Cardiac arrest

Cardiac arrest
Synonyms	Sudden cardiac death (SCD), cardiopulmonary arrest, circulatory arrest, sudden cardiac arrest (SCA)
Pronounce	N/A
Field	Cardiology, emergency medicine
Symptoms	Decreased level or total loss of consciousness, abnormal or no breathing, no pulse
Complications	If reversed, coma, persistent vegetative state, post-cardiac arrest syndrome; if not reversed, death
Onset	The risk of onset increases with age
Duration
Types	N/A
Causes	Coronary artery disease, congenital heart defect, major blood loss, lack of oxygen, electrical injury, very low potassium, heart failure, myocardial infarction
Risks
Diagnosis	Finding no pulse
Differential diagnosis
Prevention	Not smoking, physical activity, maintaining a healthy weight, healthy eating
Treatment	Cardiopulmonary resuscitation (CPR), defibrillation
Medication
Prognosis	Overall survival rate ≈10% (outside of hospital) 25% (in hospital); depends strongly on type and cause
Frequency	13 per 10,000 people per year (outside hospital in the US)
Deaths	> 425,000 per year (US)

Cardiac arrest is a sudden and unexpected loss of heart function, breathing, and consciousness. It occurs when the heart's electrical system, responsible for coordinating the heartbeat, malfunctions, leading to irregular or rapid heartbeats (arrhythmias). The most common cause of cardiac arrest is a specific type of arrhythmia called ventricular fibrillation (VF), in which the lower chambers of the heart (ventricles) quiver instead of pumping blood effectively.

Conduction of the heart. Changes in this pattern can result from injury to the cardiac muscle and lead to non-conducted beats and ultimately cardiac arrest.

Illustration of an implantable cardioverter-defibrillator (ICD)

CPR training on a mannequin

Medical personnel checking the carotid pulse of a simulated patient

Medical emergency

Cardiac arrest is a medical emergency and, if not treated immediately, can lead to death within minutes. It is important to differentiate cardiac arrest from a heart attack, although the two conditions can be related. A heart attack occurs when blood flow to a part of the heart muscle is blocked, while cardiac arrest is the result of an electrical problem causing the heart to stop pumping blood.

Causes

Cardiac arrest can be caused by various factors, including:

• Heart-related causes: coronary artery disease, enlarged heart (cardiomegaly), valvular heart disease, and congenital heart disease.
• Electrical problems: abnormalities in the heart's electrical system (such as long QT syndrome or Brugada syndrome) can lead to life-threatening arrhythmias.
• Trauma: accidents, injuries, or blunt force to the chest can cause cardiac arrest.
• Drug overdose: certain medications or drugs, especially when taken in excessive amounts, can lead to cardiac arrest. These include certain prescription medications, illegal drugs (such as cocaine), and even some over-the-counter medications.
• Drowning, choking, or asphyxiation: lack of oxygen due to these events can cause the heart to stop.
• Severe electrolyte imbalances: imbalances in minerals like potassium, magnesium, and calcium can affect the heart's electrical system and lead to cardiac arrest.
• Hypothermia: extremely low body temperature can cause the heart to stop.

Symptoms

Symptoms of cardiac arrest usually occur suddenly and without warning. They may include:

• Sudden loss of responsiveness (no response to tapping on shoulders)
• No normal breathing (gasping for air or not breathing at all)
• No pulse or heartbeat

Some individuals may experience dizziness, shortness of breath, chest pain, or palpitations before the onset of cardiac arrest. However, these symptoms are not always present.

Treatment

Immediate treatment for cardiac arrest is crucial for survival called basic life support or BLS. The primary steps are:

• Call for emergency medical help (such as 911 in the United States)
• Begin cardiopulmonary resuscitation (CPR) to maintain blood flow and oxygen supply to the brain and other vital organs
• Use an automated external defibrillator (AED) if available to deliver an electric shock to the heart and attempt to restore a normal heart rhythm

Advanced life support

Emergency medical personnel may also provide advanced life support measures, including advanced airway management, intravenous medications, and manual defibrillation.

Prevention

Preventing cardiac arrest involves addressing and managing known risk factors, such as:

• Maintaining a healthy lifestyle: regular exercise, a balanced diet, and avoiding smoking and excessive alcohol consumption can help lower the risk of heart disease and cardiac arrest.
• Managing existing health conditions: monitoring and treating conditions such as high blood pressure, high cholesterol, and diabetes can reduce the risk of cardiac arrest.
• Regular check-ups: routine medical check-ups can help identify potential risk factors or conditions that could lead to cardiac arrest.
• Avoiding drug abuse: using drugs, especially stimulants like cocaine, can significantly increase the risk of cardiac arrest.
• Knowing your family history: if you have a family history of heart disease, sudden cardiac arrest, or other heart-related conditions, inform your doctor so they can assess your risk and recommend appropriate preventive measures.

In some cases, people with known heart problems or a high risk of sudden cardiac arrest may be advised to have an implantable cardioverter-defibrillator (ICD) placed. This device can detect dangerous heart rhythms and deliver an electric shock to restore a normal heartbeat.

Gallery

• 
  Normal vs blocked coronary artery
• 
  Demonstration of electrode pad placement for defibrillation
• 
  An automated external defibrillator stored in a visible orange mural support
• 
  Short axis view of the heart demonstrating wall thickening in left ventricular hypertrophy
• 
  EKG depiction of left ventricular hypertrophy
• 
  EKG depiction of ventricular fibrillation (no organized rhythm)
• 
  Ventricular fibrillation

Summary

Cardiac arrest is the sudden cessation of the heart's pumping action, possibly due to a heart attack, respiratory arrest, electrical shock, extreme cold, blood loss, drug overdose, or a severe allergic reaction.

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