Causes of Cardiac Arrest

Cardiac arrest can be triggered by several underlying conditions or events:

1. Heart Disease:
   • Coronary artery disease (CAD): Blocked or narrowed arteries reduce blood flow to the heart, increasing the risk of arrhythmias (abnormal heart rhythms) that can lead to cardiac arrest.
   • Heart attack (myocardial infarction): A heart attack can damage the heart muscle and disrupt the heart’s electrical system, leading to cardiac arrest.
   • Heart failure: Weakened heart muscle may cause arrhythmias or other complications that can lead to sudden cardiac arrest.
   • Cardiomyopathy: A condition where the heart muscle becomes weakened or enlarged, often causing irregular heartbeats that can lead to cardiac arrest.
2. Arrhythmias (Abnormal Heart Rhythms):
   • Ventricular fibrillation (VF): This is the most common arrhythmia leading to cardiac arrest. It causes the heart’s lower chambers (ventricles) to quiver instead of pumping blood.
   • Ventricular tachycardia (VT): This is a fast, abnormal heart rhythm that can disrupt the heart’s ability to pump effectively, leading to cardiac arrest.
3. Electrical Problems:
   • Long QT syndrome: A condition in which the heart’s electrical system takes longer than normal to recharge between beats, which can lead to life-threatening arrhythmias.
   • Bradycardia (slow heart rate) or tachycardia (fast heart rate): Abnormalities in the heart’s electrical impulses can result in irregular heart rhythms that cause cardiac arrest.
4. Other Causes:
   • Severe trauma: Such as a blow to the chest or a major injury, can lead to cardiac arrest.
   • Drowning, suffocation, or choking: These conditions can cause a lack of oxygen, leading to cardiac arrest.
   • Electrocution: A powerful electric shock can disrupt the heart’s normal rhythm, potentially causing cardiac arrest.
   • Drug overdose: Certain drugs, especially stimulants or opiates, can interfere with the heart’s electrical system, leading to cardiac arrest.
   • Severe blood loss: When there is not enough blood circulating, the heart can stop.

Symptoms of Cardiac Arrest

Cardiac arrest strikes suddenly, and the person will experience a rapid loss of consciousness. Common signs and symptoms include:

• Sudden loss of responsiveness: The person collapses and is unresponsive to touch or sound.
• No pulse: There is no detectable pulse, as the heart is no longer pumping blood.
• No breathing or abnormal breathing: The person will stop breathing, or may show agonal (gasping) breaths, which are irregular and ineffective.
• Sudden collapse: The person may fall to the ground unexpectedly.

Immediate Response to Cardiac Arrest

Cardiac arrest requires immediate intervention to increase the chances of survival. The first few minutes are critical, and the response can make the difference between life and death.

1. Call for Emergency Help: Dial emergency services immediately (e.g., 911 in the U.S.) to ensure that professional help is on the way.
2. Start CPR (Cardiopulmonary Resuscitation):
   • Chest compressions: Begin chest compressions right away. Push hard and fast in the center of the chest, at a depth of about 2 inches (5 cm), and at a rate of 100-120 compressions per minute. Chest compressions keep blood flowing to vital organs.
   • Rescue breaths: If trained, give rescue breaths after every 30 compressions. If not, continue with chest compressions alone.
   • If you are not trained in CPR, hands-only CPR (just chest compressions) can still be effective.
3. Use an Automated External Defibrillator (AED): If available, use an AED as soon as possible. An AED can analyze the heart’s rhythm and, if necessary, deliver a shock (defibrillation) to restore a normal rhythm.
   • The AED will guide you through the process with clear instructions, including when to apply the pads and when to shock (if necessary).
   • If no AED is available, continue CPR until emergency responders arrive or the person shows signs of life.

Treatment of Cardiac Arrest

The goal of treatment is to restore the heart’s normal rhythm and provide adequate blood flow to vital organs.

1. Defibrillation:
   • AED: The primary treatment for cardiac arrest due to ventricular fibrillation or ventricular tachycardia is defibrillation. An AED or manual defibrillator delivers an electrical shock to the heart to reset its electrical activity.
   • Defibrillators: These may be used in hospitals or by paramedics to deliver shocks to the heart when necessary.
2. Advanced Life Support: After defibrillation, advanced treatments, including medications (like epinephrine or amiodarone), may be administered to stabilize the heart rhythm.
3. Post-cardiac Arrest Care:
   • Therapeutic hypothermia: In some cases, cooling the body (induced hypothermia) may be used to reduce brain damage after a person has been resuscitated.
   • Monitoring and support: Intensive care unit (ICU) monitoring may be required to stabilize the patient and assess the extent of any damage.
4. Addressing the Underlying Cause: Once the person is stabilized, doctors will work to treat the cause of the cardiac arrest (e.g., coronary artery disease, arrhythmias, heart attack, etc.).

Prevention of Cardiac Arrest

While cardiac arrest often occurs suddenly, there are steps that can be taken to reduce the risk:

• Managing heart disease: Effective treatment of underlying heart conditions like coronary artery disease, heart failure, and arrhythmias can reduce the risk of cardiac arrest.
• Medications: Some people at high risk for cardiac arrest may be prescribed medications like beta-blockers or antiarrhythmic drugs to prevent abnormal heart rhythms.
• Lifestyle changes: Eating a healthy diet, exercising regularly, quitting smoking, and managing stress all contribute to heart health.
• Implantable devices: For those at high risk for life-threatening arrhythmias, doctors may recommend an implantable cardioverter defibrillator (ICD). This device monitors the heart’s rhythm and delivers shocks if it detects a dangerous arrhythmia.