End-systolic volume
Also known as: ESV
End-systolic volume (ESV) is the amount of blood remaining in a ventricle at the end of contraction, roughly 50 mL in a healthy adult left ventricle. It is the low point of ventricular volume and a key input to stroke volume and ejection fraction.
End-systolic volume (ESV) is the blood left in a ventricle at the end of systole, after the heart has finished contracting and ejecting blood. The ventricle never empties completely — in a healthy adult left ventricle, roughly 50 mL remains, compared with an end-diastolic volume (EDV) of about 120 mL after filling.
ESV anchors the two workhorse equations of cardiac physiology. Stroke volume is the difference between filling and residual volume: SV = EDV − ESV, or about 120 − 50 = 70 mL per beat. Ejection fraction is the proportion of the filled volume actually pumped out: EF = SV ÷ EDV, normally in the 55–70% range. Any change in ESV directly changes both.
Two main factors move ESV. Increased afterload — the pressure the ventricle must overcome to eject, as in hypertension or aortic stenosis — leaves more blood behind, raising ESV. Decreased contractility, as in systolic heart failure or dilated cardiomyopathy, does the same: the weakened ventricle ejects less, ESV climbs, and ejection fraction falls. Conversely, positive inotropes and reduced afterload lower ESV and boost stroke volume.
The USMLE Step 1 tests ESV throughout its cardiovascular physiology and pathology material — expect to compute stroke volume and ejection fraction from given volumes, and to predict how afterload changes, inotropic drugs, and cardiomyopathies shift ESV on pressure-volume loops.
Key takeaways
- ESV is the blood remaining in the ventricle at the end of contraction — about 50 mL in a healthy left ventricle.
- Stroke volume = EDV − ESV; ejection fraction = SV ÷ EDV (normally about 55–70%).
- Increased afterload or decreased contractility raises ESV and lowers stroke volume.
- In systolic heart failure and dilated cardiomyopathy, a rising ESV drives the falling ejection fraction.
- USMLE Step 1 tests ESV in stroke volume calculations and pressure-volume loop questions.