This on-demand teaching session is relevant to medical professionals and focuses on helping them develop a comprehensive understanding of cardiology anatomy and fundamentals. Learn from experts on their revised techniques and gain knowledge on referred pain, coronary vessels and electrophysiology of the heart, along with reviewing a typical clinical scenario. Get involved through polls and Q&A and review learning resources, videos and cheat sheets.
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Cardiology Webinar 7-8pm: CARDIOLOGY - ANATOMY: Coronary arteries & supply regions, Cardiac Valves, Cardiac Conduction System, CLINICAL: Myocardial infarction, ECG interpretation, Heart Block

Learning objectives

Learning Objectives 1. Identify the anatomy of the heart, including the structure of the heart, valves, and coronary vessels. 2. Compare and contrast the sensation/manifestation of referred pain. 3. Describe the auscultation locations associated with the four heart valves. 4. Analyze an electrocardiogram (ECG) to identify characteristics of a myocardial infarction. 5. State the medical interventions used to treat a myocardial infarction.
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The following transcript was generated automatically from the content and has not been checked or corrected manually.

Manchester Royal Hospital. Thank you for joining us. We'll give everyone a few more minutes to, to kind of filter in. Um There's quite a significant lag, especially my internet is particularly poor. So they can't be particularly interactive with you guys. So what we've done so that you can get involved in the presentations is we've made poles and things for you to answer questions and get involved that way. So while people just filtering, I'll just tell you a bit about our society. So we're a small society, eight members and we have some student reps who help advertise for us. Um Basically, we've all taught anatomy last year and we found that when we went back to clinical work, it was really useful knowing that anatomy and we obviously have a passion for teaching. So we just wanted to put on some lectures for you guys and help maybe a lay a bit of the nerves before you start a new foundation placement because we're just starting up. We really appreciate any advertising or telling your friends if you found everything useful. Um And I've put some links and stuff in the chat there for you about how to access our website. We've got learning resources, videos, explanations, um, little cheat sheets and things on there. So please check that out afterwards. Um In terms of timing, we're going to do our best to stick to time. Um We're not going to have a break in between the two speakers for this session. Um We might have a break in between tomorrow, but for tonight, we're just going to keep on going through. So please bear with me. I'm not the best with technology. So if anything goes wrong and please just be patient. Um And I'll introduce, we've got Mark who's one of our committee members who's also a Junie clinical fellow. And then our two speakers for tonight, we've got um Doctor Nikita John and doctor, she had some uh um so I'll let them go ahead and start the, their talks. Okay. Hi, everyone. My name is Doctor Nikita John. Um And I'll be delivering one half of this lecture on uh cardiology. Um Just a little brief introduction. I've done a cardiology placement in my foundation years. Um And I remember how useful it was to sort of revisit my anatomy of sort of basic structure of the heart and especially of the coronary vessels and the electrophysiology of the heart before my placement. And I remember sort of splitting um cardiology learning into sort of the plumbing and electrics. And so that's how we've sort of structured your lecture for today. We're going to um, sort of base the anatomy learning around a very common clinical scenario that you might come across on your placements or your first um cardio job. And um, hopefully, um, you should be familiar with some of the concepts that we're talking about today because it's revisiting that anatomy that you did as 1st and 2nd year medical students. So I'm just share in my screen there with me. Okay. So hopefully you can all see my screen now. So cardiology is obviously a massive topic and we could do a whole lecture series on just the anatomy of the heart if we wanted to. But we're going to focus it um to the basic anatomy of the heart, the structure of the heart a bit on the valves as well. We're going to talk about the concept of referred pain. Um We're going to talk about blood supply to different heart surfaces and then I'll hand over to my colleague Sheehab who will talk about the electrical conduction components of the heart, electrical activity within the heart and E C G representation of cardiac electrical activity. So, plumbing and electrics. So a very common situation that you might find yourself in when you're on placement is um you're with the cardiology registrar and they're about to go to a any um to review a patient. Um You've heard that a