This on-demand teaching session is relevant to medical professionals and would entice them to attend, as it discusses and educates on the history and impact of coronary artery bypass grafting. It covers the development of cardiac surgery, the anatomy and physiology of the heart, the revolution of surgery in the 18th century, the significance of William Harvey and other scholars, why the heart doesn't like being touched and much more. Those who attend will also get to identify famous paintings, puzzles and problems.
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Hello Students!

Welcome to the INSINC Insight Lecture Series by SCTS INSINC.

Considering a career in medicine? Think you could be a surgeon one day? Wondering what it takes to become a cardiothoracic surgeon? You're in the right place!

This evening you will get to know the heart, inside and out, as we perform a dissection and talk you through the important cardiac anatomy. This will be followed by a short lecture on coronary artery bypass crafting (CABG), so you can put your knew found knowledge to the test!

Please note, the first part of this talk includes footage dissecting an animal heart. If you wish not to attend this part of the session for any reason, you are welcome to join us later on in the evening, using the same link.

Please get in touch if you have any questions in the meantime on

Kirstie Kirkley


Mentorship Officer SCTS INSINC

Learning objectives

Learning Objectives: 1. Identify the historical context and development of cardiac surgery. 2. Understand the anatomy and physiology of the heart. 3. Discuss the role of the heart in cardiac output. 4. Identify individuals of significance in the development of cardiac surgery. 5. Understand how manipulation of the heart can impinge on cardiac output.
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Computer generated transcript

The following transcript was generated automatically from the content and has not been checked or corrected manually.

You want me to present yeah why, not why not leave it to the expert. I don't know what's happened there right ok, hi, everybody good to not see you but see you in the chat, so I can see some familiar names from yesterday, and if you weren't here yesterday, welcome today, we're mixing it up a bit and changing the order, so I'm going to talk a little bit about coronary artery bypass grafting, which literally means what it says on the tin. It's bypassing narrowing in the coronary arteries that the blood flow can get preferentially through the new pipes or conduits, or whatever you use conduits just means another way of getting somewhere to be on um from before and after a narrowing in the coronary artery, so the heart muscle gets blood supply, so basically that that's what it is very simply thanks um and talk a little bit about history because there's always no good to know where we're coming from who's been doing things to allow us to be able to do it so that includes a bit of development of cardiac surgery and of course everyone I'm sure you'll want to see a few pictures, so there's a little bit about the actual operation in terms of anatomy, so you've already seen this picture that came up before, so who who drew this, none of these literate questions that they're pretty easy, really so uh fire away and if they're not easy, I apologize, but you'll know all about them. So next time you get asked, um so any, I know you can't speak up so you have to chat uh someone suggested davinci yep, yep excellent fine so leonardo da vinci the beautiful amazing drawing, amongst all the other clever stuff he did um did these beautiful anatomical drawings so the anatomy of the heart, it's nothing new. Um Obviously how he got his body's was a little bit sort of slightly dodgy, but we won't go there, so we've known about the anatomy, but in terms of the physiology, it was before this man and I'll literally read this while I talk until the 16 hundreds, when this gentleman was a physician, people believe in the galen system of um the circulation and they thought that the liver was the most important thing and that sort of was active in pumping blood around the body. The heart was just a passive organ. They believe that there were holes in between the two sides of the heart and that the lung added air actually in mixing in with the heart and that pushed the air, pushed the blood around. I either heart was just passive but this uh this person anyone know who he is it might even be somewhere in the picture if you will ke, nice, uh not john hunter but good, guessed william harvey evan davidson has got that right so, and he was a physician in the I think, in the 16 hundreds, anyone know where this portrait hangs might be some artists. Among you, it's good to have outside interests, so it hangs in the National Portrait Gallery, although they sometimes leave it out so no, it's so in London and he was a physician and he studied, went to various places in those days. Pad Wow was a center of excellence as well for surgery, and he got interested in the heart and he used to look at. I think little little meals, etcetera, and he would observe the heart and he actually said that it was so difficult to, I'm paraphrasing that because you can read it yourself, it was so difficult to figure out why how the motion of the heart sort of started began where it ended that only God himself could comprehend because it was happening so quickly, thanks, kirsty, and of course that's because this don't worry, this is not a science tutorial. This is what's happening in the cardiac cycle every single heartbeat, the different colors represent different things is that there's a time take, there's a key at the side, not going to go through it, but what the point is you've got it electrical activity, which is by the sea you can measure by the e. C. G. On the outside. There's changes impression Different ventricles um and a cra, valves open when