exercise electrocardiogram


exercise electrocardiogram

A record of the electrical activity of the heart taken during graded increases in the rate of exercise. See: stress testSee also: electrocardiogram

Exercise Stress Test

Synonym/acronym: Exercise electrocardiogram, ECG, EKG, graded exercise tolerance test, stress testing, treadmill test.

Common use

To assess cardiac function in relation to increased workload, evidenced by dysrhythmia or pain during exercise.

Area of application

Heart.

Contrast

None.

Description

The exercise stress test is a noninvasive study to measure cardiac function during physical stress. Exercise electrocardiography is primarily useful in determining the extent of coronary artery occlusion by the heart’s ability to meet the need for additional oxygen in response to the stress of exercising in a safe environment. The patient exercises on a treadmill or pedals a stationary bicycle to increase the heart rate to 80% to 90% of maximal heart rate determined by age and gender, known as the target heart rate. Every 2 to 3 min, the speed and/or grade of the treadmill is increased to yield an increment of stress. The patient’s electrocardiogram (ECG) and blood pressure are monitored during the test. The test proceeds until the patient reaches the target heart rate or experiences chest pain or fatigue. The risks involved in the procedure are possible myocardial infarction (1 in 500) and death (1 in 10,000) in patients experiencing frequent angina episodes before the test. Although useful, this procedure is not as accurate as cardiac nuclear scans for diagnosing coronary artery disease (CAD).

For patients unable to complete the test, pharmacological stress testing can be done. Medications used to pharmacologically exercise the patient’s heart include vasodilators such as dipyridamole and adenosine or dobutamine (which stimulates heart rate and pumping force). Stress testing should be discontinued when maximal performance has been reached or if certain criteria occur as noted in the Contraindications section. The patient’s ECG and blood pressure are monitored during the exercise phase. The test proceeds until the stimulated exercise portion is completed when a radiotracer, such as technetium-99m or sestamibi, is injected and images are taken by a gamma camera during the stimulated portion to compare with images taken at rest.

This procedure is contraindicated for

  • A variety of circumstances that may be considered absolute or relative depending on the facility’s providers:

  • Abnormal EKG changes causing symptoms related to the possibility of stress-induced infarction.
  • Acute myocardial infarction (AMI) (within 2 days) related to the possibility of stress-induced reinfarction.
  • Acute myocarditis related to low stress tolerance.
  • Aortic dissection related to the possibility of stress-induced tears and rupture.
  • Chest pain related to the possibility of stress-induced infarction.
  • Heart failure with symptoms (e.g., shortness of breath) related to low stress tolerance.
  • Mental or physical (e.g., severe leg claudication) impairment that prevents the patient from performing the required exercise.
  • Significant hypertension or hypotension.
  • Stenotic valvular disease with symptoms related to low stress tolerance from having the heart work harder to pump blood through the narrow valve.
  • Very fast (tachyarrhythmias) or very slow (bradyarrhythmias) heart rate.

Indications

  • Detect dysrhythmias during exercising, as evidenced by ECG changes
  • Detect peripheral artery disease (PAD), as evidenced by leg pain or cramping during exercising
  • Determine exercise-induced hypertension
  • Evaluate cardiac function after myocardial infarction or cardiac surgery to determine safe exercise levels for cardiac rehabilitation as well as work limitations
  • Evaluate effectiveness of medication regimens, such as antianginals or antiarrhythmics
  • Evaluate suspected CAD in the presence of chest pain and other symptoms
  • Screen for CAD in the absence of pain and other symptoms in patients at risk

Potential diagnosis

Normal findings

  • Normal heart rate during physical exercise. Heart rate and systolic blood pressure rise in direct proportion to workload and to metabolic oxygen demand, which is based on age and exercise protocol. Maximal heart rate for adults is normally 150 to 200 beats/min.

