Internal Defibrillator


  1. What is an internal defibrillator?
  2. What is its use?
  3. How does it work?
  4. Internal defibrillator preparation
  5. Post-operative care

What is an internal defibrillator?

An implantable cardioverter defibrillator (ICD), or internal defibrillator, is a device through which a sharp, high-voltage electrical current is circulated to stop and reverse arrhythmias.

It is composed of these parts:

  • Pulse generator: it is about the size of a large pocket watch. It contains a battery and electrical circuits that read the heart’s electrical activity.
  • Electrodes: are wires, also called leads, that pass through the veins to the heart. These wires connect the heart to the rest of the device. The ICD may have 1, 2 or 3 electrodes.
  • Pacemaker: Most ICDs have a pacemaker built into them.

Why is it used?

This device is used to treat ventricular arrhythmias including ventricular fibrillation or sustained ventricular tachycardia, i.e. in cases where the heartbeat is unstable and dangerous for the patient.

ICDs can have a pacemaker function, i.e. they are able to detect the heart rhythm and if the heart rate is below 60 bpm they will start pacing the heart. But unlike pacemakers, ICDs have an anti-tachycardia function.

What does it consist of?

The implantable defibrillator captures heart rhythm abnormalities and acts by automatically sending a strong and sharp electric shock, with enough energy for the arrhythmia to subside and the heart to return to its normal rhythm.

Preparation for the internal defibrillator

The defibrillator is implanted in a surgical operation of up to 90 minutes, under local anesthesia and placed in the thoracic region near the clavicle. In addition, the specialist will also have programmed the instrument with all the patient’s information prior to surgery.

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During surgery, the electrocatheters are connected to the heart and are ready to send electrical signals in the event of an abnormal heartbeat.

Care after the operation

Recovery time from the operation is approximately two weeks, although the stitches are removed on the tenth day. Periodic check-ups will also be necessary every 2 years or so to ensure that the device is functioning properly.

In case of abnormal symptoms, bruising or irritation of the area, as well as frequent discharges, it will be necessary to contact the emergency service immediately.

Finally, it should be noted that after the operation the use of magnetic resonance imaging or neuromuscular stimulation treatments will be totally prohibited.