man's just come in via ambulance. His daughter's called him an ambulance because he's got some chest pain, the any doctors have given you a bit of a handover. So this is what, you know, so far, he's a 56 year old man. He's, um, come in with some chest pain following trampoline ing with his granddaughter. So a form of activity has brought in this chest pain. His past medical history is high cholesterol. He's got borderline hypertension as well. He is medicated with statins. He is also a smoker of 20 years. So a vascular path um then to explore this pain a little bit further, we can use the tool Socrates. It's central, it's sudden in onset, it's crushing in nature and it's referred to the left shoulder and jaw. Um It's associated with nausea, breathlessness, it followed this jumping activity um and worse with sort of any more exertion. He's tried a bit of paracetamol, it's not really alleviated it. Um And the severity is five and 10. The observations are stable, relatively stable. So his SATS are 99%. He's tachycardic at 100 and 15. His Tackett me take 22 his blood pressure's stable at 145 over 95. His E C G doesn't look quite right. We're going to have a closer look at that in a second. Mm. And the, and the doctors have um sort of immediately thought of something. Um And you're probably thinking about this too. So the thing that's probably jumped into your head is heart attack is this man having a myocardial infarction. Um, that's because this chest pain is very typical for cardiac chest pain, chest pain, of course, can be muscular, skeletal, it can be um, coming from the lungs which might present it's pleuritic pain, but this particular type of chest pain is very, very, um, cardiac sounding. And that's probably because, um, you're thinking of word associations, crushing and left shoulder and jaw. But these investigations that will go on to soon will also fill that picture up for you. Um What they've done in a any of then of course, is given him some morphine oxygen nitrates, aspirin and done. Um some bloods including troponin. There's one thing that they haven't done yet, but it's okay where the cardiology team will, will do a complete review in a bit. So first, a little bit of anatomy, why did our patient get this left arm pain? So this is the concept of referral pain when pain somewhere is actually felt somewhere completely different. So, visceral organs, any internal organs are sensitive to ischemia and the visceral Afrin pain fibers. So these are the pain fibers that go up to the central nervous system actually run alongside somatic afferent fibers from cutaneous skin regions. And when that information then goes back from the central nervous system to those organs, they can be confused and they can get confused in different different parts. They can get confused in the brain or in the spinal cord. But that confusion means that pain from the heart can sometimes be felt in that cutaneous region. So the um nerve fibers that the heart viscera LaFrentz run with are usually t one to T five branches. And if we map that on dermatome, we can see that correlates with sort of for um regions. So that's why commonly pain get pain can get referred to the left shoulder. Sometimes you can also get that confusion happening with the cervical branches. Hence, while you can get pain in the shoulder or even the jaw, and this concept of referred pain isn't unique to um heart pain. Um Many organs actually referred to other places. For example, you might have heard of kidney pain or back or uh pancreas pancreatitis um being referred to the back um or gallbladder pain being referred to the shoulder. And that's usually the right shoulder because the gallbladder's on the right side. So back to our case. Um and we're having a closer look at the C C G, I'll just give you a few seconds to um evaluate the C C G and tell me what you think. There are some helpful boxes on there already um highlighting to the particular areas of interest. So there's a whole system that you can use the system to systematically go through an E C G. But uh but if you see something very obvious, you can mention that um sort of immediately. So on the C C G. You can clearly see some ST elevation in leads to three and A B F and you might already know that these regions are mapping to the inferior parts of the heart. So this is called an inferior M I. Now, what hasn't happened in a or what they haven't documented or told you yet is the cardiac exam. And it's really important to do this to listen for any new murmurs because um esc emmick um damage can cause damage to the valves and therefore you might hear a new murmur. So as part of a cardiac exam, you will auscultate the chest. So um let's have a look underneath that. What you're actually auscultate ing. So you're not actually auscultate ing the valves because the valves are actually condensed in a very small region. What you're listening for is the area on the chest with the loudest sound that's going through that valve. So for um the aortic valve, you are listening in the second intercostal space, one to the