Instant Genius - The heart, with Sian Harding

Episode Date: September 25, 2022

Sian Harding, author of The Exquisite Machine: The new science of the heart, explains how the heart works, how to keep it healthy and the future of research into this essential organ. Hosted on Acast. See acast.com/privacy for more information. Learn more about your ad choices. Visit podcastchoices.com/adchoices

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So you can experience exceptional sound at home. Music just as the artist intended. Visit name audio.com to learn more. The Bitesitesize brass class in podcast form. I'm Alex Hughes, staff writer at BBC Science Focus magazine. This week, I'm joined by Professor and author Sean Harding. She's the author of The Exquisite Machine, The New Science of the Heart. She explains how the heart works, how we can look after it,

and the biggest risks we face with our hearts. So I think a good place to start, is probably a bit of a refresher course. So could you explain what exactly it is that the heart actually does for us? So the heart pumps all the blood around the body. It has two circuits, in fact. So it's got the left circuit, which are the left ventricle, which pumps the blood into the body under high pressure through the aorta.

And that returns to the right ventricle. And then the blood goes around the lungs, where it's refreshed with more oxygen and carbon dioxide removed, and then goes back again. So it has the dual circuit there. But mainly the idea is to keep your blood pumping. And really, your heart generally beats to sort of 60, 70 beats a minute. And you probably know that if you miss four minutes of that,

that's it, your goner. And we've been studying the heart for years. It keeps us alive all day. It's very important. But how much do we actually know about it? Is there something that we know inside now? Or is there still very much a mystery to us? Well, I went into the cardiology really quite some time ago,

about 40 years ago now. And because the imaging and the methods around studying the heart were getting so much better, I could see that it was unlike the brain, which was still at very early stage of study, there was a lot we could do with this. And the imaging has got better and better, both on the sort of macro level on MRIs and, you know, the electrical activity of the heart, and on the micro and nano level on the cells. And as imaging improves, we find out more and more. And I can say that during my career, even now, even as I retire, I'm still finding out new things about the heart every day.

I think one of the major things that people are interested in the heart is about the disease itself. What are the major factors of heart disease other than, I guess, the obvious ones of people not living healthy lifestyle and alcohol? do genetics matter? Does your social status, your economic background, I assume sleep is a big factor? Yes. So the, as you say, people probably know the major risk factors about what they should take care of. High blood pressure is one, which is very common, and cholesterol, high lipids, another. And those things you can treat to some extent with a healthy lifestyle and you should definitely try to do that. But there are times when, especially as we age, that it's difficult to really keep cholesterol down or to keep your blood pressure down. And so there are very good drug

regimes now for keeping your blood pressure down and the statins for cholesterol, which really have shown massive benefits in terms of cardiovascular health and you should definitely, you know, I'm a pharmacologist and so I, we would, that person who develops drugs and so I like to say keep taking the tablets. We spent a lot of time making them and, you know, the, the drugs do work. So there are those things. Then there are things that have sort of emerged more. as you say, genetics. And many of us will carry around mild genetic mutations that could predispose us to heart disease. And some rarer ones, some more severe ones too. But when people looked at the genetics of dilated cardiomyopathy, one of the heart failure things, this was a, found, mutation Titan was found to be responsible for about 25% of these.

It's a very long protein and very prone therefore to picking up these kind of mutations. But when they looked in a normal, apparently normal population, they found that about 1% of the population also have some kind of mutation or variant in Titan. And it's sort of emerged as we've gone along that many of the people in the normal population will stay healthy. But if they have a kind of second hit, like high alcohol intake or even just high end of normal, or chemotherapy drugs or pregnancy is a big test of the heart, so they can be more susceptible to damage and getting heart failure when they encounter those things. So certainly genetics is one of them.

