The Stroke Work calculator computes work done by the ventricle to eject a volume of blood into the aorta.
INSTRUCTIONS: Choose units and enter the following:
- (PAL) Afterload Pressure
- (SV) Stoke Volume
- (m) Mass
- (v) Volume
Stroke Work (SW): The calculator returns the value as mmHg·L.
The Math / Science
Stroke Volume he volume of blood pumped from one ventricle of the heart with each beat. The formula for stroke work is:
SW = PAL ⋅ SV + 0.5 ⋅ m ⋅ v2
where:
- SW = stroke work
- PAL = Afterload Pressure
- SV = Stroke Volume
- m = mass
- v = velocity
Stroke work (SW) refers to the work done by the ventricle to eject a volume of blood (i.e., stroke volume) into the aorta. The force that is applied to the volume of blood is the intraventricular pressure. Therefore, ventricular stroke work can be estimated as the product of stroke volume and mean aortic pressure during ejection. The use of aortic pressure instead of intraventricular pressure assumes that kinetic energy is negligible, which is generally true at resting cardiac outputs. Sometimes this is simplified to stroke volume (SV) times mean aortic pressure (MAP), although this will further underestimate the stroke work.
Systolic and Diastolic Volume
End Diastolic Volume (EDV) is the volume of the ventricle before the heart contracts. End Systolic Volume (ESV) is the ventricle volume after blood has been ejected from the heart.
The typical end diastolic volume for a the average male is 120 milliliters of blood, and 50 milliliters of end-systolic blood.
