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Heart attack

Overview

A heart attack, also known as myocardial infarction, or coronary thrombosis, is when part of the heart muscle dies because it has been starved of oxygen.

A heart attack usually occurs when a blood clot forms in one of the coronary arteries (the blood vessels that lead to the heart muscle), blocking the blood supply to the heart. A blockage can also sometimes be caused by a spasm (sudden narrowing) of a coronary artery.

A heart attack often causes severe and crushing pain in the middle of the chest. This pain may then travel from the chest to the neck, jaw, ears, arms and wrists. The person may also be cold and clammy, and their skin may appear pale and grey in colour.

Risk factors

A heart attack is much more likely to occur when your arteries have become narrowed. This usually happens over a period of many years. The arteries are often narrowed by fatty deposits that form on the artery walls. There are a number of factors that can increase the risk of these fatty deposits forming. Smoking, high blood pressure, poor diet, lack of exercise and obesity are all contributing factors.

After a heart attack

Many people can make a full recovery after a heart attack. Most will be able to return to work and resume their daily activities after completing their rehabilitation.

As everyone who experiences a heart attack will face different difficulties and challenges, there is no set length of recovery period. A wide range of health professionals will provide you with all the help, support and guidance that you need during your rehabilitation process.

If you suspect that someone is having a heart attack, or you are experiencing the symptoms of a heart attack, make sure you seek medical attention immediately. The sooner the treatment is received, the more effective it will be and the greater the chance of survival.

Complications

The complications of a heart attack can be divided into those that happen immediately, and those that occur later on.

Immediate complications of a heart attack can include those outlined below.

  • Arrhythmias - these are irregular, uneven heart rhythms (either very fast or slow). If necessary, these can be corrected by passing an electric current through the heart (cardioversion). However, in most cases, your heart rate will return to normal, either naturally or with the help of medication.
  • Cardiogenic shock - is when you experience a sudden and dangerous drop in your blood pressure. Your heart is unable to supply enough blood for your body to function properly.
  • Hypoxaemia - is low levels of oxygen in your blood.
  • Pulmonary oedema - is when fluid builds up in and around your lungs.
  • Deep vein thrombosis (DVT) - this occurs when a blood clots forms in the deep veins of your legs, or pelvis. It either blocks, or interrupts, the flow of blood in your vein.
  • Myocardial rupture - occurs when your heart wall is damaged by a heart attack. It can sometimes cause the heart wall to rupture.
  • Ventricular aneurysm - this is when you develop a bulge in one of the heart ventricles (chambers).


Later complications of a heart attack can include those outlined below.

  • Aneurysm (blow out) - caused by build up of scar tissue on the damaged heart wall. An aneurysm can result in abnormal heart rhythms, blood clots, and low blood pressure.
  • Pericarditis - this condition causes inflammation of the lining of your heart. This can happen days or months after the heart attack, and can cause significant chest pain.
  • Angina - this condition can cause similar symptoms to a heart attack. The most notable symptom is chest pain. However, unlike a heart attack, the chest pain from angina should disappear naturally, usually after about ten minutes. It is caused by a shortage of oxygen to the heart.
  • Congestive heart failure - is when your heart is only able to beat very weakly which often leaves you with a feeling of breathlessness.
  • Oedema - is when fluid builds up in your ankles and legs.
  • Depression and loss of confidence.
  • Loss of sex drive and erectile dysfunction - although having sex after a heart attack will not increase your risk of having another attack, many men find it difficult to think about having sex again. If you have erectile dysfunction, it means that you have difficulty in getting, or maintaining, an erection.
  • Increased risk of heart attack in the future.

When you have a heart attack, your health will be closely monitored for several months afterwards. This is so that your GP can minimise the risk of you developing any of the complications which are described above. If you attend your regular check-ups, and follow your rehabilitation programme, your risk of experiencing complications will be greatly reduced. Early diagnosis and treatment of a complication will also help minimise the risk of permanent damage to your body.

