The flow of blood back to the heart is called venous return. Normally, venous return equals cardiac output (volume of blood pumped by a ventricle in one minute) when averaged over time. Increased venous return increases cardiac output. The pressure difference between the venous pressure and right atrial pressure determines the venous return (VR). Higher the venous pressure and lower the right atrial pressure, higher the venous return. Factors affecting venous return: a. Rhythmical contraction and relaxation of leg muscles during its movement propels the blood in the vein back to the heart and increases venous return. Valves in the veins permit unidirectional flow of blood by preventing backflow. b. Increasing the rate and depth of respiration encourages venous return. Inspiration causes a fall in the pressure within the chest and rise in the pressure within the abdominal cavity. These pressure changes help push venous blood back to the heart. c. Changes in muscle tone of veins – increased tone increases venous return. d. Changes in pressure in the tissue surrounding the veins
