How to Keep your Heart Healthy

Your heart pumps around 6,000 litres of blood around your body every day. But just how does it achieve this incredible feat? Cardiologist Dr Niall Campbell gave Chris Smith and introduction into the body's central organ...

Niall - My name is Dr Niall Campbell. I'm a consultant cardiologist, which is a heart specialist and I work at Wythenshawe Hospital, which is a large hospital in South Manchester.

The heart sits slightly to the left of the middle of our chest and it's a pump for moving blood around the body. The reason why we need to move blood around the body is to supply oxygen, sugars, and nutrients to the rest of the organs in the body.

Chris - How does this pump work - what's inside the heart that enables it to do that?

Niall - The pump has got four chambers and the heart is made up of a muscle. The two chambers at the top of the heart are called the atria, the two chambers at the bottom of the heart are called the ventricle. And there are four valves inside the heart which enable blood to flow into the heart and be pumped out of the heart in the correct direction so that blood can go from the left side of the heart to the rest of the body from the right side of the heart to the lungs where the blood can be oxygenated.

Chris - Why do you need to two halves to your heart, a right side and a left side like that?

Niall - So, blood flows to the right side of the heart from the rest of the body and that blood has low levels of oxygen. That is then pumped to the lungs where the lungs supply the blood with oxygen. Blood then flows to the left side of the heart and then that blood, which contains oxygen is then pumped back to the rest of the body, completing the circuit.

Chris - So when I put my fingers on my wrist and I feel my pulse, what does that correspond to and what is the heart doing to produce that pulse?

Niall - So, what you are feeling in your pulse is the blood flowing through your arteries and that is blood which is coming from your heart to your hand. That heart rate is controlled from the top right hand chamber of the heart from an area of the cells called the sinoatrial node, and that is almost like a beacon, or lighthouse which sends our repeated electrical signals. Those electrical signals are then transmitted from the top right chamber of the heart in a coordinated electrical system of motorways down to the bottom chambers of the heart to ensure that all the chambers of the heart pump in a coordinated fashion.

Chris - And when a cardiologist like you does an ECG you are recording that electrical activity and that tells you how the heart's performing?

Niall - That's correct. We are able to look at the ECG and we are able to work out exactly what is happening electrically in each chamber of the heart at any one time, and that enables us to make diagnoses about normal heart function but also enables us to give us an idea of what happens electrically when the heart starts to have problems.

One method being used by scientists to investigate the heart, and heart problems, is by looking at how they form in the first place. This is its embryological development. Birmingham University's Alice Roberts is a clinical anatomist and she's just written a book on the subject...

Alice - Embryology is largely just how a single cell, a single fertilised egg develops into a baby. So you look at how cells proliferate. And there's this wonderful process of origami where new tissues form and they fold in on themselves and some of it's quite destructive as well, so you get cell death occurring to separate the fingers for example. Or particularly relevant to the cardiovascular system where you get rods of tissue forming and cell death in the middle producing little tubes which will later be blood vessel.

So when you look at the development of the heart embryologically, you see that it basically forms as a contractile vessel and then it loops around and it has to undergo this process of septation.  So you get, essentially, little partitions appearing in the heart, which set it up so that at the moment of birth, it can suddenly go from supporting a single circulation to supporting a double circulation which you need if you're an air breathing animal, which you suddenly become when you're born. Up until that point you haven't been using your lungs to breathe air and instead you've been getting your oxygen from the placenta which enters the heart in a completely different way.

So embryology helps us understand the function of the heart during the antenatal period, so in that nine months when you're in your mother's womb. But also, actually, it has real relevance for understanding congenital heart defects as well. Because a lot of the problems that we see in babies hearts are because of something going slightly wrong with what is actually a very complex process in the embryo.

Chris -  Alice Roberts. And also studying how the heart develops is Sheffield University's Emily Noel.

Emily - We're trying to understand how babies are born with certain heart defects. So, why they're born with holes in their heart, arteries that don't connect up properly, and we try and understand what genes make these process happen normally and why they go wrong.

Chris - How common are these abnormalities?

