Automated Implantable Cardioverter-Defibrillator

The automatic implantable cardioverter-defibrillator (AICD) is a device designed to monitor the arrhythmias i.e, if the heartbeat beats too fast (tachycardia), too slow (bradycardia) or irregularly (atrial fibrillation). This device is small enough to be implanted under the skin in the upper chest, and it can deliver an electrical impulse or shock to the heart when it senses a life threatening change in the heart’s rhythm.

The AICD system consists of:

• A pulse generator that can send an electrical impulse or shock to the heart
• Electrodes that sense the rhythm of the heart and deliver a shock to the heart
• Batteries designed to last 4 to 5 years and deliver shocks
• A small computer chip that tells the devicewhen to deliver a shock

Defibrillators treat arrhythmias in two ways: either the device tries to stop the abnormal rhythm with high speed pacing (cardioversion) or the device delivers an electrical shock to the heart to reset its rhythm (defibrillation). It is also capable of collecting and storing information about your heart’s electrical activity for the doctor to check if required.

AICD device is used in people whose heart suddenly stops, who have excessive rapid heartbeats (ventricular tachycardia) or who are at risk for the rhythm problems due to an enlarged heart (cardiomyopathy), a poor or inadequate blood flow to the heart from a severe heart attack, or related conditions like congestive heart failure.

Preparation

Theprocedure is carried out in a cardiology laboratory called as ‘cath lab'. Before the admission time, fasting of 6 hours is recommended. Blood thinning medication(like aspirin) may be required to be stopped a few days before the procedure. Inform the doctor of all medications including any overthecounter medications. You may be required to have your blood and ECG tests, X-ray chest done prior to the procedure.

The procedure

The patient might be given a light sedative to relax. Also, after injecting a local anesthetic agent, the cardiologist will make a small cut (approx 5-8cms) in the area below the collar bone to insert the AICD. The lead wires are then passed through a vein into the heart and then tested to check their position in your heart. The leads are connected to the pulse generator, and tested. The skin is then sewn together and a small dressing applied, and the device is programmed. The whole procedure usually takes about an hour. After the procedure your heart rhythm and blood pressure is monitored, the wound site is observed for any signs of bleeding or swelling at the incision site. Hospital stays is usually only for few days with quick return to normal activities.

Following discharge

It is important that these points are discussed with the cardiologist prior to discharge:

• Possible driving restrictions
• Possible activity restrictions like heavy lifting
• Possible wound care and bathing instructions- keeping the incision clean and dry for one week
• Possible medication changes
• What to do if you receive therapy from your AICD - Living with an AICD should give the comfort that treatment for a life-threatening condition can be delivered whenever and wherever required. However, it is important to note that in the event of a life-threatening heart rhythm, the patient may faint before the AICD corrects the rhythm. Serious injury could occur if the patient faints while driving or swimming alone.
• Follow up appointment details

Monitoring regularly is recommended as to know whether the device is sensing the heartbeat properly, how many shocks have been delivered, and how much power is left in the batteries. Some electrical equipment can interfere with the AICD and is better to avoid like generators, electric motors, arc welders, transmission towers, high-voltage power lines, large stereo speakers, magnetic therapy products, running car engines etc. Cellular phones have the potential to cause momentary interference with an AICD too.