U01.21.023 Ejection Fraction (EF)

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Learning Objective:
Understand and apply the formula for ejection fraction (EF), which measures the percentage of blood ejected from the ventricle during each contraction.

Formulas:

EF = \frac{SV}{EDV}

or equivalently

EF = \frac{EDV - ESV}{EDV}

Explanation:

  • SV = Stroke Volume = blood pumped per beat
  • EDV = End-Diastolic Volume = total blood in ventricle before contraction
  • ESV = End-Systolic Volume = blood remaining after contraction
  • EF indicates systolic function — how efficiently the ventricle empties.

Normal Values:

  • Normal EF: > 55%
  • Reduced EF: < 40% → suggests systolic heart failure
  • Preserved EF: normal EF with signs of failure → diastolic dysfunction

Example:

Given:
EDV = 120 \text{ mL}
ESV = 50 \text{ mL}

EF = \frac{120 - 50}{120} = \frac{70}{120} = 0.583

✅ Answer: EF = 58.3%

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