Right atrial collapse in cardiac tamponade

Right atrial collapse is not by itself a sign of cardiac tamponade

March 13, 2022
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The timing and duration of right atrial collapse during pericardial tamponade are determined by the cardiac cycle, as well as respiratory cycle, as noted on this cliphttps://t.co/3Hy0t6iuxh pic.twitter.com/dGktfWrhmy

— Edgar Argulian (@argulian) March 11, 2022

I have read your interesting short paper. I would have added a few issues.

1. Concerning the right atrial collapse that you describe during “late ventricular diastole”.
In late diastole the inward motion of the right atrial wall is not passive (collapse) but is active, secondary to atrial systole. Following atrial systole, there is atrial relaxation which occurs during isovolumic ventricular contraction and the early phase of ventricular systole. This is where you eventually observe wall collapse. So, it very important to distinguish between atrial systole and atrial collapse. See this Lesson on Pericardial Effusion and Tamponade.

2. Right atrial collapse occurs very early with effusion because atrial pressure during atrial relaxation – which occurs during early ventricular systole – is so low. So there is no relation to tamponade status here, at least with a collapse that lasts less than 50% of ventricular systole.

3. There is a progression in echocardiographic findings which parallels the increase in pericardial pressure until the tamponade status is reached. Assuming a diffuse effusion, the first finding is right atrial collapse during ventricular systole, then diastolic collapse of the right ventricular free wall and finally interventricular septum leftward shift and stroke volume change during respiration. Of course, it is not always this simple in the real world. So, I wouldn’t diagnose tamponade with echocardiography until I see these last findings.