EA ratio < 1

[sot462004]

May EA ratio <1 happen in healthy people (not the old one)?
Because I think this ratio is dependent on pre-loading of the heart.

[kenkeith]

I don't believe the ratio of E to A changes.  The underlying cause for E wave being small would also effect A.  Put that parameter into a volume of blood basis from the left atrium to the left ventricle there can certainly be diminished of cardiac output.

Because E is the numerator of the ratio and has a longer time interval, it is difficult to envision any EA ratio being less than 1. For instance there can be stenosis (narrow opening) of mitral valve and that condition it seems will not change the ratio time but the volume (preload) of blood into the left ventricle can change...both A and E would be equally affected by the stenosis of the valve or left ventricle size and rigid wall abnormality. However, there could be  less resistance for the E phase, and the A phase has more resistance that would increase the LA pressure greater and less volume is moved during that phase or an abnormal increased pressure compensates (left atrium enlarges).

  E/A refers to time interval for each phase to fill the left venticle.  The time ratio wouldn't change but the volume of blood (preload) could be different.  E/A, it seems, in relation to preload, would not be dependant on pre-load, but preload would be dependant on the volume of blood going into the left ventricle during the E/A filling phases and the ratio does not change to the extent that more blood is pumped (A phase) into the LV than rec'd during "E" phase. Do you have an example where there could be a change in the A/E ratio?

Hope this provides a perspective, and if you have any follow up questions you are welcome to respond.  Thanks for the interesting question.  Take care.

[sot462004]

Thank you for your answer!
But my main purpose in this question is that: whether or not a normal person has an EA Ratio E wave is small too --> make EA ratio<1
Is it right?

[kenkeith]

Yes, preload is the issue.  "E" is the early filling of the left ventrical and entails about 70 to 75% normally without atrial contraction.  "A" arises due to atrial contraction forcing approximately 20-25% of the blood into the LV. The peaks of each is an E and  A wave.

Analysis: In diastolic dysfunction, a greater portion of end-diastolic volume results from late filling rather than early filling. Therefore, the E/A ratio is reduced in diastolic dysfunction.
The late phase "A" is dependent upon atrial contraction and is therefore absent in patients with atrial fibrillation, making the E/A ratio very large.

There are a number of factors that influence ventricular filling during each of these phases, but the main factor is the driving gradient (degree of stenosis) between the atrial and ventricular pressure.

To answer your question a lower than normal E/A ratio indicates diastolic dysfunction that can be due to LV heart walls thickened and/or chamber capacity is reduced by the enlarged chamber walls. Preload is compromised.

Thanks for your question, and if you have any further questions or comments you are welcome to respond.  Take care.