As I mentioned, chemotherapy, because it's being very successful in many cases like breast cancer, for example, now we're starting to see that the damage caused by chemotherapy on the heart, the heart has very little sort of reparative processes and these are kind of knocked out by the chemotherapy drugs. When your hair falls out, you know that. And so all your organs are damaged by the chemotherapy drugs. And the heart is one of those. And of course, you've only had one heart. You can grow your hair back.

So the other things that you mentioned, the social hierarchy is quite an interesting one. It's very difficult to know what you might do about this. But even animals in a cage, even mice in a cage, in a laboratory environment where they all eat the same food and they have exercise wheels to run on and they have toys to play with. So they have the same kind of environment. But those at the top of the social hierarchy,

like the alpha males will do a lot better than those at the bottom of the hierarchy, who can in fact just develop spontaneous heart disease, atherosclerosis, and furring up of the arteries. So even that social rank, and that's been reproduced in the studies of, for example, civil servants, the Whitehall studies. You can see the social hierarchy there in a set of people who really have fairly similar lifestyles. So health standards and exercise have, I mean, obviously improved drastically over the years. Has this improved our overall heart health as a society?

Yes, particularly heart attacks. There's been a really major drop in the mortality from heart attacks. And that is because people are living better lifestyles. It's also because they have things like the heart failure and statins, the statins and the blood pressure, drugs. One interesting thing, though, is that when you have something like a heart attack, or you have these other kinds of damage that I've mentioned, like chemotherapy or an inherited heart disease, if your heart is underperforming and the body is sensing that your heart has lost power, then the body responds to stimulate the heart. However, this is a kind of. However, this is a

kind of evolutionary reflex. We didn't really have heart attacks and things in, you know, our evolutionary, long evolutionary past. And so what the heart is responding to is something like, as if you were trying to run away from a predator, so the fight and flight response. So it's stimulating your heart with adrenaline. And or it's thinking you're having an injury, so you're having blood loss, hemorrhage. And so it's trying to shut down your blood.

vessels to stop blood loss. It's trying to load your body with water to replace the blood you've lost. So hormonal things come into play with that. And they're fine if they are for emergency responses and they're short term. But unfortunately, if they're prolonged as they are for over weeks or months or even years when you've got this poor heart power, then they are damaging. And so you get a second wave of damage that drives the heart into a heart failure. And this is quite distinct from a heart attack. With a heart attack, you get the pain in your jaw or your chest or down your left arm. You feel sweaty, nauseous, faint.

But heart failure is quite different. It's been described like feeling like you're drowning. So your body is loading itself with water. you get swollen limbs, swollen ankles. Water collects around your lungs, so you become breathless and very fatigued. It sort of collects around your gut, so your digestion is affected. And so that is increasing in the population because people are living in a sense with this heart damage. And so a lot of what we're treating now is heart failure.

There's probably about 900,000 people in the UK living with heart failure just now. For someone that wanted to have good health and wanted to, I guess, prolong their life, what are the key things that they should be doing? So I've mentioned getting tested and so having your blood pressure taken. And in fact, there are many sort of wellness and health. initiatives that take your, you know, we'll test your blood pressure and you become 40 or over. So certainly that and then obviously carry on with the medication. Try to keep your cholesterol down.

The Mediterranean diet is a tried and true one for, you know, with the leafy vegetables, etc. try to keep alcohol within reasonable bounds. There's some evidence that a small amount of alcohol is actually not too bad for the heart. But certainly, you know, the amount that you think of as not too much is getting lower and lower all the time. So one drink a day, one standard drink a day would be the thing. Obviously don't smoke. That's a big one, not smoking. It's probably top of the list, in fact.

