Decrease of Venous Return Caused by Right Atrial Pulsation

Over 250 records were made in 15 dogs to show the effect of artificially induced right atrial pressure pulsations on venous return. In not a single instance did the induced pulsations increase venous return, but often it decreased venous return. On the other hand, a very slight decrease in mean right atrial pressure down to the pressure level that the veins collapse completely was shown to increase venous return markedly. These experiments indicate that the benefit to venous return which results from rhythmic cardiac or respiratory suction is caused by a decrease in mean right atrial pressure.