they close. They make a noise that lub dub, which you can hear with a stethoscope. No I haven't finished yet kirstie um so lots and lots of stuff going very intricate. You can imagine that anybody fiddling or touching the heart or irritating it would interfere with this and therefore the cardiac output and therefore the BP now. Of course, I mentioned, william harvey um every time you think next slide. Please kirsty every time you talk about a first, there's always somebody else who's really done it before and it depends on your point of view anyone know who this, who did this diagram and those of you who can read clearly read easily, which you should be able to. There wasn't Hippocrates, but thank you linda, for uh communicating with me because it's quite scary when you're talking into the ether and nobody talking, yeah, even the fees um uh Did you know that or did you just read it Samuel. Uh you can answer that later, so it's guy called even the feast. He was a arab scholar position in the 2 12 hundreds and between galen and harvey. In fact, he described blood flow in the, in the pulmonary circulation and postulated and I thought about the pulmonary circulation, So when you read about somebody did this first, there's always more than you know one version of what what is first and what what isn't so I thought that was interesting because it, we don't always want to take a Western perspective, want to take a holistic global perspective, thanks, kirsty, so where does that leave surgeons, we've got an organ that's very complicated, it's very complex to understand it's very a sensitive organ. So next slide, thank you um Surgery was taking off in the sort of 18 hundreds, and here we are we're I don't know if they've got anesthesia, they were just holding people down. This is why it's called an operating theater. This is actually um a scene from uh sort of a surgeon who is very famous. I might ask you is this is very famous painting as well, so, I might ask you a little bit about that, but anyone who who this might be and anyone know where it was painted and whether and um if you get all three, I'll give you a prize and where the painting hangs so while you're thinking about that, but I can't go to next slide because you know the answers, so why is he squatting. I don't know you're talking about the previous thing, so anyone know who this might be is not Listo, who uh was father of anti sepsis. Know, I don't know who keeps saying galen, but it's not galen because he was a long time ago, so um jenna know, he invented staff daisy um it's not by Rembrandt, I thought you were saying is it rembrandt, and I was going no it's a surgeon, so uh not for sale, it's either, but thank you for interacting. So next slide, it was actually a person called Theodore Billroth, and he did a lot of somebody's got it there, so um he actually was a bit amended that name group. Um He actually was known as a father of General Surgery. He developed a lot of things There's still some operations, some historical now and now that you don't have so many bad ulcer ulcers needing surgery, but Theodore Billroth, father of General Surgery, and this is him demonstrating to his sort of male sort of students because there weren't any women there at the time or allowed to be any women there at time, no no I'm still talking about that sorry um kirsty, so he actually said any surgeon operates on the heart, should lose the respect of his colleagues, So clearly it was something that um wasn't to be done why, wasn't it to be why why should he say that why do you think he said that what happened if surgeons did try to operate on the heart well, it was because the patient died, so that's really not a good look every time you go and do something to a particular organ. The patient yeah they failed the patient died, so I'll come back before I go to the next slide, so it's billroth, so we've got um somebody got that actually it's in set in vienna and if you ever go to Vienna, there's a museum, anyone only famous museums in Vienna, which it's it's hangs in the Belvedere Museum, which is beautiful, building like an old palace, and um in fact it's where they have is it, clips the Kiss, so in one room, it's that very famous painting the kiss and everyone's queuing up and you know my husband, we try to try to do the kiss with a selfie and we're not we're not very good at it. I'm sure you'd be better at it, being sort of 10 2030 years younger and then we went into the next room and I saw this and I was gushing over it. My husband was wondering what the hell was the matter with me because nobody else was in that room, so it's in it is a beautiful museum, so next slide, please, so Bill roth said nobody should operate on the heart, but in fact somebody people do go on to do something and this guy is again there's a number of first of heart surgery depending on how you define it, but this is good. Michael ludwig renna german eminent, german, uh surgeon, and he actually his gardener came sort of fell by his side having been stabbed, and he opened the the chest and over soda superficial, a tear on the surface of the heart, and he prophetically said that he would hope it would lead to more investigations, and it showed the feasibility that if you touch the heart, you don't necessarily die, so next slide, so again, I asked you why and you answered earlier. The reason people didn't do it was most people died, So next slide so when you've got and I've told you it's because lots of complicated things happen in within the heart and it's very sensitive, so people thought about it in a different way. Next, slide piece kirsty um and this goes to the heart of why the heart doesn't like being touched various formulas you'll learn in medical school and one of the easy ones is cardiac output is heart, number of heart beats, a number of times the heart pumps, times the amount of blood in the heart, the amount of heart blood it ejects out of