The Linacre Lecture on the Law of the Heart Given at Cambridge, 1915

Abstract

IN this lecture Prof. Starling has embodied the main results of the researches which he has carried out during the last few years on the work of the heart. The starting point of the investigation was the introduction by Knowlton and Starling of the heart-lung preparation by means of which the output and efficiency of the heart could be accurately studied under practically normal conditions. By this method the influence of changes in arterial and venous pressure on the output and volume of the heart, its oxygen supply, and its efficiency have been gradually worked out. The evidence obtained from this many-sided research has gradually led up to general conclusions of fundamental importance, one of which gives the lecture its title, and states that “the energy of contraction” of cardiac muscle “is a function of the length of the muscle fibre.” In fact, the longer the fibres at the beginning of systole, the stronger is the force of the beat. This property of cardiac muscle, which is equally manifested by skeletal muscle, makes clear, for the first time, the real nature of the so-called “reserve power” of the heart. A rise of arterial pressure or an increase in venous inflow produces a greater diastolic volume of the heart—that is to say, an increased length of its fibres; the heart therefore contracts more forcibly, thereby maintaining its output against a high arterial pressure, or increasing its output when the venous inflow becomes larger.

The Linacre Lecture on the Law of the Heart. Given at Cambridge, 1915.

By Prof. E. H. Starling. Pp. 27. (London: Longmans, Green, and Co., 1918.) Price 1s. 6d. net.