Cardiac Arrest
Cardiac arrest is a life-threatening emergency where the heart suddenly stops beating. Without immediate help, death can occur within minutes. Understanding what happens during cardiac arrest and knowing how to respond can mean the difference between life and death.
Table of contents
- What Is Cardiac Arrest?
- How Cardiac Arrest Differs from a Heart Attack
- Warning Signs and Symptoms
- What Causes Cardiac Arrest
- Who Is at Risk
- Emergency Response: What to Do
- Medical Treatment
- How Common Is Cardiac Arrest
What Is Cardiac Arrest?
Cardiac arrest happens when your heart suddenly and unexpectedly stops beating.[1] When the heart stops, blood cannot flow to the brain and other vital organs. This means your body is not getting the oxygen it needs to survive.[2]
During cardiac arrest, people typically collapse and become unresponsive. They lose consciousness because their brain is not receiving oxygen-rich blood.[3] Within minutes, this puts your organs and whole body at risk of death.[3]
Cardiac arrest is also called sudden cardiac arrest because symptoms start without warning. This is why people also refer to it as sudden cardiac death.[1]
How Cardiac Arrest Differs from a Heart Attack
Cardiac arrest is not the same as a heart attack, although many people confuse the two conditions.[1] Both are medical emergencies, but they happen in different ways.
A heart attack occurs when blood flow to a part of the heart is blocked. The arteries that supply blood to your heart become clogged, usually by a buildup of plaque. This blocks blood flow and damages the heart muscle. During a heart attack, the heart usually does not suddenly stop beating.[1] You can think of a heart attack as a “plumbing” problem with your heart.
Cardiac arrest is caused by a problem with the heart’s electrical system. The electrical signals that make the heart pump become too fast or uneven, causing the heart to stop pumping blood entirely.[3] You can think of cardiac arrest as a problem with your heart’s “wiring.”
However, a heart attack can sometimes trigger cardiac arrest by causing a change in the heart’s electrical activity.[1]
Warning Signs and Symptoms
Cardiac arrest usually happens suddenly. A person experiencing cardiac arrest will:[2][4]
- Collapse suddenly and lose consciousness (pass out)
- Stop breathing or gasp for air
- Not respond to shouting or shaking
- Have no pulse
Sometimes other symptoms can occur about an hour before cardiac arrest happens. These warning signs may include:[1][3]
- Chest pain or discomfort
- Shortness of breath
- Weakness
- Fast-beating, fluttering, or pounding heartbeat (called palpitations)
- Nausea or vomiting
- Dizziness or lightheadedness
- A racing heart
However, most people do not have any symptoms until cardiac arrest happens. Sudden cardiac arrest often occurs with no warning.[1]
What Causes Cardiac Arrest
Cardiac arrest is caused by a problem with the heart’s electrical system. Before cardiac arrest happens, abnormal, rapid electrical impulses suddenly override the normal electrical signals that control your heartbeat.[3]
The most common problem that leads to cardiac arrest is an irregular heartbeat called an arrhythmia. The most dangerous type is ventricular fibrillation, where the lower chambers of your heart (called ventricles) quiver instead of beating regularly. When this happens, your heart cannot pump blood to the rest of your body.[3][6]
Several conditions and situations can lead to these abnormal heart rhythms:[3][6]
- Coronary artery disease, where the arteries of the heart cannot deliver enough oxygen-rich blood to the heart
- Cardiomyopathy, when the heart muscle becomes enlarged or stiff
- Heart attack
- Heart failure
- Heart valve disease
- Congenital heart defects (heart problems present since birth)
- Changes to your heart’s structure because of disease or infection
- Certain inherited disorders like Brugada syndrome or Long QT syndrome
- Very low blood levels of potassium or magnesium, which play an important role in your heart’s electrical system
- Major blood loss
- Severe lack of oxygen
- Recreational drugs, such as cocaine or amphetamines
- Certain medications
- Intense physical stress or activity that causes your body to release the hormone adrenaline
Although rare, a forceful blow to the chest, such as from a hard ball or steering wheel, can also cause cardiac arrest. This condition is called commotio cordis, which means agitation of the heart.[4]
Who Is at Risk
More than 356,000 Americans each year experience cardiac arrest outside of a hospital.[3] While it typically affects adults, it can happen in children too. About 23,000 children and teens experience sudden cardiac arrest each year.[17]
You are at higher risk for cardiac arrest if you:[3][6]
- Have coronary artery disease or other heart disease
- Are older (risk increases with age)
- Are a man (it is more common in men than women)
- Are Black or African American, especially if you have other conditions such as diabetes, high blood pressure, heart failure, or chronic kidney disease
- Have had a previous cardiac arrest
- Have irregular heartbeats (arrhythmias)
