It is well established that cardiac output is increased in the presence of an arteriovenous fistula. The amount of increase in cardiac output in proportion to the volume flow through such a fistulous communication has not been elucidated. A widely accepted view is that only a portion of the demand for fistula flow is met by an increase in cardiac output and that the remainder results from diversion of blood from other parts of the body to the fistula.7
The first objective of the present study was to quantitate the relationship between total fistula flow and increased cardiac output in chronic experimental fistula.
The second objective was to show, if possible, the effects of posture variation upon the flow through arteriovenous fistulas. In reference to this problem Shumacker6 states: "It was clear that the incidence and degree of cardiac enlargement or the rapidity with which enlargement took place