Work of the Heart
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Work and Calculations
A simple model pump can describe the heart. When the heart contracts it causes a decrease in the volume in the respective heart chamber. Increase in pressure closes the mitral valve and opens aortic valve. The example below shows the left ventricle.
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The heart muscle’s amount of work can be calculated from the force F of the muscle:
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In terms of pressure P on the surface area of the heart chamber, the work can be expressed:
The volume of the pumped blood during each compression is needed to calculate the work of the heart:
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During the compression, pressure increases from diastolic pressure P0 slowly up to systolic pressure Pm and falls rapidly back to diastolic pressure, after the hear muscle releases:
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This equation describes the pressure-volume relation in the pump; to calculate the work it has to be integrated over the volume:
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