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Mnemonic

Pressure-Volume Loop

A memory aid for the four sides of the ventricular pressure-volume loop.

Physiology Cardiology Cardiovascular Cardiac Physiology and Pharmacology
Expansion

Filling, isovolumetric contraction, ejection, isovolumetric relaxation, traced anticlockwise

Expansion

Traced anticlockwise from the bottom right:

  1. Filling - the bottom limb, along the end-diastolic pressure-volume relationship
  2. Isovolumetric contraction - the right vertical limb, pressure rising at constant volume
  3. Ejection - the top limb, volume falling
  4. Isovolumetric relaxation - the left vertical limb, pressure falling at constant volume

Key readings:

  • Width = stroke volume
  • Area = stroke work
  • Bottom right corner = end-diastolic volume, so preload
  • Top left corner = end-systolic volume, sitting on the end-systolic pressure-volume relationship, whose slope is contractility

Changes are then predictable. Increased preload widens the loop to the right; increased afterload raises and narrows it; increased contractility steepens the end-systolic line and narrows end-systolic volume.