Cardiac arrest is a medical condition in which the heart suddenly stops beating effectively, resulting in the cessation of blood flow to the brain and other vital organs. It is typically caused by a malfunction in the heart's electrical system, most commonly due to arrhythmias such as ventricular fibrillation or ventricular tachycardia. When cardiac arrest occurs, the individual loses consciousness and stops breathing normally, often gasping or exhibiting agonal respirations.
Immediate intervention is critical for survival. Cardiopulmonary resuscitation (CPR) and, when available, defibrillation using an automated external defibrillator (AED) can restore a normal heart rhythm if administered promptly. Survival rates decrease rapidly with each passing minute without treatment.
Cardiac arrest is distinct from, though sometimes associated with, myocardial infarction (heart attack), which is caused by a blockage in blood flow to the heart muscle. However, a heart attack can trigger cardiac arrest. Other potential causes include severe electrolyte imbalances, hypoxia, trauma, and genetic heart conditions such as long QT syndrome or hypertrophic cardiomyopathy.
Long-term outcomes for individuals who survive cardiac arrest depend on multiple factors, including the speed of resuscitation, the underlying cause, and the extent of brain injury due to oxygen deprivation. Post-resuscitation care often involves therapeutic hypothermia, monitoring in an intensive care unit, and evaluation for implantable cardioverter-defibrillators (ICDs) to prevent recurrence.
Accurate global incidence rates vary, but cardiac arrest remains a leading cause of death in many developed countries. Prevention strategies include managing cardiovascular risk factors (e.g., hypertension, diabetes, smoking) and public education on CPR and AED use.