Emily - These abnormalities are the most common birth defect that there is, at least 1% of live births. Often these are sorts of defects that need to be corrected immediately postpartum and, quite often, even if you have surgical correction of these defects, individuals can end up with lifelong complications as well.

Chris - How are you trying to get to the bottom of why they happen?

Emily - We use embryological models - things like mouse or things like zebrafish to try and understand how your heart develops normally. Understanding how an organ develops normally is very important for being able to understand then what goes wrong.  So we try and identify which genes are important for normal development and then we can systematically try to understand why these genes are important.

Chris - It is complicated but can you explain, for the likes of me, how does a heart develop and when?

Emily - The heart develops very early during embryonic development. So, in humans, your heart will have developed already by around four or five weeks after fertilisation, and the heart usually starts off as a very simple tube. This tube then undergoes quite a complex folding event, which is very important for making sure that your chambers line up properly, all your veins and arteries form properly, and it this sort of process of folding that we're very interested in and, if this process goes wrong, why you end up with defects.

Chris - So one tube bends itself into a series of wiggles, I suppose, and that gives you the sequence of chambers that the adult heart has?

Emily - Yes, that's correct. So one tube forms initially and this tube is already sort of roughly divided into what will become and atrium and what will become a ventricle.Those are the different chambers of the heart and then this tube will undergo two bending events which will mean that your atrium and your ventricle are going to be in the proper place in the adult heart, and that the sceptre between them can form properly.

Chris - Those are the walls?

Emily - Yes. Those are the walls of the heart which will separate your atrium and your ventricles.

Chris - And you're asking, well that must be obeying genetic instructions to form, so which genes are controlling it and, therefore, if it goes wrong, which genes must be going wrong?

Emily - Absolutely. So we look at all of these different aspects and say OK, what are the genes required for each of these processes and, if we don't have these genes, why doesn't the heart develop normally.

Chris - You make it sound very simple, but I'm sure it's not or you wouldn't be doing the research you're doing. How do you do that?

Emily - In my lab we use zebrafish embryos. We can either specifically knock down genes that we know are important in people and say OK, if we lose this gene in a zebrafish embryo, does it's heart not loop properly, and if it's heart doesn't loop properly, why doesn't it loop properly? And the other approach we can take is just to look in general at zebrafish that we know have heart defects and say OK, which genes have caused these defects?

Chris - You talk about fish though. How relevant is a fish to me as a human? I'm not a fish obviously.

Emily - No, of course.

Chris - Despite appearances may be deceptive.

Emily - Absolutely. Zebrafish hearts when it begins to form is very similar to the human heart. So it starts off as a tube and it undergoes looping events that are important for making sure that the chambers are lined properly. The zebrafish heart actually only has two chambers compared to the human heart, which obviously has four, but certainly these early processes of heart development are very similar. We know that a lot of the genes that govern this process are also very similar.

Chris - Once someone has been born with one of these problems, why is helpful you saying well we know which gene is was that caused that?

Emily - So there are a number of reasons why we try and understand genetically what causes congenital heart disease. One of those reasons is something as simple as genetic counselling. People who have these problems, they want to know why they they have congenital heart diseases. Information is very powerful and also it's very important that we can provide good advice to these people if they want to go on and have families of their own. So whether they're likely to pass these malformations onto their children too. The second thing is that if we know there's going to be a familial sort of genetic component to their heart disease that we can keep an eye on in pregnancies as they progress, and make sure that if there is going to be a need for surgical intervention, then that can happen as soon as it's pertinent to do so.

Chris - Some people also say, if we understand how the heart develops, we might be in a position to kickstart it into regrowing itself when it goes wrong and forming healthy tissue again in the context of disease.

Emily - Yep. And I think that's a particularly pertinent point when it comes to things like heart regeneration. So the zebrafish is capable of regenerating it's heart after it's had damage done to it and there is increasing evidence that, actually, embryonic genetic programmes are reinitiated in our hearts as it undergoes regeneration in the zebrafish. So being able to understand why these pathways are driving heart development may actually help us understand how we can activate regeneration in adults who have undergone things like a heart attack.

