"the negative ventricular tissue is steadily becoming more positive, that is its repolarizing" WHAT i thought it was ALREADY positive then returning to its resting potential which is NEGATIVE like -70mv? GODDAMIMT im so cONFUSED
yeah depolarization the myocytes should be positive and during repolarization they become negative again bc their resting membrane potential is -90 mV. this video is wrong.
T wave (repolarization) is positive deflection because its electrical vector is pointing towards the positive electrode (example lead II). You must consider negative charges outside the cell because it has an impact on the changes in electrical field in the extracellular fluid. which then travels through the body and eventually the electrode If you start with the notion that outside is negative when repolarization starts, then you will realize that - to + (dipole moment) is pointed towards the positive electrode of lead II during repolarization of ventricles. This happens because; 1) repolarization makes the outside more positive and 2) it starts from the epicardial region. This is REVERSAL of depolarization. Since you reverse the starting point of repolarization and you also reverse movement of ions (positive ions going out), dipole electric vector remains the same as during depolarization. This is more correct in terms of explaining why T wave is positive. Some use the wrong explanation of saying vector is going towards the negative electrode when it is not. And they also say things like - vector hitting the negative electrode and it becomes positive because when you multiply negative with negative it is positive (:(). It is true that repolarization WAVE is going towards the - electrode, but the dipole moment vector is pointed towards the positive electrode of lead II as it does during depolarization of ventricles.. I sincerely hope I have not offended anyone.
Wow can't believe I see you here. I was from another video that explains why T-wave is concordant to QRS and saw your comment there. This helps a lot, thanks.
The charge is not flowing through the electrode, the circuit is open when reading voltage (infinite resistance). That cannot be explained in terms of a simple electric circuit.
@@klausnewman8125 How does the skin electrode make electrons flow through the external wires? Is it because of changes in the electric field in the skin electrode? My question is, "what makes the electrons flow in the external wires (for example lead I)?"
@@texastexas4541, they don't flow in the external wires, a voltmeter (like an ECG machine) can be represented as an infinite resistor connected in parallel to the circuit. The current flowing through the external wires is just i = V/R, which is very close to zero, since R has a very large resistance.
oh god, i was stucked in the T wave for hours, i was like how the graphs still upward eventhough the explanation said the ventricular undergoes repolarization. Now i know, its because the direction of the repolarization from the apex to the base! thanks!!
So I looked it up and the reason the ventricles repolarize starting from the cells that just depolarized (rather than keeping the same order) is that the cells in the outer myocardium have a shorter action potential and so they repolarize sooner. Then, as he mentioned, the signal goes the opposite direction from the rest and is transcribed by the ECG as a positive one.
Jim S......Repolarization of human myocardium starts from the epicardium to endocardium because AP of subepicardial myocytes are shorter than subendocardial myocytes (this is very well known). cardiac dipole should be pointed towards the + of lead II or II because outside of the cells near the epicardium become positive first as membrane potential is reversed during repolarization.
everyone has his own logical way to interpretate tho it maybe not based on a scientific prespective , for me the answer to why this T wave is a positive deflexion is to find a way to undrestand two things , how the galvano is setting and when we say is a positive deflexion comparing the direction of the electrons and the settings and also how electrons move in the depolarization/repolarization , in depolarization i make a vector directred to the way electrons get out from cells pregressively and in the repolarization how the electrons get in the cells and the cells are consuming it then i see if the direction is to the positive electrod that gives a positive deflexion cus this is the electrical current direction .
I don't know if you're correct about this. I'm sure this is what you were taught, but have a read of "Spach et al., (1977) Origin of Body Surface QRS and T Wave Potentials from Epicardial Potential Distributions in the Intact Chimpanzee" or if you want something more recent, "Ramanathan et al., 2006, Activation and repolarization of the normal human heart under complete physiological conditions". The pretty much the entire ventrical myocardium repolarizes at the same time.
