Welcome to Dr. Warrick's podcast channel. Warrick is a practicing cardiologist and author with a passion for improving care by helping patients understand their heart health through education. Warrick believes educated patients get the best health care. Discover and understand the latest approaches and technology in heart care and how this might apply to you or someone you love. Hi, my name is Dr. Eric Bishop. Welcome to my podcast and videocast station. And today I'd like to talk about cholesterol and where it ends up in the artery and perhaps how it ends up in the artery. Well, I'm specifically going to be talking about a researcher, a doctor called Vladimir Subotin, S-U-B-B-O-T-I-N. And if you're interested, he's written a review. in the Drug Discovery Today journal back in 2016. Vladimir Subutin is a member of the Russian Academy of Sciences and has an interesting take on the way cholesterol ends up in the arteries. Well, I think we're all fairly familiar with the idea that cholesterol and coronary artery disease are linked. And we're also pretty comfortable with the idea of what we call the LDL hypothesis, LDL being the so-called bad cholesterol within the bloodstream. We've got lots of data over many years now that supports the premise that if we take people who are really high risk of having a heart attack and we lower their cholesterol, LDL cholesterol or bad cholesterol then we can reduce their future risk and I don't think there's any confusion or argument about that I think it'd be fair to say that cholesterol is probably not the whole story and there are certainly other issues at play such things as inflammation but of its own lowering cholesterol in high-risk individuals has been shown through research over the last decades to correlate with reduced risk. Well, the interesting thing about that is the mechanistic processes in which that occur. And when I say mechanistic, I'm talking about the mechanism or how the cholesterol gets in the arteries. To a large degree, we've often thought that the cholesterol floats around in the bloodstream. in its special little transport vehicles the lipoprotein particles which carry it around and deliver it to its location. We've generally thought that within an artery there's a point of perhaps wear and tear where for whatever reason the lipoprotein the lipid and protein particle that carries cholesterol around becomes adherent and is able to cross the inner lining of the blood vessel and deposit the cholesterol at that location. Well that's a reasonable hypothesis and it's very hard to actually measure exactly what's going on because for us to look at the exact mechanism requires us to look at a living organism and it's very hard to look at a living organism. in that detail unless you've got it under a microscope and the very fact you've got it under a microscope negates the possibility of it being a living organism anyway rest with the idea that general or popular consensus has been around the idea of cholesterol coming out of the bloodstream and into the artery wall well Sabotin in his review shares with us A number of facts and evidence suggesting that perhaps this isn't the primary mechanism, that perhaps there's another way. Let me try and break that down for you a little bit. If we think about the artery as having several layers, and the layers we call tunica, as in wearing a tunic, a top or a coat or a covering, There's three main layers that make up the artery wall. There's a inner tunic, that thin lining that is actually in contact with the bloodstream. Then there's a middle lining, and then there's an outside lining. And look, a really nice, simple way to think about those is that the inner lining, the tunica intima, is perhaps like thermal underwear that you might wear pretty thin you could almost see through it it's sheer that's what's lining the artery then the next layer might be like a thick woolen jumper that's the tunica intima and that's the middle layer and then there's the outer layer which is if you like like a waterproof over the top Now, the interesting thing is when we do look at slides under the microscope of the development of plaque in the arteries, it looks like the beginning of cholesterol buildup occurs in that woolly jumper layer. Well, that's absolutely fascinating because you'd probably think if the cholesterol was... going into the artery wall from the artery, from the inside of the artery, then it would probably accumulate just inside the tunica intima or the thermal layer that we're using as an example. So very interestingly, Sir Botan in his review talks about how this cholesterol appears to be building up in a location which doesn't quite make sense. with cholesterol migrating from the inside of the artery out, and puts the proposition that the cholesterol is not coming from inside the artery at all, that what is occurring is that there is wear and tear at a point within an artery, that wear and tear kicks off irritation, that irritation and inflammation stirs up local cells to release tissue factors, signaled to the body that there's been some sort of damage or wear and tear. Now we know cholesterol is a building block and so deals with wear and tear. Now here's the interesting thing. Sabotin suggests that instead of that cholesterol going from the inside of the artery, the actual lumen of the artery making its way out to the center or tunica intima sorry tunica media the central layer of the blood vessel what's occurring is that the very very very fine blood vessels that actually supply blood to the blood vessels and these are called vasovasorum so try and understand that there are tiny little blood vessels that actually supply blood vessels to make sure that the blood vessel is healthy Sabotin suggests that the cholesterol travels into the artery, the middle layer of the artery wall, via these very, very small blood vessels which are there to provide nourishment and nutrients for the artery. Now this is incredibly plausible and I think certainly warrants consideration and forces us to ask the question, how in fact does that cholesterol? get in the arteries well i think this is a really interesting space i think we have to be aware that cholesterol of course of its own is not the whole picture in coronary artery disease because we know that wear and tear is important we know that blood pressure is important we know that inflammation is important and also importantly we know that regardless of the mechanism of how cholesterol gets into the artery wall that lowering cholesterol in those high-risk individuals will reduce their future risk. So I hope you found that interesting. I hope that's maybe answered some questions or given you more food for thought. Either way, I'm going to wish you the very best. Take care. Bye for now. And please don't die from a heart attack. Goodbye. You have been listening to another podcast from Dr. Warrick. 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