Exercise, yes, and extremely important, particularly going from sedentary to some exercise. Of course, you can run marathons and things like that. There is some evidence that the very extreme exercise is probably a bit too much, but almost none of us will fall into that category. I think the sort of recommended thing is something like 30 minutes exercise, moderate exercise a day. So a walk, brisk walk, to housework,

anything that sort of just gets you moving, really. It's not too testing, not too difficult to get to that kind of thing. Then some of these other things, it's probably just a case of being aware. And so the chemotherapy, the social status, you know,

that that's going to be a fact, factor. But pollution also, there's a very interesting study I talk about in the book where people were asked to walk in Oxford Street, where it's all it, when it had mostly diesel traffic, etc. Just at their own pace, just for two hours. There were some healthy people, some people who had heart or lung disease. And then they were asked to also to walk separately, in Hyde Park, which is only at the end of Oxford Street. It's a lovely big park, but not, it's still in the centre of London. And the difference in pollution levels there was probably about double in the sense that it's

just under the recommended limit in Hyde Park. And it's about, it's fairly strongly over the recommended limit in Oxford Street. And in a high park, even a couple of hours walk, showed some effect on blood vessel health, for example, that lasted a couple of days, actually. It was quite gentle exercise, so, you know, nothing extreme there. But in Oxford Street, the opposite was true that there was distinct effects on the blood vessel health. I think, you know, problems decline in blood pressure, blood vessel and lung health. while walking down Oxford Street. And that was related to the pollution.

They were all wearing sensors for pollution. The noise levels also, which noise pollution is another thing. As you say, disturbance of sleep from noise pollution is a particular worry. And so those things, apart from public health initiatives, it's difficult to avoid all the time, but you can just be aware of those things. And on the opposite side of that scale, how can you tell if your heart isn't bad, Nick? What are the signs that people should be looking for so that they can go to the doctor when they are worried about things?

And so the heart attacks are the very dramatic one, obviously. There's what you need to do for a heart attack is make sure you get, you say when you get an ambulance or get to the hospital very quickly, but make it clear that you're having a heart attack because, or you think you're having a heart attack, because there are specific protocols, specific centres that you go to where they're very slick in diagnosing and treating. And what we say is time is muscle. So it's important to get to a specialist centre.

don't go and sit around in A&E waiting or wait for a point with your GP. Go straight there and as quickly as you possibly can. In terms of other problems with heart, breathlessness and not able to exercise is a warning sign. Chest pain, not like the heart attack, but sort of intermittent chest pain like angina. that's definitely a warning, and particularly if you get that at rest. Then there is one other thing that I talk about in the book quite a lot, which is having a sudden,

a sudden, very extreme emotional experience that will, can precipitate the, the heart disease. So, for example, bereavement is one of the key things, which causes this really strong emotional stimulus, causes a real surge of adrenaline. And people can suffer sudden cardiac death. And so that would be where you would really just feel faint and fall to the ground. And what's happening to your heart? heart there is there's a big disturbance in rhythm, a fibrelation. So your heart really, all the different parts of your heart are beating, but not in a synchronised way. So they can't expel blood. And once that happens, you have really four minutes for that. So that's why there are defibrillators

in many places. And you should get, you know, again, call the ambulance, obviously, but get, again, to a defibrillator, a local defibrillator, if you see somebody having this and use that. More people should really be trained in the use of defibrillators. So that's sudden cardiac death. And there's another one which is somewhat rarer. It's seen, sudden cardiac death is mostly seen in men, but it's seen men and women, but probably about 80% in men. in women, especially post-menopausal women, there's another syndrome.

And both of these are often called broken heart syndrome because of the attack, the sort of big effect of bereavement in this respect. And they are admitted to hospital thinking they're having a heart attack. And when their heart is imaged, the doctors can't see any blockage in the vessels. It doesn't look like they're having a heart attack. They can't see any damage to the heart. But what they do see is that the heart is contracting in a very strange way. So part of the heart can be contracting really vigorously.

Part of the heart, often the sort of tip of the heart, is not contracting at all. It kind of looks like it's ballooning out. This is often called Takatsubu syndrome. It was first seen in Japan. And this is the shape of the octopus pot they used to do something with octopuses, trap them, I suppose. And so it's been given that name. And it can be fatal also.