the heart pushes out of the heart and so it's simple formula, heartbeat or heart rates or pulse, or whatever you want to call it and volume of blood. We'll call it volume now. If you lift the heart or manipulate it and you saw that picture of me uh lifting a heart out yesterday. Those of us who were here yesterday, you're you actually kink the inflow, the inferior vena cava, the blue pipe that goes into it, it's not really blue uh and the superior vena cava so you've got no inflow which means you've not got not any blood volume, so it doesn't matter how hard fast the heart beats. If number of beats can be 200 or 100 but if there's zero volume, 100 times 00, so you don't have any forward flow, so you can't have a BP. Similarly, it's a very sensitive organ and it will tend to the rhythm tends to get disturbed, so if you touch it, you can very quickly go to ventricular fibrillation that wiggly line you see on, er and you sort of uh shock the patient and it gets better so you can imagine it doesn't matter how big if, in the heart distends and gets big, doesn't matter the amount of volume you've got, if there's no heartbeat because a wiggle isn't actually a beat zero times how much volume, stroke volume yeah is. Um it's still zero, so in a few minutes, there's no BP and um the heart no cardiac output. Heart muscle dies because it doesn't get any blood supply. The patient's brain dead that's what people were facing with so next slide. So when you've got a problem, you try to think about how you can actually uh get around it, so one way to think was how, do you preserve the blood flow to the rest of the body, make sure the blood body sees a BP um I, blood and blood flow without while you work on the heart. The other way to flip it is to say how do you isolate not by chopping it out and putting on a bench but isolate it mechanically from the rest of the body. Next slide, please so you can imagine, I of course I won't have a point now, will I or do I can you see my arrow okay, don't worry, then so what people thought was. If you take blood away from the right side of the heart before it enters the right atrium. I'm sure most of you know where the right atrium is before so take the blood away from the veins before they enter the right atrium, do, whatever you want to so the heart isn't having to do any work and then pop the blood back into that bright red A, sending aorta to send fresh blood back figure out what to do in between those two points, then you can actually touch the heart. It doesn't matter if it stops, um etcetera because the rest of the body is still getting a blood supply. So next slide people started working and there's a lot of things there were a couple of people who develop prototypes, and this is your now in the 19 fifties Uh These were two of them, Gibbons, was a certain eminent surgeon, doggerel was a engineer, and like many inventions and progress made in the field of medicine. It's often collaboration between different fields and they came up. This is a very, very complicated prototype of the first heart lung machine and the next side shows you what our typical um heart lung machine there's various different sort of makes, and essentially you'll see that on the left side as you look at it, um you can see the back of a surgeon um There's a perfusionist missing, so I don't think they're actually on you know The patient is attached to the heart lung machine, but you've got tubes going to and from the patient. They bring back blue blood which isn't really blew it sort of very dark purple. If you give blood you can see, it comes out very dark maroon e, that's deoxygenated blood, it goes into the machine you can do whatever you fancy to the blood you can warm it cool it, add oxygen, take away, carbon dioxide filter, any muck out of it, and then circuit um and then circulate it back into, have an active pump, which pumps it back into the ascending aorta, so now you can do you've got something that does the job of the heart and lungs. Happy days. Next slide please, but it still leaves a heart that's bouncing around and can be a little bit awkward to uh um do very delicate surgery with sutures that you can only see with microscopic sort of a glass magnifying glasses, so you really want to stop the heart you can do there is surgery that you can do with the beating heart, but that's not the point of this talk. This is talking about the basics of coronary surgery, so people started thinking okay now how how do you actually stop the heart safely, so on the next slide, you'll see that people worked out that if you put a clamp in between the heart and where you return blood to the ascending aorta, you can actually isolate the heart then that's not good because the heart's not getting any blood supply, but if you then inject some potassium rich solution, the heart actually stops, so you don't do that at home. You know it's in a controlled environment When the heart purse, patient is already on the heart, lung machine, so that's supporting the rest of the body, you then place a clamp to stop the heart blood flow to the actual heart and then proper potassium rich solution, which will go down into the aorta and down the corey arteries and the heart becomes soft and floppy and placid and then you can sort of maneuver it and we'll forget about topical cooling, so so now you've got the set up ready to actually potentially in in theory and in practice to do an heart operations. The next slide, please kirsty, so we can finally talk about tory artery bypass grafting. Next slide uh why are we doing any operation. When you get asked, when you're in medical school, why you do an operation, there's only ever two reasons it doesn't matter what specialty you're in you're either doing it for symptom relief I mean think of all the orthopedic procedures. When people you know their quality of life is affected, so you're doing it for symptom relief. It's not going to save their life