Cardiac Cycle and Hemodynamics · USMLE Step 1

What happens to ejection fraction (EF) if end-systolic volume (ESV) increases but end-diastolic volume (EDV) remains constant?

  1. EF increases
  2. EF decreases
  3. EF remains unchanged
  4. EF becomes greater than 100%
Show answer and explanation

Correct answer: EF decreases

Ejection fraction is defined as SV/EDV, i.e., (EDV – ESV)/EDV. If ESV increases while EDV is unchanged, SV decreases, so EF decreases.

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