For the body to function properly, the heart needs to pump blood at a sufficient rate to maintain an adequate and continuous supply of oxygen and other nutrients to the brain and other vital organs. Cardiac output is the term that describes the amount of blood your heart pumps each minute. Doctors think about cardiac output in terms of the following equation:
Cardiac output = stroke volume × heart rate
Your stroke volume is the amount of blood your heart pumps each time it beats, and your heart rate is the number of times your heart beats per minute.
What is a normal cardiac output?
A healthy heart with a normal cardiac output pumps about 5 to 6 litres of blood every minute when a person is resting.
When does the body need a higher cardiac output?
During exercise, your body may need three or four times your normal cardiac output, because your muscles need more oxygen when you exert yourself. During exercise, your heart typically beats faster so that more blood gets out to your body. Your heart can also increase its stroke volume by pumping more forcefully or increasing the amount of blood that fills the left ventricle before it pumps. Generally speaking, your heart beats both faster and stronger to increase cardiac output during exercise.
Why is maintaining cardiac output so important?
Sufficient cardiac output helps keep blood pressure at the levels needed to supply oxygen-rich blood to your brain and other vital organs.
Other Works Consulted
- Hoit BD, Walsh RA (2011). Normal physiology of the cardiovascular system. In V Fuster et al., eds., Hurst's The Heart, 13th ed., vol. 1, pp. 94–117. New York: McGraw-Hill.
Current as ofJuly 22, 2018
Author: Healthwise Staff
Medical Review: Rakesh K. Pai, MD - Cardiology, Electrophysiology
Anne C. Poinier, MD - Internal Medicine
Martin J. Gabica, MD - Family Medicine
Adam Husney, MD - Family Medicine
Stephen Fort, MD, MRCP, FRCPC - Interventional Cardiology