right sternal edge. For the pulmonary valve, you're listening in the second intercostal space in the right, in the left sternal edge. For the tricuspid valve, you're listening at the fourth intercostal space at the left sternal edge. And for the mitral valve, which is actually here, you're listening to it way over here because that's where it's her best. And that's the midclavicular line, fifth intercostal space. Let's have a closer look at the structural anatomy of the heart and have a look at the valves in some more detail. Okay. So this is um a video taken from a complete anatomy. So here on the superior aspect of the part, you see three great vessels, that's the imperial uh the aorta and the pulmonary arteries. And if we turn around, we'll see the pulmonary veins. Okay. So they went on valves and what develops the valves, prevent backflow and then the heart contracts. It's really important that blood is able to move in the correct direction. We also have valves between a trickle and ventricle are atrial ventricular valves and valve between our greatest arteries and vegetables are um we can see are palm knee and chaotic files. So we're going to have a look in a bit more detail at one of these valves right now is our aortic valve. It's usually try cost. You can see the three costs, but some people actually only have two valves and these people are probably two diseases like aortic stenosis. A synopsis, by the way is when the valve open comes too tight and then the heart has to work how to push the blood through. It's a common reason why people get valve replacement. When you're on um your cardio job, you might learn about people having tap meets or mechanical or diabetic bob place. You might have noticed two little holes and that's where the on arteries um originate from. We'll have a look at, I'm a bit more teeter later. Other valve are the pulmonary valve that you can see, for example, on this in tier. So another semilunar valve and then our atrioventricular valves, the traffic custody and nitro um and these valves open during diastole, which is a ventricular filling stage and shut your death and shut during cystically. Now going down into the ventricle, you can see the heart strings or corn attendant that are attached the ventricular wall by the papillary muscles, the papillary muscles contract when the ventricular wall contract and the papillary muscles pulled all the bowels in the ventricles to prevent them from party too far backwards for the atrial contraction. Now, if the port a tendon rupture or the papillary muscles become paralyzed, then the valve will bulge too far backwards and least for regurgitation. So, as you can imagine if there's any damage to these ventricle injectables from uh following an M I, then you can get regurgitation these valves, okay. So I said we'd go back briefly to um the origin of the coronary arteries. You might have noticed these two little sinuses in that video. Um But don't worry if you didn't, they're quite hard to miss. So the coronary arteries before the aorta pump before the heart pumps, all of that blood out of the aorta to the rec to the rest of the body, it actually diverts a small amount back to itself. And um these can be found um just behind the left and right leaflets of the aortic valve. So we said that the aorta was tricusp ID. Okay. So there's a right posterior and left cusp and behind the right custody of the right coronary artery and behind the left cusp, you have the left coronary artery and these ionic sinuses feel during diastole to prevent backflow. So, of course, there's some anatomical variation, but we'll talk about the most common um mapping of our coronary arteries. So most people have a right coronary artery and a left coronary artery. And the branch, the main branches from them are the sinoatrial branch which supplies the sinoatrial node, which is very important. Um The right marginal branch and the posterior descending branch also known as the posterior interventricular branch because it runs at the back, posterior interventricular group, the group between the left and right ventricle. And this particular branch is a very important branch because it supplies um the A V node which is very important for the electoral conduction of the heart. And depending on where this branch is found, we call that side of the heart dominant. So the majority of people are right side a dominant when you refer to the heart. And that's usually because the posterior descending artery is a branch of the right coronary artery. But in a smaller amount of people, um the posterior interventricular or posterior descending branch is actually a branch of the left coronary artery So those people will be called left sided, dominant. The main coronary arteries that arise from the left coronary artery are the lad the left anterior descending artery also known as the anterior interventricular artery that then gives um branches of diagonal arteries and also the left circumflex artery which gives off left marginal branches. So blood supply to these regions. The important concept