Cardiac Output

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Cardiac Output

Topic Overview

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. The heart pumps about 75 mL each time it beats, and it beats an average of 70 times each minute.

  • Cardiac output = stroke volume × heart rate
  • Cardiac output = 75 mL × 70 beats per minute
  • Cardiac output = 5.3 litres per minute

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 maintain blood pressure at the levels needed to supply oxygen-rich blood to your brain and other vital organs.

Related Information

Credits

By Healthwise Staff
Primary Medical Reviewer E. Gregory Thompson, MD - Internal Medicine
Primary Medical Reviewer Brian D. O'Brien, MD - Internal Medicine
Specialist Medical Reviewer Robert A. Kloner, MD, PhD - Cardiology
Last Revised October 14, 2010

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