An Automated Implantable Cardioverter-Defibrillator (AICD) or an implantable cardioverter-defibrillator (ICD) is a device that is placed in the chest & monitors the heart rate & rhythm. In cases a fast abnormal heart rhythm is detected, the device provides energy to the heart muscle which normalize the heart rhythm.
The ICD comprises of two parts:
First part is the Lead(s) which are made up of wires and sensors that monitors the heart rhythm and delivers energy used for pacing.
The second part is the Pulse Generator which has a battery that houses energy, & a tiny computer that receives information from the leads to determine how the heart is beating.
Types of ICDs
A lead is attached in the right ventricle that provides energy to the ventricle to restore a normal heart rhythm.
Leads are attached in the right atrium and the right ventricle which provides energy to the right atrium and then to the right ventricle that helps the heart to pace in a normal sequence.
Leads are attached in the right atrium, the right ventricle and the coronary sinus that lies adjacent to the left ventricle and helps the heart beat in a more efficient way. It is specifically used for patients suffering with heart failure.
Functions of ICD
- When the heart beat is too fast, a chain of small electrical impulses are delivered to the heart muscle which restores heart rate and rhythm. This is known as Antitachycardia Pacing (ATP)
- A low-energy shock is delivered which restores heart rhythm. This is known as Cardioversion.
- When the heart is beating too fast, a high-energy shock is delivered to the heart muscle which restores heart rhythm. This is known as Defibrillation.
- When the heart beat is too slow, a small electrical impulses is delivered to the heart which stimulates the heart muscle to maintain a suitable heart rate. This is known as Bradycardia pacing.
Conditions in which ICD is implanted
- Episode of sudden cardiac arrest (ventricular fibrillation).
- People who are at high risk for sudden cardiac arrest.
- Hypertrophic cardiomyopathy.
- Dilated cardiomyopathy.
- Ventricular tachycardia.
ICD Implant Procedure
The ICD may be implanted in two ways:
Endocardial (transvenous) Approach
The first way is the endocardial (transvenous) approach. It the most approach in which ICD is implanted. In this approach, a small incision is made under the collar bone. The lead is inserted into the heart, through a vein. The generator is placed in the upper chest, under the skin & attached to the lead(s).
The second way is epicardial approach. This requires open-heart surgery. The lead is sewn onto the heart instead of placing the lead through a vein.
The morning after the implant, the patient will undergo a chest X-ray to make sure the ICD leads are in the proper position and the ICD will be programmed to ensure it is functioning properly.
Precautions after ICD Implantation
- Avoid vigorous exercises, including golf, tennis, swimming, bicycling, bowling or vacuuming
- Don’t lift anything weighing more than 5 pounds
- Avoid strenuous exercise programs
- It is safe to talk on a cellphone, but avoid placing the cellphone within 6 inches of the ICD implantation site when the phone is turned on.
- After surgery, the patient will receive a card that stating he/she have an ICD. Show this card to airport personnel because the ICD may set off airport security alarms.
- Avoid scanning with a hand-held detector to less than 30 seconds over the site of the ICD or make a request for a manual search.
- Some procedures, such as magnetic resonance imaging (MRI), magnetic resonance angiography (MRA), and radiofrequency or microwave ablation are not recommended after ICD implant.
- Stand at least 2 feet (0.6 meters) from welding equipment, high-voltage transformers or motor-generator systems.
- Keep magnets at least 6 inches (15 centimeters) from the ICD site.