here is that generally the artery, um the area that the artery passes over is the area that it confuses. And the heart muscle does not have very good collateral or backup blood flow. So if one area is blocked, then usually the other arteries cannot get to that area quickly enough to re perfuse it. So the heart is very susceptible to ischemia. Therefore, it's very important to know which specific part of the heart is supplied by which specific arteries and some areas will be more important than others. And another concept is if that the blockage is in a distal artery, that damage will be less than if it is more proximal to those fine is's. So let's have a little look at this image. So the right coronary artery supplies the right atrium. And the right ventricle branch of that is the right marginal artery which supplies the right ventricle and the apex. So you can see here that the right marginal supplies more of the inferior aspect of the heart than the um the main right, than the initial right coronary artery, you also have the sino um atrial branch, which isn't on here, that's going to supply the S A N node. Then the left coronary artery is actually a very small amount and it quickly branches into the left anterior descending artery that supplies um uh the sort of um other half of the right ventricle part of the left ventricle and also this interventricular septum. Then your left marginal artery is supplying the sort of lateral edge of the left ventricle. And then the left circumflex artery is running in the atrioventricular groove and it supplies the left atrium and left ventricle this region here. Okay. And so you can imagine that blockage to a particular area will um almost completely um cause a schemer to that area that it's supplying, which can be critical knowing these branches are really helpful because um especially if you find yourself in a cath lab and you're watching as um the cardiologist is um re perfusing an area. It might help you understand the process a little bit better and oriented yourself to exactly where you are in the heart. So left coronary artery branches, you have the L A D which goes down the interventricular groove. You have the diagonal artery which are branches of the L A D. You have the left circumflex artery which circumflex is around the atrioventricular groove. And the marginal branches are the marginal artery is a branch of the left circumflex. Okay. And then your posterior interventricular artery. So in so on the left, the left circumflex sometimes extends to a posterior interventricular artery. And about 20% of people who are turned left, dominant branches of the right coronary artery. You have the sinoatrial artery, you have the right marginal artery, you have the posterior interventricular artery in the majority of people. Okay. So now let's do a little exercise together to see how much of that we've absorbed. So, a Paul is about to come onto your screen very shortly. Can you please um label one for me? We'll just wait a few seconds until people have had a chance to do. You answer. You can't, you can't see the answer until you've answered. And don't worry, it's all anonymous. Okay. Well done a few, few answers coming through. Now, that's really good. So one is actually the left coronary artery. So the bit that we term the left coronary artery is actually just a tiny mini, little bit that comes from the left sinus before it branches into the two main branches. Okay. The L A D and the left circumflex. So one is actually left coronary artery, Elsie. A so well done if you got that right. Okay. So let's have a go up to now just waiting Francis to come in. So well done. It looks like most people have got that right. So that's our left anterior descending artery. So that's are really long artery between our two ventricles are right ventricle and are left ventricle. Okay. What about three well done our circumflex for those who got it right. So, circumflexing around towards the positive posterior part of the um left, left heart along that atrioventricular groove is our circumflex artery. What about four? So four is a branch from our circumflex artery. Well, then I think everyone's got that right. That's our marginal artery. So um so people might, might have more than one marginal artery. So you might see it um termed on a Cath report as M one M two. And that's just referring to multiple marginal arteries. What about five? So five is a branch of our lady? Well done. That's our diagonal branch. Then again, we can have more than one branch from the lady. One might be termed D one, D two, D three, D four. Okay, let's move to the other side now. So we've done our left coronary arteries, um Left coronary branches. Um Let's move to the right side. So what are we calling this part? Well done. So, so the right coronary artery has actually turned right coronary artery for far longer than the left coronary artery is termed left coronary artery because it's left coronary artery splits off quite early on the right coronary artery actually just extends to the to the uh sort of circumplex