or you do an operation of prognosis with the wrong life, that's the case with many cancer um surgeries, so in car, chorionic bypass grafting. We're usually doing it to relieve symptoms and improve the quality of life, so relieving their angina, which is there chest pain and often be patient's present with breathlessness, which is this near um or to improve their lifespan in that we'll have done. Um Many studies show whether you can be managed with just medicines or with stenting and that's beyond the scope of this. You know talk, we're talking about coronary bypass from or whether the pattern of anatomy and the evidence shows that surgery is best. So these are the reasons why we operate on patient, so next life is, so I guess the next thing should be what is angina, so how about. I know it's um chest pain, but what does the actual word mean where does it come from any takers for that mm do do do do. I don't know if there's a delay because there's no answers yet. Uh Someone said angio means vessel I think uh yes, but that's not what I'm looking for some angina. Greek latin, yeah. There's actually debate whether it is greek or latin. Um yeah it's caused my low blood flow uh. It does mean chest pain essentially heart attack is slightly different. That's actually when the artery comes, completely blocked and yet the, some of the muscle actually dies and it is caused by reduced flow blood flow to the heart, so what's the next slide kirsty what if I put so it um It comes from angina pectoris, which is um and zero means to choke or throttle because people often describe a really tight feeling or like an elephant sitting on their chest or a pressure or heaviness pectus means chest, and it's a disc described by this position. Heberden, there's some debate whether it would he described in 17 72 or a bit earlier, but that's neither here that and he described it really beautifully. I mean he described that it would come on, it would come in the chest that would so severe. You thought you were going to die um. And it stopped. It was worse when you're walking, so it came on not on ex exercise, but if you stopped, it would vanish. They're very clear uh good description and in fact, um he also described things called Heberden's nodes, which uh you get in arthritis, which kirsty knows about, but when you get taught about them in medical school, you can say yes. I know because problematic, taught me that, so my work will have been done next slide. Please so back to Connery Surgery. Thanks kirsty. First of all you want to establish the anatomy as I said the bypass surgery, there's two bypasses and people sometimes get, uh forget there's a heart, lung bypass machine and when we start it and start it up, we talked about going on bypass or coming off bypass. Then there's the operation you do we do valve surgery. We do lots of different types of surgery, but the surgery we talk about is also called bypass surgery because you're bypassing the narrowings in the coronary arteries. Now. First of all, if you know need to know what you're bypassing, you need to establish the anatomy, so on the next slide, this is just for your information. This a couple of projections of the heart in different angles and this is um uh it wouldn't look red in a really angiogram. I'll show you so people undergo an angiogram often done from the radial artery in the wrist, sometimes from the femoral artery, and they thread a a catheter, which just means a very fine tube backwards up the artery, so it will then go up the artery and find the ascending aorta and then they try to engage it into the mouth of the left and the right cory artery. They push diet flush dye and they take x ray images and the dye comes up as white and you'll see this. This is sort of uh Corey anatomy and if you go to the next slide kirsty um this is actually um a left Corey injection, so you can see a catheter at right at the top coming in near the sea of the Coriander, Graham and it's injecting dye down and you'll see and I can't point, I don't know if kirsty can because um I'm guessing you can't see my arrow okay, okay, no well, no but just on the just below where it says descending cory artery you can see there's die going down and there's a narrowing and I'm trying to point to it and I'm afraid that it's not working, so you can see that. If you did, if there was this narrowing here and near the top of the picture, you would want to put a bypass graph beyond beyond their next slide. Please again, this is a right Corey injection, and because my point is not working, someone's very thoughtful when they made the slide, i. M. E, uh and put an arrow with the narrowing is, so this is an injection of the right coronary artery and you can see it's nice and smooth and then sort of a third of the way down, it's almost like a pinhole and so there's a tiny amount of dye going down and then going out, so you can imagine if you attach something that took blood from the aorta, something like a vein perhaps, and then sutured it to below where that arrow is blood would actually, then pro, go down this new vein and supply the heart the rest of the heart muscle, thanks kirsty, so you've got your anatomy uh and you say they need to bypass operations a double bypass. Um you you've got them in the operating. There's all sorts of things that have to happen you have to prepare the patient you have to consent, then there's lots of other things but we're just focusing on the operation so they come to have the coronary artery bypass grafting. So next slide, please like any essay or question or short story. There's a beginning, middle and in the end and you have to uh once the patient's in east ties and I've said you've all done all your safety checks and the rest of the team is the person running the heart lung machines. There, you open up the chest and that's called the stine autumn e, you open that cut the skin, the fat, and then you separate the bone, the