Stressful experience and cardiorespiratory disorders. Ever since Selye's time, the belief has persisted that the outcome of stressful experience is disease. The likelihood of this eventuality is increased when the experience is damaging, unavoidable, or uncontrollable. However, in most stressful instances, these conditions do not occur. The experience either is overcome or produces disturbances in physiological functions without structural change. The prevalence of "functional" disorders are far more common in medical practice than is disease. Among the most interesting of these is the hyperventilation syndrome, which may mimic or be confused with ischemic heart disease. Its symptomatology and physiology are complex. The syndrome may produce coronary vasospasm, but it may also complicate ischemic heart disease. It is even believed that chronic hyperventilation may be a risk factor for ischemic heart disease. Stressful experience consisting of various tasks and challenges may also produce myocardial perfusion deficits in ischemic heart disease, presumably secondary to vasospasm. These deficits are in turn considerably more frequent in any one patient than ST segment changes in the electrocardiogram or the incidence of angina pectoris. Vasospasm is in turn related to cardiac arrhythmias, which may occur with ischemic heart disease during a variety of stressful experiences and during outbursts of anger. Finally, the role of stressful experience in inciting ischemic heart disease and its complications remains moot. 