AS: Aortic Valve Area (Hakki)

Estimate aortic valve area


The Hakki formula (with subsequent correction by Angel) relies on the ratio of peak-to-peak instantaneous gradients and thus may be non-physiologic. In mild-moderate stenosis the peak-to-peak gradient, does not reflect mean gradient however it is often close to mean gradient for severe stenosis. In general it has excellent correlation with the Gorlin equation.

The normal aortic valve area is 3-4 cm2. Symptoms tend to not be apparent until the AS is severe (<1cm2). If a patient presents with symptoms and the AVA is measured in the mild-moderate range alternative causes should be explored before attributing them to AS alone.


Oh J, Seward JB, Tajik AJ.

The Echo Manual 3rd edition. Lippincott, Williams, Wilkins. 2007

Kern MJ.

The Cardiac Catheterization Handbook 4th Edition. Mosby 2003

Hakki AH, Iskandrian AS, Bemis CE, Kimbiris D, Mintz GS, Segal BL, Brice C.

Circulation 1981, 63 (5): 1050-5

Angel J, Soler-Soler J, Anivarro I, Domingo E.

Catheterization and Cardiovascular Diagnosis 1985, 11 (2): 127-38

The AS: Aortic Valve Area (Hakki) calculator is created by QxMD.

By using this site you acknowledge that you have read, understand, and agree to be bound by our terms of use and privacy policy. All content and tools are for educational use only, are not meant to be a substitute for professional advice and should not be used for medical diagnosis and/or medical treatment.

1. Cardiac Output?

0/4 completed