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The left and right ventricles each pump the same volume of blood through the aorta and pulmonary artery.

The volume of blood pumped through each ventricle per minute can be calculated as cardiac output.

Cardiac output can be calculated using the following equation:

Units:

• CO - ml per minute (ml/min) or l per minute (l/min)
• SV - ml or l
• HR - beats per minute (bpm) (beats/min)

Stroke volume is the volume of blood pumped out of each ventricle each time the heart beats

Heart rate is the number of beats per minute and is the same as your pulse rate.

If the heart rate increases, cardiac output increases. Also if stroke volume increases, cardiac output will increase.

Calculating SV or HR

Either rearrange the above equation (SV = CO/HR or HR = CO/SV)

Or use this formula triangle to help:

Cover up what you want to find with your finger and write down what is left. This will give the correct formula. If you want SV, cover SV with your finger and you are left with CO/HR.

For example, if the stroke volume at rest is 70 ml and the heart rate is 70 bpm, then the cardiac output is 70 × 70 ml per minute = 4900 ml/min or 4.9 l/min.