Ten Minute ECG (Part 1)--Okay, It Is 20 Min But I Tried

[zepoe]

Thank you for posting this, excellent!

[warrannz]

Hi again, just read the above post and found the 'show more' with pdfs. thanks again.

[warrannz]

Hi, This is great! Where can I find the picture of the blue heart with the lead triangle on it and the different colored direction arrows indicating the direction of depolarization and the corresponding ecg tracing? Thanks heaps for this and the directions to the books. EXCELLENT

[TommyDWatson]

Not sure if you even check these any more. How do I get these slides? Can I buy them from somewhere? It would be a great tool to have for those of us becoming Paramedics and RNs.

[hennagerdj]

@TommyDWatson If you open up the "show more" tab, there is a link to the PDFs. I should also note that I need to make a correction to the diagram but have not had the chance. Originally, I had read that repolarization occurs in the opposite direction of depolarization. But, based on figure 6.7 of Bioelectromagnetism (Malmivuo) I changed the direction. I forgot to change the direction on the second side of the diagram. My apologies. Best to you and yours.

[TommyDWatson]

@hennagerdj Its still a great tool! If you ever update it I would love to have a copy. I would also like to ask you for permission to hand it out to my fellow students in our Paramedic Program this fall. I've made A's in both A&Ps, Micro, .....etc. It was always just knowing how to answer questions. You make it easy to understand the information.

[xxthunderbird46xx]

thank youuuuu :)

[Smokefest99]

voice is very annoying

[VinceScot]

I have just wasted 7mins listening to an introduction without learning a thing only to hear 2 mins worth of real information. I should have watched something else, not sure where this gets five stars from

[sxewas]

hay! i am doing a poster presentation at university on ECG and the cardiac axis, i would love to use the diagram of the 12-lead ECG (the one on the right at the start). could i please get the source or if its your work could i get some information so i can cite it in my references. thank you.

[PrimeParadox]

Question sir. Why is it that the repolarization of the ventricle is of the same direction as its depolarization? Why is it not repolariaed backwards like that of the atrium?

[hennagerdj]

@PrimeParadox : My interpretation is that it is not so much the direction of the voltage change in the cell that is detected by the ECG (+ to - or - to +) as it is the direction of the voltage change as it moves across cells. The length of the action potential near the pacemaker is long and so depolarizes first but repolarizes last. In the inferior atria, the action potential is much shorter. So, overall depo. flows down but since inferior atria repols. first, the repol. wave moves up.

[hennagerdj]

@PrimeParadox In the venticles, the action potentials are more the same length so depolarization and repolarization vectors travel in the same direction. I am also neglecting the voltages the move from inside the heart to the outer layers in order to simplify. Those voltage vectors also make the repolarization vector the same as the depolarization. Thank you for your comments. I am certainly no expert but I am trying to make sense the the building blocks of ECG. Take care.

[ipyonoti]

I may be wrong i just read that the wavefront of repolarization travels broadly in the opposite direction to the wave of depolarization. A wavefront of the opposite polarity travelling in the opposite direction gives a deflection in the same direction on the ECG recording.

[ipyonoti]

So in short, it "travels" in the same direction! :) thanks Hennagerdj! i enjoy your videos, thanks for the effort to put up such amazing videos :)

[zbotto]

@PrimeParadox because the proximal (basal) parts of the ventricle by design spend more time in depolazied state than the distal (apical) parts (slower potassium channel activation maybe?).

but your question is 4 months old, it's probably already answered by now

[ffhuisma]

@hennagerdj: Hi there, I found your video very helpful, but I too was confused about why the repolarization arrows point different directions in the atria and the ventricles, so I went to the sources that you point out in your video. It turns out that the direction of charge DOES matter (whether it is going from negative to positive or positive to negative.) --continued

[ffhuisma]

@hennagerdj: To quote from the bioelectromagnetism book (section 15.2), "When the depolarization front propagates toward a positive electrode, it produces a positive signal," and "When the direction of propagation of a repolarization front is away from the positive electrode, a positive signal is produced."

Then, referring to the Investigative Electrocardiography book you refer viewers to (section 1.5.3), "the direction of repolarization is in reverse to depolarization".

[ffhuisma]

@hennagerdj: So, it turns out that you drew the vectors correctly in your diagram. The direction of repolarization is the same as that for depolarization in the atria, but because the charge is going the opposite direction (repolarization goes from pos to neg, instead of neg to pos like depolarization does), the vector points the opposite direction. The repolarization vector is drawn in the right direction in the ventricle because it actually goes the opposite direction (nobody knows why).

[ffhuisma]

@hennagerdj: sorry, didn't clarify that the direction of repolarization in the VENTRICLE is opposite to the direction of depolarization, whereas they are both in the same direction in the atria.

[dappijue]

This was pretty entertaining in a way I don't think it was meant to be :)