Heart attack

What is a heart attack - a doctor speaks

The heart is the organ which keeps us alive by pumping blood around the body, delivering oxygen and other nutrients to all of the cells. It consists of highly specialised muscle cells which remain in place and active for the whole of a lifetime. These muscles get their own blood supply through three main coronary arteries. A heart attack happens when blood flow to part of the heart is blocked, often by a blood clot, causing damage to the affected heart muscle. The medical term for a heart attack is myocardial infarction.

Almost all heart attacks follow a gradual build-up of deposits of fatty material in the coronary arteries, a process called atherosclerosis. Without warning, these deposits can crack open and attract blood clots, causing complete blockage of the artery. The risk of a heart attack is increased by smoking, high cholesterol, high blood pressure, diabetes and family history of heart disease. Men are also more likely to have a heart attack than women.

We asked Dr Raj Kharbanda, a consultant cardiologists at the John Radcliffe Hospital in Oxford to help explains what is a heart attack is. In the video clips he gives an introduction to heart attack, its causes and treatments and a view for the future.

What is a heart attack?

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So my name is Raj Kharabanda and I’m one of the consultant cardiologists at the John Radcliffe Hospital in Oxford.

Would you like to tell us what a heart attack is?

So the heart is, basically, an important muscle, which is working all the time, and it gets it’s blood supply through main, three main arteries and a heart attack is when one of those arteries, or fuel pipes, is blocked by a blood clot and so the area of heart muscle supplied by that artery no longer gets it’s blood supply and, as a result of that, it doesn’t work properly and causes pain because the heart, that area of the muscle is not getting enough blood. So that’s, basically, what causes a heart attack is a clot inside one of the main arteries and that damages the heart muscle over time.

Are there different types of heart attack?

There are so depending on where the blockage occurs and how long the blockage stays for will determine how much damage there is to that heart muscle. So sometimes the clot can dissolve itself and patients may have had an episode of pain, which resolves on it’s own, but can leave some damage to the heart and sometimes that clot can reform but most the conventional kind of heart attack is where the clot remains and it needs treatments to reopen the blocked artery.

What are the symptoms of heart attack?

So the classic symptoms are pain the chest, occasionally, going down in to the arms or up into the neck, associated with sweating and sickness and shortness of breath. That’s the sort of classic description. About one in five patients may have a heart attack without any symptoms and, occasionally, the symptoms can be very atypical, as we call them, so not typical symptoms, things like back ache, toothache, feeling generally unwell. So there are a number of ways in which heart attacks can present.

A heart attack usually causes severe pain in the centre of the chest. The pain usually feels like a heaviness or tightness, which may also spread to the arms, neck, jaw, back or stomach. Sometimes the pain can be mild and be mistaken for indigestion. Some people can have a heart attack without experiencing pain. A person having a heart attack may also sweat, feel light-headed, feel sick or feel short of breath or have an overwhelming feeling of anxiety.

If an ambulance has been called, an ECG is done to record the person’s heart’s electrical activity establishing whether a coronary artery is blocked or the heart is not getting enough blood. In hospital, more sophisticated tests are used to get more information and diagnose a heart attack which include blood tests, an ultrasound or an angiogram test. in an agiogram, a thin, flexible tube is passed into the artery, into which dye is injected which shows narrowed areas or blockages in the artery on a x-ray.

Diagnosis & treatment with pictures

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So typically a patient having a heart attack with the classic symptoms of pain, tight feeling in their chest, sweating, feeling generally unwell would call an ambulance. The ambulance would make a ECG recording, which is the electrical activity of the heart, and from the pattern of the recording make a diagnosis of whether this was due a blocked artery and, if it was, then the ambulance would, basically, drive the patient to a hospital that could offer them primary angioplasty, which is the balloon stretching treatment, to open the blocked coronary artery and that takes place in what looks very much like an operating theatre but is a cardiac catheterisation laboratory, which is the room where this procedure is performed.

Doctors aim to treat the person having a heart attack as quickly as possible to restore the blood supply to the heart by opening and keeping open the artery that is blocked. The blocked artery can be opened with a treatment called angioplasty (a fine, flexible, hollow tube – with a small inflatable balloon at its tip which, when inflated, squashes the blockage allowing the blood to flow more easily) and stenting (a small tube of stainless steel mesh inserted into the artery to keep it open). This treatment is not available in every hospital in the UK but the ambulance crew can make the diagnosis and transfer the patient to the nearest specialist centre as quickly as possible.

Diagnosis and treatment

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So the most important tool, which we have, is speaking to the patient. Often, that’s the most important thing that we need to do, take a good history but also we do a recording of the heart’s electrical activity with an ECG, which involves putting stickers on the heart and recording, making electrical recordings of the heart, and the pattern of the electrical recording tells us whether one of the main arteries is blocked or the heart is not getting enough blood. So the ECG is really the mainstay of treatment in making the diagnosis in the very early phase and later on, we can use other sophisticated tests including blood tests or ultrasound of the heart or doing an angiogram test to get an idea of what’s going on in the arteries.