About 5% of people who come in with this will have this problem. So it's about 80% of these people who are coming will be post-menopausal women. but and about 5% of the whole population come in like this will could can die but but of those who remain they people don't quite know what to do they sort of give supportive care the doctors and they will could can recover very quickly and so they they can recover in days or weeks and have um yeah it's difficult to say because you didn't see their heart beforehand, but reasonably normal effect. Maybe there's some residual damage, we're not completely sure, but they have, to all intents and purposes, a normal heart. So this is a very interesting difference.

And there's a paper that I often quote, which is, the football, for example, is an extremely strong stimulus for this. There's about 30% increase in cardiac events around the time of the World Cup and particularly if there's a penalty shootout. There's this particular

paper which describes a family in Chile who were watching the World Cup final against Brazil and their team was playing Brazil with the family. And they lost

on the final penalty kick. And then there was a huge argument, it arose in the family. And after that, the father was taken to hospital with chest pain. And in fact, his heart went into fibrillation, and it couldn't defibrillate him,

and sadly he died. But the mother was brought into the same emergency room, about an hour or so later, and she had developed the Takatsubu syndrome, And so she had this acute heart failure to start with. But then she recovered fully and went home. So this is a real demonstration of the difference between men and women in this disease. You mentioned quite a lot then about the emotional side of heart failure and the heart in general.

Could you explain a little bit about where this belief of a heart being attached to love and emotion and romance has come from? That was a more historical thing when people didn't completely know what the heart did. But I think possibly because you can sense your heart. Some people are better at sensing their heart than others. It's called interoception, this ability to sense what's happening inside your body. But most people can understand when their heart is racing or pounding, if they're being running or if they've been frightened, they've been watching a horror film. So most people can feel that.

And in fact, the sensing of your heart, having these kind of, this kind of racing is enough to amplify your fear, for example. So in fact, if you could play recording of a racing heart to somebody and you tell them it's their heart, they will, you can even precipitate a panic attack in that case. So there is a little tiny plexus of nerves inside the heart, which it has both sensing nerves as well as nerves to, you know, receive messages from your brain. and it can tell your brain, you're frightened in that sense. In your book, you talk about issues with the heart being often the result of treatment for other issues like cancer, for example. Is this something that can be balanced out or is it currently a bit of a unsolvable problem? It's been tougher to solve than we've thought that the early cancer drugs are, mostly just poisonous, really.

And so they poison the very rapidly dividing cells, one of which is a cancer, more than they would to other cells that are not dividing. And so we knew that they were pretty damaging for the body. But they're very good for the cancer, so you can't not use them. Then more specific drugs like monoclonal antibodies like her set. for things like the cancers that, of which have estrogen receptors, for example, like breast cancer, they were developed and they thought that that would solve the problem. But actually, the first trials were very disappointing, and there was probably about,

especially when they were mixed with the older cancer, some of the older cancer drugs, probably about 25% of patients in one trial, for example, went into heart failure. and it was estimated at that time that even with the new drugs, that nine years after you had the diagnosis from breast cancer, you were more likely to die from the heart effects of the treatment than you were from the cancer recurring. So there's a lot of work being done about this. So a lot of drugs and now it's very, they're taking trouble to,

tests the drugs for both cardiac and cancer effects before bringing them to market. So there's a lot of new drugs coming onto the market, which are going to be better, we hope, for that. The oncologists and the cardiologists are teaming up at various hospitals so that you have a clinic. So you can understand if anybody's particularly at risk, you can monitor the people as they go through the chemotherapy. You can get get them, this sort of protective heart failure type drugs quickly if necessary. So there's definitely a lot of work. There are cardio oncology societies specifically aimed at thinking about all the studies around this area.

Something that I think has seen massive growth in recent years is the use of heart rate. trackers, whether that's through smart watches or through dedicated heart rate trackers, is this something that we should be wearing and monitoring or should we be taking some sort of measure of our heart health throughout the day? It's not a bad idea. One of the things you can see that's very useful to know is your resting heart rate. And your resting heart rate should be, well, once it goes above 70, you should just start to take care about that. And if it's getting up into the 18th, 90s, then that's a predictor of bad heart health in the future. Obviously, your heart rate goes up when you exercise, and that's good.

