pls help me in this q

[rose82]

If P wave arises in ST segment,then an ectopic beat usually originates from

atria
upper bundle of Hiss
lower bundle of hiss

Im actually reading for NBDE and this q has been breaking my head...so if any kind soul could explain and let me know a good source for reading up on ectopic beats...it would be great

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[Domenech]

Probably Upper bundle of His if by upper bundle, they mean the one in the ventricular septum. I guess the discharge would occur while ventricles have begun depolarize and by the time reaches the SA Node, ventricles would have depolarized already. Or could be lower bundle if it's at the lower part of the his bundle. Would have helped if they illustrated on a heart.

Anyone else?

 

[Nesiritide]

Just thinking out loud here, but how else would you get a P wave if it atria aren't depolarizing?

 

[username456789]

Just thinking out loud here, but how else would you get a P wave if it atria aren't depolarizing?

Exactly my line of reasoning (which admittedly may be flawed).

 

[rose82]

Does it mean that the question is wrong?