Causes
 

The factors that increase the risk of a heart attack include:

  • increasing age (men over 45 years of age, and women who are over 55 years of age),
  • smoking,
  • being overweight, or obese,
  • high blood pressure,
  • high blood cholesterol level,
  • a diet high in saturated fats (animal fats),
  • diabetes,
  • a family history of heart disease, and
  • lack of regular exercise.

The risk of a heart attack is also increased if you have:

  • angina (chest pain, or discomfort, caused by a lack of oxygen to your heart),
  • had a previous heart attack, or
  • had heart surgery.

Sometimes, angina can be mistaken for a heart attack because the signs are similar. However, unlike a heart attack, angina will usually disappear within 15-20 minutes of resting, and/or taking medication.

Diagnosis
 

If you are having a suspected heart attack, you will usually be taken to hospital so that tests can be carried out to confirm the diagnosis. Some of these tests are outlined below.

 

Electrocardiograph (ECG)

 

An electrocardiograph (ECG) helps to trace the electrical activity of the heart. Every time your heart beats, it produces tiny electrical signals. An ECG machine records these signals on to paper, allowing your doctor to see how well your heart is functioning. An ECG can detect damage to your heart muscle, or problems with your heart rhythm. It can also show if you have had a heart attack, either recently, or some time ago.

The test takes about five minutes and is painless. During the test, electrodes (flat metal discs) are attached to your arms, legs, and chest. Wires from the electrodes are connected to the ECG machine, which records the electrical impulses.

 

Cardiac enzyme tests

 

When your heart has been damaged by a heart attack, it causes certain enzymes to slowly leak into your blood. Enzymes are special proteins which help regulate the chemical reactions that take place in your body. If you have had a suspected heart attack, a sample of your blood will be taken so that it can be tested for these heart enzymes. Your enzyme levels will be measured through a series of blood samples taken over a few days.

A chest X-ray may also be taken to look for any enlargement (swelling) of your heart.
 

Treatment

Most heart attacks can be successfully treated if immediate medical help is provided. The sooner the treatment, the more effective it will be, and the greater the chance of survival.

Treatment during a heart attack

Cardio-pulmonary resuscitation (CPR)

If someone is not breathing, coughing, moving, or responding to stimulation (being touched or spoken to), immediate lifesaving treatment with cardio-pulmonary resuscitation (CPR) should be started. CPR consists of giving 30 chest compressions to massage the heart for every two mouth-to-mouth resuscitation breaths.

If your heart has stopped (cardiac arrest), the medical team at the scene, or in hospital, will try to restart it using a device called a defibrillator. This sends an electric shock across your chest to kick-start your heart. The heart rhythm may become temporarily irregular as it recovers, so this treatment is best given when the heart is being continuously monitored on an electrocardiograph (ECG) in an ambulance, or in hospital. 

Aspirin

 

If you are having a heart attack, you will normally be given a one-off 300mg dose of aspirin. This helps to prevent the blood clot in your coronary artery from getting bigger. Ideally, it should be chewed, or taken dissolved in water, to ensure that it gets into your bloodstream as quickly as possible.  

Thrombolytics

 

Also known as 'clot-busters', thrombolytics dissolve the clot in your coronary artery, allowing blood to flow back to the damaged heart muscle. Commonly prescribed thrombolytics include alteplase and streptokinase. 

During a heart attack, thrombolytics are given by injection as soon as possible, ideally within one hour of symptoms starting. The part of the heart muscle starved of blood does not die immediately. If blood flow is restored within a few hours, much of the heart muscle that would have been damaged will survive.  

Morphine

 

Morphine is a strong type of painkilling medication. A dose of this medicine may be injected into your bloodstream to help ease pain and discomfort, and to reduce anxiety.  

Treatment following a heart attack  

Following a heart attack, you may need to take a number of different medicines. They will help to reduce the risk of a further heart attack occurring. You may need to take them indefinitely. 

Anti-platelets

 

Anti-platelets help to reduce the 'stickiness' of platelets (tiny particles in blood that help it to clot). When a large number of platelets stick to an atheroma or plaque (fatty deposit) inside an artery, they can form a thrombosis (clot). If this happens in a coronary artery, it causes a heart attack.  