The WHO rate bad air quality as one of the leading causes of heart attacks and strokes worldwide. It's also known that people who lay asphalt have a much higher rate of heart disease. David Newby, at the University of Edinburgh, explained to Chris Smith how he is investigating why this is.

Chris -  But it's not just fish that are exposed to oil-based pollution: bad air quality is now considered to be one of the leading causes of heart attacks and strokes worldwide. Dave Newby, at the University of Edinburgh, has been investigating how...

Dave - My name's Dave Newby, I'm a British Heart Foundation John Wheatley Chair of Cardiology at the University of Edinburgh.

People have observed for quite a while that high air pollution has bad health effects and that's been known since the mid-1900s. What people have appreciated more recently is that beyond the obvious that air pollution can make your breathing bad, it actually increases the risk of heart attacks and strokes.  So that's where I start to become interested because of this association of air pollution and you having heart attacks and heart disease. And not only getting it over time but also there's evidence that it actually triggers a heart attack.

Chris - This isn't just because people who are struggling to breathe that's just a stressful situation and that makes them have a heart attack - there's something more going on?

Dave - That's right, yes. It's more than that because the pollution that's in the air is actually sometimes imperceptible . The particles in the air are so small you can hardly see them, so it's not that. People keep asking well, what's the mechanism of that? OK, you see the association but it doesn't make sense to me. So what we did we set off on a programme of work to look at the mechanisms of how air pollution can do this and it was in many ways quite intriguing. So what we did was we worked with some investigators in Sweden. We went there because they have a unique exposure chamber and they have, of course, a Volvo engine. So what we did we had this diesel Volvo engine and we diluted down the exhaust and then fed it into this chamber which, of course, did raise some eyebrows I have to say.

Chris - Hang on a minute! You put people in a chamber and you blow in car exhaust for them to breathe?

Dave - Absolutely.

Chris - How did you get that through an ethics committee?

Dave - That's exactly what the British Heart Foundation said to me. And what was quite interesting was when I pointed out to them the levels inside this chamber were lower than the levels outside their front door because, at that time, they were in a very, very polluted area of London which was absolutely the highest levels in London recorded just round the corner. So I said to them if it's ethical for them to invite me down from Edinburgh to London to their polluted city and go on their committee, then it's ethical for me to do that. And it was diluted of course so the levels that we have are the levels you would expect at the roadside of a busy road and so this was relevant to what we see in the cities.

We got people to exercise gently in those chambers to breathe in this and then we looked at how their blood vessels responded. Now what we found was that the blood vessels were more tight and more constricted, they didn't relax as much, and the blood that flowed through it was much more sticky, and much more likely to cause blood clots. And those two things together, blood vessels that aren't relaxing, that are tight and have blood clots are just the recipe for heart attacks and strokes.

Chris - Do you know what component it was in the smoke that was doing that?

Dave - Yes. So in the exhaust, there are various different things. There are gases but there are also these particles. They are really tiny particles so they are so small you cannot see them by the naked eye. They are what we call nanoparticles - really tiny. It seemed to be those particles and they're covered in bits of metal, bits of unburned fuel, organic components, metals, and these things can react quite nastily to biological tissues, and what we were able to show was that it seems to be these tiny microscopic particles are what seemed to be causing the problem.

Chris - Just because you breathe them in or do they go further afield in you body once you breathe in?

Dave - Yes, that's a very important question and, actually, if I'm truly honest we don't really know for certain but there are three potential mechanisms. One - it goes into the lung, the lung doesn't like it and sends out messages to the rest of the body. Another mechanism is that they go deep into the lung, they get gobbled up by the cells of the body (the immune cells), and then they go into the bloodstream, and there they might harm the blood vessels, or they could even go straight into the bloodstream. We have some some preliminary data that these particles are so tiny, so small that they can cross cell membranes and get into the bloodstream. There they might actually cause the furring up of the blood vessels and cause heart attacks and strokes.

Chris - What about actually monitoring the real life experience of people in real life situation to see what their exposure is. Can we do that - do we have that sort of data?

