Clinical Exercise Testing

1. Clinical Exercise Testing

2. Indications and Purposes The exercise test may be used for Diagnostic (identify abnormal physiologic responses), Prognostic (identify adverse events), and Therapeutic (gauge impact of a given intervention) purposes as well as for physical activity counseling and to design an exercise prescription.

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4. Diagnostic Exercise Testing (cont.) • Patients with a high probability of disease (e.g., typical angina, prior coronary revascularization, myocardial infarction) are tested • to assess residual myocardial ischemia, • to assess threatening ventricular arrhythmias, and • for prognosis rather than for diagnostic purposes.

5. Exercise Testing for Disease Severity and Prognosis • The magnitude of ischemia caused by a coronary lesion generally is • directly proportional to the degree of ST-segment depression, the number of ECG leads involved, and the duration of ST-segment depression in recovery; and • inversely proportional to the ST slope, the rate pressure product (RPP) at which the ST-segment depression occurs, and the heart rate maximum, SBP, and metabolic equivalents achieved.

6. Exercise Testing AfterMyocardial Infarction • Exercise testing after myocardial infarction can be performed • before or soon after hospital discharge for prognostic assessment, • for exercise prescription, • for evaluation of further medical therapy, and • for interventions including coronary revascularization.

7. Exercise Testing AfterMyocardial Infarction (cont.) • Submaximal exercise testing provides sufficient data to assess the effectiveness of current pharmacologic management as well as activities of daily living and early ambulatory exercise therapy recommendations. • Symptom-limited graded exercise tests are considered safe and appropriate early after discharge (~14–21 d) for exercise prescription and physical activity counseling and further assessment of pharmacologic management efficacy.

8. Functional Exercise Testing Functional exercise testing is valuable for • physical activity counseling, • exercise prescription, • disability assessment, • helping to estimate prognosis, and • return to work evaluation (if occupation requires aerobic activity).

9. FIGURE 5.2. Nomograms of percent normal exercise capacity in men with suspected coronary artery disease who were referred for clinical exercise testing and in apparently healthy men and women. METs, metabolic equivalents. Reprinted with permission from (51) and (28). (continued) 28. Gulati M, Black HR, Shaw LJ, et al. The prognostic value of a nomogram for exercise capacity in women. N Engl J Med. 2005;353(5):468–75. 51. Morris CK, Myers J, Froelicher VF, Kawaguchi T, Ueshima K, Hideg A. Nomogram based on metabolic equivalents and age for assessing aerobic exercise capacity in men. J Am Coll Cardiol. 1993;22(1):175–82.

10. FIGURE 5.2. (continued) Nomograms of percent normal exercise capacity in men with suspected coronary artery disease who were referred for clinical exercise testing and in apparently healthy men and women. METs, metabolic equivalents. Reprinted with permission from (51) and (28).

11. FIGURE 5.2. (continued) Nomograms of percent normal exercise capacity in men with suspected coronary artery disease who were referred for clinical exercise testing and in apparently healthy men and women. METs, metabolic equivalents. Reprinted with permission from (51) and (28).

12. Exercise Test Modalities • The treadmill is the most common exercise testing mode. • Treadmills in clinical exercise laboratories should be electronically driven, allow for a wide range of speed (1–8 mph or 1.61–12.8 km ∙ h−1) and grade (0%–20%), and be able to support a body weight of at least 350 lb (159.1 kg).

13. Exercise Test Modalities (cont.) • The treadmill should have handrails for balance and stability; but given the negative impact tight gripping of the handrails can have on both the accuracy of estimated exercise capacity (estimated VO2peak with handrail gripping is greater than measured VO2peak) and the quality of the ECG recording, handrail use should be discouraged or minimized to the lowest level possible when maintaining balance is a concern. • An emergency stop button should be readily visible and available to both the subject undergoing testing and supervising staff . . .