Abnormal findings related to

  • Activity intolerance related to oxygen supply and demand imbalance
  • Bradycardia
  • CAD
  • Chest pain related to ischemia or inflammation
  • Decreased cardiac output
  • Dysrhythmias
  • Hypertension
  • PAD
  • ST segment depression of 1 mm (considered a positive test), indicating myocardial ischemia
  • Tachycardia

Critical findings

    N/A

Interfering factors

  • The following factors may impair interpretation of examination results because they create an artificial state that makes it difficult to determine true physiological function:

  • Anxiety or panic attack.
  • Drugs such as beta blockers, cardiac glycosides, calcium channel blockers, coronary vasodilators, and barbiturates.
  • High food intake or smoking before testing.
  • Hypertension, hypoxia, left bundle branch block, and ventricular hypertrophy.
  • Improper electrode placement.
  • Potassium or calcium imbalance.
  • Viagra should not be taken in combination with nitroglycerin or other nitrates 24 hr prior to the procedure because it may result in a dangerously low blood pressure.
  • Wolff-Parkinson-White syndrome (anomalous atrioventricular excitation).

Nursing Implications and Procedure

Pretest

  • Positively identify the patient using at least two unique identifiers before providing care, treatment, or services.
  • Patient Teaching: Inform the patient this procedure can assist in assessing the heart’s ability to respond to an increasing workload.
  • Obtain a history of the patient’s complaints or clinical symptoms, including a list of known allergens, especially allergies or sensitivities to latex or medications used to pharmacologically exercise the patient’s heart.
  • Obtain a history of the patient’s cardiovascular system, symptoms, and results of previously performed laboratory tests and diagnostic and surgical procedures.
  • Inquire if the patient has had any chest pain within the past 48 hr or has a history of anginal attacks; if either of these has occurred, inform the health-care provider (HCP) immediately because the stress test may be too risky and should be rescheduled in 4 to 6 wk.
  • Obtain a list of the patient’s current medications, including herbs, nutritional supplements, and nutraceuticals (see Effects of Natural Products on Laboratory Values online at DavisPlus).
  • Review the procedure with the patient. Address concerns about pain related to the procedure and explain that some discomfort may be experienced during the stimulated portion of the test. Inform the patient that the procedure is performed in a special department by an HCP specializing in this procedure and takes approximately 30 to 60 min.
  • Sensitivity to social and cultural issues, as well as concern for modesty, is important in providing psychological support before, during, and after the procedure.
  • Record a baseline 12-lead ECG and vital signs.
  • Instruct the patient to wear comfortable shoes and clothing for the exercise.
  • Instruct the patient to fast, restrict fluids, and avoid tobacco products for 4–6 hr prior to the procedure. Protocols may vary among facilities.
  • Make sure a written and informed consent has been signed prior to the procedure and before administering any medications.

Intratest

  • Potential complications:

  • Myocardial infarction (MI)

  • Observe standard precautions, and follow the general guidelines in Patient Preparation and Specimen Collection. Positively identify the patient.
  • Ensure the patient has complied with dietary and tobacco restrictions for at least 4 to 6 hr prior to the procedure.
  • An IV access may be established for emergency use.
  • Avoid the use of equipment containing latex if the patient has a history of allergic reaction to latex.
  • Have emergency equipment readily available.
  • Instruct the patient to void prior to the procedure and to change into the gown provided.
  • Place electrodes in appropriate positions on the patient and connect a blood pressure cuff to a monitoring device. If the patient’s oxygen consumption is to be continuously monitored, connect the patient to a machine via a mouthpiece or to a pulse oximeter via a finger lead.
  • Instruct the patient to walk on a treadmill (most commonly used) and use the handrails to maintain balance or to peddle a bicycle. As stress is increased, inform the patient to report any symptoms, such as chest or leg pain, dyspnea, or fatigue.
  • Turn the treadmill on at a slow speed, and increase in speed and elevation to raise the patient’s heart rate. Increase the stress until the patient’s predicted target heart rate is reached.
  • Instruct the patient to report symptoms such as dizziness, sweating, breathlessness, or nausea, which can be normal, as speed increases. The test is terminated if pain or fatigue is severe; maximum heart rate under stress is attained; signs of ischemia are present; maximum effort has been achieved; or dyspnea, hypertension (systolic blood pressure greater than 200 mm Hg, diastolic blood pressure greater than 110 mm Hg, or both), tachycardia (greater than 200 beats/min minus person’s age), new dysrhythmias, chest pain that begins or worsens, faintness, extreme dizziness, or confusion develops.
  • After the exercise period, allow a 3- to 15-min rest period with the patient in a sitting position. During this period, the ECG, blood pressure, and heart rate monitoring is continued.
  • Remove the electrodes and cleanse the skin of any remaining gel or ECG electrode adhesive.

