Norm of Stress / Exercise Test
Client reaches and maintains 85% of his/her target heart rate, without cardiac symptoms.
Test results usually include the following information:
ECG: baseline and during test, including the presence of changes
Estimate of exercise capacity
Any cardiac symptoms occurring during the test
Criteria used for ending the test: determination of whether the maximal heart rate was attained
Blood pressure and any arrhythmias occurring during the test
Usage of Stress / Exercise Test
Coronary artery disease; evaluation of cardiopulmonary fitness and exercise tolerance; preoperative screening for clients at high risk for surgical cardiovascular compromise; assessment of the efficacy of interventions such as coronary artery bypass graft, coronary angioplasty, medications, and cardiac rehabilitation; dysrhythmias; and valvular competence.
Description of Stress / Exercise Test
Stress testing measures the efficiency of the heart during a period of physical stress on a treadmill or on a stationary bicycle. The effects of exercise on cardiac output and myocardial oxygen consumption are evaluated by concurrent monitoring of electrocardiograms, blood pressure, and oxygen consumption. An advantage of exercise testing is that it can identify (in a safe environment) individuals prone to cardiac ischemia during activity, when resting electrocardiograms are normal.
Professional Considerations of Stress / Exercise Test
Consent form IS required.
Cardiac ischemia, including myocardial infarction, dysrhythmias, hypotension, hypertension, dizziness.
Cardiac contraindications: Active unstable angina, aortic stenosis (hemodynamically significant), chest pain, cardiac inflammation (endocarditis, myocarditis, pericarditis), congestive heart failure (acute), coronary insufficiency syndrome, digitalis toxicity, electrolyte abnormalities (severe), heart blocks (2°, 3°), hypertension (SBP >200 mm Hg, or DBP >110 mm Hg), left bundle branch block or other uncontrolled dysrhythmias, left ventricular hypertrophy, myocardial infarction (recent), obesity (weight higher than capacity of equipment, usually 350 pounds), pacemaker (fixed-rate), recent significant changes in ECG, thromboembolic processes (active).
Other contraindications: Alcohol intoxication, asthma (severe) or chronic obstructive pulmonary disease, infection (acute), pulmonary embolism (recent), thrombophlebitis; also inability to walk on a treadmill or pedal a bicycle.
- Have emergency equipment readily available.
- See Client and Family Teaching.
- The stress test is performed by specially trained (that is, ACLS-certified) nurses, exercise physiologists, and physical therapists. The American Association of Cardiovascular and Pulmonary Rehabilitation has recommended direct physician supervision of all initial stress tests and tests for individuals considered at high risk for complications.
- Attach electrocardiogram leads and a blood pressure cuff.
- While the client is on a treadmill, stationary bicycle, or stair stepper, computerized electrocardiographic recordings and blood pressure readings are obtained. Oxygen consumption may be measured by having the client breathe through a special mouthpiece during exercise.
- The client is stressed in stages by increases in miles per hour and the percentage grade of elevation of the treadmill.
- The test is terminated when any of the following occurs:
- a. Signs of ischemia are present (ST-segment depression of ≤1–2 mm for a duration >0.06 second, or ST-segment elevation).
- b. Maximum effort has been achieved.
- c. A predetermined target has been achieved.
- d. Dyspnea or hypertension >250 mm Hg systolic blood pressure is achieved.
- e. Tachycardia >200 beats per minute minus the client's age is reached.
- f. New dysrhythmias, new conduction impairments (that is, heart block), or increasing ectopy is seen.
- g. Chest pain with or without ECG changes is seen.
- h. Faintness, weakness, dizziness, or confusion is seen.
- Blood pressure fails to rise as body exercise stress increases.
- j. There is extreme fatigue or request by the client that the test be stopped.
- The client should be monitored at rest until the heart rate, blood pressure, and electrocardiogram are at baseline values.
- Remove the electrodes and the blood pressure cuff.
Client and Family Teaching
- Wear flat walking or tennis shoes and comfortable attire.
- According to physician preference and instructions, gradually discontinue beta-blocker drugs before the test.
- Fast from food and fluids and refrain from smoking and caffeine usage for 4 hours before the test.
- Clients may take all their medications as usual.
- During the test, immediately report to the technician any chest pain, dizziness, light-headedness, nausea, or discomfort you experience.
- After the test, rest for a few hours at home.
Factors That Affect Results
- False-positive electrocardiogram responses are caused by anemia, digitalis, diuretics, estrogen, hypertension, hypoxia, Lown-Ganong-Levine syndrome, syndrome X in women, or valvular heart disease.
- False-positive results may be caused by the following baseline ECG abnormalities:
- a. 1 mm or more elevation or depression of the ST segment
- b. Right or left ventricular hypertrophy
- c. T-wave inversions in multiple leads from an old injury
- d. Abnormal conduction, such as increased Q-T interval, ST-T changes, and right or left bundle branch blocks
- False-positive results occur more frequently in women than in men.
- False-negative tests occur when individuals with known significant CAD fail to demonstrate exercise-induced ST-segment depression.
- Conditions that may affect performance include lung disease, muscle pain, and electrolyte imbalances.
- In males, ischemic ST-segment displacement >0.1 mm of 80-msec duration during exercise but not found at rest means a five times greater risk of coronary heart disease.
- Exertional hypotension may indicate left coronary artery disease, myocardial ischemia, or left ventricular dysfunction.
- The exercise stress test may also be performed with radionuclide (thallium) or radiopharmaceutical (sestamibi) perfusion studies. See Heart scan.
- Shaw et al. (2006) found that the addition of functional capacity estimation via the Duke Activity Status Index in symptomatic females before exercise testing improved detection of clients most likely to benefit from the pharmacologic stress test (see Stress test, Pharmacologic), combined with activities to manage their specific risks for coronary heart disease.
- See also Stress test, Pharmacologic.