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The reason it’s so often fatal? During a sudden cardiac arrest, your heart completely stops beating, says Shepal Doshi, M.D., director of cardiac electrophysiology at Providence Saint John’s Health Center in Santa Monica, Calif. If it doesn’t start back up again within a few minutes, you’re toast.
The condition often strikes without warning, and doctors aren’t exactly sure how to prevent it. But swift action once it occurs can save lives, says cardiologist and researcher Matthew J. Budoff, M.D., of the David Geffen School of Medicine and Harbor-UCLA Medical Center in Torrance, Calif.
What Is Sudden Cardiac Arrest?
You might hear “sudden cardiac arrest” and “heart attack” used interchangeably, but they are actually two different problems. Simply put, a heart attack is a plumbing problem—usually, a clot blocking blood flow to the heart. Cardiac arrest, on the other hand, is an electrical issue.
Your heart beats 100,000 times a day, Dr. Doshi says. And each bet requires an electrical charge. When you lose power, things get ugly fast. Think of what happens when your phone goes from low battery to no battery—it simply shuts down.
In most cases, cardiac arrest occurs because of an arrhythmia, or abnormal rhythm, in your heart’s ventricles. When your ticker’s working properly, these lower chambers squeeze and release to a regular beat, pushing life-giving blood to your brain and other organs. (Here’s why your heart occasionally skips a beat.)
But when the ventricles lose power, they quiver rapidly instead, in a specific type of rhythm problem called fibrillation. No blood reaches your vital organs, Dr. Budoff says. Within a few minutes, you have brain damage—then, you die.
Why Does Sudden Cardiac Arrest Occur?
The problem often starts with a weakened heart wall, Dr. Doshi says. Some people are born with a condition called cardiomyopathy, a disorder where your heart muscles become enlarged, thick, or rigid. As a result, it’s less able to pump blood throughout your body.
Others develop cardiomyopathy over time, due to high blood pressure, disease in the valves of their heart, or abusing drugs or alcohol. Scarring from prior heart attacks may play a role, since scar tissue may impede your heart’s electrical signals.
These structural issues all raise the risk of ventricular fibrillation—and, therefore, make you prone to cardiac arrest.
“Think of your heart as a house, and the walls are the muscle,” Dr. Doshi says. “If the wall gets eaten with termites, the electrical wires which are in the wall can start shorting out, too.”
Other potential causes include low levels of the minerals magnesium or potassium, which play a key role in the electrical signals your heart sends. That’s why intense workouts that send a surge of adrenaline through your body may trigger sudden cardiac arrest in people at risk, such as people born with cardiomyopathy.
And though cardiac arrest is different from a heart attack, a heart attack can trigger immediate cardiac arrest, Dr. Budoff says. So you could suffer cardiac arrest as a result of a heart attack.
Who Is At Risk Of Sudden Cardiac Arrest?
A family history of cardiac arrest or other heart problems elevates your danger level, Dr. Budoff says. In fact, having a first-degree relative—parent, sibling, or child—who had sudden cardiac arrest doubles your risk.
Your parents can also pass down genetic conditions that mess with your heart’s rhythm and leave you prone to ventricular fibrillation (for instance, long QT syndrome, a disorder that increases the length of time your heart needs to recharge between beats).
People with cardiomyopathy have about five times the risk of sudden cardiac arrest as people without this heart abnormality. Scary, since many are unaware they even have the condition, Dr. Doshi says.
What’s more, since heart attacks can lead to sudden cardiac arrest, all the normal factors that weigh heavy on your heart—extra pounds, a lack of exercise, smoking, and an unhealthy diet—also boost your odds, Dr. Doshi says.
All that said, many people who experience sudden cardiac arrest have apparently healthy hearts and no risk factors, Dr. Doshi says. Now, that doesn’t mean you should freak out about dropping dead. But it does mean you should know your family history, stay alert to symptoms, and be prepared to act swiftly if you see someone else go down.
How Can You Identify Sudden Cardiac Arrest?
About an hour before a sudden cardiac arrest, you might feel nauseous, vomit, or have chest pain or shortness of breath. Immediate warning signs of sudden cardiac arrest include heart palpitations or a racing heartbeat, dizziness or lightheadedness, or just feeling more winded or fatigued than usual, Dr. Doshi says.
But two-thirds of the time, sudden cardiac arrest has no symptoms. You simply lose consciousness—and your pulse.
That’s why it’s extra important that you know what to do if you see someone suddenly go down. Here’s your course of action: First, call 911 immediately. Then look for an automated external defibrillator (you’ll often find them in gyms, malls, and other public places). Open it and follow the diagram inside, Dr. Doshi says. The machine may also give audio instructors for proper use.
After defibrillation—or right away, if you don’t find an AED—start performing CPR. If you’re not trained, you don’t have to give mouth-to-mouth. Just use your hands to push on the chest at a rate of about 100 to 120 beats per minute (sing Stayin’ Alive to keep count). Keep it up until help arrives. Here’s how to perform CPR the right way.
Can You Prevent Sudden Cardiac Arrest?
That’s tricky, since doctors aren’t sure why most cases occur, Dr. Doshi says. But all the tried-and-true ways of taking care of your heart health can make a difference. These include maintaining a healthy weight, eating a nutritious diet, exercising, and not smoking.
If you have a family history of sudden cardiac arrest or worrisome symptoms like racing heartbeats or unusual fatigue, talk to your doctor. He or she might do a test like an electrocardiogram (EKG) to check your heart’s electrical function or take images of it using echocardiography or magnetic resonance imaging (MRI).
If you’re deemed high-risk, you may get an implanted defibrillator, an internal device that automatically shocks your heart if it stops. “It’s like having your own paramedic,” Dr. Doshi says.
People who survive cardiac arrest once are usually at risk of experiencing it again. Defibrillators can increase their odds of survival, research shows. Many also take medications to regulate their heart rhythm.