New concepts are created to clear confusion and bring clarity. We know all along low gradient AS is a hall mark of severe LV dysfunction. Now we suddenly invented normally contracting LV can also cause low gradient due to low flow when the aortic valve orifice becomes very critically narrow .
How can it occur ? . . . few suspect it to be semantics !
The terminology that is often used in recent times when describing severe aortic stenosis.This is called Low gradient severe AS with preserved LV function .
But logic would say blood flow is required to produce gradient .If it falls extremely low the gradient is likely to fall.
If that is the case every severe AS patient will experience low flow at least in few beats . Is this the reason why we find it very difficult to reproduce the exact gradient ?
Low flow ,Low gradient aortic stenosis is not a new entity .It is the way we look at the data. It remains a fact , severe AS can be diagnosed with 2D features alone , without the help of Doppler.We also know Doppler is less reliable than 2D in many situations for various reasons .The most important being it’s dependence on angle of doppler intercept and LV contractile force.
Read the argument by Nikolaus Jander from Germany
http://eurheartjsupp.oxfordjournals.org/content/10/suppl_E/E11.full.pdf+html
Dr.S.Venkatesan MD 
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