I didn't know if I would get a response. So just to make me seem like less of a dick: Really nice video, and absolutely what is taught in the majority of med schools, and you can find lots of citations to support it too, but most of them don't actually go back to any original research to back them up. As I say, have a look at the Ramanathan paper, but just to quote from it "This static pattern reflects the relatively slow process of repolarization, which, unlike the localized and propagated depolarization process, covers the entire ventricular myocardium. We describe T wave epicardial potential patterns using subject no. 1 as a representative example (Fig. 4). During T wave onset, a maximum (dark red) appears over the anterior surface (Fig. 4A Upper); it remains static and intensifies during peak T wave (Fig. 4A Lower Left). Negative potentials (green and blue) cover most of the apical and inferior LV and persist through T wave peak (Fig. 4A Right). These human patterns are consistent with T wave patterns in the chimpanzee heart (3)."
The T wave does not have a negative effect on your heart! I know it seems like it might, but don't fall into the trap of thinking that. Sorry it took me so long to respond!
My t waves are negative. No other signs of a problem, not even in mri scan... No changes the last ten years, so it seems to be benign. All leads are affected
A decent explanation and a good show but you miss out the critically important bit at the end. That is you do not explain WHY the wave of repolarization spreads from apex to base? The key feature here, that is not explained, is that the action potential duration is short at the apex and long at the base. No room explain further! Go figure! (The answer to the earlier comment about why can't text books be this simple is...because it's not that simple!).
@@danieldebruijn2107 The answer does not shift the problem - it points out that the video does not actually address the REAL explanation for the 'inverted' T wave - which is base-apex differences in repolarisation time. In answer to your question: Simply put, base-apex (and transmural) differences in action potential duration are caused by regional differences in ion-channel expression. As to teleologically WHY this is a design feature? This is another question and this box is too small to explore the answer. Read the literature!
@@danieldebruijn2107 K channels (specifically IKs and IKr are also higher in the apex than the base. Many papers show this - as well as LV vs RV differences and transmural differences. See for example Brunet et al (DOI: 10.1113/jphysiol.2004.063347).
According to Guyton and Hall, repolarization occurs that way because the septum and the endocardium are the last parts of the heart to contract. That means that those parts still are depolarized, but if you draw your attention to the ventricular walls you will realise that the muscle of such area is already repolarized. And that is why repolarization happens like that. It's quite hard to explain, even in person, but hopefully it helped you a bit. Cheers from Mexico.
@@angeloviedo4604 yeah actually! There must be some logic to it; I'll wait until I'm satisfied with a nice answer. Thanks alot for your efforts dude. Love your food, Cheers from India.
This video is the gold standard for explanation of this topic
Thanks so much.
Helpful, amusing, and straight to the point. This is amazing.
"the negative ventricular tissue is steadily becoming more positive, that is its repolarizing" WHAT i thought it was ALREADY positive then returning to its resting potential which is NEGATIVE like -70mv? GODDAMIMT im so cONFUSED
yeah depolarization the myocytes should be positive and during repolarization they become negative again bc their resting membrane potential is -90 mV. this video is wrong.
Thanks a lot. This explained a lot that was left out in the course. You, sir, have successfully earned a subscriber.
Thank you.
why text books could not have been so simple? thanks, this helped a lot
Thank you so much. I couldn’t find ANY videos explaining Ventricular Repolarization in the heart.... but this definitely helped. Thank you!!!!
Awesome. Glad you got something out of it!
Aaron Carlson thank you! If you have any more information on Ventricular Repolarization specifically, I'd appreciate if you would share? 😀
Ooh myyy finnaly undertood this!!
Great Edit👍
T wave (repolarization) is positive deflection because its electrical vector is pointing towards the positive electrode (example lead II). You must consider negative charges outside the cell because it has an impact on the changes in electrical field in the extracellular fluid. which then travels through the body and eventually the electrode If you start with the notion that outside is negative when repolarization starts, then you will realize that - to + (dipole moment) is pointed towards the positive electrode of lead II during repolarization of ventricles. This happens because; 1) repolarization makes the outside more positive and 2) it starts from the epicardial region. This is REVERSAL of depolarization. Since you reverse the starting point of repolarization and you also reverse movement of ions (positive ions going out), dipole electric vector remains the same as during depolarization. This is more correct in terms of explaining why T wave is positive. Some use the wrong explanation of saying vector is going towards the negative electrode when it is not. And they also say things like - vector hitting the negative electrode and it becomes positive because when you multiply negative with negative it is positive (:(). It is true that repolarization WAVE is going towards the - electrode, but the dipole moment vector is pointed towards the positive electrode of lead II as it does during depolarization of ventricles.. I sincerely hope I have not offended anyone.
