Clinical Resources

Hakki Simplified Valve Formula

Quick Cath Lab Valve Area Estimation

Simplified approximation of the Gorlin equation. Assumes that HR × SEP ≈ 1000/44.3 when HR is 60–100 bpm. Allows rapid valve area estimation in the cath lab with only CO and peak gradient.

e.g. 4.5
Peak-to-peak gradient from simultaneous LV–Ao pressure tracings
For accuracy check · most accurate at HR 60–100 bpm

Formula

AVA = CO / √(Peak Gradient)

Limitations

  • HR dependence: Less accurate at HR <60 or >100 bpm. Use full Gorlin formula in these cases.
  • Low flow: In low-output states, may underestimate severity. Consider dobutamine stress catheterization.
  • Peak vs. mean: Hakki uses peak-to-peak gradient (not mean gradient). Not interchangeable with echo-derived mean gradient.

Reference

Hakki AH et al. (1981) — A simplified valve formula for the calculation of stenotic cardiac valve areas. Circulation. 63(5):1050–1055.