breast bone with a sauce. So now there are going to be some pictures. Hopefully, it's uh not too distressing, but if you don't want to see any pictures with blood turn away now. Please this is your two uh second warning okay, so next slide and I'll try and orientate you so if you imagine the patient, their head is coming out of the, at the bottom of the slide, uh In fact that's a drape the green bit at the bottom is a drape and on below the drape, or on the other side of the drape. The unisys will be standing um the feet are coming out of the top of the slide, so you're looking at the top half of the chest and that's something called external sore hall sore and you can see that the assistant is retracting the skins. It doesn't get caught, and these are air driven power source, and you split the sternum so that thanks kirsty the next bit so you've got through the bone. Uh At the same time, it's not all the action is happening at the chest. When you first start going to theaters and doing um as a young doctor, often you'll be harvesting the condo it's harvest, meaning a word for taking them out, you know, treating them gently and then taking them out of their natural sort of place Now, the don't want to you know cardiac surgeons. Something you don't even always see in medical schools. I don't want to make it too difficult, but we have two areas that we take conduits or new pipes from next slide. Please kirsty um we um take the often take or almost always take the left internal mammary artery now to orientate You hear the patient's head is on the left of the screen. The legs are on the right of the screen. The breast bone is split and you have a special retractor where you lift up the chest wall on that side, and there's an artery that runs a long parallel to the midline and it supplies branches to the chest wall, eventually goes the abdomen and you take that away you sort of free, that off the chest wall leave it attached at the top in in the sort of neck area, so there's blood flow coming out and you sever it at the divide, it at the bottom, so it's actually got a blood supply and this is one of the vessels will use to bypass beyond the narrowing next, slide, please and the other main source of conduit is a vein harvest, so we usually take it from the left leg. I am not gonna ask what it is it's a long saphenous vein here, they have actually managed. They've actually done a bridge over the knee, so which is one of the techniques you can use so that the and you sort of dissect under that bridge bridge of skin so that because the knee joint moves around and that will be you know, you're you then divide it and if blood went from the foot end to the groin end, you can actually inject blood and that's the way you'd use it, so this obviously you have to attach. When you do the anastomosis on the heart, you have to it's been taken out of the leg. There are other veins in the leg available, so that you know the vein you still have venous return from the leg and you can use it for bypass grafts. Next, scientist, um the next bit, you've opened up the chest. You've got your new pipes that you're going to use or tubes and so you want to expose the heart so same. Next slide same orientation as before the head is at the bottom. The legs um the bottom of the chest is at the top the right. Um As you look at the right, the right hand side of the slide is the right hand side of the chest. These the metal blades you can see are opening up the chest and you've opened the pericardium, which is that layer outside the heart now Kirsty, Ask you a question before didn't she if you have blood outside the heart, but within the sac, that's called the tamponade and you can imagine the sac is reasonably um sort of tight across the heart, a little bit of fluid that the heart sort of can sort of smoothly move with it. You can imagine if there was blood collected in there, we hadn't opened the pericardium, the blood would start squashing the heart so that it can't fill up and then you know if you can't don't have any volume, you don't have any sort of blood coming out and at the bottom end of the heart that sort of bright pink thing is he ascending aorta. Now remember, we're looking at it sort of upside down that's going to the head and at the bottom most of what you can see that yellowish stuff is fat on the right ventricle. The heart is rotated so you can't really see the left ventricle because it's sort of to the left, more under the left side of the that metal blade and that purplish thing you see is the right atrium where you know you get your electrical activity starting their their thanks kirsty. Next bit, so you've exposed the heart you've actually got to it. It's beating away. You want to thin the blood by giving a drug because if you expose the blood to, if you can't make a cut, eventually clots, doesn't it blood doesn't like being in contact with abnormal or um certain external services, so you're thin the blood and then you add some pipes to connect, which we call cannulate, which connects the patient to the heart lung machine. The heart lung machine isn't on yet. So next two slides. Please uh this is a cannula going into that light pinky thing again head at the bottom. Um uh The diaphragm is at the top of the slide and this is a candle in the ascending aorta. You make a reasonably big hole to pop that in and then you secure it with ties. The next slide and that will return the blood to the heart, and this is a tube in the right eight room, which is going to collect that blue deoxygenated blood, send it to the heart lung machine when you ask the machine to be turned on and then return it to that chaotic candela next slide piece so you're pretty much ready to go on to bypass, you can start the heart lung machine because you're taking blood out the heart rather being big and sort of beating. It'll carry on beating, but it will deflate so in front of you because all the blood is being