Dave - We do. We can use personal monitoring so you wear this lovely backpack which monitors the quality of the air. It measures the particles, the mass, the number of particles, the gases in the air, and so you've got like a portable laboratory on your back. And we walked around Beijing just before the Olympic Games and we were able to see the quite dramatic levels of air pollution there. 

We actually then went on to do a study where we got patients to wear a face mask. It's an industrial mask, this is not the simple cloths that you see people put in front of their faces. But this is a mask that's very efficient, takes out a lot of these particles and when we got people to walk round just for one day with these masks on, their blood pressure was lower, their breathing was easier, and some of the measures that we did of how much heart stress they were under were much lower. So actually stopping breathing in some of these particles in the air around you does seem to have benefits for the body.

Heart attacks are very common, but thankfully many more people are surviving them these days. The downside though is that victims often suffer health effects afterwards, like chronic heart failure, despite getting to hospital quickly and undergoing emergency treatment. It turns out that opening up blocked arteries that cause heart attacks tackles only half the problem. To explain why, and what happens when a person suffers a heart attack, Colin Berry, professor of cardiology at the University of Glasgow spoke to Chris Smith...

Colin - Classically, it's the sudden blockage of one of the main arteries in the heart and that is typically caused by the breakdown of the wall of the heart artery because it's diseased. Fatty plaque has accumulated at one or more places, the plaque ruptures, that exposes the constituents of the wall of the artery to the blood and normally they don't meet, but when they do they're not a great mix and a blood clot forms and that blood clot leads to loss of flow in the heart artery that is experienced by the patient as chest pain.

Chris - Does that mean that the heart downstream of that blockage, that part of the heart is destined to die unless someone like you comes along?

Colin - Yes. Bluntly, that is the case and, within 60 minutes almost certainly, some of those heart muscle cells will have started to die off and within 2 hours it will be threatened and beginning to die off almost irrecoverably.

Chris - What's the current gold standard treatment? What's the best way do we think at the moment of managing a person in that situation?

Colin - The whole team is working in emergency care circumstance to achieve restored flow in the heart artery as quickly as possible. We put a plastic tube in the wrist, we put a long catheter to the heart arteries, we inject dye using camera imaging, and we identify the blocked artery and, as quickly as possible, we pass a wire through that blockage, open the blockage by placing either a balloon or, indeed, sucking out the clot. Whilst the situation looks so much better with flow restored in the heart artery, I know from my research that there is a different story that is operative at the level of the heart muscle.

Chris - Go on...

Colin - All the small vessels in up to half of patients are all blocked.

Chris - What do you mean?

Colin - So the treatment pathway focuses on the main artery, which is large, but that artery has myriads of small vessels. Imagine the arborisation from a tree; these small vessels and all the little leaves are all blocked with microclots.

Chris - Is that something that happened at the time that the patient had the initial event or are you saying that in going in and focusing on getting that clot out and opening up the artery, all we've done is export the problem downstream? We've broken bits of it up and they've floated off down the artery and lodged making more blockages downstream?

Colin - Yes, that is a very likely scenario.

Chris - So what you're saying is you have taken patients in in which this intervention has been carried out and you can see evidence that these vessels are blocked after what we currently regard as the gold standard treatment of unclogging arteries?

Colin - It represents a limitation of medical practice. We have focused on the main life-threatening problem and successfully treated the patient in that regard, but it has left a legacy of problems within the small vessels of the heart that can lead to heart failure in the longer term.

Chris - What are you proposing to try and do about this?

Colin - Historically heart attack was treated with a clot breaking drug. What we propose to do here is to give a small dose, a fraction of the dose, directly into the heart artery to break down all those microclots. That is the focus of this new trial called Ttime.

Chris - The idea being then that you go in, do what you've just described. You still open up the artery but anticipating that you will dislodge stuff that's going to go downstream and block those vessels. Anticipating that's going to happen, at the same time you're going to put in some clot busting chemicals which will hopefully prevent those other small blood vessels getting blocked or unblock them if they are blocked already, and that should reduce the risk of onward complications?

Colin - And we have to wait for a couple of years to know the answer to that question.