So a heart, the basic aim of treating a heart attack, in the initial phase, is to restore the blood supply to the area of the heart where the artery is blocked and then the latter phases are to help the heart to recover and to heal.

So, in the earliest phase, we know that the timing is very important and that the quicker we can open the artery and keep it open that we know that patients do better. So in the past we used to use very powerful blood thinners called clot busters to administer to patients even in the ambulance or as soon as they arrived in hospital but we now know that we can get a better opening of the artery with a treatment called angioplasty and stenting. And that involves being treated with a small procedure where we put a tube into either the wrist artery or the leg artery, pass a catheter or a tube into the heart artery that we think is blocked. We then pass a very fine wire to open up the narrowing and then by giving various drugs, we can dissolve away the clot. We can then stretch any narrowings that are present in the artery with a balloon and then you usually put something called a stent inside, which is a like a metal scaffolding to keep the artery open and that treatment is delivered round the clock and the aim is to get patients to that treatment as quickly as we possibly can.

Is that type of treatment available in most hospitals?

So it’s not available everywhere and but certainly in the UK the plan is that most areas will be, most patients will have access to that treatment and that there’s a rolling programme of that. So not all centres offer this service round the clock. Some offer it nine to five but, basically, the ambulance crews who deal with the majority of heart attacks would make the diagnosis and would transfer the patients to a centre that could offer them that treatment as quickly as possible.

Dr Raj Kharbanda shows the equipment used in an angioplasty (see also ‘Angioplasty and stents’).

A doctor demonstrates the equipment used in an angioplasty

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So a patient is having what we call an angioplasty we need to get to the arteries, which are the tubes that supply the blood to the body, and we are, essentially, going against the flow of blood to reach the heart and this is the sort of plastic tube that might be put into the wrist or the artery at the top of the leg in order for us to get into the blood supply.

This is a catheter, which is a tube with a hollow inside. Basically, that passes through the catheter that it’s in the either the wrist artery or the leg artery and it passes through back up and, essentially, we reach the heart with this catheter and by injecting dye we can look at the heart arteries and see where the blockage is. Through this we can then pass a very fine wire to open the artery and then use our balloons and stent treatments to keep the artery open.

So this is what a stent would appear like. There is a metal spring, if you like, just mounted on to a balloon.

So it’s a stent there. Okay there’d be a wire and a balloon going into the heart artery.

So that’s the balloon, which has now been expanded and that would be inside the artery and when we let the balloon down, and this is the stent, which would stay inside the artery and act as scaffolding to keep the artery open.

There are two different kinds of heart attacks: STEMI (where the ECG shows that the coronary artery is completely blocked) and non-STEMI (where ECG reveals that by the time the person arrives in hospital the clot has dissolved and the artery is no longer completely blocked).

Stemi and non-stemi heart attacks

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The terms STEMI and non-STEMI are in the literature and what STEMI refers to is something called ST elevation myocardial infarction. So the ST refers to the pattern of one of the segments which we look for on the ECG. So an ST elevation heart attack is, essentially, a pattern of ECG recording which tells us that the heart artery is blocked completely. That area is not getting a blood supply and the ECG recordings change in a way that past, gives us that information and the treatment for that sort of heart attack with that sort of ECG is to rush to the cardiac hospital to try and open the blocked artery as quickly as possible.

Sometimes we find that patients have that sort of blocked artery ECG but, by the time they arrive in hospital, the ECG has got better because their own clot busting in the blood and their own ability to dissolve the clot, has dissolved the clot and opened the artery. Often they will still undergo an emergency angiogram, which is the x-ray pictures of the arteries, to see whether there is a narrowing that is still at risk of blocking again. So the and the non-ST elevation heart attacks are, basically, when the ECG doesn’t show us that very specific pattern but it shows us other changes on the ECG where we know that an area of the heart muscle has not got an adequate blood supply, may have suffered some damage but we don’t have that very marked change that tells us that the artery is blocked at that time. So it may be that the artery is blocked and then unblocked but left a signature that that process is going on and those patients, at the moment, are not managed with very, very emergency angiography i.e. getting the pictures and looking at the heart arteries but are conventionally treated with drugs to thin the blood and then undergo that same investigation of an angiogram and possibly an angioplasty within a few hours or days rather than having it very, very early on as an emergency procedure.

