What is a heart attack?

The correct medical term for a heart attack is myocardial infarction. Myocardial is from a Greek word meaning ‘heart’ and infarction comes from a Latin word that means ‘to plug up’.

Pacemaker

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This is a pacemaker as seen on cardiac angiography. Angiography is a graphical record of the heart muscle action.

Rights: Carter Newton (MD)Thomas F Heston (MD)

A heart attack occurs when an artery taking oxygenated blood to the heart muscle becomes blocked, preventing oxygen from reaching the heart muscle. This can cause damage to the muscle tissue.

Heart attack diagram

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A heart attack occurs when an artery taking oxygenated blood to the heart muscle becomes blocked, preventing oxygen from reaching the heart muscle. The blockage can lead to the heart stopping beating.

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The blockage can lead to the heart stopping beating or may cause the heart to beat in irregular patterns. These irregular heartbeats are called arrhythmias. A particularly serious arrhythmia is called ventricular fibrillation.

The blockage in the artery can be caused by a clot of blood or by the sudden rupturing of fatty material that tends to build up on the artery walls over many years.

White blood cells trap fat and cause the build up of fatty material called plaque (a bit like the plaque on your teeth) on the walls of the artery. It causes the walls of the artery to harden and become less flexible. When the plaque comes off the side of the wall, it can block the artery, stopping the blood flowing directly, or because of the breaking away, the artery tries to heal itself by clotting (just like when you cut your skin), and the blood clot can then also block the flow of blood.

Lifestyle factors such as smoking, eating foods high in cholesterol or fat, or not doing enough exercise contribute to the build up of plaque. Heart disease is a very serious health problem. In New Zealand, a person dies from a heart attack every 90 minutes!