Cardiac Arrest: Causes, Symptoms, Types & Tests

Cardiac arrest is a sudden, life-threatening event where the heart stops beating effectively, cutting off blood flow to the brain and other vital organs. Unlike a heart attack, which is usually due to blocked arteries, cardiac arrest is primarily an electrical malfunction. This condition can lead to death within minutes if not treated immediately, which makes early recognition and emergency response crucial. In this blog, we explore the causes, symptoms, types, diagnostic tests, and frequently asked questions about cardiac arrest to help you better understand this medical emergency.

What is Cardiac Arrest?

Cardiac arrest is the abrupt loss of heart function, breathing, and consciousness. It usually results from an electrical disturbance in the heart that disrupts its normal pumping action, preventing blood flow to the body. When the heart stops, the brain and other organs quickly become deprived of oxygen. Without prompt intervention, such as cardiopulmonary resuscitation (CPR) or defibrillation, cardiac arrest can lead to death within minutes. It’s important to note that cardiac arrest isn’t the same as a heart attack. A heart attack is a circulation problem caused by a blocked artery, while cardiac arrest is an electrical problem affecting the heart’s rhythm. However, a heart attack can sometimes trigger cardiac arrest.

Causes of Cardiac Arrest

Cardiac arrest can happen unexpectedly, even in seemingly healthy people, but several underlying causes increase the risk:

• Coronary artery disease (CAD): The most common cause in adults; blocked or narrowed arteries can disrupt heart rhythms.
• Heart attack (myocardial infarction): Can trigger dangerous arrhythmias leading to cardiac arrest.
• Cardiomyopathy: Disease of the heart muscle can enlarge or weaken the heart.
• Electrical abnormalities: Conditions like Long QT syndrome, Brugada syndrome, or Wolff-Parkinson-White syndrome can lead to fatal arrhythmias.
• Heart valve disease: Malfunctioning valves can strain the heart.
• Congenital heart disease: Structural problems present at birth.
• Severe blood loss or trauma: Can reduce blood flow to the heart.
• Drug misuse: Stimulants like cocaine can trigger arrhythmias.
• Electrolyte imbalances: Abnormal potassium or magnesium levels can disrupt heart rhythm.
• Commotio cordis: A sudden blow to the chest, often during sports, can cause cardiac arrest, especially in young athletes.

Symptoms of Cardiac Arrest

Cardiac arrest often happens suddenly, and the first signs are dramatic. Symptoms may include:

• Sudden collapse: The person falls and becomes unresponsive.
• No pulse: Heart has stopped beating effectively.
• No breathing or abnormal gasping: Breathing may stop or become irregular.
• Loss of consciousness: Due to lack of blood flow to the brain.

In some cases, warning signs may appear minutes or hours before cardiac arrest, such as:

• Chest discomfort or pain
• Shortness of breath
• Weakness or fatigue
• Palpitations or rapid heartbeat
• Dizziness or fainting (syncope)

Types of Cardiac Arrest

Cardiac arrest is primarily caused by abnormal heart rhythms (arrhythmias). The most common types include:

1. Ventricular fibrillation (VF):
   • The most frequent cause.
   • The heart's ventricles quiver ineffectively instead of pumping blood.
   • Requires immediate defibrillation.
2. Ventricular tachycardia (VT):
   • A very fast heart rhythm that can deteriorate into VF.
   • Can be sustained (lasting more than 30 seconds) or non-sustained.
3. Asystole:
   • Known as “flatline.”
   • Complete absence of electrical activity; the heart stops beating.
   • Often has a poor prognosis.
4. Pulseless electrical activity (PEA):
   • Electrical activity is present, but the heart doesn’t pump effectively.
   • May result from severe trauma, electrolyte imbalance, or other underlying issues.

Tests Used to Detect Cardiac Arrest and Underlying Causes

During cardiac arrest, the immediate focus is on restoring heartbeat, but after stabilization, several tests help determine the cause:

• Electrocardiogram (ECG): Measures the heart’s electrical activity and identifies arrhythmias.
• Blood tests: Check for heart damage markers, electrolyte imbalances, or underlying conditions.
• Echocardiogram: Uses ultrasound to visualize heart structure and function.
• Coronary angiography: Examines arteries for blockages that could cause heart rhythm problems.
• CT or MRI scan: Provides detailed images of the heart and detects structural abnormalities.
• Electrophysiological study: Maps the heart’s electrical system to pinpoint arrhythmia sources.
• Holter monitor: Worn for 24–48 hours to detect intermittent rhythm issues.
• Genetic testing: May be recommended if inherited heart rhythm disorders are suspected.
• Treatment and Prevention
  Immediate response and long-term strategies are crucial for managing cardiac arrest:

• Cardiopulmonary resuscitation (CPR): Keeps blood flowing to vital organs until professional help arrives.
• Defibrillation: An automated external defibrillator (AED) delivers an electric shock to restore normal rhythm.
• Advanced life support: Includes medications, airway support, and hospital care.
• Implantable cardioverter-defibrillator (ICD): A device implanted in patients at risk of recurrent cardiac arrest.
• Medications: Such as beta-blockers, antiarrhythmics, or drugs to manage underlying heart conditions.
• Lifestyle changes: Quitting smoking, eating a heart-healthy diet, regular exercise, and managing stress.
• Surgery or procedures: To correct heart defects or unblock arteries.

Complications of Cardiac Arrest

If not treated immediately, cardiac arrest can cause:

• Brain damage: Even brief interruptions in blood flow can injure brain cells.
• Organ failure: Due to lack of oxygen.
• Recurrent cardiac arrest: Without treatment, the underlying cause may trigger another episode.
• Death: Cardiac arrest is fatal if untreated within minutes.

Conclusion

Cardiac arrest is a sudden and serious condition that can strike without warning. While it differs from a heart attack, it can sometimes be triggered by heart disease, electrical abnormalities, or trauma. Recognizing symptoms, understanding risk factors, and knowing how to respond—such as starting CPR or using an AED—can save lives. Advances in imaging tests, implantable devices, and medications have improved prevention and survival rates. Regular check-ups, healthy lifestyle choices, and prompt medical attention remain key in reducing the risk of cardiac arrest and ensuring long-term heart health.

Frequently Asked Questions (FAQs)

What is cardiac arrest?

Cardiac arrest is when the heart suddenly stops beating effectively, cutting off blood flow to the body.

How is cardiac arrest different from a heart attack?

A heart attack is due to blocked arteries, while cardiac arrest is caused by an electrical disturbance stopping the heart.

Can cardiac arrest happen without warning?

Yes, though some people experience warning signs like chest pain or dizziness.

What tests help diagnose cardiac arrest causes?

Tests include ECG, echocardiogram, angiography, MRI, and electrophysiological studies.

How is cardiac arrest treated immediately?

Through CPR and defibrillation using an AED.

Can cardiac arrest be prevented?

Managing risk factors, regular check-ups, and using devices like ICDs in high-risk patients can help.

What is the survival rate for cardiac arrest?

Survival improves significantly with immediate CPR and defibrillation.

Are young people at risk for cardiac arrest?

Yes, especially those with genetic heart conditions or after severe chest trauma.