MEDizzy - A hospitalized patient has an ejection fraction of 0.4, a

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CARDIOVASCULAR PHYSIOLOGY

A hospitalized patient has an ejection fraction of 0.4, a heart rate of 95 beats/min, and a cardiac output of 3.5 L/min. What is the patient’s end-diastolic volume?

ExplanationFirst, calculate stroke volume from the cardiac output and heart rate: Cardiac output: stroke volume × heart rate; Thus, stroke volume: cardiac output/heart rate: 3500 mL/95 beats/min: 36.8 mL. Then, calculate end-diastolic volume from stroke volume and ejection fraction: Ejection fraction: stroke volume/end-diastolic volume; thus, end-diastolic volume: stroke volume/ejection fraction: 36.8 mL/0.4 : 92 mL.