What is Heart Disease

Chris - Heart disease, apart from killing one person in three who will be listening to this programme, must be a very broad term; it must be one of the most mis-used terms, what does it actually mean?

Niall - It is a broad term, it covers a wide variety of different problems. People can have problems with their heart arteries, the heart muscle, the electrical circuitry of the heart; for which some of those patients will need pacemakers. Some of those problems will overlap, for example a patient who develops problems in the heart arteries may go on to develop a problem with the heart muscle or the electrical circuitry of the heart.

Chris - Who gets it?

Niall - Anyone can get it, some people specifically in terms of people who have narrowing in the walls of the heart arteries, and there are certain risk factors for that. People who smoke are more likely to get it, people who have diabetes, high blood pressure or high level of fats in the blood can get it.

Chris - When we say 'you've got problems with your heart', what's actually provoking those problems and how would the factors you just mentioned lead to the condition?

Niall - Essentially, going back to basics, the heart is a pump. A large muscle is the engine system of the heart and the engine needs it's own plumbing system, called the coronary arteries. The coronary arteries can, if we live in a western society, develop narrowing over time and all of the factors I mentioned can encourage narrowing to occur. If those narrowings become very severe, or if a clot develops in one of the heart arteries, then one of those arteries can become blocked, the area of muscle supplied by that particular coronary artery can become damaged, and that it what's known as a heart attack.

Chris - What's actually going on in the artery, to get that furring up, those plaques that are made of that fatty material?

Niall - Essentially each artery has got three layers. Its got an inner layer, which is closest to the blood; a middle layer, which has a muscle layer which allows the body to regulate the diameter of the artery, we can also give particular drugs to change that size. There's also an outer lining, which connects the artery to the outer structures. For example when people smoke or have high levels of fats in their blood, they are more likely to develop fatty deposits on the inner lining of the artery. That can pre-dispose people to heart attacks.

Chris - So why does it take 40 or 50 years for this to manifest, and why does it run in families?

Niall - Even if you look at very young children, you can see if you live in countries such as ours with our diet and our lifestyle, that the basic building blocks of these fatty deposits are beginning to occur. Narrowing occurs over many years, it's often only when they get into their 40s or 50s that those narrowings will occur. There are some people with family conditions who are more likely to develop heart disease, often conditions where they have very high levels of fats within the blood. If you have high levels of fat within the blood, fatty deposits are more likely to develop and that makes heart disease more likely to occur.

Chris - So is there anything we can actually do once these vessels become furred up in this way?

Niall - There are medicines which can treat it, if someone is actually having heart attack and the heart artery completely blocks, there are two main treatments which doctors can use. The first is the use of 'Clot-busting' drugs, a treatment we call thrombolysis, where very strong clot-busting drugs are given into somebody's vein to open up the clot. Newer treatments are being developed where we can pass wires and tubes up from the top of someone's leg or wrist directly into someone's heart artery. While the patient is awake, we can open up the heart artery and place a special metal scaffold, called a stent, to keep the artery open.

CHRIS - Why do you need that metal scaffold? Why can't you just squash the fat out of the way and be done with it?

Niall - When we pass wires and balloons down people's heart arteries that does cause some local damage to the artery, and there is evidence that actually putting a stent in will stop it furring up later.

CHRIS - So what's the difference between that and a heart bypass?

Niall - Imagine the heart arteries as pipes, and imagine a blockage. In the same way as a road bypass will go around a town which causes a lot of congestion, a heart bypass takes one of a persons own arteries or veins, connects it to the area before the blockage, and then to the area after the blockage, bypassing the blockage. It's not actually opening up the artery itself, it's encouraging flow beyond the narrow.

CHRIS - So this approach you mentioned when you can thread something up from the leg is going to be a lot better than having to give someone a pretty serious operation.

Niall - Certainly when someone is having a heart attack, people who do heart bypass operations would say that it's preferable that someone has this procedure with a stent. However, some people will need a heart bypass operation if they have had a heart attack. These operations are also done in patients who haven't had heart attacks, as there may be other good reasons to operate, such as severe narrowing in a lot of important arteries.

CHRIS - As you go further down an artery it gets smaller and smaller, what about when the vessel gets so small that the damage is beyond the reach of one of these techniques?

Niall - There is a range of very good tablets which can be used to treat symptoms and also there's a lot of new research such as using stem cells to try and improve the heart function.

CHRIS - When someone has a 'Heart Attack' what does that mean compared with a 'Cardiac Arrest'?

Niall - That causes a lot of confusion for many people. A heart attack is actually when one of the heart arteries blocks up, and results in an area of heart muscle actually dying. The larger the area of muscle supplied by that artery, the more damage will occur to the heart muscle.

A cardiac arrest is when the heart actually stops beating. There's a variety of things that can cause cardiac arrests; heart attacks can cause cardiac arrest but, for example, if someone were to develop a large blood clot in their lungs that could also cause a cardiac arrest.

Dave - When some of the heart dies in a heart attack, does it ever re-grow or is it just gone forever?

Niall - At the moment, what we know is that the heart muscle can't come back to life once it's died. If the heart attack has been small, or moderately sized, then the other areas of heart muscle which haven't actually been effected by the heart attack can take over the function of the damaged muscle. That can still allow the heart to work quite effectively.