WHAT IS EMERGENCY EXTERNAL DEFIBRILLATION? | WELLBEING

Emergency external defibrillation utilizes high-voltage electrical energy in a very short time (0.03 - 0.10 seconds) to discharge through the heart, depolarizing the entire heart muscle to restore a normal heart rhythm. It terminates tachyarrhythmias that are overriding the sinus rhythm, creating conditions for the sinus rhythm to regain its role as the primary pacemaker. The electrical shock causes depolarization of all excitable myocardial cells, interrupting re-entry circuits or inactivating ectopic foci by resynchronizing electrical activity within the myocardial cells.

Emergency external defibrillation should be performed as quickly as possible, ideally as soon as the following tachyarrhythmia patterns are recorded on paper or on the ECG monitor.

There are 2 types of electrical shock:

• Synchronized Cardioversion: Discharges electrical current synchronized with the QRS complex (usually on the R-wave, or S-wave if R is absent, to avoid the T-wave) of the patient to convert the rhythm.

• Defibrillation (Unsynchronized): Discharges electrical current at any point in the patient's cardiac cycle (unsynchronized).

Mechanism of Action of External Defibrillators

The Automated External Defibrillator (AED) is a useful device in the first aid process for victims of cardiac arrest. This is a medical device, yet people with absolutely no experience or medical knowledge can use it effectively.

The defibrillator/AED is capable of delivering a very large electrical current passing through 2 electrode pads placed on the victim's body. At this moment, the heart will stop beating for a brief period; combining this with CPR creates conditions for the heart to restart beating rhythmically and stop fibrillating. Only then can the heart effectively pump blood throughout the body.