artery. Um It doesn't, it doesn't sort of change its name then to circumflex artery, it just sort of, it does the circumflex in, it goes round um the atrioventricular groove, but actually doesn't change name to the right circumflex artery. Just, it just makes that whole movement. And it's called the right coronary artery because it's not given off a sort of a two way street to, to a brunch. Sorry, I've given, I've given you the answer there. So seven. So I was being a bit tricky here. So you're all right. I was just being, I was just trying to be a trickster. Um The posterior interventricular artery is also known as the posterior descending artery. And this used to confuse me so much when I was um when I was learning this the first time round about, you know how these arteries were named and just to make them worse, each artery has um has more than one name. So, uh so don't get confused if you see the left anterior descending, called the anterior interventricular or the posterior um interventricular known as the posterior descending. Um It's just trying to make your life harder than it needs to be. It's just, it's just the same thing, however, you name it and um right dominant artery, if you put that down as well, it's okay because on this person, it is right, dominant and last one, right marginal artery is what you've probably guessed so far. So, um it's a branch of the right coronary artery and um it's applying sort of this uh lateral, right sided wall. So if you got that right. Well done, I hope that was useful. I'm gonna not hand over to Sheehab to continue our cardiology presentation. Thank you, Nikita. Hi, everyone. My name is Shehab. I am a clinical education fellow at the Walton Center in Liverpool and carrying on from the case where Nikita has left us off. So your patient within the ambulance, uh apologies first about how I sound. I caught some cold over the weekend and I hope it's not projecting too bad over to you guys. So your patient was in the ambulance and you had the handover from the ambulance or like from what the code, any coordinator has told you before. Now they have arrived to any and you got called to see them by the any staff because they have informed you that this patient is unwell. They're scoring quite hard in the deteriorating. So they've done the doctor's APC. You've got to do your a TUI assessment as usual airway was patent, but the patient was gasping for prep for breath. His respiratory, it was 25 with auction situation of 91% chest was a bit clear though and moving on to see found the heart rate to be 40 and his blood pressure's 60/40 appeals, bail and clammy. You couldn't really do a skin trigger or a capillary refill. His BM was five and G C S and disability. Why it was okay? He was GCS 15 and there's nothing on exposure. So they've done repeat E C G and asked for an urgent um geography given the most likely diagnosis here. Let's have a quick look at that repeat E C G. And you can mention in the comments if anybody has an idea about what the spot diagnosis of this E C G is. Okay. Okay. Well, as you can see, it's a third degree heart block. So how did we find out? That's what we're going to talk about right now. So how do you actually look at a C G rhythm strap? So this is from the resource council, a less protocol of how you review any an E C G rhythm strip. There are quite a few things to look at and that will help you decide what the rhythm is and how to deal with it. So the first thing is if there any electrical activity at all, as you can see in our patient there was we can see it's not an asystole, it was not an pulses, electrical activity either. Uh were there a Q R s where they're a ventricular rate? And yes, you could see it. So the ventricles are actually contracting. So that's also a good sign that helps you decide whether what the next step is going to be like. Then you're trying to find out if the QRS is regular or irregular. So here you're trying to really think about things as in the conduction to the ventricles regular there. If the impulse coming from the ventricles, is it from the ventricles and the atria or is it just multiple foresee that are stimulating the heart? Basically? And then you're looking at the width of the QRS, is it narrow or broad? And why does that matter to you? Because it's, it helps you decide whether or not it's coming from the normal region reach normal pathway of the electrical conduction from the atrium to the septum to the ventricles in the correct direction. That's a faster conduction. So it's a narrower curious complex. If it's going the other way around spreading from the ventricle upwards towards the rest of the ventricle is going to be a broader a a wider QRS. And then you're looking at the atrial activity if there are P waves or not. So if you are already established that the ventricles are working, you're trying to figure out whether they are producing impulses or not. And the next step is you're actually trying to see are the atrial working or not. So, can you see P waves here? Yes, we could see some P waves, small P waves