Disease of the Month: Heart attack

A heart attack happens when the supply of blood to the heart is suddenly blocked, usually by a blood clot. Lack of blood to the heart can seriously damage the heart muscle.

Known medically as a myocardial infarction or MI, a heart attack can also be called acute coronary syndrome or coronary thrombosis.

What causes a Heart Attack?

Coronary heart disease is the main cause of heart attacks. This is when the coronary arteries (the major blood vessels that supply the heart with blood) narrow and become clogged up with deposits of cholesterol - the deposits are called plaques.

At the time of a heart attack, one of the plaques ruptures, causing a blood clot to develop. This clot can block the coronary artery, starving the heart of blood and oxygen, triggering a heart attack.

The heart requires a continuous supply of oxygen-rich blood and if this supply is suddenly stopped, heart muscles may be damaged and begin to die.

Other less common causes for a heart attack can include:

•  Drug misuse such as cocaine or amphetamines can cause a narrowing of the coronary arteries, restricting blood supply and triggering a heart attack

• An aneurysm (a weakness in a blood vessel wall) can develop in the coronary arteries and although less common than other types of aneurysms, if a coronary artery aneurysm bursts, the blood supply to the heart will cease, triggering a heart attack

•  Hypoxia (lack of oxygen in the blood) can occur due to carbon monoxide poisoning. The heart will receive un-oxygenated blood resulting in damage to the heart muscles, triggering a heart attack.

Heart Attack diagnostics

An electrocardiograph (ECG) is an important test that should be carried out within 10 minutes of being admitted to hospital with a suspected heart attack. The ECG measures the electrical activity of the heart and records the hearts electrical signals onto paper, allowing to check how well the heart is functioning. The ECG both helps confirm the diagnosis of a heart attack and helps determine what type of heart attack has occurred.

Other tests can be used to determine the state of the heart and also check for related complications. Due to heart attacks being medical emergencies, some tests are only carried out once the initial treatment has started and the condition is stabilised.

• Blood tests. Damage to the heart from a heart attack causes proteins to slowly leak into the blood. If a suspected heart attack has occurred a series of blood samples will be taken so it can be tested for these heart proteins (known as cardiac markers) and measured over the course of a few days. This allows the damage suffered to the heart to be assessed and checks how well the response to treatment is going.

• Chest X-ray. This can be carried out if the diagnosis of a heart attack is uncertain and there is another cause of the symptoms, or to check whether complications have occurred as a result of the heart attack.

•  Echocardiogram. This can be used to determine which areas of the heart have sustained damage.

•  Coronary Angiography. This will help to identify whether a blockage or narrowing has happened in the coronary arteries and if so, pinpoint the exact location.

Types of Heart Attack

An electrical measurement recorded by the ECG known as the ST segment can classify heart attacks and this corresponds to the level of damage inflicted on the heart. The higher the ST segment is, the greater the damage is likely.

•  ST segment elevation myocardial infarction (STEMI) is the most serious type of heart attack. There is a total blockage of the coronary artery which can cause extensive damage to a large area of the heart.

•  Non-ST segment elevation myocardial infarction (NSTEMI) can be less serious than a STEMI as the supply of the blood to the heart is only partially blocked resulting in a smaller section of heart damage. A NSTEMI is still serious medical emergency.

What is the difference between a Heart Attack and Cardiac Arrest?
Cardiac arrest is different from a heart attack as when a cardiac arrest occurs the heart stops pumping blood around the body, resulting in unconsciousness and abnormal breathing. 

To have any chance of surviving a cardiac arrest, immediate cardiopulmonary resuscitation (CPR) and defibrillation is needed.

Treatment

For the most serious form of heart attack (STEMI) there are two main treatment options. A combination of medication to dissolve the blood clot to restore the flow of blood to the heart (thrombolysis) and surgery to widen the coronary artery (coronary angioplasty).

NSTEMI is usually treated initially by blood thinning medication.  In some instances a coronary artery bypass graft or coronary angioplasty may be recommended after the initial treatment with medication.

Reducing the risk of another Attack

Recovering from a heart attack can take several months and rehabilitation should not be rushed. The two main aims of the recovery process are:

•  To gradually restore physical fitness levels in order to resume normal activities.

• To reduce the risk of another heart attack

In order to reduce the risk of having another heart attack some lifestyle changes may be recommended together with taking a long-term course of different medications.

Lifestyle changes could include:

•  Quitting smoking

•  Not exceeding the daily recommended limits of alcohol and avoid binge drinking

• Maintaining a healthy weight

• Dietary advice

• Regular physical activity after a sufficient physical recovery is made from the effects of a heart attack

Four types of medication are widely used to reduce the risks of further heart attacks:

•  ACE inhibitors - used to lower blood pressure

•  Anti-platelets - a medication that can help prevent blood clots

•  Beta-blockers - used to protect the heart from further damage (help to relax the heart's muscles to reduce strain on the heart)

•  Statins - used to lower the blood cholesterol level.

Outlook

For people who have suffered from a heart attack the outlook can vary significantly depending on:

•  Age - more complications are likely the older the age

•  Heart attack severity - how much of the heart muscle was damaged during the heart attack

•  How long it took to receive treatment - the outlook tends to be worse the longer the delay

Around one-third of people who have a heart attack die as a result, often before the person reaches hospital or within 28 days after the heart attack. The outlook improves dramatically for people who survive for 28 days after the heart attack.

Prevention

Making lifestyle changes is the most effective way to prevent heart attacks or reduce the risk of another heart attack:

•  Eat a healthy, balanced diet

•  Avoid smoking

•  Maintain blood pressure at a healthy level

•  Do not exceed the recommended levels of alcohol

•  Maintain a healthy weight

•  Take regular exercise

Other risk factors

• Diabetes - the increased levels of blood glucose can damage the coronary arteries making them more susceptible to coronary artery disease

• Age and sex - coronary heart disease is more likely the older you get and men are two to three times more likely to have a heart attack than women

•  Family history - there is a higher risk of developing heart disease if you have a first-degree relative (a parent, brother or sister) with this history.  n

Neil Hartigan is underwriting development manager at VitalityLife (formerly PruProtect)