More about Implantable Cardioverter Defibrillators (ICDs)
Many people have questions about these devices,
how they work and why a doctor might decide to offer one to a patient
as part of treatment for a disturbed heart rhythm. Here are a few of
the questions we hear most often.
Q. Will an ICD cure my heart rhythm problem?
A. No, it won’t. Cure is a word that means "completely
and permanently rid the patient of the difficulty", and that’s
not what an ICD is for. In some cases an electrophysiogist can provide
an actual cure for a rhythm disturbance, sometimes by performing an
ablation. (For more information about ablation, please click here.) An
implantable defibrillator is most commonly used as one part of a
patient’s treatment; it is the part that remains constantly
prepared to act instantly if the heart rhythm changes for the worse.
It treats the problem, then, each time it occurs. Many doctors use an
ICD in combination with rhythm control medications called
antiarrhythmics. Their goal in such cases is to use the medication to
keep the rhythm from getting too fast, and to use the ICD as a "failsafe"
device to protect the patient should the heart rate speed dangerously
despite the medication.
Q. Is an ICD the right treatment for every kind
of rhythm disturbance?
A. No, it isn’t. Implantable cardioverter defibrillators are intended to treat the very serious rhythm problems that can arise in the lower portion of the heart (the ventricles), not disturbances in other areas. In the near future, ICDs will be available which can be used for patients with these other rhythm problems. Doctors can very often provide good heart rhythm control for patients with medication alone. When a patient’s symptoms worsen, however, or when the problem is persistent or potentially dangerous, the doctor may perform an electrophysiology study (an EP study) to learn more about the rhythm and the treatments which can best deal with it. In some cases an electrophysiologist may not even need a study; the problem and its solutions are plain from the beginning. If an ICD is one of those solutions, the doctor will know and discuss it with the patient.
Q. Do shocks from an ICD hurt?A. Most patients who have received shocks from their ICDs tell us that "hurt" is not the word they’d choose to describe the experience. We always hear from them that shocks are startling, jolting, unsettling, and it’s easy to understand why. To begin with, the ICD delivers a shock to prevent a dangerously fast heart rhythm from hurting a patient. That rhythm, then, must be present for the device to recognize before it does anything. All by itself, the rhythm may cause discomfort—dizziness, lightheadedness, palpitations, an "about-to-faint"feeling—and then, very suddenly, the ICD provides the shock to bring the rhythm back to normal. Naturally, this is startling. In addition, the jolt is a powerful one, selected specifically by the doctor to control the heart without delay.
Q. If someone is touching me at the moment I get a shock from my ICD, will anything happen to them?A. No, nothing will happen to them. A shock from an ICD is a bit different from a shock given externally—for example, by paramedics or emergency room workers, with "paddles" on the chest. When we defibrillate someone externally we use a great deal of energy, to be certain that after it has travelled the distance from the outside to the heart itself, there will be enough left to do the job. However, the ICD has an important advantage: it shocks the heart directly, right through the wiring that connects it to the heart. Therefore, it can accomplish the same thing using far less energy, since all of its energy is focused on the place where the problem is. That means that the amount of energy that escapes to the surface, where someone might be touching us, is very difficult to detect, and completely harmless.
Q. If I have an ICD implanted, can I return to life as it was before my rhythm became disturbed?A. In many cases, once the doctor has started treatment to control a patient’s heart rhythm, which might include medication, ablation, a pacemaker, an implantable cardioverter defibrillator, or some combination of them, life can begin its return to normal. Most patients have been able to return to work, school, and their usual activities including driving, sexual relationships, and exercise, once the doctor can see that these things are safe. How long it will take, of course, depends on the individual patient and certainly on whatever other medical problems (besides the rhythm disturbance) he or she may have. Here, one’s physician is the best source of information.
Q. Where within me will the defibrillator be placed?A. In earlier days, when ICDs were much larger, they were too large to implant anywhere but in the abdomen. Now that they have been miniaturized, doctors usually implant them in the chest, most often a little lower than the clavicle (the collarbone), on either the right or the left side of the chest. Because they have a certain amount of thickness, patients often can feel and see the outline of the device under the skin.
