Implantable Cardioverter Defibrillator (ICD) or AICD
An ICD continuously monitors the heart’s electrical activity and if the device detects a dangerous arrhythmia, such as ventricular tachycardia or ventricular fibrillation, the Implantable Cardioverter Defibrillator can treat it by delivering an electrical shock to the heart to restore a normal rhythm. The shock is delivered through the leads and is timed to the patient’s heartbeat to ensure that it is delivered at the most effective time essentially “rebooting” the heart and returning it to a normal rhythm. In other words, it causes the heart to stop beating for a brief moment to resynchronize all heart cells. When the heart restarts, it often resumes a normal rhythm. Another way the ICD can terminate a dangerous tachycardia is by anti-tachycardia pacing (ATP). During an ATP therapy, the ICD sends rapid pacing pulses to the heart to interrupt the fast arrhythmia. The pacing pulses are delivered through the ICD leads, and the pacing rate and intensity are customized based on the patient’s individual needs and the specific arrhythmia being treated. The biggest advantage of ATP is that it is painless and uses less energy compared to shocks. In addition to treating fast heart rates, ICDs can also pace the heart to treat slow heart rhythms. This is achieved by sending small electrical impulses to the heart through the leads to stimulate the heart muscle and maintain normal heart speed.
There are several types of ICDs available, each designed to meet the specific needs of different patients. The main types of ICDs include:

Subcutaneous ICD
A subcutaneous ICD (S-ICD) is implanted under the skin of the chest and does not require leads to be placed inside the heart. Instead, the device delivers electrical shocks through a lead that runs along the outside of the chest wall.

Biventricular ICD
A biventricular ICD has three leads that are placed in the right atrium, right ventricle, and left ventricle of the heart. This type of ICD is used to treat patients with heart failure and lack of synchrony between the ventricles (the heart's lower chambers beat out of sync with each other).

Dual-chamber ICD
A dual-chamber ICD has two leads that are placed in the right atrium and right ventricle of the heart. This type of ICD is used to treat patients with ventricular arrhythmia who also require significant pacing for slow heart rate.

Single-chamber ICD
A single-chamber ICD has one lead that is placed in the right ventricle.
The type of Implantable Cardioverter Defibrillator that is best for a patient depends on several factors, including the underlying heart condition, base line ECG, the patient’s medical history, and their individual needs and preferences. The decision on which ICD to use should be made by the patient’s electrophysiologist based on a comprehensive evaluation.
The procedure to implant an Implantable Cardioverter Defibrillator typically takes 1-2 hours and is performed under local anesthesia, with the patient awake but sedated. Here are the general steps involved:
A small incision is made in the chest near the collarbone, and the electrophysiologist creates a pocket under the skin for the ICD device.
The ICD and leads are then inserted into the pocket created earlier under the skin. The device is then tested to ensure that it is functioning properly and delivering the correct electrical impulses.
The electrophysiologist will use a special programmer to communicate with the ICD and program the parameters depending on the case.
The patient will need to have regular check-ups with their doctor to ensure that the ICD is functioning properly and to make any necessary adjustments to the device’s programming.
The effectiveness of ICD therapy in treating arrhythmias and saving lives has been well-established through numerous clinical trials and real-world experience. In general, Implantable Cardioverter Defibrillator therapy has been shown to be highly effective in preventing sudden cardiac death and improving survival in patients with arrhythmias. However, like all medical devices, there are small potential risks and complications associated with ICD therapy that should be discussed with the patient prior to implantation.