Wow can't believe I see you here. I was from another video that explains why T-wave is concordant to QRS and saw your comment there. This helps a lot, thanks.
Thanks for the explanation!!!
The charge is not flowing through the electrode, the circuit is open when reading voltage (infinite resistance). That cannot be explained in terms of a simple electric circuit.
@@klausnewman8125 How does the skin electrode make electrons flow through the external wires? Is it because of changes in the electric field in the skin electrode? My question is, "what makes the electrons flow in the external wires (for example lead I)?"
@@texastexas4541, they don't flow in the external wires, a voltmeter (like an ECG machine) can be represented as an infinite resistor connected in parallel to the circuit. The current flowing through the external wires is just i = V/R, which is very close to zero, since R has a very large resistance.
oh god, i was stucked in the T wave for hours, i was like how the graphs still upward eventhough the explanation said the ventricular undergoes repolarization. Now i know, its because the direction of the repolarization from the apex to the base! thanks!!
clear as a day :)
but you forgot to mention one thing: song name??
Its time for my massive AAAAAAAAAAAAAAAAAAAAAAAAHHHHH NOW I GET IT! You're a life saver.
So I looked it up and the reason the ventricles repolarize starting from the cells that just depolarized (rather than keeping the same order) is that the cells in the outer myocardium have a shorter action potential and so they repolarize sooner. Then, as he mentioned, the signal goes the opposite direction from the rest and is transcribed by the ECG as a positive one.
I could finally understand this! It was killing me. Thanks
thank you! i was so confused as a lot of the teaching doesn't explain this phenomenon.
This video is by far the best video I have seen!!!!!!!!!!!
Good job. U deserve a lot of views.
Thank you.
Great explanation, for this i waited 7 years
This was so well-explained that I figured it out by 1:30 thanks to your diagram!
Top 10 cardiology mysteries of all time
This was helpful, especially using the wheels as a way to grasp the concept. Thank you!
Not only i have the T wave pretty clear now, i also unterstood why the Herzmyozyten are positive 😂. Thanks a lot man :)) Subscribed 🌟🌟🌟 + Liked : )
Thank you form the bottom of this heart ❤
Jim S......Repolarization of human myocardium starts from the epicardium to endocardium because AP of subepicardial myocytes are shorter than subendocardial myocytes (this is very well known). cardiac dipole should be pointed towards the + of lead II or II because outside of the cells near the epicardium become positive first as membrane potential is reversed during repolarization.
man i love you, you helped me so much!!!
This is brilliant, thank you.
If only everybody explained science so simply
Thanks a lot! First video that managed to describe concordant T-waves ! 👍🏼
Glad you found it useful!
Brilliant animation!
Thank you, thank you.
Super cool presentation, thanks
I still don't get it 😭. What does repolarization get represented by a counterclockwise wheel 😭
everyone has his own logical way to interpretate tho it maybe not based on a scientific prespective , for me the answer to why this T wave is a positive deflexion is to find a way to undrestand two things , how the galvano is setting and when we say is a positive deflexion comparing the direction of the electrons and the settings and also how electrons move in the depolarization/repolarization , in depolarization i make a vector directred to the way electrons get out from cells pregressively and in the repolarization how the electrons get in the cells and the cells are consuming it then i see if the direction is to the positive electrod that gives a positive deflexion cus this is the electrical current direction .
Is known, why this happens? Why does the repolarization occur in the opposite direction ?
So appreciated. 😊 Thank you
But why is it from the bottom up?
Great explanation. Thanks.
No, thank you.
Thank you so much.
I have t wave inversion in lead 3. Should I be worried?
What came of your ecg showing t wave? I had it in 3 leads but now only in 1 they did every other test and they said it's nothing to worry about.