One way to keep your heart pumping is to become a MAMIL: a Middle-aged-man-in-lycra! A phenomenon that has men in their 50s getting out and doing lots of running - but there's also a worry that over-exerting can actually be what causes some 'MAMILs' to have a heart attack. Georgia Mills caught up with Sanjay Sharma, from St George's University of London, to find out if running can ever be dangerous...

Sanjay - We all know that exercise is good for you. People who exercise regularly have a favourable lipid and blood pressure profile, they are less likely to be overweight and diabetic. And by controlling all these risk factors for atherosclerosis, which is what causes heart attacks, they reduce their risk of dying from a heart attack by 50% when they reach their 50th or 60th birthday. So everybody knows that exercise is very good for you, and everybody should be doing it to gain an additional 3 to 7 years of life.

But what the MAMILs all about is a 40-60 year old man, gets to middle age and sees the middle age spread around the abdomen and decides I need to do something about this because I've heard that people who don't may die from a heart attack. They often join the gym or a running club and they soon realise they are as good as people who are younger than them.  And the good news for everybody is that as one ages, of course the facial expression changes, the hair changes, but what doesn't change very much is your skeletal muscle and your ability to engage in endurance events. To give you some idea, if we look at the average times of marathon finishes between 20 and 49, there's not much difference.

Georgia - Wow! Is this true of men and women?

Sanjay - This is true of men and women. So, of course, men realise at the age of 40 or 50 that they can actually beat people who are younger than them and being ultra-competitive, this drives them on and that is usually what gives birth to the Middle Aged Man in Lycra who spends most weekends competing and exercising, and this is very, very, good for you. The one thing that everyone worries about a little bit, of course, is that is paradox that although exercise protects from heart diseases it can, in some people, precipitate or trigger a sudden death, usually in someone whose got a silent cardiovascular abnormality. We actually look at the demographics of people that die; they are usually middle aged (between 43 and 55), they're almost always men...

Georgia - So, as you say, there are clues then at who might be more at risk?

Sanjay - Around 55% of people who die have already got established risk factors for coronary heart disease so that's one thing to look for and try and rectify. One can rectify someone's cholesterol, or blood pressure, or even sugar control.

The second thing is that about 15% have a previous cardiac history and, what's worrying, is that about 30% of people have reported symptoms suggestive of cardiac disease such as chest tightness that's brought on by jogging, or breathlessness that disproportionate to the amount of exercise being performed, or palpitations or a feeling of dizziness during exercise. These are all ominous symptoms.

So the things to look for are: am I overweight, have I got a high cholesterol, have I got high blood pressure, am I diabetic, has someone in my family died below the age of 50. These are all warning symptoms and if you've got  those, you do need to be assessed in a professional physician setting.

Georgia - Every now and then on the marathon you do see someone who's dies unexpectedly during it. And maybe it doesn't happen that much but does stick with you and I guess it's worrying. You think should I exercise, are the benefits worth it? What would you say to that?

Sanjay - I think everybody in this country, in fact, everyone in the universe must exercise. There is no medication invented yet that has the benefits of exercise i.e. anti-aging, preventing cardiac diseases, preventing depression, preventing dementia, preventing osteoporosis. If we packaged up exercise into a pill, it would be known as the miracle pill and, unlike medications, exercise is free, it can be performed at any time, and it's usually devoid of some of these side effects that you get with medication, so everyone should be exercising. The amount of exercise that you need to do is about 30 minutes of moderate exercise five times a week. By that, I mean a jog at a 15 minute mile pace, so four miles an hour. That's what you need to do to achieve these benefits. That's not to say that you have to do that, you can do less and still achieve benefits compared to people who don't do anything.

Now in terms of marathon running, I want to allay your anxieties. The death rate in marathons is about 1 in 50,000. The reason why it appears more is because many marathons, such as the London marathon, are under the radar of the media and are televised, so when something does happen to someone who's actually trying to raise money for charity by doing something that's good for them, it does to really, really captivate the audience, it captures the heart of the nations, but these deaths are rare. They're usually due to people who already have predisposing factors to cardiac disease. So I would say that if you've got any of the risk factors I've just talked about, then you should be tested out before you embark on something like marathon running.