Current statistics demonstrate that almost any person may be suffering from some degree of hypertension or arteriosclerosis, and that if he enjoys an extended life span, he is likely to sustain a "heart attack" from which his chance of dying is great. Cardiovascular disease has, therefore, become an incident of modern living, and cardiovascular injuries are one of the most controversial areas of liability in the field of workmen's compensation. The conflict concerning heart cases, and especially those related to the "stress incurred," arises primarily from the difficulty of proving causation. The confusion arising from conflicting judicial construction of terms such as "usual strain," "unusual strain," "exceptional strain," is compounded by the conflicting expert medical testimony presented in these cases. Beyond these inconsistencies in both the medical and legal literature, there is the basic conflict between medical and legal concepts of causation. The descriptive phrase, "stress and strain," as applied to the exertion allegedly causing the cardiovascular crisis involved in a particular case may aptly be applied to the incompatibility between legal principles and the opinions of medical experts.
Chester M. Denwicz, Stress-Caused Heart Attacks, 14 Clev.-Marshall L. Rev. 322 (1965)