The Cardiovascular
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Aortic valve area (continuity equation)

Aortic valve area (continuity equation)
LVOT diameter
LVOT VTI
cm
Aortic valve VTI
cm
Body surface area (optional)
m²
Complete the fields above to see the result.

When to use

  • Grading aortic stenosis severity, especially when transvalvular gradients may be misleading (low flow, low ejection fraction, or high output).

Formula

AVA = (LVOT CSA × LVOT VTI) / AV VTI, where LVOT CSA = π × (LVOT diameter / 2)².

Pearls and pitfalls

  • The dimensionless index avoids LVOT diameter measurement altogether and is useful when the LVOT cannot be measured reliably.
  • In low-flow low-gradient aortic stenosis with reduced ejection fraction, dobutamine stress echocardiography distinguishes true-severe from pseudo-severe stenosis.

References

  1. Baumgartner H, et al. Recommendations on the Echocardiographic Assessment of Aortic Valve Stenosis: A Focused Update. J Am Soc Echocardiogr. 2017;30(4):372–92.