Remarks on Failure of the Heart from Overstrain
Authors: None Roy, J. G. Adami
Journal: BMJ (1888)

IT has long been known that there is a connection between the work done by the heart and disease of that organ.For example, we may recall the fact that in intra-uterine life, when the right side of the heart is mainly concerned in the circulation of the blood, the valves of the right heart are more liable to disease than 1 those on the left side, while after birth the valves of the left side, which have more work to perform than the right heart, are also more frequently affected.It is known, also, that certain forms of heart disease, so- called "ooverstrain" of the heart, are due to the organ being called upon to perform more work than it is capable of com- passing without harm to one or other part of its complicated mechanism.The chief recognised cause of this form of over- strain is active or prolonged muscular exertion, which, as we know, involves a higher arterial pressure than the mean normal, and an increased supply of blood to the contracting muscles.It is, moreover, recognised that there are many other conditions besides those mentioned which throw increased work upon the heart, and which may lead to disease of the organ, such as certain forms of acute or chronic renal disease, syphilis, and, in genaeral, all those conditions in which the arterial blood-pressure is higher than normal.The diseases of the heart which result in such cases are, in some instances, chiefly evident in the valves; while in others the muscular wall of the organ is the part in which the effects of the overwork are most marked.We may mention, also, that in disease of the valves, however produced, the effect of the incompetence or stenosis is to throw more work upon the heart, so that one main result of valvular disease is to increase the work of the organ, or part of the organ.The pathology, therefore, of overwork necessarily underlies the pathology of failure of the heart from disease of its valves.lWhen, also, from any cause the muscular power of the heart is diminished, whether from imperfect blood-supply, fatty degeneration, or impaired quality of the blood, or from any of the many known causes by which the power of con- traction of the heart is impaired, we have a condition in which the relation between the work required of the organ and its power of doing that work is affected in an analogous way to that which occurs when the work of the heart is increased, and its power remains constant.These considerations induced us to make a series of experiments on the effect upon the heart of variations in the work which it is called upon to perform in conditions of health and disease.Inspeakingof thework doneby the lheart, werefer to the mechani- cal units of work done by the organ in a certain given time, and whiclh can be foundbymultiplyingthe quantity of brood thrownout by the heart by the pressure against which that blood is thrown out; that is, the two factors to be considered are-the quantity of blood expelled by the ventricles in a given time, and the arterial pressure.Thus, in investigating the relation of the work of the hleart to the effects of that work upoIn the organ, it is with these two factors that we have to deal.They can most conveniently be considered separately, and such separate consideration or investigation is, many cases, desirable, seeing that as causes of disease they do not necessarily go hand-in-hand; indeed, in cer- tain caes one of them may be exclusively active.