Low dose aspirin is the preferred anti-platelet following a heart attack. You will normally be prescribed a 75mg dose to take once a day.

If you have a stomach ulcer, or asthma, you may not be able to take aspirin. Options if you have a stomach ulcer include taking an additional medicine to 'protect the stomach'. And, options if you have asthma include taking a different anti-platelet medicine such as clopidogrel. 

Beta-blockers

 

Beta-blockers (such as metoprolol, propranolol, timolol, and atenolol) help to protect the heart after a heart attack. They make the heart beat slower and with less force in order to lessen the work it has to do. Beta-blockers also stabilise the heart's electrical activity.  

Angiotensin-converting enzyme (ACE) inhibitors

Angiotensin-converting-enzyme inhibitors (ACE) inhibitors open up your blood vessels and lower blood pressure, which help to ease the burden on your heart. They also help to protect your heart from further damage.  

ACE inhibitors such as lisinopril, perindopril and ramipril are started at a low dose, which is slowly increased over a period of two to four weeks. Before you start taking an ACE inhibitor, you will normally have a blood test to check your kidneys are functioning normally. Seven to ten days after your first dose, your kidneys will be tested again. This is because ACE inhibitors can affect the kidneys of a small number of people who take them.  

Statins

 

Statins help to lower your blood cholesterol level by preventing cholesterol from being made in your liver. Generally, the higher your blood cholesterol level, the greater your risk of developing plaques (fatty deposits) in your arteries. The aim is to reduce your total blood cholesterol level to less than 4mmol/l, or by 25% of the original blood level, whichever gives the greatest reduction. Commonly prescribed statins include atorvastatin, fluvastatin, pravastatin, rosuvastatin and simvastatin.  

Surgery 

After having a heart attack, if your heart has been seriously damaged, you may require surgery to treat it. Two of the most common surgical procedures are outlined below.  

Angioplasty

 

Angioplasty is a type of surgery which opens up a coronary artery. It is usually carried out after you recover from your attack. However, in some specialist units, an angioplasty may be performed as an emergency treatment for people having a very serious heart attack.  

A tiny wire with a sausage-shaped balloon at the end is put into a large artery in your groin, or arm. It is then passed through your blood vessels up to your heart and into the narrowed section of a coronary artery using X-ray guidance. The balloon is then inflated inside the narrowed part of the artery to widen it. A stent (a flexible metal mesh) is usually inserted into the artery to help keep it open.  

Coronary artery bypass graft (CABG)

 

A coronary artery bypass graft (CABG) is a form of surgery which allows a blocked blood vessel to be bypassed with healthy blood vessel segments (grafts) taken from other parts of the body. Segments of vein from your legs, or chest, are used to create a new channel through which the blood can be directed past the blocked part of your artery. More blood can then get past into your heart muscle. However, not everyone with angina is suitable for this surgery as it depends on where the narrowed arteries are. 

Symptoms

The common symptoms of a heart attack are:

  • crushing central chest pain, or mild chest discomfort,
  • shortness of breath,
  • clammy, sweaty, and grey complexion,
  • dizziness,
  • nausea and vomiting,
  • restlessness,
  • coughing,
  • a general feeling of being unwell, and
  • a frightening sense that one is about to die.

The pain that you experience when having a heart attack often starts in your chest and then travels to your neck, jaw, ears, arms and wrists. Sometimes, it travels between the shoulder blades, back, or to the abdomen.

The pain can last from five minutes to several hours. Moving around, changing your position, or resting, will not stop, or ease, the pain. The pain may be constant, or it may come and go, and feel like pressure, squeezing, or fullness.

Some people do not feel any pain during a heart attack. This is known as a 'silent' heart attack and tends to affect people with diabetes, or those who are over 75 years of age.

Some evidence suggests that up to 20% of mild heart attacks go undiagnosed. This means that some people, because of previous undiagnosed attacks, may be suffering progressive damage to the heart muscle