14. Exercise Test Modalities (cont.) • Cycle ergometers are the most common exercise testing modes used in many European countries. • Cycle ergometry is less expensive and requires less space than treadmill testing and is a viable alternative to treadmill testing in individuals with obesity and those who have orthopedic, peripheral vascular, and/or neurologic limitations. • The cycle ergometer must include handlebars and an adjustable seat, allowing for the knee to be flexed ~25 degrees of full extension in a given subject.

15. Exercise Test Modalities (cont.) • Incremental work rates on an electronically braked cycle ergometer are more sensitive than mechanically braked ergometers because the work rate can be maintained over a wide range of pedal rates. • Because there is less movement of the patient’s arms and thorax during cycling, it is easier to obtain better quality ECG recordings and blood pressure measurements.

16. Exercise Test Modalities (cont.) • However, stationary cycling is an unfamiliar method of exercise for many and is highly dependent on patient motivation. • The test may end prematurely (i.e., because of localized leg fatigue) before a cardiopulmonary endpoint has been achieved. • Lower values for maximal oxygen consumption during cycle ergometer testing (vs. treadmill testing) can range from 5% to 25%, depending on the participant’s habitual activity, physical conditioning, leg strength, and familiarity with cycling.

17. Exercise Test Modalities (cont.) • Arm ergometry is an alternative method of exercise testing for patients who cannot perform leg exercise. • Because a smaller muscle mass is used during arm ergometry, maximal oxygen consumption during arm exercise is generally 20%–30% lower than that obtained during treadmill testing. • Although this test has diagnostic use, it has been largely replaced by the nonexercise pharmacologic stress techniques that are described later in this chapter.

18. Exercise Test Modalities (cont.) • Arm ergometer tests can be used for physical activity counseling and exercise prescription for certain disabled populations (e.g., spinal cord injury). • Arm ergometer test can be used by individuals who perform primarily dynamic upper body work during occupational or leisure time activities.

19. Exercise Protocols • The protocol employed during an exercise test should consider • the purpose of the evaluation, • the specific outcomes desired, and • the characteristics of the individual being tested (e.g., age, symptomatology).

20. Exercise Protocols (cont.) • Most common exercise test protocols • Bruce • Ellestad • Naughton • Balke-Ware • Ramp

21. Exercise Protocols (cont.) • Advantages of the ramp approach include • avoidance of large and unequal increments in workload, • uniform increase in hemodynamic and physiologic responses, • more accurate estimates of exercise capacity and ventilatory threshold, • individualized test protocol (ramp rate), and • targeted test duration (individualized ramp protocols).

22. Measurements During Exercise Testing • Common variables assessed during clinical exercise testing include • heart rate • ECG changes, • blood pressure, • subjective ratings, • signs and symptoms, and • expired gases and ventilatory responses.

23. 16. Brubaker PH, Kaminsky LA, Whaley MH. Coronary Artery Disease: Essentials of Prevention and Rehabilitation Programs. Champaign (IL): Human Kinetics; 2002. 364 p.

24. Heart Rate and Blood Pressure (cont.) • Heart rate and blood pressure responses should be measured before, during, and after the GXT. • A standardized procedure should be adopted for each laboratory so that baseline measures can be assessed more accurately when repeat testing is performed.

25. Potential Sources of Error in Blood Pressure Assessment • Inaccurate sphygmomanometer • Improper cuff size • Auditory acuity of technician • Rate of inflation or deflation of cuff pressure • Experience of technician • Reaction time of technician • Faulty equipment • Improper stethoscope placement or pressure • Background noise • Allowing patient to hold treadmill handrails or flex elbow • Certain physiologic abnormalities (e.g., damaged brachial artery, subclavian steal syndrome, arteriovenous fistula)

26. Subjective Ratings and Symptoms • The measurement of perceptual responses during exercise testing can provide useful clinical information. • Somatic ratings of perceived exertion (RPE) (see Chapters 4,7, and 10) and/or specific symptomatic complaints include • degree of chest pain, burning, and discomfort; • dyspnea; • light-headedness; and • leg discomfort/pain.

27. Frequently used scales for assessing the patient’s level of angina (top), claudication (middle), and dyspnea (bottom).

