PUMPING AND OXYGENATING SYSTEMS

WERE there any conclusive evidence as to the role of the pulse in the circulation of the blood, our choice of a mechanical substitute for the heart would have to be made wholly on these grounds. However, no such evidence is available and though we must assume that the human body is adapted to a pulsatile flow, it is dear that wide variations in pulse pressure and contour are acceptable. The cardiovascular malformations of coarctation of the aorta and aortic valvular incompetence indicate that the extremes of minimum and maximum pulse amplitudes are equally well tolerated. Thus without exacting physiological criteria to satisfy, the factors underlying the choice of pump are essentially practical.