defibrillators

Defibrillators are medical devices designed to treat life-threatening arrhythmias by delivering an electrical shock to the heart with the goal of restoring a normal heartbeat. They are used in both emergency and clinical settings to address potentially fatal rhythms such as ventricular fibrillation and pulseless ventricular tachycardia.

There are two main categories: external and implanted. External defibrillators include automated external defibrillators (AEDs), which analyze the heart rhythm and guide lay rescuers through shock delivery, and manual external defibrillators used by trained professionals who select the energy level. Implanted cardioverter-defibrillators (ICDs) are surgically placed devices that monitor heart rhythms and deliver shocks automatically when dangerous rhythms are detected, providing ongoing protection against sudden cardiac death in high-risk patients.

How defibrillators work varies by type but follows a common principle: they assess the heart’s electrical activity and deliver a controlled electrical impulse to depolarize cardiac cells, interruptting the abnormal rhythm and allowing the heart’s natural pacemaker to resume a normal rhythm. Modern AEDs offer step-by-step prompts and typically deliver biphasic shocks in the range of about 120 to 200 joules for adults.

Defibrillators are indicated for shockable cardiac arrests and certain high-risk conditions, but they are not effective for non-shockable rhythms such as asystole or pulseless electrical activity. Real-time use is time-critical; immediate CPR and rapid defibrillation improve outcomes.

Maintenance involves regular battery checks, pad or electrode replacement, and ensuring accessibility and proper function. Training in basic life support and device use is commonly recommended for responders and caregivers.