The Role of Anaerobic Metabolism in the Performance of Mild Muscular Work. II. The Effect of Asymptomatic Heart Disease1

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Abstract
Patients with clinical evidence of heart disease but no symptoms of congestive heart failure have an adequate response of the O2 transport system during mild exercise so that body tissues are forced to rely on anaerobic metabolism to only a very small extent. Patients with atrioventricular valvular deformities may have an inadequate response of cardiac output before any other measurable physiologic change occurs, and this may appear and grow worse for at least 4 years before clinical cardiac insufficiency appears. By contrast, patients who have had semilunar valvular deformities or essential hypertension for years, even with evidence of myocardial deterioration, usually have an adequate cardiac output response unless full blown congestive heart failure is present. Changes in cardiac output and arteriovenous O2 difference are not reliable indications in themselves of normal or adequate cardiac responses.