Implantable Cardioverter Defibrillator Complications

Implantable cardioverter defibrillators (ICDs) are pacemaker-like devices that continuously monitor your heart rhythm, and, if a life-threatening cardiac arrhythmia occurs, will automatically deliver lifesaving treatment. They are commonly used in people who have a high risk of ventricular tachycardia or ventricular fibrillation.

ICDs are extremely effective and generally quite safe. Still, it is possible for you to experience complications with your ICD system. These ICD complications fall into two general types: surgical complications, and post-surgical complications.

Surgical Complications

The surgery to implant an ICD is pretty routine and straightforward, and can usually be done without any problems. However, surgical complications do sometimes occur.

The main risks related to ICD implantation surgery include:

• Bleeding
• Infection
• Pneumothorax
• Damage to the heart or to a blood vessel

The overall risk of having any of these complications is around 2 to 3%, and most of the time any surgical complications that do occur are minor and can be easily treated. The risk of actually dying from an ICD implantation procedure is very low — well below 1%.

Infections, which can occur in up to 1-2% of ICD surgeries, do present a difficult management problem. If the ICD system becomes infected, then the entire ICD system (the ICD generator and all the leads) usually must be removed in order to successfully cure the infection with antibiotics — and once the infection is cleared up, another ICD system will need to be implanted.

You will be exposed to these same surgical risks each time your ICD generator needs to be replaced (roughly every 6 to 10 years, when the battery begins to wear out). Your risk from this replacement surgery is generally lower than for the initial surgery. This is because the replacement surgery usually requires only replacement of the ICD generator itself, and not the ICD leads, which reduces to nearly zero the risk of pneumothorax, and of damage to the heart or blood vessels.

However, there is some evidence that the risk of infection is a bit higher with replacement surgery than with the initial surgery.

Complications That Can Occur After Surgery

Once you are past the surgical implantation of an ICD and are completely healed, you should expect to be able to return to your normal life. However, there is still a small risk of developing post-surgical complications.

Post-surgical complications of ICD therapy include:

• Lead complications, such as lead "dislodgement"(movement of the leads out of their proper position) or lead fracture. A malfunctioning lead can cause the loss of effectiveness of the ICD system, or inappropriate shocks (see below).
• Movement of the ICD generator out of its proper position, which can cause pain, skin erosion or bleeding.
• Inappropriate shocks, which cause pain, and can produce psychological trauma.
• ICD malfunction.

The most common of these complications are inappropriate shocks, that is, shocks delivered by the ICD because the device “thinks” a life-treating arrhythmia is occurring when actually it is not. 

ICD shocks are not particularly dangerous, but they hurt. While the shocks are designed to be delivered only when a life-threatening arrhythmia occurs, about 20% of people with ICDs at one time or another will receive shocks for other reasons. These inappropriate shocks can be caused by any very rapid heart rhythm such as atrial fibrillation, or by the rapid heart rate that you get from strenuous exercise.

Preventing further inappropriate shocks depends on what is causing them. If an inappropriate shock occurs due to atrial fibrillation or exercise, in most cases the doctor can "re-program" the ICD to reduce the chance of further inappropriate shocks.

But sometimes inappropriate shocks can happen because one of the leads has become loose or has developed a tiny fracture. Preventing inappropriate shocks caused by an ICD lead problem usually requires a surgical procedure.

Finally, because ICDs are complex electronic devices that contain numerous essential (and delicate) components, sometimes one of these components can fail to operate normally. If this happens, the ICD may not be able to deliver therapy when it is needed, or it may deliver inappropriate shocks. An ICD that fails to function normally almost always needs to be removed and replaced with a new device.

In the effort to reduce complications that sometimes occur with standard ICDs, subcutaneous ICDs have been developed recently. These devices are implanted under the skin in the chest area, and entirely avoid having to place leads within blood vessels. This avoids any complications related to the heart and blood vessels that sometimes occur with a standard ICD. While subcutaneous ICDs have their own set of problems, early experience suggests that the incidence of dangerous complications may be reduced with these devices.

Fortunately, the large majority of people who have ICDs never experience any serious complications with their devices.

The idea of receiving an ICD is simply to protect you from dangerous arrhythmias; it is not meant to drastically change your life.

A Word From Verywell

While implantable defibrillators are generally very safe and effective, it is important to know what kinds of complications they can produce. Most complications can be managed successfully, as long as they are addressed appropriately.