The Relative Importance of the Performance of Work and the Initial Fiber Length in Determining the Magnitude of Energy Liberation in the Heart

Contractile Element Work: A Major Determinant of Myocardial Oxygen Consumption*

“…Thirty-four studies were carried out in 23 mongrel dogs weighing from 13 to 24 kg, anesthetized with either sodium pentobarbital, 25 mg per kg, with or without morphine sulfate premedication, 3 mg per kg, or chloralose, 50 to 70 mg per kg, with morphine sulfate premedication. The details of the experimental design have been presented in the preceding paper (15).…”

“…In 1927 Starling and Visscher proposed that the energy requirement of the heart was determined by its initial fiber length (1), and this observation was confirmed by others (2,3). Rhode, on the other hand, stated that only ventricular pressure and heart rate determined the oxygen consumption of the heart (4).…”

“…Rhode, on the other hand, stated that only ventricular pressure and heart rate determined the oxygen consumption of the heart (4). In an effort to resolve the importance of both fiber length and pressure generated, stroke work was examined but found by a number of workers to correlate poorly with oxygen consumption (1)(2)(3)(5)(6)(7)(8). As early as 1915, Evans and Matsuoka suggested that myocardial wall tension may be the major determinant of myocardial oxygen consumption (5).…”

The energy liberation at constant diastolic fibre length in the tortoise heart with particular reference to the effect of the emptying pressure

“…It should be noted that Stella's results were obtained with the tortoise ventricle, whereas those of Starling & Visscher were with the dog's heart in the heart-lung preparation. Several investigators have confirmed the Starling & Visscher results in the mammalian heart [Hemingway & Fee, 1927; Gremels, 1933;Peters & Visscher, 1936] and in the amphibian [Clark & White, 1928Eismayer & Quincke, 1930;Decherd & Visscher, 1933, 1934. According to Stella, all other investigators worked over a limited range of pressures and, therefore, failed to observe the relation he described.…”

News from the American Heart Association

“…At the high cardiac output, stroke volume was 44.1 ml, stroke work was 36. 5 fig. 5), mean aortic pressure was 100 mm Hg, stroke volume 33.4 ml, stroke work 39.1 gram-meters, TTI 3500 mm Hg see/min and MVo, was 19.6 ml/min.…”