Determinants of stroke work in the dog heart-lung preparation

¹ Department of Physiology, The Ohio State University, Columbus, Ohio

The left ventricle in a dog heart-lung preparation was subjected to slowly oscillating changes in arterial pressure load and/or end-diastolic pressure. Classical work curves were obtained when end-diastolic pressure changes were made cyclically and the arterial pressure held constant. When the arterial pressure was oscillated and the end-diastolic pressure held constant, left ventricular stroke work was found to be a function of the arterial pressure. Hence, it is shown that stroke work is a function of both the end-diastolic pressure and the arterial pressure. The performance of the heart was further examined by studying the dependence of the basic quantity stroke output on the two independent variables, arterial pressure and end-diastolic pressure. The relationship between these two independent variables and stroke power was also determined, and it was found that, at low end-diastolic pressure, arterial pressure changes had little effect on stroke power, but that at high end-diastolic pressure, the effect of arterial pressure changes became rather more marked.

Key Words: relationship between stroke work and arterial pressure • relationship between stroke power, arterial pressure and EDP • relationship between stroke output, arterial pressure and EDP

Submitted on May 27, 1963