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.
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.
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.
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).
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).
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.
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‘).
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