What is a heart attack?

A heart attack is caused by a sudden stoppage of blood flow to your heart muscle. If the blood flow is not quickly restored, the heart can be permanently damaged. A heart attack needs prompt medical attention, otherwise it can cause chronic health issues or potentially death.  

Causes

The main blood supply to the heart muscle is via coronary arteries. These arteries are prone to being narrowed due to a build up of fats within their walls. This is known as atherosclerosis, or cholsterol plaques. If there is widespread or significant atherosclerosis within the coronary arteries the condition is known as coronary heart disease

Coronary heart disease increases the risk of developing a heart attack. The plaques can spontaneously rupture, triggering a blood clot to form on its damaged surface. If the blood clot gets big enough, it can completely block your coronary arteries, causing a heart attack. 

The different stages leading to a coronary artery blockage and heart attack. 

Coronary heart disease

Coronary heart disease occurs when the supply of blood to the heart is blocked or interrupted due to a build-up of fatty deposits in the coronary arteries. Angina and heart attack are both examples of coronary heart disease.

Coronary arteries

An artery that supplies blood to the heart muscle.

Risk factors

There are a number of factors that can increase your risk of developing coronary heart disease and subsequently, a heart attack. These include:

  • Cigarette smoking;
  • Elevated cholesterol levels (dyslipidaemia); 
  • High blood pressure (hypertension);
  • Elevated blood glucose levels caused by conditions such as diabetes;
  • An inactive lifestyle, being overweight or obese, and;
  • Personal or family history of vascular disease, such as angina or heart disease.

Cholesterol

A type of fat produced by the body that is necessary for metabolism.

Coronary heart disease

Coronary heart disease occurs when the supply of blood to the heart is blocked or interrupted due to a build-up of fatty deposits in the coronary arteries. Angina and heart attack are both examples of coronary heart disease.

Diabetes

A metabolic disorder that is caused by problems with insulin secretion and regulation and which is characterised by high blood sugar levels. Also known as diabetes mellitus.

Signs and symptoms

Common symptoms of heart attack include:

  • Pain, discomfort or tightness in the chest that may also radiate to the jaw, neck, arms, shoulder or back;
  • Shortness of breath;
  • Palpitations, which is the sensation of a rapid or irregular heartbeat;
  • Excessive sweating;
  • Nausea or vomiting, and;
  • Feeling dizziness.

Symptoms of a heart attack can vary. Some individuals with a heart attack may report severe chest pain, while others may only experience indigestion. If you have diabetes, are elderly or have high blood pressure (hypertension), you may not even notice any pain. A common sensation is the feeling that "an elephant is sitting on the chest". If you have angina, the symptoms of a heart attack may be similar but more severe, last longer or not respond to treatment.

If you are unsure if you are having a heart attack, do not delay, call an ambulance straight away. The longer you wait, the greater your chances of complications.

Diabetes

A metabolic disorder that is caused by problems with insulin secretion and regulation and which is characterised by high blood sugar levels. Also known as diabetes mellitus.

Methods for diagnosis

Your doctors will run a series of diagnostic tests to confirm the suspicion of a heart attack. While these tests are being performed, you will also be given some treatment to make you more comfortable, such as oxygen, pain-relief medications, and medications to help improve blood flow to the heart muscles. 

Common tests that are performed include: 

Electrocardiogram

Electrocardiography (ECG) uses electrodes attached to your chest to check your heart rhythm. The beat of your heart is caused by coordinated electrical currents through its cells. This test is used to determine if there are any abnormalities in your heart rhythm. During a heart attack, certain areas of your heart may be damaged. The ECG can tell your doctor if this is likely to have happened. 

Electrocardiography procedure to monitor your heart rhythm. 

Cardiac enzyme test

A cardiac enzyme test is a blood test - the most commonly measured enzyme is troponin. Damage to the heart, such as that caused by a heart attack, releases cardiac enzymes into the bloodstream. Blood may be taken multiple times as it can take several hours for this test to be positive after a heart attack.

Chest X-ray

If you have chest pain, your doctor is likely to order a chest X-ray. This can exclude other causes of chest pain and also determine if you have a build-up of fluid on your lungs due to your heart attack.

