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Posts Tagged ‘LA volume by mri’

What is the relationship between Left atrial size and mitral “E” decceleration time ?

Posted in Uncategorized, tagged , , , , , , , , , , , , , , , on March 29, 2025|

I saw two patients recently, with a similar degree of hypertension and LVH. One with a normal-sized LA and the other with a mild LA enlargement.

When checked for the “E” declaration time, it was found to be absolutely normal in the patient who had LAE. The one with normal LA size had a relatively short DT and his functional capacity was less.

52-year-old man with HT, and LVH with mild LAE. His E DT was very much normal a1 178 ms. He has a good functional capacity. I expected a grade 2 diastolic dysfunction. But, none of the other parameters were convincing. Used to think, if LA is enlarged, it must be a little advanced form of diastolic dysfunction. Though It is still true in many, but, this case, demand us to dwell into these two important parameters of LV diastolic function.

What is the relationship between Left atrial size and Mitral “E” decceleration time ?

The conventional and straightforward answer is they are inversely related.

We know Left atrial size typically reflects the chronicity of elevated left atrial pressure or volume overload, which can result from conditions such as mitral valve disease, left ventricular dysfunction, or atrial fibrillation. An enlarged LA is often a marker of prolonged stress on the atrium due to increased filling pressures or impaired left ventricular relaxation.

Mitral E velocity deceleration time (DT) is a measure derived from Doppler echocardiography, representing the time it takes for the early diastolic filling velocity (E wave) to decline from its peak to baseline.

In healthy individuals with normal LA size and normal diastolic function, DT is typically within a normal range (e.g., 160–240 ms), and LA size does not significantly influence DT. In pathological states, an enlarged LA (e.g., LA volume index >34 mL/m²) combined with a shortened DT (<160 ms) indicate restrictive physiology or advanced diastolic dysfunction.

Question 2

Is this Inverse relation always right ?

There is generally an inverse relationship between LA size and mitral E velocity DT in the context of diastolic dysfunction with elevated LA pressure. LA size increases due to pressure overload, DT tends to decrease. However, the exact relationship is much more complex. If LA enlargement is due to volume overload (e.g., chronic mitral regurgitation) without significantly elevated pressure, DT may not shorten dramatically.

If the LA is stiff and non-compliant, the E deceleration time is likely to be short, and an inverse relation is acceptable logic. But, if the LA is more accommodative and relaxed, mild enlargement actually reduces the LA mean pressure, and E deceleration gets normalized even if it was prolonged earlier due to diastolic dysfunction.

LA behaviour is still a mystery X factor in diastolic dysfunction.

This throws up a fundamental question in our understanding of diastolic dysfunction. Some degree of LA flexibility and compliance reduces the LA mean pressure, and could relieve the symptoms. In this process, the mitral DT also is kept within the normal limits. In fact, now I have asked my fellows to analyze a concept of normalization of DT with progressive LA dilatation in hypertensive patients. This is contrary to the belief that LA dilatation is an ominous sign.

I think it is worth propsoing and pursuing a new concept.” LA dimension has a U curve phenomenon at least within the certain Iniital increments either in size or volume” . LA cannot be too stiff, at the same time it can’t yield out like a balloon.When does an LA decide to dilate and when does it resist is the question ? An agile atria without fibrosis, degeneration, and optimal fluidity extracellular matrix could be the defining factor.

Final message

Understanding the duality in the realtionship between LA size and E deccleration time seems to be crtical. A stiff, non-compliant LA aligns with a short DT and an inverse relationship with LA size in high-pressure states.A relaxed, accommodative LA with mild enlargement may not affect DT significantly and could even normalize it by reducing LA pressure, especially if DT was prolonged due to early LV diastolic dysfunction.

This behavior underscores why LA size and DT must be interpreted along side other factors like LA pressure estimates (e.g., E/e’ ratio), LV compliance, and the underlying pathology.

* A research question for fellows in cardiology

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LA volume assessment : A critical parameter with a time trouble !

Posted in Cardiology Illustrations, cardiology physiology, Left atrial enlargement, Uncategorized, tagged , , , , , , , on February 8, 2023|

LA dimension and volume have become vital parameters in recent times, especially, with the entity of HFpEF is becoming so common. LA not only acts as a live barometer, reflecting all that happens in LV, but it is also a chronic marker of LV diastolic function. (Funnily referred to as HBA1c of diastolic dysfunction) 

What is normal LA dimension & volume ? 

  • Normal left atrial diameter < 4.1 cm in men or < 3.9 cm in women
  • Normal left atrial volume indexed for body surface area (BSA) is 34 ml/m2 for both women and men 

Which part of the cardiac cycle do we measure? 

Ever since Wiggers introduced the overwhelming concept of LV systole and diastole, most of us ignored the fact that atria do have a separate contraction relaxation cycle, independent of what happens in the ventricle. Of course, atria and ventricles act as a single chamber in diastole. In reality, atria lack true boundaries when it acts as a conduit. The LA dimension varies considerably during the atrial cardiac cycle. Look at the  LA pressure-volume loop, which can frighten anyone, with its horizontally lying figure of 8 pattern. During every cardiac cycle, the volume reaches atleast two troughs and one peak.

Don’t get frightened with this graph, spend some time, and you will get it right, Begin at  “3” o clock position with the onset of diastole with a downsloping green loop, that continues as the red line of atrial contraction to end up in systole. The entire black loop, that happens during ventricular systole depicts the true reservoir function. with MV closed. ,

 

As of now, we have a consensus, LA volume is measured typically in LV end-systolic frame. ( Rather, we measure it at maximum LA volume ) However, we have 4 different LA  volumetric components to assess, as this article excellently depicts. (Hoit BD. Left atrial size and function: role in prognosis. J Am Coll Cardiol. 2014 Feb 18;63(6):493-505.)

What could be the limitations of the traditional end-systolic measurement?

No single measurement will give an overall LA function assessment. But still, Somehow, we have measured the maximum LA  volume as a reference of true diastolic function. This happens in LV end-systolic point where atria reach the maximum size. But, here is a catch, we assess the left atrial function before its main physiological function of emptying takes place.

How about assessing  LA efficiency after it completes its job, ie end diastole? 

In LV function end-systolic dimension has pride of place as it is devoid of influence from loading condition. If applying the same logic, the “end atrial” systolic dimension(Which is the same as LV end-diastolic point/or post A ) should be perfect. It can also help measure the residual LA volume after its systole.

A potential advantage of LV end-diastolic dimension (The Heart & Soul study )

Maybe, this is less affected in the presence of MR systolic jet will spuriously elevate LA volume. In AF also this parameter is less likely to be influenced by LA preload.

Final message

Suddenly, we are debating a fundamental Issue, ie timing of LA measurement. While the end-systolic size/volume is the current standard, the LA dimension in the end diastole also provides useful info. There are at least 4 different LA volumes, at different parts of the LA cycle that need to be studied for a proper understanding of diastology (Unlike LV which has only two).

Now, we may need to ponder, if there is a mean LA volume, measured with the 3D volumetric analysis or MRI, that could be representative of the global LA function. 

Reference

Thadani SR, Shaw RE, Fang Q, Whooley MA, Schiller NB. Left Atrial End-Diastolic Volume Index as a Predictor of Cardiovascular Outcomes: The Heart and Soul Study. Circ Cardiovasc Imaging. 2020 Apr;13(4):e009746. doi: 10.1161/CIRCIMAGING.119.009746. Epub 2020 Apr 20. PMID: 32306763; PMCID: PMC8846436.

 

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