all around in different spots here and there. And then the last question, you're just trying to figure out if there is a connectivity or a connection between the atrial impulse and the venture clear dimples. So if they related in the P wave related to the QRS or not. And as you can see here, they're completely not, not related, you can see some of them proceeding, some of them following the QRS complex and they are at an irregular uh pace and pattern in relation to the QRS. So that means that there's no connection between the atria and the ventricles at all. And that's a third degree heart block. Okay. Well, how does, how does that relate to us? Why did that happen in this case? Well, to answer this, we'll see what the surgeons have done. Actually. First talking you through a little bit of what um an angiography looks like. This is a video from the manufacturer of some uh angiography, stents and medical devices. This is how they go through this, how they gain access the femoral artery through the groin through which they pass what they call the six French sheet and the six French sheath is like any of your endoscopic things. It's basically um porter that will allow you to both your catheter through and they're going all the way through abdominal water to the ascending of water, to the arch of the water all the way to your erotic ascending water. Basically. And then through that, they pass on the catheter and the catheter again, a sense through uh common iliac up too. Your abdominal water, thoracic or water or tea, Karsch. And then they retract the sex f and here they start injecting the dye. They've gone into the left um coronary artery. And here you can see the left coronary artery and its branches nicely. You can see the lady and you can see the marginal and you can see the circumflex on this side. Here, you can see there is narrowing in the left a lady, but that's just to show you what a narrowing looks like that's not related to our case here. And then they do a run on the right coronary to check this patent as well because the right coronary and its branches patent and okay in this case. So that's what basically and and geography would look like. And knowing the anatomy helps you when you look at the scan uh to, to realize where you are, where you castor, where your captors are parked basically and what vessels or branches are the contrast going through. So in our case, that patient had an angiography that showed that snare going over there. So here you can see that's the right coronary and that's here at the quite proximate actually to where it originates from the coronary sinus from the water. It's, you can see very close to it is a narrowing in the right coronary artery here. Well, why, why did he get a third degree heart block? What, why is that area relevant? It's because of how the electrical conduction of the system happened through like anything else in our body and all the activity of any muscle is controlled by electrical impulses and the heart is just a big muscle and it has its own electrical conduction system. So it originates from within, as you know, from within the heart itself is starting from the right atrium. You've got the S A node and that originate, that's your pacemaker. That's what creates the impulses to begin with. And that goes down through specific track, some fibers in the atria and the ventricles to go from the S A note to the atrioventricular or a V node. And from that to the anterior part of the interventricular septum and then splits into right and left bundles to go all the way to the perkin g fibers or muscles of the heart that actually eventually contracts. So in our case here, what happened is your essay node was working because we could see some P waves and it was sending um signals to the atrioventricular node because we could see the atrium contracting on both sides. So well, that, that will give us a good P wave that you can see. It is a good size for you. If it's not small view, if it's not an atrial flutter or fibrullation wave that's tiny and you can't, you can almost neglect it right. So what happens from here is that this goes into the anterior part of the septum into the bundle of his, which is in the anterior part of interventricular septum. And then that bundle of his runs into the proximal part of the septum and then splits into right and left bundle branch is, and they buy uh propagation, send these impulses to the right and left ventricles to the perkin G fibers. So they can contract. So to have a P wave and a QRS that is narrow, that means that basically we have impulses coming into like we have impulses in their left verticals, they are contracting and we have impulses in the atria, they are contracting, but there is no connection between. So the blockage have to be somewhere between the A V N and the bundle of heads before it splits into your left and right bundle branch. So it's somewhere proximal here between the right atrium and the interventricular septum. And if you look at at the blood supply of this area, as we mentioned earlier, it would be