The life and times of Donald A. McDonald

Donald A. McDonald (1917-1973) was a pioneer in hemodynamics. He was Oxford educated and served on the faculty of Universities in both Great Britain and the USA. The problems that were the main theme of his text Blood Flow in Arteries published in 1960 were those concerned with pulsatile blood flow and the associated pulsatile pressure changes. At that time pulsatile flow of liquids had received little attention from scientists compared with the tremendous volume of work on steady flow. Quite apart from the far from easy solution of the characteristics of pulsatile flow in elastic tubes, the circulation of blood in animal arteries adds other problems. For example, the flow-ejection pattern of the heart is complex and the elastic properties of the arteries are non-linear. To analyze such a system it is necessary to simplify. This simplification can either take the form of an analogue model to represent the behavior of the whole circulation or to analyze individual sections of the circulation and attempt to build up a synthesis of the whole from component parts. Of the analogues that had been used previously the “Windkessel” completely dominated the field. The alternative approach of building from the investigation of single regions began, in McDonald's case, experimentally with the measurement of pulsatile flow in arteries at the beginning of 1950, but only developed physical and mathematical direction with the collaboration of J.R. Womersley in 1953. The first step was the measurement of pulsatile blood flow in the basilar artery. From his observations here he was led to the consideration of pulsatile flow conditions in arteries in general, and within a few years McDonald, and the collaborators he attracted, had virtually transformed the subject. The core of his approach was the use of Fourier methods to describe arterial events as steady-state oscillations. This approach has since been followed by researchers throughout the world with enormously fruitful results.