A defibrillator is a device that sends electrical energy, or shock, to the heart. The aim of using a defibrillator is to treat cardiac arrest. The need for this generally arises when the patient has ventricular fibrillation or ventricular tachycardia, which are life-threatening arrhythmias that occur when contraction of the ventricles becomes abnormal. Defibrillators have electrocardiogram (ECG) leads and adhesive patches (or paddles). The adhesive electrodes are the patches placed on the patient’s chest that deliver an electric shock.
The history of defibrillation
In 1899, two physiologists from the University of Geneva, Jean Louis Prevost and Frederic Batelli, discovered that small electric shocks could cause ventricular fibrillation in dogs. Later, in 1933, a device was invented to send an electric shock to the heart as a substitute for administering cardiac medications.
In 1947, the first defibrillation was carried out by Claude Beck who was a professor of surgery at Case Western Reserve University. The defibrillator he used had internal paddles that were placed on each side of the heart.
Before the end of the 1950s, defibrillation was successfully performed only when the chest cavity of the patient was open during the surgery. In this case, the defibrillator had electrodes in the shape of paddles so that flat ends could be placed on either side of the exposed heart.
As the 1950s gradually came to an end, the closed-chest defibrillator device was invented. One of the basic differences between the open and closed-chest devices was that the closed-chest defibrillators required more voltage for operation. It was invented by Dr. V. Eskin and A. Klomov.
Thus far, the defibrillators in existence used alternating current. In 1959, Bernard Lown began to develop new ideas to make the device more energy efficient. Lown’s work led to the discovery of direct current (DC). Further development lead to the Biphase Truncated Exponential (BTE) waveform. With the BTE waveform, the defibrillators could use lower energy levels, which reduced the weight of the defibrillators that were later manufactured.
In the 1960s, Professor Frank Pantridge of Belfast began to introduce portable defibrillators for hospitals. This invention is now one of the most important tools that emergency medical services carry to resuscitate people that suffer cardiac arrest. Portable units set forth the production of automatic defibrillators—devices with the ability to analyze heart rhythms.
The biphasic waveform did not completely replace the Lown waveform until the end of the 1980s. The waveform allowed defibrillators to work more quickly than the previous types. This, in turn, reduced the energy level needed for defibrillation. The success rate for treating cardiac arrest also improved.
In 1969, the research for making implantable cardioverter-defibrillator (ICD) began as a result of needing to provide adequate health care for victims of cardiac arrest. In 1980, the first implantable device was used at John Hopkins Hospital by Dr. Levi Watkins. Today, frequent victims of cardiac arrest are given the device for their aid at any time.
Types of defibrillators
There are different kinds of defibrillators in use today. They include the manual external defibrillator, manual internal defibrillator, automated external defibrillator (AED), implantable cardioverter-defibrillator (ICD), and wearable cardiac defibrillator.
-
Manual external defibrillator: These defibrillators require more experience and training to effectively handle them. Hence, they are only common in hospitals and a few ambulances where capable hands are present. In conjunction with an ECG, the trained provider determines the cardiac rhythm and then manually determines the voltage and timing of the shock—through external paddles—to the patient’s chest.
-
Manual internal defibrillator: The manual internal defibrillators use internal paddles to send the electric shock directly to the heart. They are used on open chests, so they are only common in the operating room. It was invented after 1959.
-
Automated external defibrillator (AED): These are defibrillators that use computer technology, thereby making it easy to analyze the heart’s rhythm and effectively determine if the rhythm is shockable. They can be found in medical facilities, government offices, airports, hotels, sports stadiums, and schools.
-
Implantable cardioverter-defibrillator: Another name for this is automatic internal cardiac defibrillator (AICD). They constantly monitor the patient’s heart, similar to a pacemaker, and can detect ventricular fibrillation, ventricular tachycardia, supraventricular tachycardia, and atrial fibrillation. When an abnormal rhythm is detected, the device automatically determines the voltage of the shock to restore cardiac function.
-
Wearable cardiac defibrillator: Further research was done on the AICD to bring forth the wearable cardiac defibrillator, which is a portable external defibrillator generally indicated for patients who are not in an immediate need for an AICD. This device is capable of monitoring the patient 24-hours-a-day. It is only functional when it is worn and sends a shock to the heart whenever it is needed. However, it is scarce in the market today.
When not to use a defibrillator
Defibrillation is not indicated if the heart rhythm has completely stopped, as in asystole, or sometimes called “flat line,” or has pulseless electrical activity (PEA). Also, defibrillation is not indicated if the patient is conscious or has a pulse. Inappropriately given electrical shocks can cause dangerous arrhythmias, such as ventricular fibrillation.
Although defibrillators have specific indications and were initially exclusive to trained professionals, it is now possible to have one at home. Modern defibrillators are easy to use and do not require years of experience. In fact, a few tips from a health-care professional and a review of the manual are all that may be needed to correctly intervene in a cardiac emergency. This development is helpful in reducing the number of death rates caused by sudden cardiac arrest and other heartbeat-related problems each year.
In order to get AED training check our online CPR and AED course or online CPR First Aid certification.
Resources
For more information on defibrillation and diseases that require a defibrillator, please visit the following websites:
-
Simulation of cardiac defibrillation: Images and diagrams of how defibrillators work.
-
The history of defibrillators: Discovery of defibrillation and cardiac pathophysiology.
-
What is an automated external defibrillator?: Overview of AEDs used to treat cardiac arrest.
-
Cardiac arrest: Cardiac arrest is popularly known as sudden cardiac death. Its common name truly identifies how dangerous it is.
-
Cure for sudden cardiac arrest: The defibrillator is the fastest device that is suitable for treating sudden cardiac arrest. A type of defibrillator for this is the automated external defibrillator.
-
Guide to defibrillation: Complete guide to defibrillation including materials needed and steps required.
-
Implantable cardioverter-defibrillator: This is suitable for patients that frequently experience fibrillation or ventricular tachycardia.
-
Ventricular tachycardia overview: This condition refers to very fast heartbeats in the heart. It starts from the ventricles.
-
Treatment options for tachycardia: Tachycardia is best treated with implantable cardioverter-defibrillator (ICD). The ICD is also recommended for fibrillation.
-
What are the risks of having an implantable cardioverter-defibrillator?: Article covers the concerns and risks of the implanted defibrillator.
-
The history of fibrillation and defibrillation: This site discusses the rigorous works that were done by notable scientists such as Carl Ludwig in the 19th and 20th centuries.
