What is Cardiac Arrest?

Cardiac arrest occurs when the heart stops pumping blood effectively to the body and brain. A person in cardiac arrest is clinically dead.

According to the American Heart Association, each year, over 600,000 people suffer cardiac arrest in the United States. Over 350,000 of those events take place outside of a hospital. Cardiac arrest due to Heart Disease is the number 1 cause of death in the United States.

Chances of Survival for Cardiac Arrest

The survival rate for cardiac arrest varies by age and location. For Out-of-Hospital Cardiac Arrest (OHCA), the survival rate is just under 10%. Adults who suffer an In-Hospital Cardiac Arrest (IHCA) have a survival rate of approximately 22%. For pediatric IHCA, the survival rate ranges from 6.5% for infants to 21% for teens.

Immediate CPR and defibrillation will provide the best chance of survival.

What Causes Cardiac Arrest?

Cardiac arrest in adults occurs when the heart stops pumping blood effectively, typically due to an electrical malfunction that disrupts its normal rhythm. The most common causes are:

Heart-related (most common)

• Coronary artery disease (CAD): Blocked arteries to the heart muscle.
• Heart attack (myocardial infarction): A blockage in a coronary artery can cause dangerous arrhythmias that cause cardiac arrest.
• Arrhythmias: Abnormal heart rhythms, especially ventricular fibrillation (VFib) and ventricular tachycardia (VTach).
• Cardiomyopathy: Enlarged or thickened heart muscle increases the risk of arrhythmias.
• Heart failure: A weak heart muscle is prone to rhythm disturbances.
• Valvular heart disease: Severe narrowing or leakage of the valves can put stress on the heart.

Non–heart–related (secondary cardiac arrest)

• Respiratory problems: Severe asthma, choking, drowning, or suffocation.
• Massive blood loss or shock: Trauma or internal bleeding.
• Electrolyte imbalances: Low potassium or magnesium can cause arrhythmias.
• Drug overdose or toxicity: Especially opioids, cocaine, or certain medications.
• Severe infection (sepsis): Can overwhelm the heart and circulation.
• Severe hypothermia or hyperthermia.
• Pulmonary embolism (PE): A large blood clot in the lungs.

What is Cardiac Arrest In Children?

Cardiac arrest in children is rare compared to adults, and the causes are often quite different. In children, it’s usually not caused by sudden heart rhythm problems, as in adults, it’s most often the end result of something else that went wrong first.

Common causes in children include:

Respiratory problems (most common trigger)

• Severe asthma attack
• Choking/airway blockage
• Drowning
• Severe pneumonia or bronchiolitis
• Suffocation

Severe trauma or injury

• Major blood loss.
• Head injury.
• Severe shock from burns or crush injuries.

Congenital heart defects (present from birth)

• Structural heart problems.
• Abnormal heart rhythms from inherited electrical disorders (e.g., Long QT syndrome, WPW).

Severe infections

• Meningitis or encephalitis.
• Sepsis (overwhelming infection).

Electrical or metabolic issues

• Heat stroke or hypothermia.
• Abnormal electrolytes (potassium, calcium, etc.).
• Severe low blood sugar.

Poisoning or overdose

• Ingesting medications, household chemicals, or drugs that affect the heart or breathing.

Clinical Death vs Biological Death

Clinical death begins as soon as someone’s heart stops pumping blood effectively. In approximately 4-6 minutes, permanent damage due to a lack of oxygen begins. Performing CPR can supply oxygenated blood to the brain and major organs to postpone the onset of biological death. Hypothermia can also postpone biological death.

Clinical Death

• Definition: The stage when a person’s heartbeat and breathing stop.
• Significant attributes:
  • No pulse, no respiration.
  • Blood circulation ceases, oxygen delivery stops.
  • Brain cells begin to suffer from oxygen deprivation, but not all cells are dead yet.
• Reversibility: Potentially reversible if CPR, defibrillation, or advanced life support is started quickly (usually within 4–6 minutes before severe brain damage).
• Duration: Short window of opportunity before it progresses to biological death.

