The implantation of a defibrillator/pacemaker system (commonly called ICD) is performed for the prevention and avoidance of sudden cardiac death (SCD).
The defibrillator device consists of two parts:
The pulse generator, which produces impulses to make the heart “beat”, and the defibrillation circuit, which can deliver electrical therapy (defibrillation) to restore life-threatening tachycardias (e.g., ventricular tachycardia, ventricular fibrillation/flutter) and restore normal heart rhythm.
It may have one, two, or in some cases, three leads (electrodes) that receive and deliver impulses to and from the heart.
The ICD draws power from a small battery sealed inside it and does not function until the heart rate falls below the preset threshold or rises to dangerous, preset frequencies. At that point, it activates, sending small electrical impulses to the heart to “make it beat” or, in the case of tachycardia, an electrical shock to restore the heart rhythm.
The ICD will be programmed, monitored, and reprogrammed (if necessary) periodically so that its function adapts to your needs. This is usually done through appointments at the outpatient cardiology clinic, where your doctor, with the help of an external device (programmer), will monitor and adjust your device.
The battery condition of your defibrillator will be checked at each appointment, and its remaining life will be calculated. The battery is non-rechargeable and usually lasts 5-7 years, depending on usage. When it needs to be replaced, the entire defibrillator will be replaced in a procedure similar to the initial implantation.
Types of defibrillators:
- Single-chamber: Has one electrode in the right lower (right ventricle) chamber of the heart.
- Dual-chamber: Has two electrodes, one in the right upper (atrium) chamber of the heart (right atrium) and one in the right lower (right ventricle) chamber of the heart (ventricle).
- Biventricular: Has three electrodes, one in the right upper chamber of the heart (right atrium), one in the right lower chamber of the heart (right ventricle), and one in a coronary vein (usually the lateral vein), for pacing of the left ventricle as well. This type of device is used in special cases with severe heart failure and specific intraventricular conduction disorders.
Your doctor will decide which type of defibrillator is most appropriate for your condition and your illness.
