cardiac output The amount of blood per minute pumped out by each of the two ventricles of the heart. A typical value in an adult at rest is 5 litres per minute. The output of each ventricle is the product of the stroke volume (about 70 ml) and the heart rate (about 70 per minute). The output increases with muscular activity, in work or exercise perhaps to a maximum of 4–5 times the resting rate in an average healthy person, or up to 6–7 times in athletes; heart rate increases by a greater factor than stroke volume.

Stuart Judge

cardiac output The volume of blood pumped per minute by each ventricle, which is also the total blood flow through the pulmonary circuit. At rest, normal human cardiac output is approximately 5 litres per minute, rising to 22 litres per minute during maximum physical exertion. The cardiac output can be calculated from heart rate (number of beats per minute) and stroke volume (volume of blood expelled from the heart per beat).