Q. Is a defibrillator implantation an open heart operation?A. No, it isn’t. Implanting an ICD these days is much simpler than it was a few years ago, and often takes less than an hour to complete. The physician who performs this procedure is the best source of information about what sort of anesthesia will work best for an individual patient. As a rule, though, patients do very well with sedation to keep them in a light state of sleep, in combination with local anesthetic to completely deaden the area where the device is implanted. The incision is usually a small one—three or four inches wide—and travels horizontally on the chest. After the ICD is in place and the incision is closed, the doctor applies a bandage to protect the site and returns the patient to his or her hospital bed, often with no trip to the recovery room. Most patients notice some soreness once the local anesthetic has worn away; this typically lasts about a week, getting less and less each day. As they would after any operation, doctors advise patients with new ICDs to avoid getting the site wet for several days after the ICD has been implanted.
Q. How is the ICD powered?A. Implantable cardioverter defibrillators are powered by batteries. The variety used has been chosen because of its long service period and because of the very predictable way in which its power is gradually used. Naturally, an ICD which delivers a great many shocks will wear out sooner than one which seldom needs to provide that therapy. Nonetheless, most ICDs last five years and often more. Checking the battery is, of course, an important part of any evaluation of the device, and doctors are careful to do this as a portion of their routine follow-up for patients with ICDs. A normal clinic visit to the electrophysiologist or cardiologist for such a patient usually includes interrogation of the device. This means that we use a piece of equipment called a programmer to "ask" the ICD to show its battery voltage, its settings, any rhythm disturbances it has detected, and any therapy it has delivered since the last visit. Long before the battery is ready to expire, and long before the performance of the ICD changes in any way, an interrogation like this will show the doctor that the time is approaching to consider a replacement ICD. At that point a brief hospital stay is arranged—typically no more than one or two days—to allow the doctor to remove the old ICD and replace it with a fresh one. Replacement procedures are often simpler than original implantations, and so take the doctor and patient even less time.
Q. How often do ICDs require checking in the doctor’s office?A. Physicians vary in their opinions about this. Some say they prefer to see their ICD patients every two months, or even more often when they feel the heart rhythm needs especially close observation. Others ask their patients to return every four or six months, and this is more common among patients whose rhythms are quite stable.
Q. Is it true that people with defibrillators shouldn’t go near microwave ovens?A. No, it isn’t. A number of years ago, when both pacemakers and microwave ovens were made very differently, some pacemakers reacted badly in the presence of those old-style microwave ovens. As a result, pacemakers were from that point constructed in a way that protected them from that influence and modern pacemakers are no longer affected by microwave ovens. This is also true for ICDs. However, doctors advise their ICD patients to avoid a few things. The first is very powerful magnets, such as you might find used in a junkyard to lift discarded automobiles, or contained within the cases of powerful stereo speakers. Smaller, weaker magnets (like those used to hold notes on a refrigerator, or those found in telephone receivers) pose no difficulty at all. The very powerful electromagnetic field generated by the equipment used for magnetic resonance imaging (MRI) should also be avoided, as should the field present very near to an automobile ignition system. The doctor’s major concern when considering these matters comes from awareness that a very strong electromagnetic field temporarily deactivates the ICD. Although this effect persists only as long as the patient is in the field, returning the ICD to full function as soon as the patient is distant from the magnetism, naturally the physician doesn’t want the device’s operation suspended even briefly.
Q. Are there support groups for people with ICDs?A. Yes, there are. What is it like to live with a serious heart rhythm disturbance? Those who know best are those who live that life every day, and there is always something vital to be learned from hearing them. This institution has a support group and, as in most places, the group is intended to serve the needs of patients and those who are closest to them. Many such groups are sponsored by hospitals and often meet in the hospitals at frequencies which vary from one place to another. The support group is not "group therapy" in the sense usually intended by psychotherapists; it is simply an occasion for people who face serious heart rhythm problems to gather and speak primarily with one another. The typical support group meeting provides a speaker, often a doctor or nurse, to briefly discuss some technical aspect of care for such patients. Additionally, it provides a larger portion of time for the patients—and for those close to them, often in a separate room—to share their feelings with the help of a professional and in a place of safety where confidentiality is respected. In these group meetings, it’s very common for some participants to share a good deal, while others prefer to observe quietly and benefit in that way. The most important thing to remember about the support group is that there is no "right" or "wrong" way to participate. Participation itself—simply being there in the presence of those others who understand from their own experience how you feel—is a powerful force for emotional healing for patients and families.