Types of Defibrillator Implants

There are different variations of defibrillator implants available for patients. The differences between these devices is not very significant, and the type of defibrillator implant that is right for you will depend upon your current cardiac condition.


A defibrillator implant, like many other implantable cardiac devices (e.g. pacemakers) feature two primary components that are vital for the implanted device to function properly. The first component of a defibrillator implant is the pulse generator. This small, battery powered generator is responsible for charging and delivering specified amounts of electrical energy into the next component of a defibrillator implant, the lead(s). The amount of energy released from the pulse generator varies depending upon the defibrillator’s sensing technology and data that it receives from the sensing leads connect to your heart. The leads are the second primary component of a defibrillator implant. Some defibrillator implants have just one lead, while others feature up to three leads. The amount of leads that you need for a defibrillator implant will depend on what areas of your heart need external energy to function properly.

Single Chamber ICD

A single chamber implantable cardioverter defibrillator is a kind of defibrillator implant that uses only one sensing lead to function. This lead is typically connected to the right ventricle (RV) of the heart. A single chamber implantable cardioverter defibrillator functions by delivering a certain amount of electrical energy through the one sensing lead into the right ventricle of the heart. This causes your right ventricle to contract normally and continue beating.

Dual Chamber ICD

A dual chamber implantable cardioverter defibrillator is a kind of defibrillator implant that uses two sensing leads to function.  These two leads are placed in different areas of the heart. One lead is placed in the right atrium (RA) of the heart, and the other lead is placed in the right ventricle (RV). In order to function properly, the defibrillator implant will release a certain amount of  electrical energy in the lead connect to the right atrium; shortly after the first lead fires, the second lead connect to the right ventricle of the heart will be sent a certain amount of electrical energy as well. This sequential firing of the two leads, which are placed in two distinct areas of the heart, allow for the heart to beat in a normal rhythm.

Biventricular Pacing Defibrillator (also called a Cardiac Resynchronization Therapy Defibrillator)

These devices are relatively new and feature two or three leads that are connected to the heart in separate areas. These cardiac regions include the right atrium (RA), the right ventricle (RV), and the left ventricle (LV). Typically, these leads are placed in their appropriate region through the coronary sinus vein. Biventricular pacing also refers to Cardiac Resynchronization Therapy, both of which are a form of pacing therapy that allows your heart to beat normally. In addition, it has been proven to increase patients’ ejection fraction by five to ten percent and higher. This form of cardiac implant is usually combined with a defibrillator as patients who qualify for this type of therapy may also be at high risk of cardiac arrest. The Cleveland Clinic has stated that about 90% of patients who receive biventricular pacing also receive a defibrillator.

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