In July 2023, rising American basketball star Bronny James collapsed on the court during practice and was sent to the hospital. The 18-year-old athlete, the son of famous LA Lakers legend LeBron James, had suffered a cardiac arrest.
Several media organizations incorrectly referred to the incident as a “heart attack” or used the terms interchangeably.
Heart attack and cardiac arrest are different but interrelated concepts related to the heart.
By knowing some background on how the heart works, we can see how they differ and how they are related.
understanding the heart
The heart is a muscle that contracts to act as a pump. When it contracts, it pumps blood – which contains oxygen and nutrients – to all the tissues in our body.
For the heart muscle to work effectively as a pump, it needs a blood supply delivered by the coronary arteries. If these arteries are blocked, the heart muscle does not get the blood it needs.
This can cause the heart muscle to get injured or die, and result in the heart not being able to pump properly.
Heart attack or cardiac arrest?
Simply put, a heart attack, technically called myocardial infarction, describes injury to or death of the heart muscle.
A heart attack, sometimes called a sudden cardiac arrest, occurs when the heart stops beating, or in other words, stops working as an effective pump.
In other words, both are related to the heart not working properly, but for different reasons. As we’ll see later, one can lead to the other.
Why does this happen? Who is at risk?
A heart attack is usually caused by a blockage in the coronary arteries. Sometimes this is called coronary artery disease, but in Australia, we refer to it as ischaemic heart disease.
In about 75% of people, the root cause is a process called atherosclerosis. This is when fatty and fibrous tissue builds up in the walls of the coronary arteries, forming plaque. Plaque can block a blood vessel or, in some cases, cause a blood clot to form.
Atherosclerosis is a long-term, stealth process, with many risk factors that can affect anyone. High blood pressure, high cholesterol, diet, diabetes, stress, and your genes are all involved in this plaque-building process.
Other causes of a heart attack include a spasm of the coronary arteries (causing them to narrow), a chest injury, or any other cause that reduces blood flow to the heart muscle.
Whatever the cause, blocking or reducing blood flow through these tubes prevents the heart muscle from getting enough oxygen and nutrients. Therefore, cells in the heart muscle can become injured or die.
But cardiac arrest is the result of irregularities in the heartbeat, which makes it harder for the heart to pump blood around the body effectively. These heartbeat irregularities are usually caused by an electrical malfunction in the heart. There are four different types:
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Ventricular tachycardia: A fast, abnormal heart rate in which the heart beats more than 100 beats per minute (a normal adult, resting heart rate is usually 60-90 beats per minute). This fast heart rate prevents the heart from filling with blood and thus pumping adequately
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ventricular fibrillation: Instead of regular beats, the heart begins to quiver or “fibrillate,” resembling a bag of worms, resulting in an irregular heart rate greater than 300 beats per minute
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Pulseless electrical activity: This occurs when the heart muscle fails to generate enough pumping force following electrical stimulation, resulting in no pulse
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Asystole: The classic flat-line heart rhythm seen in films, which indicates no electrical activity in the heart.
Heart attacks can result from a number of underlying conditions, whether or not related to the heart, such as drowning, trauma, choking, electric shock, and drug overdose. The cause of James’ heart attack was a congenital heart defect, a heart condition he was born with.
But among the many causes of heart failure, ischemic heart disease, aka heart attack, is the most common cause, accounting for 70% of all cases.
So how can a heart attack lead to cardiac arrest? You may recall that during a heart attack, the heart muscle can become damaged or parts of it can die. This damaged or dead tissue can impede the heart’s ability to conduct electrical signals, increasing the risk of developing an arrhythmia, potentially leading to cardiac arrest.
So, while heart attack is a common cause of a heart attack, a heart attack does not usually cause a heart attack.
What do they look like?
Because a heart attack suddenly causes the heart to stop pumping effectively, the most common signs and symptoms are sudden loss of consciousness, loss of pulse or heartbeat, breathing stoppage, and pale or bluish skin.
But common symptoms of a heart attack include chest pain or discomfort, which may also appear in other areas of the body such as the arms, back, neck, jaw or stomach. Shortness of breath, nausea, dizziness, paleness and sweating are also common.
What is its message?
Although both heart attack and cardiac arrest are disorders related to the heart, their mechanisms and outcomes are different.
A heart attack is like a blockage in the plumbing supplying water to a house. But cardiac arrest is like an electrical fault in the house wiring.
Despite their different nature, both conditions can have serious consequences and require immediate medical attention.
(Michael Todorovic, Associate Professor of Medicine, Bond University and Matthew Barton, Senior Lecturer, School of Nursing and Midwifery, Griffith University)
(This article is republished from The Conversation under a Creative Commons license. Read the original article.)
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)