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% 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:

• 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
• 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
• pulseless electrical activity: arises when the heart muscle fails to generate sufficient pumping force after electrical stimulation, resulting in no pulse
• 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% 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.

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.

Australia has often been called the “allergy capital of the world”.

An estimated one in ten Australian children develop a food allergy in their first 12 months of life. Research has previously suggested food allergies are more common in infants in Australia than infants living in Europe, the United States or Asia.

So why are food allergies so common in Australia? We don’t know exactly – but local researchers are making progress in understanding childhood allergies all the time.

What causes food allergies?

There are many different types of reactions to foods. When we refer to food allergies in this article, we’re talking about something called IgE-mediated food allergy. This type of allergy is caused by an immune response to a particular food.

Reactions can occur within minutes of eating the food and may include swelling of the face, lips or eyes, “hives” or welts on the skin, and vomiting. Signs of a severe allergic reaction (anaphylaxis) include difficulty breathing, swelling of the tongue, swelling in the throat, wheeze or persistent cough, difficulty talking or a hoarse voice, and persistent dizziness or collapse.

Recent results from Australia’s large, long-running food allergy study, HealthNuts, show one in ten one-year-olds have a food allergy, while around six in 100 children have a food allergy at age ten.

In Australia, the most common allergy-causing foods include eggs, peanuts, cow’s milk, shellfish (for example, prawn and lobster), fish, tree nuts (for example, walnuts and cashews), soybeans and wheat.

Allergies to foods like eggs, peanuts and cow’s milk often present for the first time in infancy, while allergies to fish and shellfish may be more common later in life. While most children will outgrow their allergies to eggs and milk, allergy to peanuts is more likely to be lifelong.

Findings from HealthNuts showed around three in ten children grew out of their peanut allergy by age six, compared to nine in ten children with an allergy to egg.

Are food allergies becoming more common?

Food allergies seem to have become more common in many countries around the world over recent decades. The exact timing of this increase is not clear, because in most countries food allergies were not well measured 40 or 50 years ago.

We don’t know exactly why food allergies are so common in Australia, or why we’re seeing a rise around the world, despite extensive research.

But possible reasons for rising allergies around the world include changes in the diets of mothers and infants and increasing sanitisation, leading to fewer infections as well as less exposure to “good” bacteria. In Australia, factors such as increasing vitamin D deficiency among infants and high levels of migration to the country could play a role.

In several Australian studies, children born in Australia to parents who were born in Asia have higher rates of food allergies compared to non-Asian children. On the other hand, children who were born in Asia and later migrated to Australia appear to have a lower risk of nut allergies.

Meanwhile, studies have shown that having pet dogs and siblings as a young child may reduce the risk of food allergies. This might be because having pet dogs and siblings increases contact with a range of bacteria and other organisms.

This evidence suggests that both genetics and environment play a role in the development of food allergies.

We also know that infants with eczema are more likely to develop a food allergy, and trials are underway to see whether this link can be broken.

Can I do anything to prevent food allergies in my kids?

One of the questions we are asked most often by parents is “can we do anything to prevent food allergies?”.

We now know introducing peanuts and eggs from around six months of age makes it less likely that an infant will develop an allergy to these foods. The Australasian Society of Clinical Immunology and Allergy introduced guidelines recommending giving common allergy-causing foods including peanut and egg in the first year of life in 2016.

Our research has shown this advice had excellent uptake and may have slowed the rise in food allergies in Australia. There was no increase in peanut allergies between 2007–11 to 2018–19.

Introducing other common allergy-causing foods in the first year of life may also be helpful, although the evidence for this is not as strong compared with peanuts and eggs.

What next?

Unfortunately, some infants will develop food allergies even when the relevant foods are introduced in the first year of life. Managing food allergies can be a significant burden for children and families.

Several Australian trials are currently underway testing new strategies to prevent food allergies. A large trial, soon to be completed, is testing whether vitamin D supplements in infants reduce the risk of food allergies.

Another trial is testing whether the amount of eggs and peanuts a mother eats during pregnancy and breastfeeding has an influence on whether or not her baby will develop food allergies.

For most people with food allergies, avoidance of their known allergens remains the standard of care. Oral immunotherapy, which involves gradually increasing amounts of food allergen given under medical supervision, is beginning to be offered in some facilities around Australia. However, current oral immunotherapy methods have potential side effects (including allergic reactions), can involve high time commitment and cost, and don’t cure food allergies.

There is hope on the horizon for new food allergy treatments. Multiple clinical trials are underway around Australia aiming to develop safer and more effective treatments for people with food allergies.

Jennifer Koplin, Group Leader, Childhood Allergy & Epidemiology, The University of Queensland and Desalegn Markos Shifti, Postdoctoral Research Fellow, Child Health Research Centre, Faculty of Medicine, The University of Queensland

This article is republished from The Conversation under a Creative Commons license. Read the original article.