Cardioverter/ Defibrillator Implantation
For dangerously fast heart rhythms or very weakened hearts at high risk for these rhythms, an Implantable Cardioverter/Defibrillator (ICD) provides life-saving therapies within seconds. ICD systems can be placed through the veins from the shoulder region below the collarbone, or along the outside of the rib cage along the breastbone.
Implantable Cardioverter/Defibrillator Therapy
Within the range of heart rhythm disorders, some are dangerously fast and a risk to life. Not all fast heart rhythms are dangerous, but in some cases, the very fast rate creates disordered heart muscle activity that is unable to sustain a patient’s circulation. In this case, the patient may lose consciousness or experience Sudden Death due to Cardiac Arrest. (have links to dictionary for these)
Ventricular Tachycardia (VT) and Ventricular Fibrillation (VF) are the two main classes of such dangerously fast heart rhythms. Both of these heart rhythm disorders originate in the ventricles – the lower chambers of the heart. Normal rhythm, by comparison, begins in the atria – the upper chambers of the heart – before traveling to the lower chambers.
Implantable Cardioverter/Defibrillators (ICDs) provide constant monitoring and instant, life-saving therapy for these dangerous rhythms.
An Electrophysiologist may recommend ICD therapy to a patient who has already survived Cardiac Arrest, or a patient who has such serious heart disease that the risk of experiencing Cardiac Arrest is very high. A full Electrophysiology consultation is required to determine whether ICD therapy is appropriate.
Implantable Cardioverter Defibrillator
Because ICDs include a Capacitor to store the energy required for a shock, use a different battery composition to build a charge, and have more programming options, they are larger than a Permanent Pacemaker, but still fit comfortably beneath the skin.
ICDs can act like Permanent Pacemakers and provide pacing for very slow heart rates as well, however, most patients do not require this function automatically. Each ICD is individually programmed to suit the patient’s clinical needs. Programming is done at the time of the surgery, but also at each follow-up visit in the Cardiac Device Clinic, under the direction of an Electrophysiologist.
Cardiac Device Programmer
Much like a Permanent Pacemaker, an ICD system involves placing one or two wires, or leads, into the heart using a large vein which run just below the collarbone. These leads allow electrical signals to travel to and from the ICD and the heart itself; from the heart to allow the ICD to monitor the rhythm; from the ICD to provide treatment as necessary.
The surgery to implant an ICD may occur in the Electrophysiology Suite or the Operating Room. A fluoroscope, a form of continuous X-ray camera, is used to place the leads in the heart.
Fluoroscopic image of ICD system in place
Chest X-ray showing Transvenous ICD system in place.
There are two kinds of ICD systems: Tranvenous, and Subcutaneous. Transvenous (through the vein) is by far the more common of the two, as these systems were invented over 30 years ago and were the standard of care until recently. Subcutaneous (under the skin) is a recent innovation, allowing ICD therapy without using a vein or placing any wires in the heart – everything is outside the ribcage, under the skin.
Subcutaneous ICD System
Subcutaneous ICD system in place