Defibrillation is used in a couple of different scenarios that primarily include those in which a patient goes through sudden cardiac arrest (SCA).
There are different types of defibrillators that have different applications. For example, AEDs are typically used by bystanders to administer electric shocks to those in cardiac arrest. Bystanders can complete CPR AED courses to sharpen their skills and respond to various cardiac arrest emergencies.
Manual defibrillators, on the other hand, are used by medical professionals to administer multiple types of shock depending on the various heart arrhythmias. You can also have defibrillators either inserted into patients or placed on their bodies to administer shocks throughout the day.
What Is a Defibrillator?
Defibrillation is a procedure used to treat life-threatening conditions that affect heart rhythms. The procedure involves the delivery of electric shocks to accomplish a specific heart rate. This electric shock causes the depolarization of the heart muscles and re-establishes the normal conduction necessary for the heart to achieve a steady rhythm. The device that delivers this shock is known as the defibrillator.
There are different types of defibrillators used for different purposes such as internal defibrillators and external defibrillators. Medical professionals might also implant defibrillator devices to administer shocks to patients throughout the day when the device identifies an abnormal heart rhythm.
Defibrillation was first presented in the medical community in 1899 by Prevost and Batelli, two physiologists from the University of Geneva in Switzerland. In animal studies, they observed small electric shocks delivered to the heart could trigger ventricular fibrillation while the delivery of larger shocks triggered the opposite.
Types of Defibrillators
Manual External Defibrillator
All defibrillators operate under the same essential principle: to save the lives of those in cardiac arrest. But how are manual defibrillators different from automatic defibrillators? To start, they have advanced capabilities. Manual defibrillators have a number of different settings that enable the medical professional to adjust the applied energy.
This means that medical professionals can monitor the patient’s heart rhythm and apply a different shock level based on that rhythm. AEDs are considered public access devices used by bystanders. Manual defibrillators are meant for medical professionals only.
Manual defibrillators have three modes of operation: synchronized cardioversion, external defibrillation, and internal defibrillation. They also have pacing capabilities other defibrillators do not. Non-invasive transcutaneous pacing can be used for clinically stable patients without high risks of decompensation.
Some examples of patients who benefit from pacing include:
- Those with acute myocardial infarction are showing signs of early heart block.
- Those awaiting cardiac surgery.
- Those awaiting placement of a permanent pacemaker, generator change, or lead wire replacement.
- Those undergoing catheterization or angioplasty.
- Those at risk of developing post-cardioversion bradycardia.
Manual external defibrillators can also perform cardioversion, a medical procedure that restores normal heart rhythms in people that have abnormal arrhythmias. This is typically performed by sending electric shocks through electrodes placed on the heart.
Implantable Cardioverter Defibrillator
Internal cardioverter defibrillators are battery-powered devices placed under the skin that keep track of your heart rate. Wires connect the ICD to your heart and deliver an electric shock if it detects an abnormal heartbeat.
ICDs can prevent sudden deaths in patients that have known arrhythmias such as sustained ventricular tachycardia or fibrillation. Your doctor can also recommend an ICD if you or your child is at risk of a life-threatening ventricular arrhythmia that can cause:
- Heart attack
- Sudden cardiac arrest
- Long QT syndrome
- Brugada syndrome
- Congenital heart disease or underlying conditions for sudden cardiac arrest.
ICDs can identify when the heartbeat is not normal and return it to a normal rhythm and it gives the following benefits:
- If your ICD has a pacemaker feature when your heartbeat is too slow, it works as a pacemaker and sends tiny electric signals to your heart.
- When your heartbeat is too fast or chaotic, it gives defibrillation shocks to stop the abnormal rhythm.
- It works 24 hours a day.
Manual Internal Defibrillator
Manual internal defibrillators use internal paddles to administer electric shocks directly to the heart. These defibrillators can be used on open chests as well as in the operating room and it was invented in 1959.
Automated External Defibrillator
Automated external defibrillators are used to revive someone from sudden cardiac arrest. This typically occurs when a disruption in the heart’s electrical activity causes a dangerously rapid heartbeat known as ventricular tachycardia. The primary difference between these defibrillators and manual defibrillators is that bystanders can use AEDs while manual external defibrillators can only be used by medical professionals. Automated external defibrillators are typically used in conjunction with CPR to keep the blood flowing throughout the body and supply the brain with oxygen.
Wearable Cardiac Defibrillator
The wearable cardioverter defibrillator is a rechargeable external device that can be worn under your clothing all day to protect the wearer from potentially life-threatening ventricular tachyarrhythmias. The WCD delivers high-energy shocks whenever it detects these arrhythmias and it is typically used as a bridge between an implantable cardioverter-defibrillator, heart transplantation, or left ventricular assist devices.
It can also be used after the temporary removal of an ICD until doctors reimplant the device. IN patients with myocardial infarction, WCDs can be useful in the immediate period following the infarction.
There are five primary groups of defibrillators and each one has a distinct purpose. Automated external defibrillators are intended for bystanders responding to cardiac arrest emergencies. Manual defibrillators are for medical professionals so they can analyze a few different rhythms and decide which one fits best.