Exercise tests in the diagnosis of coronary heart disease.

T HE DIAGNOSIS of coronary stenosis can be made easily from the history alone if typical symptoms of angina pectoris are present. When these symptoms are atypical, however, the diagnosis is more difficult. For instance, pleural or pericardial irritation, intercostal neuralgia or sternal or humeral bursitis may be aggravated by exercise, and spastic pain from the gastrointestinal tract may be also partly relieved by nitroglycerin.14 If the patient happens to know the typical subjective complaints of angina, he may consciously or unconsciously shape his own symptoms to resemble them. On the other hand, true angina may sometimes be characterized by a completely atypical localization of the pain. We know now that true anagina is caused by insufficient blood supply to the heart, and this insufficiency should also affect the heart muscle and be reflected in the electrocardiogram. If the resting electrocardiogram shows definite signs of acute coronary insufficiency, Ino further tests are needed to confirm the clinical diagnosis. If the electrocardiogram is within normal limits, however, or shows changes that can be explained by other factors than coronary stenosis, it becomes necessary to wait for a spontaneous anginal attack, or to submit the patient to the conditions that usually provoke his anginal complaints to see whether a deficiency of the coronary circulation then becomes apparent. These conditions act usually by increasing the work of the heart and its oxygen consumption until the coronary circulation, which can only increase to a limited degree because of the