siphoned out to the machine and recirculated, it's not in the heart next side piece, so you can then you're on the heart lung machine yeah that was just to remind me to say that and then you give this heart stopping solution. Next slide. Please kirsty now you don't want it to give to the rest of the body, so you can't now see the cannula or you can just about see the cannula at the bottom just above the drape, the aortic cannula, but you put a little pipe nearer to the heart, put a clamp between those two pipes and then flush it with potassium and stop the heart, and I don't want to get too technical, so we'll carry on to the next bit and you can finally start performing the anastomosis, which means you're connecting mouth to mouth, so you can have an estamos is in the stomach. Were talking about vascular ones, so the next slide you'll see heart in a fairly similar position, the heart that's a diaphragm at the top of the slide and you can well, you can see you've got some hands, you've got some very fine instrument, you've got a little you can see some the yellow, which is fat and if you concentrate you can see within that yellow, there's a little sort of fairly faint pink line and that's how small the coronary artery is you can't see the future because it's so fine and uh the person on the left of the screen in there forceps, they've got the left internal memory and the person in the right is suturing that memory to an opening, so it's very, very fine surgery. Uh Next, slightly so you do the similar bit to the vein. You, then with the vein, you have to connect the top end of the vein to the ascending aorta, restart the heart under all the bits, you've come stop, the heart wean off the heart lung machine. Take the pipes out, give something to reverse the heparin, close things up and um so the next bit I've tried to summarize. By saying occasionally, next slide you need to give the heart a bit of a jolt to get it started and next slide and once you're not bleeding and you put your chest drains in, etcetera. Next slide you close the chest with stainless steel wires and then sutures to your fat and and neatly close your skin job done except it isn't really because these patient's can be very unstable and they spend the next few hours. Hopefully, just a few hours or overnight on intensive care wake up the next day most of my patient's go home day five. If all is well can be complications, I could see earlier. There were some questions. Yep you can have all sorts of things going wrong and you counsel patient about that and you do as many things to try and minimize it. Next slide, please Kirsty, so, this is sort of you were having a double bypass graft. This is an anatomical thing of the left internal memory, uh a right Corey artery bypass graft, although it's not re usually by graft there, but it's just a schematic thing the next slide. Please right, so in summary, it's a safe, well established procedure, I mean the first ones here were in in the sort of seventies, and because once we had the heart lung machines, a lot of valve surgery was done and cory artery surgery really sort of took off in the seventies and the eighties is well established. Now, it's evidence space, it gives good symptomatic relief and it gives prognostic benefit compared to other modes like just medicine, I e, it will prolong your life and and give you extra years, so so it's a survival benefit, and I think that's all, I wanted to say about it next slide. Please so yeah that that was it that clearly, I can't tell you everything about heart, the heart lung machine. The history of surgery Hope you learn a little bit more about that later in the week and everything you know want to know about cardiac surgery that's sort of a postgraduate thing, but hopefully that gives you a feel for it. So if there's a few questions now or I've been furiously typing away. Thank you ok, excellent. Hopefully, people have some really really great questions off the back of that, so I tried to save them till the end, because I thought you would be best to answer them okay, okay, we'll see so someone had asked is there a limit to how long someone can be on bypass and then I guess following on from that someone else had asked what are some of the long term complications of being on bypass. Yeah well. Uh risks, benefits, nothing comes for free. Unfortunately, and yeah, we try to minimize you want to minimize the time patient's time on bypass and even further minimize that extra time the separate time when the heart is stopped as well because even though it stopped and in theory it doesn't need any energy. There will still be some act, activity that we can't see it sort of cellular level, so so which means the heart is sort of dying a bit even though we've protected it, so the risks of bypass, so we do try to do things as quickly as possible and different people have different speeds. It's important not to rush now. The theoretical disadvantages you're taking blood from somebody you're whizzing around an abnormal sort of circuit, your the blood you know is being subjected to share forces uh and it it can sort of deteriorate. You activate all sorts of inflammatory processes, so the longer you are on, bypass the sicker you can be and take longer to recover and you know and we might see sort of low BP and unable to control the BP with drugs, etcetera. So you want to minimize the time, but you take as long as you need to take to do the operation safely and sometimes things go wrong, uh and you have to go back on the heart lung machine. Clearly, the patient's are then sicker and need uh often end up and there's some operations where you have to be on the heart lung machine machine a long, a long time like dissection, which is you know an emergency or maybe some aneurysm operations or if you're doing a double valve and three graft that is going to take longer, but it comes with it. You know it's consequences, which may include