Biological Death

• Definition: The stage when irreversible damage to cells and organs has occurred, especially in the brain.
• Significant attributes:
  • Brain death (irreversible loss of brain function).
  • Permanent cessation of circulation and respiration.
  • Cells and tissues undergo necrosis (breakdown).
• Reversibility: Irreversible — resuscitation is no longer possible.
• Onset: Usually occurs after clinical death has lasted too long (beyond 4–6 minutes without oxygen, though exact timing can vary).

Heart Attacks

Myocardial infarction, also known as a heart attack, is a serious medical emergency. It occurs when normal blood flow to the heart is abruptly stopped, usually due to a blood clot or other blockage in a coronary artery. The blockage deprives the heart of oxygenated blood, causing damage or death to the heart muscle if not treated promptly. 

Coronary Arteries

The heart muscle (myocardium) receives its blood supply through the coronary arteries. A steady supply of oxygenated blood is necessary for the heart to function correctly.

• Blockages
  • A heart attack occurs when one or more of these arteries become blocked, most often by a blood clot that forms on top of a plaque buildup (atherosclerosis). 
• Ischemia
  • The blockage leads to ischemia, meaning the heart muscle is not receiving enough oxygen. 
• Infarction
  • The lack of oxygen can cause infarction, which is the death of heart muscle tissue.

Symptoms

• Chest pain
  • The most common symptom is a crushing, squeezing, or pressure in the chest. 
• Other symptoms
  • Can include shortness of breath, sweating, nausea, vomiting, lightheadedness, and pain radiating to the jaw, neck, back, or arms. 
• Symptoms can vary
  • Individuals may experience different combinations and intensities of symptoms. 

Risk Factors For Cardiac Arrest

Principal Risk Factors

• High blood pressure (hypertension): Causes damage to arteries as well as increases the formation of plaque.
• High cholesterol (especially LDL, low HDL): Increases plaque formation in arteries.
• Smoking: Damages blood vessels, reduces oxygen supply, and promotes clotting.
• Diabetes: High blood sugar levels can harm blood vessels. Which can accelerate atherosclerosis.
• Obesity/overweight: Increases strain on the heart and is often tied to high BP, cholesterol, and diabetes.
• Physical inactivity: Increases the chances of obesity, high cholesterol, or high blood pressure.
• Unhealthy diet: High in saturated/trans fats, sodium, and added sugars.
• Family history of heart disease: Especially if close relatives had heart disease at a young age.
• Age: The risk increases after age 45 in men and after age 55 in women.
• Sex: The risk increases at a younger age in men. For women, in addition to age, the risk also increases after menopause.

Additional/Contributing Risk Factors

• Chronic stress: Raises blood pressure and promotes unhealthy behaviors.
• Excessive alcohol use: Raises blood pressure and triglycerides.
• Sleep apnea: Linked to hypertension and heart strain.
• Drug use: Especially cocaine or amphetamines, which can also trigger sudden heart attacks.
• Autoimmune or inflammatory diseases, such as lupus or rheumatoid arthritis, also increase cardiovascular risk.

Having multiple risk factors together (for example, smoking + high BP + diabetes) dramatically increases the chance of a heart attack as well as sudden cardiac arrest.

What To Do If You Suspect Cardiac Arrest

If you are with someone, instruct them to call 911 and activate the EMS System. It’s essential to get EMS on the way as quickly as possible. They provide a higher level of emergency care. If an AED is available, instruct someone to retrieve it. Check for signs of circulation and begin CPR if necessary.

If you are alone and the victim is an adult. Call 911 immediately and get the AED if one is available. Return to the victim ASAP, check for signs of circulation, and begin CPR if necessary.

If you are alone and the victim is a child or infant. Check for signs of circulation, and begin CPR if necessary. Perform 1 minute of CPR. Then call 911 and activate the EMS system. Since children usually experience cardiac arrest due to respiratory issues, they will need oxygen.

For more information or to take a free CPR class, check out our list of free classes.

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