Here we see that a normal ECG and 2 pathological ECGs are shown below, and we have this table down here that shows our 1, 2, 3 different ECGs or electrocardiograms that we're going to need to analyze. And it says a, for each ECG, identify it as normal or pathological. B, if possible, identify and label at least 1 p wave, QRS complex, and t wave on each diagram. We also note here not all waves or complexes may be present in all ECGs. And then, finally, it says, in simple terms, what part of the heart's conduction system do you think may be failing each pathological ECG? Alright. So as we look at this, I think, for me, the easiest way to do this is just start labeling these complexes and waves, and if I can do it, it's going to be normal. If I have trouble, it's going to be abnormal. So in this first one, I see a p wave, I see a QRS complex, and then I see a t wave. Though that looks relatively normal, this does kinda look like a big space there, but we'll come back to that in a second. Now as I keep going, I have a p wave and then nothing. It looks like I have another p wave and then nothing. I have another p wave, and then we have another QRS complex. Alright. So I was able to label things there, but as you look at this ECG, does that look normal or pathological to you? Well, to me, it looks pathological, so I'm going to put a p there. And it looks pathological because it looks like I have these p waves that are not followed by QRS complexes. That's a problem. So in simple terms, what part of this conduction system do you think may be failing? Well, the p wave is depolarization of the atria. The atria, therefore, are depolarizing here, but the ventricles seem not to be depolarizing regularly. That means that that action potential stalls out somewhere going from the atria to the ventricles. So what does that action potential have to pass through? It has to pass through the AV node and the AV bundle. So because this ventricle isn't contracting regularly, it tells me that that action potential must be stalling out somewhere in here. Now the technical term that we're looking at, this is a heart block, and it's actually quite serious. Alright. As we look at our second one, I can label things again. Well, I'm going to look for my p wave, QRS complex, and t wave, and look, p wave QRS and my t wave. That looks normal. And as I look down, that normal pattern just repeats over and over again. So does that look normal or pathological to you? Well, this just looks like our normal ECG. I'm going to give it an N. Therefore, what's the failing part of the conduction system? Nothing's failing, so I don't really need to write anything in that box. Alright. Our final one here. Let's see what we can label in this ECG down here at the bottom. Well, as I look there, I don't think I can name a p wave. I do see depolarizations here that represent the depolarization of the ventricles. Those seem to be happening. Right? I see a lot of those QRS complexes, but I can't see the p waves and I can't see the t waves. So knowing that, normal or pathological. Well, this looks pathological to me. So because I see that QRS complex, that tells me that the ventricles are contracting. But in between, when I would expect to see that normal P wave, I just get this sort of fluttering, this random depolarization and repolarization. Now, I know that's not from the ventricles, because the ventricles are giving that QRS complex. So what must be happening here? This is atrial fibrillation. Now you can see in sort of more simple terms, you could say there's something wrong with the atria. The atria are not passing that action potential correctly. But what we're seeing here is this sort of random unorganized depolarization on the cells in the atria that we call fibrillation. Okay. Now again, you do not need to be an expert at reading these ECGs and identifying pathologies. But hopefully, you see here that by knowing what you're supposed to see, it's actually not that hard to figure out what is pathological and what might actually be going wrong in the heart when you see it. Alright. With that, we got more practice to follow. Give it a try.