Defibrillator: When Is It Necessary?

What is an Implantable Cardioverter-Defibrillator (ICD)?

An implantable cardioverter-defibrillator (ICD) is a vital medical device used to treat potentially fatal cardiac arrhythmias. Also referred to as an implanted cardioverter-defibrillator or an automatic implantable defibrillator, this device is usually placed under the skin, near the heart, during a surgical procedure called ICD implantation. The function of the implantable cardioverter-defibrillator is based on the detection of abnormal heart rhythms, such as serious ventricular arrhythmias. When the ICD identifies a dangerous arrhythmia, it can deliver a precise electric shock to restore the normal heart rhythm or emit electrical stimulations to stabilize the heart. ICD implantation is generally recommended for patients at high risk of sudden cardiac death, thus providing vital protection in cases of cardiac emergencies.

How Does a Defibrillator Work?

The defibrillator, powered by a battery or plugged into an electrical outlet, generates precise electrical discharges that are transmitted to the heart via two metal plates (electrodes or paddles) placed on the chest. The application of the two electrical plates can be done at different points on the torso. The most common positions are: one just below the shoulder (right clavicle) and one just below the left armpit (left mid-axillary).

What Causes Cardiac Arrest?

Cardiac arrest can be caused by various circumstances, but the effect is the same: blood can no longer reach the tissues and organs which, not receiving oxygen, suffer and die. The heart may stop beating due to a severe and extensive heart attack or lack of oxygen in case of suffocation. Sometimes, during cardiac arrest, blood does not circulate because the heart, particularly the ventricle, moves, but irregularly and rapidly (fibrillation and tachycardia), and does not have the effective push to pump blood. If the arrest is due to ventricular fibrillation and a defibrillator is available, it is sufficient to deliver an electric shock to interrupt the fibrillation, so that the electrical system is reset and the muscle fibers resume contracting regularly.

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Different Types of Defibrillators

Manual Defibrillator

The manual external defibrillator is a device associated with an electrocardiogram instrument, which can only be used by a physician. From a functional point of view, combining the manual defibrillator with an electrocardiogram device is essential. Indeed, based on the electrocardiographic tracing, the physician decides on the electrical discharge to be transmitted to the patient.

Correct use of the manual defibrillator requires specific training on both the operation of the defibrillation device and that of an electrocardiograph. Due to the specific preparation required, and for other reasons, the manual defibrillator is a device that is practically only used in hospitals or in certain ambulances.

Semi-automatic Defibrillator

The semi-automatic defibrillator has technology capable of analyzing a subject's heart rhythm and determining the electric shock to be delivered. This is a particular type of defibrillator that can also be used by non-medical personnel, or even any citizen. Indeed, no diagnosis is entrusted to the operator: it is the machine itself that analyzes the patient's heart rhythm and indicates whether defibrillation is necessary or not. The heart rhythm analysis takes 10 to 20 seconds and is performed using the same metal plates as those used to transmit the electric discharge. It is not possible to deliver a shock if the machine has not established that it is necessary, as the button is automatically blocked. When a shock is necessary, the operator only has to press the shock button, ensuring that no one is touching the patient.

Automatic Defibrillator

The automatic defibrillator is capable of analyzing the heart rhythm, independently determining the electrical discharge to be transmitted to the patient, and delivering it without the rescuer having to press a button. In other words, the user of an automatic defibrillator only has to operate the device, place the metal plates on the person to be defibrillated and let the device do its work. In public places, compared to semi-automatic models, automatic defibrillators, although easier to use, are less common.

Implantable Cardioverter-Defibrillator

The implantable cardioverter-defibrillator, or ICD, is a small portable defibrillator capable of monitoring a person's heart rhythm and delivering an electric shock to the heart if necessary. It is indicated in situations other than sudden cardiac arrest. Indeed, it is used in people who already have a heart problem and who are implanted by a surgical procedure. It is inserted into the subcutaneous tissue, just below the left clavicle. It is connected to the heart by leads, which monitor the heart rhythm and transmit the electric discharge, if necessary.

What Type of Monitoring Should I Undergo After Implantable Cardioverter-Defibrillator Placement?

Two or three months after the implantation of the implantable cardioverter-defibrillator, a check-up is scheduled. After this first visit, subsequent visits will be scheduled once every six months, except in special situations.

In general, an ICD lasts 4 to 5 years. Lifespans less than 4 years, while possible, are rare and are related to the high energy consumption necessary for normal operation. However, you can ask your electrophysiologist, during your check-up visit, what the remaining battery life is.