And usually if you exercise a lot, then your resting heart rate will go down. And so that's good. And then there are just starting to come out. Some of the watches can detect arrhythmia's rhythm disturbances in your heart. There's a very common one called atrial fibrillation, which is good to, catch early. And so some of them, the monitors have got that.

And even if it just brings you to the doctor to have a proper ECG done, that's probably a good idea. I mean, it's very interesting all the different the development of the different devices. There are now a way of

thinking about maybe through earphones, which you, your AirPods, for example, where you've got there in your ear, you might be able to detect not only the heart rate, but perhaps blood pressure as well. Also, some of the things like when you eat, they can detect what, you know, they can give an idea about what you're eating. And so you can understand that's much more reliable than people reporting what they're

eating, which tends to be, like reporting of alcohol, tends to be a little bit on the optimistic side. So that's good. There's, there are, you've seen probably the airport sensors where you can see the people where they've got a fever, for example. But adapting those kind of sensors to be, to understand from the small fluctuations in the light signals coming from the face of the person, their heart rate or even, even possibly blood pressure and putting those around in homes where people are vulnerable, where you need to understand whether they're going to have a problem. And so you can track people, monitor them in their own home.

And I think we've made it quite clear throughout this that heart medicine is moving at an incredible pace. what improvements do you think we might see in treatment in the next few years? There's a couple of really big areas. One is the gene therapy. I described a very early trial in the book, and that really just showed us we needed more of the gene to get in, really. But the British Heart Foundation, which in the years, UK fund about half of all cardiac research have just given a big prize of 30 million to a team

led by Oxford but worldwide also who are aiming to use the new genetic techniques of gene therapy or gene editing where you use something like CRISPR CAS 9 to snip out bits of genes or insert bits of genes and to tackle inherited genetic conditions. So this is a big challenge, because the technology is quite new, and there are all sorts of complications in terms of trying to get these genes into people. But that's a really huge area that's going to expand enormously soon. The other thing that I worked on a lot was cell therapy. And one big sort of success has been making new heart tissue but from just ordinary cells.

So you probably heard about embryonic stem cells. And there are a small number of cells that occur in the early fertilized egg, which can then go on to produce all the organs in the body. So if you take them out and you culture them, they can make cart or lung or kidney cells. And so if you get the right kind of combination of factors, using the kind of things that the body itself would use during development, growth factors and things like that.

So you can make from those cells beating heart muscles, cells. Now, that was very informative, but are using embryos, of course, has huge ethical connotations. And so it's illegal in the UK with strict regulation, but many other countries have problems with this. And so it was fantastic when about just over 10 years ago, a guy called Shunu Yamanaka was won the Nobel Prize because he showed you could take an ordinary cell from your body. He used skin cells because skin will grow quite well in a petri dish. Or you can use cells that you isolate from your blood or even those waste cells you can pick up from urine. And anyway, anything that will grow nicely in a dish, you can treat with reprogramming factors to kind of reset them to be like embryonic.

stem cells. You take out the messages that make them what they are and you reset them, turn the clock back, like default factory settings, so they become stem cells. And stem cells can reproduce indefinitely, a bit like cancer cells in a way, but then they can be turned into all the different organs of the body. And so in our lab, which was a very ordinary kind of lab, we were able to make patches of heart cells beating away about the size of your thumb. And it really was only the cost that stopped us from being able to make bigger ones. Now, people have made ones the size of the palm of your hand, for example, which is just the right size to go over a scar in a heart that's had a heart attack.

And early studies have begun. They've begun around 2020. and we've just had some news from the Japanese who did some of the first ones, that they're safe, and that there's some indication of the benefit. But these are very early, small studies. Thank you for listening to this episode, Instant Genius. That was Sean Harding. If you'd know more about The Heart, check out her book, The Exquisite Machine.

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