Fiona Grace Peterson Aug 2, 2018:

area fractions This may be it - unfortunately I don't have time to research further.

https://pdfs.semanticscholar.org/2acd/0bc5fca3f7eac59681eb9d...

Indexes of diastolic function were measured from the systemic atrioventricular valve inflow Doppler and included peak E and A velocities, peak filling rate normalized for stroke volume, the fractions of filling in early and late diastole (E and A area fractions), and the E/A velocity and area ratio.

https://www.ncbi.nlm.nih.gov/pubmed/1951081

pennylyd (asker) Jul 31, 2018:

Yes that was my general idea too - I found a similar article classifying AVA (aortic valve area) < 1.0 cm2 as severe aortic stenosis. I just couldn't understand the 'fx' -

Marina Della torre Jul 31, 2018:

To Marco:
Great!

Marco Solinas Jul 31, 2018:

To: Asker By reading this article: https://myheart.net/articles/aortic-stenosis-a-tight-aortic-... (which gives a very clear destcription of aortic stenosis), I have convinced myself that your "area fx" is the area of the opening of the aortic valve (less than 1 cm2 in severe cases). As to the exact meaning of "area fx", "free cross-sectional area" comes to mind. However, it is just a guess on my part.