Heart Attack

What is a ‘heart attack’?  Is it the same as ‘heart failure’? How does a ‘heart attack’ come about? Is a heart attack the same as a ‘coronary’?

To answer the second question first, heart failure and a heart attack are NOT the same; heart failure is when the heart is no longer up to the job of pumping blood around the body (more of which at a later date). A heart attack, known technically as ACUTE MYOCARDIAL INFARCTION, or an MI, is when part of the heart muscle (the ‘myocardium’) dies (an ‘infarction’). Why does it die, though?

The heart needs blood, as does every part of you. It gets it from 3 coronary arteries (the name comes from the same route as ‘coronet’ meaning ‘crown’, because they look (if you squint hard) like a crown around the heart. Unfortunately, they’re prone to ATHEROMA (about which more at a later date) which narrows them by causing plaques to form on the internal surface.

Angina is heart pain caused by a reduction in blood flow to the heart and is often caused by atheroma. Those who get it are lucky, but most people don’t get it. The first sign that they have atheroma affecting the coronary arteries is when a sudden block occurs in one of them, and the blood supply to a part of the heart muscle suddenly stops. The muscle dies and that is a ‘heart attack’.

Why does the blood supply suddenly stop? Usually because the blood clots on an atheromatous plaque, and that blocks the artery completely. So, a ‘heart attack’ is the same as a ‘coronary’, but medics talk of an MI.

Unfortunately, the pathologist won’t see any change in the heart muscle if the patient dies quickly after the MI. She/he won’t see much with the naked eye for quite a few hours, even if it’s examined down the microscope. The clot in the coronary artery is the clue.

But why do people actually die from a heart attack?

Normally, because the heart’s rhythm changes catastrophically due to the shock of the heart muscle death. It may stop beating completely (ASYSTOLE) or it may just twitch uncontrollably (VENTRICULAR FIBRILLATION).

But most people who die of heart disease don’t suffer from a heart attack…

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