Physiology · Cardiac Physiology (Cycle, Output, ECG, Electrophysiology)

A patient is found to have a left ventricular end-diastolic volume of 140 mL and an end-systolic volume of 70 mL. Aortic diastolic pressure is 80 mmHg and left ventricular systolic pressure at peak is 130 mmHg. Which of the following correctly describes the pressure-volume loop of this ventricle?

  • A Stroke volume is 70 mL and ejection fraction is 50%
  • B Stroke volume is 140 mL and ejection fraction is 100%
  • C Stroke volume is 70 mL and ejection fraction is 70%
  • D Stroke volume is 70 mL and ejection fraction is 35%
Correct answer: A. Stroke volume is 70 mL and ejection fraction is 50%

Explanation

Stroke volume equals LVEDV minus LVESV: 140 − 70 = 70 mL. Ejection fraction = SV/LVEDV = 70/140 = 50%, which is the lower limit of normal. The pressure-volume loop width represents SV, while EF reflects systolic contractile efficiency; both are simultaneously described by option A.

Reference: Guyton & Hall, Textbook of Medical Physiology, 14th ed.

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