 What's up everybody? This is Dr. Ali Hader here, interventional cardiologist. Today's video we're going to be talking about the basics of coronary anatomy. Okay? Again, if you don't follow me on social media, check me out on Instagram at your heart doc or Twitter at your heart doc one. Definitely like this video. Please share it with your friends and give me some comments on what you think. So we're going to be talking about anatomy here. So this is the diagram of the heart we're going to use. Now, remember the heart's a three-dimensional organ and we're going to be looking sort of in two dimensions. So please keep that in mind. Let's get some landmarks. Over here is going to be our left ventricle side. Over here is sort of going to be our right atrium. Okay? The left atrium is going to be sort of sitting behind here if you can imagine. It's a posterior structure. Whereas the right ventricle is going to kind of sit anterior over here. Keep that in mind. Over here is our AV groove. Okay? This is the separation between the atrium and the ventricles. And that's important because that's sort of where the right coronary artery and the circumflex are going to run. Over here is our aortic valve. Up here is the aorta. These are our three coronary sinuses. And over here is going to be our left coronary osteum. And here is the right coronary osteum. In terms of walls, up here is going to be our anterior wall and antrolateral segments. Down here is our apex. And this is our inferior wall. So keep that in mind. Okay? So with that, let's start with the right coronary artery. This is going to come off the right coronary os. It's going to give this early branch called the conus. And we're going to get some of these marginal branches that are going to supply the right ventricle. The body of the right coronary is going to come down along the AV groove. Okay? This is our RCA. Again, this is the conus up here. And these are RV marginal branches supplying the right ventricle. Okay? As this wraps around, it's going to supply the inferior wall in most patients with the PDA, which is going to run along here. This is almost like a mirror image of the LED as you'll see. Now, depending on the anatomy, there can be other branches here. Often you'll have at least one, if not more, RPL branches that supply more of the infolateral wall. And everybody's anatomy is a little different. It can be small, they can be big, et cetera. So these are the basics of the right coronary artery. Moving on to the left, the left main is going to be coming off, again, the left coronary ostium. Okay? This is going to bifurcate, in general bifurcate, into the LED, the left anterior descending, which is going to be coming down here. We're going to get some diagonal branches supplying the intralateral segments. And this is going to come down around the apex, like that, and generally supply some distal infra-apical segments there. So this is our LED, put another septal here, put another septal here, this is our LED. Okay? These are going to be septal branches, of course, supplying the septum, and these are going to be diagonal branches. These are supplying the intralateral segments. Okay? Now the circumflex is the second artery coming off the left main. That's going to, again, go posteriorly, run along the AB groove. Okay? Now we'll probably get an early branch here. This is called this one of our OMs. So this is our circumflex. This is an obtuse marginal artery. And the body of the circumflex is going to run again behind us here, along the AB groove on the opposite side, mirror image of the right, and give some branches in the infralateral wall. Okay? So the circumflex, again, wrapping around, going behind, along the AB groove, and it's going to be giving off these lateral branches. So obtuse marginal 1 is the first branch. The second branch will be called obtuse marginal 2 and 3, et cetera. Now the higher the obtuse marginal branch is more intralateral, whereas as you wrap around and go more distal, these are more infralateral branches. Okay? So there can be sort of overlap between obtuse marginal diagonal, as you can see, depending on where they come off. Now in some cases, you may even have a third artery coming off the left main. So you may have a branch here. Okay? The ramus branch, ramus branch. Okay? So this is when you have a trifurcating left main. It's sort of just an anatomical variation. The ramus serves as basically the same thing as a very high obtuse marginal or a very high diagonal. It just happens to come off right in between the two, therefore it deserves its own name, the ramus. You'll see this in a small percentage of patients. Okay? Quickly by dominance. Black here. Dominance. So what is dominance? We talk about right dominant. Okay? This is an 85% of the patients, of people. This is when the PDA arises from the RCA. Okay? Pretty simple. This is like exactly what we see here. The PDA is coming off the RCA. Okay? Now the other people left dominant, 15% of the people will have that. That's when the PDA comes off the circumflex. Okay? So in that situation, that situation, this would be very small. The right corner area would basically only be supplying RV marginals. It is not very important. Okay? But the circumflex would be very, very large. It's going to come down along the AV groove and supply the PDA, which we would call the LPDA. Okay? So an LPDA means the PDA coming off the circumflex left dominant, whereas an RPDA would mean right dominant. And again, important to know because in these cases we don't really care much about the right cornering. Okay? So quickly now I just want to try to correlate some of what we know now to EKG territory. Right? So when we're trying to localize a patient with a STEMI, for example, we're looking at the leads in the EKG that are sort of representing which arterial territory is involved. So first off, down here on the inferior wall leads 2, 3, and F. These are going to be representing what's going on inferiorly and infralaterally. So the PDA, RPL, all the territories involved with the RCA are generally going to be reflected by these leads. Now, if you look, the circumflex also comes down and supplies these sort of infralateral leads. So the circumflex also can show evidence of leads 2, 3, and F. And again, it all depends on where these branches are actually coming off and what's being represented. Now when you are in these infralateral segments, like these distal obtuse marginals, or perhaps there's another PL sitting over here, you're going to get some lateral involvement. So think of this as behind us here, that's kind of the infralateral segment, right? That's going to show evidence of V5 and V6 often as these lateral leads. Okay? Now, looking at the LAD, in general, the precordial leads are what's going to show LAD involvement. So V1, V2, V3, and V4. Think of these as our anterior leads. Okay? Now V1, we call this the septal lead. So if you see ST elevation in V1, you know it's going to be approximately probably before the first major septal here. Okay? So that's important to know. Also, sometimes V1, which is sort of a right-sided lead, can also show up in terms of right ventricular infar. So if you have inferior elevations with a V1 involvement, think of a proximal RCA with right ventricular involvement. Whereas if you have all the precordial leads involved, all right? And V1, think of a very proximal LAD involvement. Okay? Now leads 1 and L leads 1 and L are sort of our high lateral leads. Okay? Now these are lateral leads, but they're more sort of the intralateral segments, right? So you're going to see this high obtuse marginals, ramus branch that we saw before, diagonal involvement. So oftentimes you're going to see precordial leads with lead 1 and L when you have a big LAD involving a large diagonal. Okay? But you could also see 1 and L involvement, sometimes even in isolation if there's an obtuse marginal branch or that ramus branch that we talked about. Okay? So that's again sort of the basics. Hopefully this gave you a little bit of the lay of the land on coronary anatomy and a little bit on its correlations with EKGs. And if you have any questions, please hit me up. Again, these were really basic. There's a lot of variations in patient's anatomy, but I think understanding the basics is critical. So again, please smash that like button, share the video if you liked it, and leave me a comment. Until next time.