from your right coronary artery as Nikita was saying earlier. And that me makes sense that the blockage of the proximal right coronary with a thick, the electrical conduction in this area. So now this is what each part of them do. The sinoatrial node is located in the right atrium and it's a disjunction between the Spiriva and Akiva enters. You can see it in the posterior wall of the right atrium and then it sends the signals to the A V node which is close to the ab septum. And the and from there, it carries that to the bundle of his which is near the tricuspid valve in the anterior part of the symptom. He's got a specialized issue that sends down the membrane as part of that sent to your part of your septum before it divides into your two main bundles. And then you left, the bundle goes to the left ventricle and the Birkin g fibers, the right one goes to the right uh right ventricle and it's burgundy fibers and they are eventually contracting or carrying it into the Mary Cardi. Um that contracts okay. Now, that's just a summary of how it looks like how that spreads. Like your essay know does your pacemaker that that's what regulates your heart rate. When you pick up an E C G rhythm strip in anywhere in the hospital, it will now automatically tell you on it if it's a no dollar rhythm or s a node rhythm, normal rhythm or is it just something abnormal? And that is the only part that's allowed to be spontaneous? So, if you get another focus that starts to rebel and sends its own signals to the rest of the heart that will create this arrhythmia or arrhythmia and you'll get an irregular electrical activity in the heart, right? So how do we actually measure or how do we pick up that electrical activity? It through an E C G and you would have been called so many times to see E C G that are less than optimum. They all do they don't always look that nice. Neat and pretty when they pick them up, any, any, when people are in a rush to do them, and that just relates to the position of the leads. And again, this is like what Nikita was telling you about when you're examining, when you're doing your cardiac examination. This is similar scenario here. You're trying to put your lead where the on the chest wall in the direction of the propagation of the electrical impulse coming from these specific parts of the heart. So the right atrium, we'll send impulses to your right arm. Your left 18 will send to your left arm right and tear part of the wall will send parts to your, well, you've got the far 53456 and the three as well. So V three and the four will be the lateral aspect for. So interior aspect of the septum five and six will be a lateral aspect. V one and V two will pick up signals from your right atrium s sorry from your right side of your heart. And you've got lead three E V F and lead to will pick up in fear part of the heart because it's boo shaped and it's sitting on the diaphragm, sending the signals down below and that's how you can actually see it here. So lied one and five and six are your lateral aspect of the heart. So, left ventricle basically and left side your anterior symptoms, view 123 and four and your V 23 and aVF comes from, you're um inferior part, the boot shape of the heart. It even looks like a boot on the scan if you draw it. So. Mhm That's how you position your leads. And you all know how basically the position of the leads will actually be a major contribution to where if you position them optimally, you get an optimal E C G like this one. If you don't, then there would be probably uh less like signal interference and you get a lot of haziness and a lot of uh irregular signals coming through here. So this is just going to do a quick recap of what um what the electrical conduction system of the heart looks like and how to over um like to have to quickly or how to systematically review an E C G rhythm strip. I would really recommend that you guys review the LS um chapter or where it goes through this arrhythmias and gives you your peri arrest rhythms, whether they are tacky or Prodia rhythms and they all use the same format that we've just used now. So to recap, we've gone over the basic anatomy of the heart chambers and valves and all we've gone through some of the blood supply as well. We've talked about the referred pain and why it presents in different organs and what the mechanism and theory behind it looks like we talked about the anatomy of the electric conduction components of the heart and how the electrical activity propagates from the sa node all the way to the cardiac muscles. And we've just mentioned how to read an E C G and giving you some sort of a tool to over um to use when you're doing when you're overlooking any E C G or any random strip that you're presented by your colleagues in the hospital. I hope that was useful. Thank you so much for attending this lecture today. I hope we didn't take so much of your time. Um We would be doing more. There are two more lectures coming in tomorrow and the day after on the relevant uh kinetic clinical scenarios that you would get as well. Uh