When singer Tom Petty died last week, reports variously said that he has suffered a cardiac arrest or a heart attack.
For most people, they’d likely be considered synonymous, but that’s not the case, as a story on The Conversation cleverly explains.
Both are types of heart disease, as is heart failure, but Anna Beale, a doctor who has a PhD in cardiology, likens a cardiac arrest – as Petty suffered – to an electrical failure, while a heart attack is a problem with the plumbing, and heart failure is a carpentry issue.
In short, our heart beats steadily because it has a natural ‘pacemaker’ that sends electricity through it, with ‘wiring’ cells throughout the heart that respond to the signal by beating. There’s also mains circuits to direct the flow of electricity, that act as backups as part of the circuit fails.
Diseases such as blocked arteries, genetic conditions, and plain old age-related degeneration can cause these failures, which can be in the form of a power failure or a surge of electricity, both of which can stop the heart from pumping. These, in effect, are the two main types of cardiac arrest.
In this case, CPR is vital, Beale explains, saying that when the heart stops beating, blood stops getting to the brain and the rest of the body, and that will cause death.
A heart attack, meanwhile, is when the heart itself is starved of blood and oxygen, usually because arteries leading into and out of the heart are full of plaque and narrowed as a result. Sometimes this plaque, which is made up of cholesterol, fatty cells and immune cells, breaks off and makes a clot that blocks the blood flow through the artery.
When starved of blood and oxygen, the heart muscle tissue starts to die, and won’t beat. That’s the heart attack, but the tissue death can set off a cardiac arrest as well.
Heart failure, on the other hand, is due to the heart being able to supply the body with enough blood, usually because its weak and thus can’t pump enough, or has stiffened so can’t properly fill with blood. Heart failure can be caused by many conditions, from genetic disorders and heart attacks to infections and high blood pressure.
Heart failure fatalities are often the result of a cardiac arrest, as the heart’s weak carpentry starts causing electrical problems.