The lack of blood to the heart can seriously damage the heart muscle. If left untreated, the heart muscle will begin to die. The outlook for people who have a heart attack is highly variable and is dependent on two important factors:

how quickly they receive treatment after the onset of the heart attack (ideally treatment should begin within 90 minutes of the onset of symptoms)
how well they respond to treatment within the first 28 days after the heart attack

“In England in the 1960’s 70% of people (7 out of 10) died from heart attacks. In 2017 the death rate has reduced to 30% (3 out of 7). 70% of people now survive heart attacks.” (British Heart Foundation - Coronary heart disease statistics March 2017).

How serious is a heart attack?

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How serious is a heart attack?

So like all things, there are some heart attacks, which are very serious, and there are some heart attacks which are less serious. It really is determined by where the artery is blocked and how much damage to the heart occurs. No heart attack is insignificant and all heart attacks carry some risk but it’s very difficult for the patient to know whether they’re having a very large heart attack with lots of heart muscle that’s being damaged or a very small heart attack with very small muscle that’s being damaged.

And, in fact that information really we can only work out a few days down the line and based on our blood tests and heart scans we can determine how much damage there’s been to the heart and also assess what the other arteries are like. So it’s very difficult to give that information very early on but there are some heart attacks which are very small, which don’t affect a large area of the heart, and patients do very, very well after that.

So I think that our management of heart attacks has really improved a lot but it means that there are a few very, very sick patients and most patients are doing much, much better and it’s probably the few very sick patients that need the sort of highest intensity of treatment now.

Cardiac rehabilitation begins in hospital, and before discharge a member of the rehabilitation team will provide the patient with detailed information about their state of health and how the heart attack may have affected it, the medications they will need to take when they leave hospital. They will be told the risk factors that contributed to the heart attack and advised about the lifestyle changes needed to address those risks factors (see ‘Cardiac rehabilitation and support’). Most patients may have one or two reviews in the outpatient clinic and then go on to lead a normal life.

Aftercare after a heart attack

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So most patients would be in hospital three to five days in sort of modern heart attack management. They would be discharged on a cocktail of medication including blood thinners, drugs to help the heart to heal and to recover and drugs to help with their blood cholesterol level. And those medications are really to help both the arteries and the heart to heal and to stop the processes from developing.

They would be seen by members of our rehabilitation team, usually in hospital, and then as part of a ongoing programme of rehabilitation both to help them recover from the event but also in terms of education about why this may have happened and what future precautions patients can take to prevent further events from occurring.

And, usually, they don’t need to be seen in hospital clinic outpatients routinely unless they have a specific reason such as there’s been a extensive amount of damage to the heart or one of the valves has become leaky or they’ve developed a problem. And so most patients would have rehabilitation, medical treatments, may have one or two reviews in the outpatient clinic but by but then go on to lead a normal life without needing to come to the hospital routinely.

Lifestyle changes can reduce the risk of having a heart attack including quitting smoking, having a healthy diet, keeping weight under control, and getting regular exercise (see ‘Ideas about causes’ and ‘Preventing another heart attack’).

Regrets not changing his lifestyle and attending check-ups following his heart attack and feels...

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So heart attacks are a very frequent occurrence and, I think the BHF say it’s something like there’s a heart attack every two minutes in the UK. So it’s a very frequent problem and it still remains a frequent problem. In terms of factors which we know increase the risk of heart attack, getting older. As the arteries get older they develop the propensity to develop narrowings so age is a factor that predisposes to heart attacks. But the risk factors that we think about when we think about these coronary narrowings, the most important is smoking, history of diabetes, high blood pressure, high cholesterol, having a family history of heart disease and that’s unrelated to all the other things but also directly related. And we know, for example, that being overweight and not exercising contributes to your blood pressure and the cholesterol levels. So it’s a combination of lifestyle events that contribute to your risk of developing a heart attack. We know, for example, that the recent ban in smoking has significantly reduced the risk of patients presenting with heart attack. So smoking is a very powerful way to, or stopping smoking is a very powerful way to reduce an individual’s risk of a heart attack. And in terms of, we know that populations in general are getting healthier and that overall the incidents of heart attack over the past twenty years has reduced.

Differences between a heart attack and cardiac arrest

"Although a heart attack can lead to a cardiac arrest, they are not the same thing.

A heart attack is a sudden interruption to the blood supply to part of the heart muscle. It is likely to cause chest pain and permanent damage to the heart. The heart is still sending blood around the body and the person remains conscious and is still breathing.

A cardiac arrest occurs when the heart suddenly stops pumping blood around the body. Someone who is having a cardiac arrest will suddenly lose consciousness and will stop breathing or stop breathing normally. Unless immediately treated by CPR this always leads to death within minutes.

A person having a heart attack is at high risk of experiencing a cardiac arrest.

Both a heart attack and a cardiac arrest are life-threatening medical emergencies and require immediate medical help.

Call 999 if you think you are having a heart attack or if you witness someone having a cardiac arrest.” British Heart Foundation 2017

Last reviewed June 2017.
Last updated June 2017.