28. Gas Exchange and Ventilatory Responses • Currently, the combination of standard GXT procedures and ventilatory expired gas analysis (cardiopulmonary exercise testing) is the clinical standard for patients with CHF being assessed for transplantation candidacy and individuals with unexplained exertional dyspnea. • The direct measurement of oxygen uptake is more reliable and reproducible than estimated values from treadmill or cycle ergometer work rates.

29. Arterial Blood Gas Assessment During Exercise • In patients who present with unexplained exertional dyspnea, pulmonary disease should be considered as a potential underlying cause. • It is important to quantify gas partial pressures in these patients because oxygen desaturation may occur during exertion.

30. Indications for Terminating Exercise Testing ABSOLUTE INDICATIONS • Drop in systolic BP of ≥10 mm Hg with an increase in work rate, or if systolic BP decreases below the value obtained in the same position prior to testing when accompanied by other evidence of ischemia • Moderately severe angina (defined as 3 on standard scale) • Increasing nervous system symptoms (e.g., ataxia, dizziness, or near syncope) • Signs of poor perfusion (cyanosis or pallor) • Technical difficulties monitoring the ECG or SBP • Subject’s desire to stop • Sustained ventricular tachycardia • ST elevation (+1.0 mm) in leads without diagnostic Q waves (other than V1 or aVR)

31. (cont.) Indications for Terminating Exercise Testing RELATIVE INDICATIONS • Drop in systolic BP of ≥10 mm Hg with an increase in work rate, or if systolic BP below the value obtained in the same position prior to testing • ST or QRS changes such as excessive ST depression (>2 mm horizontal or downsloping ST-segment depression) or marked axis shift • Arrhythmias other than sustained ventricular tachycardia, including multifocal PVCs, triplets of PVCs, supraventricular tachycardia, heart block, or bradyarrhythmias • Fatigue, shortness of breath, wheezing, leg cramps, or claudication • Development of bundle-branch block or intraventricular conduction delay that cannot be distinguished from ventricular tachycardia • Increasing chest pain • Hypertensive response (SBP of >250 mm Hg and/or a DBP of >115 mm Hg). aVR, augmented voltage right; BP, blood pressure; DBP, diastolic blood pressure; ECG, electrocardiogram; PVC, premature ventricular contraction; SBP, systolic blood pressure; V1, chest lead I. Reprinted with permission from (25). 25. Gibbons RJ, Balady GJ, Bricker JT, et al. Committee to Update the 1997 Exercise Testing Guidelines. ACC/AHA 2002 guideline update for exercise testing: summary article. A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee to Update the 1997 Exercise Testing Guidelines). J Am Coll Cardiol. 2002;40(8):1531–40.

32. Postexercise Period • Regardless of the postexercise procedures (active vs. passive recovery), monitoring should continue for at least 6 min after exercise or until ECG changes return to baseline and significant signs and symptoms resolve. • ST-segment changes that occur only during the postexercise period are currently recognized to be an important diagnostic part of the test.

33. Postexercise Period (cont.) • HR and BP should also return to near baseline levels before discontinuation of monitoring. • The HR recovery from exercise is an important prognostic marker that should be recorded (see Chapter 6).

34. Imaging Modalities • Exercise echocardiography • Cardiac radionuclide imaging • Pharmacologic stress testing • Computed tomography

35. The ACSM Clinical Exercise Testing Key Points are as follows: • Although a clinical exercise test may not be indicated for most individuals about to begin an exercise program (see Chapter 2), the high value of information obtained from this procedure is not debatable. • Aerobic capacity may be one of the single best prognostic markers in all individuals regardless of health status. • Standard clinical exercise testing is well accepted for the assessment of individuals with signs and/or symptoms suggestive of CVD. • The use of cardiopulmonary exercise testing, which combines standard clinical exercise testing with simultaneous ventilatory expired gas analysis, is common practice in patients with CHF as well as those with unexplained exertional dyspnea. • The recent recognition that appropriately trained nonphysician personnel can safely perform a clinical exercise test may result in the expanded use of this valuable procedure in various clinical settings.