How does a Defibrillator Stop Cardiac Arrest and Heart Fibrillation?
AED (Automated External) Defibrillators Used to stop Sudden Cardiac Arrest
Defibrillation is the process of restoring a "fibrillating" or arrythmic heart to a normal rhythm. It actually stops the heart (which is beating out of sync and not properly pumping) so it can re-start with a consistent rhythm.
If you’ve been to an airport, community center, or large public gathering place in the last few years, you may have noticed a new item under a sign that says “AED” with a symbol of a heart. Automated External Defibrillators are used in the event of sudden cardiac arrest, which may come without warning. The use of a defibrillation device may be the only chance to save the victim, and should used as quickly as possible. If no defibrillator is available, CPR should be performed until help arrives.
Sudden cardiac arrest (SCA) can be caused by cardiac arrythmias, ventricular fibrillation, and ventricular tachycardia. It can be treated with a defibrillator, which is either a professional grade model used in hospitals or an automated external defibrillator (AED) which can be bought for less than $1500.
The act of defibrillation actually stops the heart and allows it to regain a normal rhythm. The heart has its own built-in pacemaker, in the heart’s sinoatrial node, which reestablishes "sinus rhythm" which is a regular heartbeat. You may have heard the word “sinus” on medical shows and wondered why people were talking about the nasal region, but in this case it refers to the fact that a normal heartbeat is present.
The difference between automated defibrillators and models used in hospitals is in the ease of use and the features that diagnose the patient before delivering a shock. If the heart is not in fibrillation, no shock is delivered. Unfortunately, not all sudden deaths are treatable, as they are not all the result of cardiac problems. Implantable defibrillators can be used in patients who have known heart problems and a high likelihood of sudden cardiac arrest, but in fact they are almost always implanted in people who have had cardiac episodes in the past.
Automated external defibrillators (AEDs) are commonly used by people with minimal training, and are designed to be user friendly. They have disposable pads which are attached to the patient, who is almost always unconscious at this point. This is why there is a common phrase "you can't use a defibrillator on yourself." The defibrillator takes 10-20 seconds to diagnose a heart rhythm,
and then it delivers a shock. In most cases, paramedics and hospital personnel will get better results with manual defibrillators because they are trained to recognize a bad heart rhythm, but the defibrillator is still the next best thing. Once an episode of defibrillation is recognized by the AED, it will apply a shock, and may even use a biphasic waveform, which alternates the direction of the pulses to prevent injury and ensure success.
Once the heart is restarted, the patient should seek prompt medical attention, and new pads for the defibrillator should be obtained.
Notes and Special Information
Special note: Proper use of an AED unit may require training for the best results. Also, sometimes the defibrillator can't save a life but at least you tried.