Sudden Cardiac Arrest
Sudden cardiac arrest (SCA) is a life-threatening emergency where the heart unexpectedly stops beating, requiring immediate intervention with a defibrillator.
What is Sudden Cardiac Arrest (SCA)?
Sudden cardiac arrest (SCA) is a condition in which the heart suddenly stops beating, causing blood flow to the brain and other vital organs to cease. Without treatment, SCA usually results in death within minutes, though quick treatment with a defibrillator can be lifesaving.
SCA vs. Heart Attack
It is important to distinguish SCA from a heart attack:
- Heart Attack: Occurs when blood flow to the heart is blocked. The heart usually does not stop beating during a heart attack.
- SCA: The heart stops beating entirely. SCA can sometimes occur after or during recovery from a heart attack.
Causes and Risk Factors
SCA is caused by electrical system failures that lead to arrhythmias. Specific causes include:
- Ventricular fibrillation: A type of arrhythmia where the ventricles beat too fast and irregularly to pump blood.
- Coronary artery disease (CAD): Plaque buildup in arteries that blocks oxygen-rich blood flow to the heart.
- Physical stress: Including intense physical activity (releasing adrenaline), low potassium or magnesium levels, major blood loss, or severe lack of oxygen.
- Inherited disorders: Conditions affecting heart structure or rhythm.
- Structural changes: Such as an enlarged heart due to high blood pressure or heart infections.
Risk factors include being older, being male, being Black or African American (especially with comorbidities like diabetes or hypertension), having a history of arrhythmias, heart attack, heart failure, or substance use.
Symptoms and Diagnosis
The primary sign of SCA is loss of consciousness (fainting). Some individuals may experience a racing heartbeat, dizziness, light-headedness, chest pain, shortness of breath, or nausea in the hour preceding the event. Because SCA happens without warning, it is usually diagnosed after the event by ruling out other causes.
Treatment and Emergency Response
SCA requires immediate treatment with a defibrillator to restore a normal heart rhythm. If you suspect someone is having an SCA:
- Call 9-1-1 immediately.
- Use an automated external defibrillator (AED) if available in public spaces.
- Perform cardiopulmonary resuscitation (CPR) until a defibrillator is available.
Survivors are typically monitored in a hospital and may receive an implantable cardioverter defibrillator (ICD) to prevent future episodes. Treatment for underlying conditions, such as angioplasty or bypass surgery for CAD, may also be necessary.