- Have a personal or family history of sudden cardiac arrest or inherited heart disorders
- Have a heart that pumps less than 35% of its blood when filled (called low ejection fraction)
- Have a family history of heart problems, heart disease before age 50, or sudden unexplained deaths
- Use drugs or alcohol heavily
However, half of cardiac arrests happen to people who did not know they had a heart problem.[2] Sudden cardiac arrest happens in people with and without heart disease.[3]
Emergency Response: What to Do
Cardiac arrest is a medical emergency. Most cardiac arrests occur outside of hospitals, which means emergency care depends on family, friends, or people nearby.[13] Quick action is needed to save a person’s life or prevent permanent brain damage. The faster someone gets help, the better their chances of survival with good health outcomes.[3]
If you see someone collapse and suspect cardiac arrest:[13]
- Check if the person responds to shouting and tapping on their body
- Check for breathing and a pulse
- If the person is not breathing normally and does not respond, call 911 (or your local emergency services number) immediately
- Start CPR right away
- Look for an automated external defibrillator (AED)
Cardiopulmonary resuscitation (CPR) keeps enough oxygen in your lungs and gets it to your brain until help arrives or until an electric shock can restore a normal heart rhythm.[3] You don’t need training to give CPR. The American Heart Association recommends doing CPR with hard and fast chest compressions. Push down hard and fast in the center of the chest. Time your pushes to the beat of the song “Stayin’ Alive” (100-120 pushes per minute).[1]
An automated external defibrillator (AED) is a portable device that can restore a normal heart rhythm by giving an electric shock to the heart.[2] AEDs are often available in public places like airports, stadiums, offices, schools, and shopping centers. These devices are designed so that untrained bystanders can use them. They “talk” to the user with step-by-step voice instructions.[13] If you find an AED, follow its instructions carefully.
Calling 911 and immediately treating with CPR and defibrillation can save the life of a person in cardiac arrest.[2] Most people who have cardiac arrest do not receive treatment quickly enough to survive. Nine out of 10 people who have a cardiac arrest outside of a hospital die—often within minutes.[2] Every minute that passes without intervention reduces the odds of survival by 10 percent.[6] But if someone immediately receives CPR and an AED shock if needed, their survival odds can double or even triple.[6]
Medical Treatment
When emergency medical personnel arrive, they will continue CPR and use professional defibrillators to try to restart the heart.[1] Emergency treatment for sudden cardiac arrest includes both CPR and shocks to the heart with a defibrillator.[1]
If you survive cardiac arrest and reach the hospital, doctors will run tests to determine what caused it. These tests may include:[11]
- Blood tests to check for heart damage or abnormal levels of minerals, hormones, and chemicals
- Electrocardiogram (ECG or EKG) to measure your heart’s electrical activity and show if your heart has been damaged
- Echocardiogram, which uses sound waves to create images of your heart in motion to show how blood flows and whether there is heart damage
- Ejection fraction measurement to see what percentage of blood your heart pumps out when it beats
- Chest X-ray to show the size and shape of your heart
- Cardiac MRI to see detailed pictures of your heart and blood vessels
- Cardiac catheterization to see if your arteries are narrowed or blocked
Treatment after cardiac arrest may include:[13]
- Targeted temperature management to protect your brain by keeping your body temperature low
- Oxygen therapy to help get enough oxygen into your body
- Medications to treat the underlying causes
- Procedures or devices to prevent future cardiac arrests
If you’re at high risk for cardiac arrest, your doctor may recommend an implantable cardioverter defibrillator (ICD). This device is placed inside your body and monitors your heart. It delivers an electrical shock when needed to restore a normal heart rhythm.[3]
People who survive cardiac arrest can experience brain injury, injury to internal organs, and psychological distress like anxiety, post-traumatic stress disorder, and depression.[4]
How Common Is Cardiac Arrest
Cardiac arrest is a common cause of death. In the United States, more than 356,000 people each year experience cardiac arrest outside of a hospital.[3][4] Cardiac arrest causes about 300,000 to 450,000 deaths in the United States each year.[2] It accounts for about half of the deaths linked with heart attack and stroke.[2]
Black men and women are more likely to die from out-of-hospital cardiac arrest than White men and women.[4] People at highest risk are older adults and men.[4]
About 60% to 80% of people who have an out-of-hospital cardiac arrest die before reaching the hospital.[4] The overall survival rate is approximately 10% for cardiac arrests that happen outside of a hospital and 25% for those that happen inside a hospital.[7]
