A computer-assisted system for clinical use in maximal exercise testing
The three types of diagnostic tests used in clinical evaluation are for discovery of disease, confirmation of disease, or exclusion of disease.1 Maximal exercise testing as is currently employed for detecting coronary atherosclerotic heart disease (ASHD) and evaluating patients receiving either medical or surgical treatment for coronary artery disease can be classified as a discovery test. Although graded exercise testing falls short of perfection in the process of differentiating between normal subjects and ASHD patients, the test is clinically useful in the discovery process both for asymptomatic patients and for those in whom there is a suspicion of ASHD based on the clinical history, physical examination, or interpretation of the resting electrocardiogram.2–11 In addition, quantitative exercise testing is used with increasing frequency for the serial evaluation of patients before and after myocardial revascularization.12–16 In the past 11 years a variety of technological improvements have resulted in increased sensitivity and specificity for exercise testing in patients with ASHD.17–24
This paper describes an on-line, real-time minicomputer-based maximal stress testing system. Technical solutions for improved signal quality, signal analysis, and clinical reporting are described.
Multiple lead electrocardiography
Multiple lead exercise electrocardiograms increase the yield of positive tests when compared to single lead systems.7, 18, 19, 21 Nevertheless, most patients who have abnormalities in cardiac repolarization during exercise have these changes in a lead similar to V5.18,19 By recording the Frank lead Orthogonal electrocardiogram and a bipolar precordial lead (CM5), the spatial and proximity chest lead S-T segment changes are obtained.