I don't know if you're correct about this. I'm sure this is what you were taught, but have a read of "Spach et al., (1977) Origin of Body Surface QRS and T Wave Potentials from Epicardial Potential Distributions in the Intact Chimpanzee" or if you want something more recent, "Ramanathan et al., 2006, Activation and repolarization of the normal human heart under complete physiological conditions". The pretty much the entire ventrical myocardium repolarizes at the same time.
I have forwarded your message to my brother, who wrote the video. Thanks.
I didn't know if I would get a response. So just to make me seem like less of a dick: Really nice video, and absolutely what is taught in the majority of med schools, and you can find lots of citations to support it too, but most of them don't actually go back to any original research to back them up. As I say, have a look at the Ramanathan paper, but just to quote from it "This static pattern reflects the relatively slow process of repolarization, which, unlike the localized and propagated depolarization process, covers the entire ventricular myocardium. We describe T wave epicardial potential patterns using subject no. 1 as a representative example (Fig. 4). During T wave onset, a maximum (dark red) appears over the anterior surface (Fig. 4A Upper); it remains static and intensifies during peak T wave (Fig. 4A Lower Left). Negative potentials (green and blue) cover most of the apical and inferior LV and persist through T wave peak (Fig. 4A Right). These human patterns are consistent with T wave patterns in the chimpanzee heart (3)."
You'"re awesome :) great edit too
Thank you Vusi!
entertaining and useful! great job!
how does hyperkalemia cause a spiked T wave?
thank you so damn much lol. finally understand this.
Great video. But what exactly does the negative T wave have on your heart? It sounds like it's detrimental could you please explain more about that
The T wave does not have a negative effect on your heart! I know it seems like it might, but don't fall into the trap of thinking that. Sorry it took me so long to respond!
What does it mean when your T wave goes down instead of up on ekg?
there is some sort of ischemia
Nice job
just amazing!! thanks a lot .
Thanks!
Why is t wave voltage less than qrs wave voltage
It's over a longer period of time.
This helped a lot!!!!! Thank u so much!!!!!!
Amazing
Best explination ever
My t waves are negative. No other signs of a problem, not even in mri scan...
No changes the last ten years, so it seems to be benign. All leads are affected
good stuff 😌
thank you so much
Think you so match sir
A decent explanation and a good show but you miss out the critically important bit at the end. That is you do not explain WHY the wave of repolarization spreads from apex to base? The key feature here, that is not explained, is that the action potential duration is short at the apex and long at the base. No room explain further! Go figure! (The answer to the earlier comment about why can't text books be this simple is...because it's not that simple!).
@@danieldebruijn2107 The answer does not shift the problem - it points out that the video does not actually address the REAL explanation for the 'inverted' T wave - which is base-apex differences in repolarisation time. In answer to your question: Simply put, base-apex (and transmural) differences in action potential duration are caused by regional differences in ion-channel expression. As to teleologically WHY this is a design feature? This is another question and this box is too small to explore the answer. Read the literature!
@@danieldebruijn2107 K channels (specifically IKs and IKr are also higher in the apex than the base. Many papers show this - as well as LV vs RV differences and transmural differences. See for example Brunet et al (DOI: 10.1113/jphysiol.2004.063347).
Awesome
Thankyou
I don't know who to asked , in my T wave axis is said 8 degrees
So basically what happens is the opposite of the opposite, thats why there is no change in the reading
Thanks
That was helpful ty
Awesome, thank you.
thanks !!!
Thanks for watching!
I don't understand why the repolarisation occurs from apex to base 😭
According to Guyton and Hall, repolarization occurs that way because the septum and the endocardium are the last parts of the heart to contract. That means that those parts still are depolarized, but if you draw your attention to the ventricular walls you will realise that the muscle of such area is already repolarized. And that is why repolarization happens like that.
It's quite hard to explain, even in person, but hopefully it helped you a bit.
Cheers from Mexico.
@@angeloviedo4604 yeah actually! There must be some logic to it; I'll wait until I'm satisfied with a nice answer.
Thanks alot for your efforts dude.
Love your food,
Cheers from India.
too confusing
G R E A T
but y tho
Yeah this made perfect sense. Not. Lol where the HELL are the videos for dummies Re: inverted T waves???
bruh