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.
Robert O Bonow, Blase A Carabello et al.
Oh J, Seward JB, Tajik AJ.
Hakki AH, Iskandrian AS, Bemis CE, Kimbiris D, Mintz GS, Segal BL, Brice C.
Angel J, Soler-Soler J, Anivarro I, Domingo E.