portion of your stress, EKG changes, how much workload your heart was subjected to (METs), and ejection fraction (EF).