Echocardiogram

Echocardiography uses ultrasound waves to create an image of the heart. It allows your doctor to see the size of your heart and also how well it's working. It can indicate how hard your heart is pumping blood, whether there is heart valve leakage and highlight areas of damage. An echocardiogram is not usually performed immediately, but in the days to weeks after a heart attack.

Coronary angiogram

A coronary angiogram involves a thin catheter being inserted into one of your major arteries in your groin or arm, a under local anaesthetic. The tip of the catheter is manoeuvred to near the coronary arteries, where radioactive dye is injected to highlight the coronary arteries, using X-rays. Any blockages or narrowing in the coronary arteries can be viewed. 

Catheter

A thin, flexible tube inserted through a narrow opening into a body cavity for removing fluid.

Cells

The fundamental unit of life; the simplest living unit that can exist, grow, and reproduce independently. The human body is composed of trillions of cells of many kinds.

Local anaesthetic

A type of medication that, when administered to an area, creates a localised loss of sensation by blocking nerve activity.

Coronary arteries

An artery that supplies blood to the heart muscle.

Electrodes

A sensor that detects electrical currents.

Types of treatment

Prompt diagnosis and treatment is essential for limiting the amount of damage to your heart. Treatment begins at the initial suspicion of a heart attack. This may include oxygen, pain-relief medication, aspirin (to thin the blood and prevent further blood clotting), and nitroglycerin (to reduce stress on the heart and improve blood flow through the coronary arteries). You will be closely monitored to recognise any complications at the earliest opportunity. 

Treatments aimed at removing blockages and restoring blood flow within the coronary arteries include:

Coronary angioplasty and stenting

Coronary angioplasty is a procedure that can be perfomed at the same time as a coronary angiogram. If a blockage or narrowing is diagnosed on the angiogram, specialised catheters can be used to enter the coronary arteries. These catheters are able to extract blood clots or dilate narrowed arteries to restore blood flow. A self-expanding stent can also be inserted, through a similar catheter, to keep the arteries open. 

Coronary artery bypass graft

A coronary artery bypass graft (CABG) is a type of open-heart surgery, designed to bypass narrowed blood vessels and increase blood flow to certain areas of the heart. The operation involves using healthy veins or arteries taken from another region of the body, to replace narrowed, blocked or diseased coronary arteries. This procedue is done a under general anaesthetic and can take several hours to perform.

Medications

Thrombolytics

Medications, called thrombolytics, can be given as an injection to break down the blood clots that caused the heart attack. This medication is generally used in hospitals that lack the facilities to do angioplasty. 

Anticoagulants

Medications, called anticoagulants, such as heparin or low-molecular weight heparin, are given to help prevent the formation of further blood clots. Anticoagulant medication is generally continued for a few days after the initial heart attack, where the risk of further heart attacks is greatest. 

Catheter

A thin, flexible tube inserted through a narrow opening into a body cavity for removing fluid.

General anaesthetic

An anaesthetic given to a person to put them to sleep while having an operation or medical procedure. Afterwards, the person regains consciousness and usually has no memory of the procedure. A general anaesthetic is given in hospital by a specialist called an anaesthetist.

Coronary arteries

An artery that supplies blood to the heart muscle.

Potential complications

Further heart attacks

Having a heart attack increases the risk for further heart attacks in the future. To reduce this risk, maintaining a healthy lifestyle and adhering to certain medications, have been shown to be effective. These medications include:

  • Beta-blockers, which block the action of your sympathetic nervous system on your heart. This reduces the amount of stress on your heart by slowing it down;

  • ACE (angiotensin converting enzyme) inhibitors, which block the production of a hormone called angiotensin II to lower your blood pressure. This in turn lessens the pressure and stress placed on your heart;

  • Aspirin, which stops your blood platelets clumping together to form clots, and;

  • Statins, which reduce the amount of certain cholesterols in the blood. Cholesterol is linked to atherosclerosis and coronary heart disease, so managing cholesterol levels can help protect against further heart attacks. 