death, stroke, renal failure, or these kind of big complications. So um what do you want me to answer. Next, there are so many questions, but I think people do often need blood transfusions. We try to be vigilant and we use something called the cell saver, which has heparin, in which is a sucker with heparin in it, so it thins the blood and then we can actually reuse it um and sort of purified and reuse it into the same patient. So um some has asked about breast uh There was a very good question about potassium, which I know is slightly complicated one to explain as to why the heart but it was why is potassium so important and why why do you need to inject it to be able to stop the heart and then also how to different questions, yeah how do you reverse the effects of the potassium okay fine so good question, last question is good uh well you need potassium for all. Your you know some you might have done uh a level or doing a level biology, most we've done a level you need potassium. It's part of it um part of the thing that keeps the cell membrane stable. It's something that action potentials. All your activity, electrical activity is all to do with sodium, potassium, various sort of uh processes, and um what's the word I'm looking for you know you have sort of uh you have sodium potassium that stabilize the membrane and other things like calcium, So you need it sort of most basic processes too much calcium, potassium and you actually have uh that you d state you destabilize the the cell membrane and so it can't be affected by anything so you can't stimulate it and you get that's why you get the flatted arrest. You don't want it in the rest of your circulation, so it's limited the potassium is limited to the body to the, to the heart and then when you actually stop and you re perfuse the heart with normal blood that sort of flushes out of the system and and the potassium in the body never gets too high because it's just local to the heart and then it's um so I hope that hopefully that explained that so the the pump that was the word I was looking for, I wasn't making something up, thank you, have sir something yeah, I am conscious of time and okay video of a half a section that we were hoping to play there are lots of really really good questions in the chat, but what I'm doing is, I'm I'm writing mall down at the end and hopefully we'll be able to answer them either throughout the week or at the end of the week. At the quiz session okay and I'm sorry, I apologize it won't take too long wendy and no and no no only natural conduit arteries better than veins in theory, Vienna, anything manmade has been shown because it's so narrow there, so narrow for the heart that they just clot off, so an arm veins are no good as well, so and don't use those, not that you would at home. Thank you very much everybody, and I look forward to the next session okay, so um without fellow, I do, I'll pass over to Wendy and kim, who are scrub practitioners in bristol, and if I've um asked to come along this evening to do a dissection with you, um so, I'm going to share the video now. Um I can't see the chat, so, hopefully, I'll answer the questions at the end, and I'll just mute myself um okay, sorry, I'm still sharing screen there, we go um okay can everyone see that I'll put it in proper see the video okay. I think so um is kim there, I can say it kirsty great I'll go back on a second and meat myself is everyone in the chuck, oh yeah great lovely, is kim able to yeah give me that mm, where, is she sorry I'll go back on the video in a second, just yeah, just like all right mike to work okay um So, I've just told her what to do so. She can hear me so, there's a little but um right at the bottom of the page with the microphone, don't do the one on the picture with your initials, nope right, she's gonna ring, she's ringing okay oh all right all right, no I can't get the oh when did you want to just mute a sec, yeah um are you able to answer a couple of the extra questions just while we uh yes, of course fire away, I'll do my best um We had a few interesting questions about the use of artificial hearts and three d printing. I didn't know if you have any comments on that well, yeah, I mean obviously that would be the holy holy grail wouldn't it it would be to have something printed and people have tried with the valves and sort of having sort of uh sort of basic architecture and try to get sort of cells to um you know populate through the valves um There's nothing we have uh artificial hearts but their mechanical hearts at the moment, and there's no ideal thing that you have sort of theoretical problems with blood clotting, infection because even though you can have artificial hearts, they still need a battery that are all sort of, but there are a few prototypes like the jarvik, where everything is fully inside, but as to present it actually making something three g that is actually of um sort of human origin. I mean I think we're a little bit far away from that, but it's a really exciting and active area of research, so and then some other questions, so I thought one of the questions that was really interesting was how do you balance the risk of clotting and bleeding. It's very interesting because you've got to give heparin to thin the blood, so you can actually use the heart lung machine. Then at the end of the operation, you reverse the heparin with something called protamine, which sometimes people can have an allergic reaction to so you have to give that very very carefully and and then a lot of the time spent after the operation, it's not just doing all the fun, It's not just about the middle bit but actually drying up, which we, which we mean by making sure the patient isn't bleeding too much. And then because if they bleed you've got to bring them back out, you know you don't want them to have a tampon odd, or lose lots of volume and uh it's not just blood they lose, they lose all