Post-Test

  • Inform the patient that a report of the results will be made available to the requesting HCP, who will discuss the results with the patient.
  • Instruct the patient to resume usual activity, as directed by the HCP.
  • Instruct the patient to contact the HCP to report any anginal pain or other discomforts experienced after the test.
  • Nutritional Considerations: Abnormal findings may be associated with cardiovascular disease. Nutritional therapy is recommended for the patient identified to be at risk for developing CAD or for individuals who have specific risk factors and/or existing medical conditions (e.g., elevated LDL cholesterol levels, other lipid disorders, insulin-dependent diabetes, insulin resistance, or metabolic syndrome). Other changeable risk factors warranting patient education include strategies to encourage patients, especially those who are overweight and with high blood pressure, to safely decrease sodium intake, achieve a normal weight, ensure regular participation of moderate aerobic physical activity three to four times per week, eliminate tobacco use, and adhere to a heart-healthy diet. If triglycerides also are elevated, the patient should be advised to eliminate or reduce alcohol. The 2013 Guideline on Lifestyle Management to Reduce Cardiovascular Risk published by the American College of Cardiology (ACC) and the American Heart Association (AHA) in conjunction with the National Heart, Lung, and Blood Institute (NHLBI) recommends a “Mediterranean”-style diet rather than a low-fat diet. The new guideline emphasizes inclusion of vegetables, whole grains, fruits, low-fat dairy, nuts, legumes, and nontropical vegetable oils (e.g., olive, canola, peanut, sunflower, flaxseed) along with fish and lean poultry. A similar dietary pattern known as the Dietary Approach to Stop Hypertension (DASH) diet makes additional recommendations for the reduction of dietary sodium. Both dietary styles emphasize a reduction in consumption of red meats, which are high in saturated fats and cholesterol, and other foods containing sugar, saturated fats, trans fats, and sodium.
  • Social and Cultural Considerations: Numerous studies point to the prevalence of excess body weight in American children and adolescents. Experts estimate that obesity is present in 25 % of the population ages 6 to 11 yr. The medical, social, and emotional consequences of excess body weight are significant. Special attention should be given to instructing the child and caregiver regarding health risks and weight control education.
  • Recognize anxiety related to test results, and be supportive of fear of shortened life expectancy. Discuss the implications of abnormal test results on the patient’s lifestyle. Provide teaching and information regarding the clinical implications of the test results, as appropriate. Educate the patient regarding access to counseling services. Provide contact information, if desired, for the American Heart Association (www.americanheart.org), the NHLBI (www.nhlbi.nih.gov), or the Legs for Life (www.legsforlife.org). Reinforce information given by the patient’s HCP regarding further testing, treatment, or referral to another HCP. Answer any questions or address any concerns voiced by the patient or family.
  • Depending on the results of this procedure, additional testing may be performed to evaluate or monitor progression of the disease process and determine the need for a change in therapy. Evaluate test results in relation to the patient’s symptoms and other tests performed.

Related Monographs

  • Related tests include antiarrhythmic drugs, apolipoprotein A and B, AST, atrial natriuretic peptide, BNP, blood gases, blood pool imaging, calcium, chest x-ray, cholesterol (total, HDL, LDL), CT cardiac scoring, CT thorax, CRP, CK and isoenzymes, echocardiography, echocardiography transesophageal, electrocardiogram, glucose, glycated hemoglobin, Holter monitor, homocysteine, ketones, LDH and isos, lipoprotein electrophoresis, lung perfusion scan, magnesium, MRI chest, MI infarct scan, myocardial perfusion heart scan, myoglobin, PET heart, potassium, pulse oximetry, sodium, triglycerides, and troponin.
  • Refer to the Cardiovascular System table at the end of the book for related tests by body system.