Irregular heartbeats

Any damage that occurred during a heart attack can leave scar tissue. This scar tissue can cause electrical instability in your heart, leading to irregular heart rhythms, known as arrhythmias. Generally arrhythmias can be treated with medication and are often short-lived. However, some arrhythmias need to be managed with an implantable cardiac pacemaker and/or defibrillator (ICD), which is a small electrical device surgically placed in your chest. Once implanted, a pacemaker can help maintain a minimum heart rate, and a defibrillator can automatically shock the heart, should there be a dangerous or chaotic arrhythmia.

Heart failure

If your heart was badly damaged during a heart attack, it may mean that your heart cannot pump enough blood around your body to prevent fluid build up. This is called heart failure. Heart failure is treated with medications to help it pump more effectively and prevent fluid retention.

Cardiogenic shock

Cardiogenic shock is a serious complication following a heart attack. It occurs when your heart muscle has been so badly damaged it cannot provide blood for many of your vital functions. Treatment may involve medications to raise the blood pressure, surgery to fit an intra-aortic pump, or coronary graft bypass.

Valve damage

If your heart valves are damaged during a heart attack, it can lead to serious leakage by the valve and in severe cases, death. Valve replacement surgery can rectify this situation using animal or artificial valves. You may need to take blood-thinning medications for the rest of your life, depending on the type of valve used.

Heart rupture

A heart rupture is a serious complication after a severe heart attack. It occurs when your heart walls, valves, or muscles split apart. Treatment is usually surgery, but the outlook tends to be poor in this situation.

Angiotensin II

A hormone that causes blood vessels to constrict, increasing blood pressure.

Beta-blockers

Substances that hinder the activity of hormones such as adrenaline by blocking the beta receptors, found in many organs but particuarly the heart and blood vessels. These are used to treat a range of conditions including high blood pressure and migraines.

Cholesterol

A type of fat produced by the body that is necessary for metabolism.

Coronary heart disease

Coronary heart disease occurs when the supply of blood to the heart is blocked or interrupted due to a build-up of fatty deposits in the coronary arteries. Angina and heart attack are both examples of coronary heart disease.

Platelets

Small blood cells found in the blood that are essential for clotting to occur.

Intra-aortic pump

An inflatable device that is inserted temporarily into the aorta to help improve blood flow to the heart and other organs. Also known as intra-aortic balloon pump.

Prognosis

Many people will continue to live active and fulfilling lives after a heart attack, although you may have chronic health issues that are likely to need ongoing medications and medical follow-up. It is perfectly natural to feel anxious about getting fit again, but it is the best way to avoid having a repeat attack.

Cardiac rehabilitation programs are designed specifically around your personal health circumstances and will start before you leave hospital. The idea of these programs is to gently help you raise your fitness level, while providing you with good advice on becoming a healthier person. Having had a heart attack puts you at much greater risk of experiencing another, or developing a sudden fatal heart arrhythmia. Actively working with your doctor to adopt a heart-friendly lifestyle and reduce coronary heart disease will increase your chances of leading a full life.

Coronary heart disease

Coronary heart disease occurs when the supply of blood to the heart is blocked or interrupted due to a build-up of fatty deposits in the coronary arteries. Angina and heart attack are both examples of coronary heart disease.

Prevention

Life after a heart attack can be seen as a huge learning curve, a chance to change unhealthy habits and get a second chance at life. Alongside medication, changes in lifestyle and diet are essential to reduce your risk of having another heart attack. Your doctor and care team, which may include a dietitian, physiotherapist and exercise specialist, will support you each step of the way. The aim of the program is to teach you how to become healthier and enjoy the process. Lifestyle changes may include the following:

  • Eating a healthy diet, with an increased intake of naturally oily fish such as mackerel or salmon each week, eating five portions of fruit or vegetables daily and replacing butter or margarine with olive oil;
  • Losing weight;
  • Not smoking and limiting your alcohol intake, especially if you have high blood pressure;
  • Working with your cardiac rehabilitation team to gradually building up the amount of exercise you do, until you are doing around 150 minutes each week, and;
  • Getting your family or friends involved - suggest a daily walk or leave the car at home whenever possible.

Most of all enjoy the process - getting fit will greatly reduce your chances of having another heart attack.