Exercise testing. Procedures and implementation.
Although important strides have been made in related procedures, exercise ECG remains an invaluable tool in the initial assessment of coronary disease and yields a great deal of prognostic information. Access to limited health care resources often hinges on its outcome. Proper methodology is critical to patient safety and to obtain accurate results. The importance of patient education, physician interaction with the patient, skin preparation, and criteria for exclusion and termination cannot be overemphasized. A brief physical examination and 12-lead ECG in both the supine and standing positions should precede exercise testing. Few studies have correctly evaluated the relative yield or sensitivity and specificity of different electrode placements for exercise-induced shifts in the ST segment. The use of other leads in addition to V5 increases test sensitivity, but the specificity may be reduced. ST-segment changes isolated to the inferior leads are frequently false-positive responses. Vectorcardiographic and body surface mapping lead systems do not appear to offer any advantage over simpler approaches for clinical purposes. Changes caused by exercise electrode placement can be kept to a minimum by placing arm electrodes on the shoulders, off of the chest. The exercise protocol should be progressive, with even increments in speed and grade whenever possible. Smaller, even, and more frequent work increments are preferable to larger, uneven, and less frequent increases, because the former yield a more accurate estimation of exercise capacity. The value of individualizing the exercise protocol rather than using the same protocol for every patient has recently been emphasized by many investigators. The optimal test duration is from 8 to 12 minutes, and the protocol workloads should be adjusted to permit this duration. Because ramp testing uses small increments, it permits a more accurate estimation of exercise capacity and can be individualized for every patient to yield a targeted test duration. Target heart rates based on age should not be used because the relationship between maximal heart rate and age is poor and varies greatly. The Borg scale is a useful means of quantifying an individual's effort. Exercise capacity should not be reported in total time but rather as the VO2 or MET equivalent of the workload achieved. This permits comparison of the results between many different exercise testing protocols. Gas-exchange techniques can greatly supplement exercise testing by adding precision and reproducibility and increase the yield of information concerning cardiopulmonary function. Estimating work from treadmill or cycle ergometer workload introduces a great deal of error and variability.(ABSTRACT TRUNCATED AT 400 WORDS)
Cardiology Section, Veterans Affairs Medical Center, Palo Alto, CA 94304.
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Myers
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Froelicher
D000075202:Contraindications; D003327:Coronary Disease / Q000534:rehabilitation*; D004562:Electrocardiography / Q000295:instrumentation; D005080:Exercise Test / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D009203:Myocardial Infarction / Q000534:rehabilitation*; D010100:Oxygen / Q000502:physiology; D010147:Pain Measurement; D012815:Signal Processing, Computer-Assisted
D010100:Oxygen