sorts of other sort of factors. You have to balance that with then the next day or the next morning, you're going to start giving them aspirin again or something of the similar, think, so because you don't want the actual graphs the clot off, so it's always a balancing act, but you do need to stop the bleeding uh once you're off bypass, and um but as I said we then give it all seems very contradictory, You have to give something to thin the blood the day after two, usually aspirin or clopidogrel something or Plavix um to make sure that the platelets don't stick within this new pipes, so so that's a balancing act of tricky one sometimes and yes um uh warfarin was sometimes used in the old days as a rat poison, not that now, it's not a nice way to go so happy to answer any questions any more questions, and how long does the procedure roughly take. When taking into account the precision surgery, it sort of takes, we did, I would do two a day. Some people you know if you're all sort of very I'm really fast, aren't, I clever, I can do three a day, but most people do to to operations a day so morning and afternoon, I think I'm quicker at valve, so I can do because I mainly because you don't need to wait for the conduit to be harvest and that internal memory to be taken, so I you know I do uh an Avr able to buy replacement, I can do it in less than three hours. That's no you know that's nice, it's quite good fun you you know 11 30 sort of you know, putting your feet up in between cases, um but any you know 4 to 5 hours, I think four hours isn't unreasonable to to say to people and if you stay longer in theater, it doesn't mean something has gone bad while you're on by party, it might have taken longer to harvest the, you might not find any vein and you had to go to the other leg to get some vein because you don't want to put varicose veins on on somebody's heart, that's not not the best thing for them so. Um I think there were questions about the breast bone and ribs that we don't um cut the ribs. We go through the breast bone, and we use stainless steel wire and no it doesn't go off in uh in sort of airport scanners or anything so. Uh No it's not an obstacle if you wear glasses, I'm wearing reading glasses the last few years because uh because I'm getting old and apparently that's what happens to people. Um so no most of us um certainly for connery surgery should wear glasses anyway, even plain glasses for eye protection. You know the even though you do tests on people, you don't want to get blood in your iron end up with hepatitis or hiv, or whatever or anything really most of us were something called loops, L0 ups, and they are plain like if you don't have any spectacles, they're just plain glasses and onto the middle of them um minor work, they have magnifiers, so when you look if you look around, you can just see normally through and if you have prescription is is, you can actually have prescription lenses in your glasses and then if you have for your close vision, you have magnifiers and most of us use turn half loop. Some people pediatric surgeons often use 3.5 loops and you have a limited when you look through them, you have limited vision in terms of diameter uh and you have limited depth of vision, so you get measured up so that you don't have to slouch too much or whatever so so, yeah glasses not a barrier at all so. Um I don't understand that question is that called a graft. I don't know, um I can keep talking if we and maybe and we'll see how Wendy and kim do no, no it's um um There was one question about further up about the different types of of surgery that you can do on hearts obviously cabbage that we've talked about Tonight is just one of them, but I didn't know whether you had okay well. I mean if you're doing sort of big sort of headline stuff your corner, the artery bypass grafting, then you have valve surgery, valves can be, uh you could be replacing valves or repairing valves and all valves are repairable. You might be operating on the ascending aorta. Uh It might be aneurysmal. It's big that word that it might have torn. You might be doing various sort of sections of the aorta and the uh as it turns into the arch, so those are the sort of things, but there's lots of others as pediatric cardiac surgery. There's transplantation surgery. Some people focus just on the aorta, summer mitral repair experts, and of course cardiothoracic, so we're talking about cardiac today, but they there's it's actually includes the whole world of thoracic surgery, which isn't just lungs and lung cats, although clearly that's a large part of it, but it has all sorts of, there's lots of stuff in the mediastinum, which is the inside the thoracic cavity. It's not just the heart and lungs. You have lots of various tissues and you can develop sort of tumor's and masses that can compress you can have problems with the veins uh. I think I'm doing quite well. I think I should get a prize for carrying on talking here so uh there's something about hiv, I saw earlier, know you do the same operation, but clearly you have to be very careful if somebody has a hepatitis B or hiv, you probably try to minimize the theater personnel. You probably wouldn't have anybody in theater afterwards and be scrupulous about cleaning you do all these things Anyway, you should do sort of good practice and sort of try to avoid any injuries, etcetera, but then sometimes when you're trying to be extra careful things can actually go wrong, so, I I stabbed myself with hep, was it heavy or hep c patient last year with the scalp because I was being so careful and I was exaggerating lee, sort of giving my knife away and as I said before I always say, it's like korea uh choreographed ballet, everyone knows what they're doing and I try to make an extra obvious thing that I was stepping away from the second assistant and managed to not move my right hand out of the way, so there we are these things happen