The percentage of blood pumped out of the left ventricle with each beat is known as what?

• A. Stroke Volume
• B. End Systolic Volume
• C. Ejection fraction
• D. Cardiac Output

Answer: (C)

The concept being tested is ejection fraction. It’s the percentage of blood in the left ventricle that is pumped out with each beat. It’s calculated by dividing the stroke volume (the amount ejected per beat) by the end-diastolic volume (the total filled volume before contraction) and multiplying by 100. This tells you how effectively the ventricle empties during systole. Normal values are about 55–70%. A lower value indicates reduced systolic function. Cardiac output, by contrast, is the amount of blood pumped per minute (heart rate × stroke volume); stroke volume is an absolute volume, not a percentage, and end-systolic volume is the volume remaining after contraction.