What’s the difference between a heart attack and cardiac arrest?
One’s about plumbing, the other wiring
Gold Coast (The Conversation): In July 2023, rising US basketball star Bronny James collapsed on the court during practice and was sent to hospital. The 18-year-old athlete, son of famous LA Lakers’ veteran LeBron James, had experienced a cardiac arrest.
Many media outlets incorrectly referred to the event as a “heart attack” or used the terms interchangeably.
A cardiac arrest and a heart attack are distinct yet overlapping concepts associated with the heart.
With some background in how the heart works, we can see how they differ and how they’re related.
Understanding the heart
The heart is a muscle that contracts to work as a pump. When it contracts it pushes blood – containing oxygen and nutrients – to all the tissues of our body.
For the heart muscle to work effectively as a pump, it needs to be fed its own blood supply, delivered by the coronary arteries. If these arteries are blocked, the heart muscle doesn’t get the blood it needs.
This can cause the heart muscle to become injured or die, and results in the heart not pumping properly.
Heart attack or cardiac arrest?
Simply put, a heart attack, technically known as a myocardial infarction, describes injury to, or death of, the heart muscle.
A cardiac arrest, sometimes called a sudden cardiac arrest, is when the heart stops beating, or put another way, stops working as an effective pump.
In other words, both relate to the heart not working as it should, but for different reasons. As we’ll see later, one can lead to the other.
Why do they happen? Who’s at risk?
Heart attacks typically result from blockages in the coronary arteries. Sometimes this is called coronary artery disease, but in Australia, we tend to refer to it as ischaemic heart disease.
The underlying cause in about 75 per cent of people is a process called atherosclerosis. This is where fatty and fibrous tissue build up in the walls of the coronary arteries, forming a plaque. The plaque can block the blood vessel or, in some instances, lead to the formation of a blood clot.
Atherosclerosis is a long-term, stealthy process, with a number of risk factors that can sneak up on anyone. High blood pressure, high cholesterol, diet, diabetes, stress, and your genes have all been implicated in this plaque-building process.
Other causes of heart attacks include spasms of the coronary arteries (causing them to constrict), chest trauma, or anything else that reduces blood flow to the heart muscle.
Regardless of the cause, blocking or reducing the flow of blood through these pipes can result in the heart muscle not receiving enough oxygen and nutrients. So cells in the heart muscle can be injured or die.
But a cardiac arrest is the result of heartbeat irregularities, making it harder for the heart to pump blood effectively around the body. These heartbeat irregularities are generally due to electrical malfunctions in the heart. There are four distinct types:
1. ventricular tachycardia: a rapid and abnormal heart rhythm in which the heartbeat is more than 100 beats per minute (normal adult, resting heart rate is generally 60-90 beats per minute). This fast heart rate prevents the heart from filling with blood and thus pumping adequately
2. ventricular fibrillation: instead of regular beats, the heart quivers or “fibrillates”, resembling a bag of worms, resulting in an irregular heartbeat greater than 300 beats per minute
3. pulseless electrical activity: arises when the heart muscle fails to generate sufficient pumping force after electrical stimulation, resulting in no pulse
4. asystole: the classic flat-line heart rhythm you see in movies, indicating no electrical activity in the heart.
Cardiac arrest can arise from numerous underlying conditions, both heart-related and not, such as drowning, trauma, asphyxia, electrical shock and drug overdose. James’ cardiac arrest was attributed to a congenital heart defect, a heart condition he was born with.
But among the many causes of a cardiac arrest, ischaemic heart disease, such as a heart attack, stands out as the most common cause, accounting for 70 per cent of all cases.
So how can a heart attack cause a cardiac arrest? You’ll remember that during a heart attack, heart muscle can be damaged or parts of it may die. This damaged or dead tissue can disrupt the heart’s ability to conduct electrical signals, increasing the risk of developing arrhythmias, possibly causing a cardiac arrest.
So while a heart attack is a common cause of cardiac arrest, a cardiac arrest generally does not cause a heart attack.
What do they look like?
Because a cardiac arrest results in the sudden loss of effective heart pumping, the most common signs and symptoms are a sudden loss of consciousness, absence of pulse or heartbeat, stopping of breathing, and pale or blue-tinged skin.
But the common signs and symptoms of a heart attack include chest pain or discomfort, which can show up in other regions of the body such as the arms, back, neck, jaw, or stomach. Also frequent are shortness of breath, nausea, light-headedness, looking pale, and sweating.
What’s the take-home message?
While both heart attack and cardiac arrest are disorders related to the heart, they differ in their mechanisms and outcomes.
A heart attack is like a blockage in the plumbing supplying water to a house. But a cardiac arrest is like an electrical malfunction in the house’s wiring.
Despite their different nature both conditions can have severe consequences and require immediate medical attention.
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London, Nov 22: A bomb disposal squad deployed as a “precaution” to the South Terminal of Gatwick Airport concluded an investigation into a "security incident" on Friday after making a “suspect package” safe.
The South Terminal of Gatwick Airport, the UK's second busiest airport after Heathrow, which was briefly shut owing to the incident reopened following the incident.
The Gatwick is around 45 km south of London.
Two people detained during the enquiries have since been allowed to continue their journey as the airport was opened.
“Police have concluded their investigation into a report of a suspect package at Gatwick Airport. Officers from the EOD (Explosive Ordnance Disposal) team made the package safe, and the airport has been handed back to its operator,” Sussex Police said in an updated statement.
“Two people detained while enquiries were ongoing have subsequently been allowed to continue their journeys. There will remain an increased police presence in the area to assist with passengers accessing the South Terminal for onward travel,” the statement added.
Earlier on Friday, the incident caused severe disruption at the busy airport’s South Terminal, while the North Terminal of Gatwick Airport remained unaffected.
“Police were called to the South Terminal at Gatwick Airport at 8.20 am on Friday (November 22) following the discovery of a suspected prohibited item in luggage,” a Sussex Police statement said.
“To ensure the safety of the public, staff and other airport users, a security cordon has been put in place whilst the matter is dealt with. As a precaution, an EOD (Explosive Ordnance Disposal) team is being deployed to the airport. This is causing significant disruption and some roads around the South Terminal have been closed. We’d advise the public to avoid the area where possible,” it said.
Footage on social media taken outside the airport showed crowds of frustrated travellers being moved away from the terminal building.
Gatwick said it was working hard to resolve the issue.
“A large part of the South Terminal has been evacuated as a precaution while we continue to investigate a security incident," the airport said in a social media post.
“Passengers will not be able to enter the South Terminal while this is ongoing. The safety and security of our passengers and staff remain our top priority. We are working hard to resolve the issue as quickly as possible.”
Train and bus services that serve the airport were also impacted while the police carried out their inquiries.
In an unrelated incident in south London on Friday morning, the US Embassy area in Nine Elms by the River Thames was the scene of a controlled explosion by Scotland Yard dealing with what they believe may have been a “hoax device”.
“We can confirm the 'loud bang' reported in the area a short time ago was a controlled explosion carried out by officers,” the Metropolitan Police said in a post on X.
“Initial indications are that the item was a hoax device. An investigation will now follow. Some cordons will remain in place for the time being but the majority of the police response will now be stood down,” it added.
