Pacemakers and Defibrillators: Frequently Asked Questions

Pacemakers and Defibrillators: Frequently Asked Questions
Brian Olshansky, MD, Professor of Internal Medicine, 
Division of Cardiology 
University of Iowa Hospitals and Clinics
What is the difference between a pacemaker and an implantable defibrillator?
Dr. Olshansky: In electrophysiology we treat heart rhythm problems, such as when the heart becomes irregular, when it gets fast or when it gets slow. There are various ways to treat heart rhythm problems. If the heart rhythm gets very slow and it is not treatable with changes in medications then a pacemaker is needed.
What a pacemaker does is keep the heart beating at the proper rate and from beating too slow. You can adjust the pacemaker so that it can be suitable for either the top or bottom heart chambers or both, depending on what type of pacemaker it is and the needs of the patient. It also will only work if it is needed, it doesn't work all the time.
An implanted defibrillator is a bigger device. It is there to prevent death from a cardiac arrest. The device shocks the heart if it needs to be shocked, because of a life-threatening rhythm disturbance from the lower chambers of the heart. It can correct this rhythm. Because it has a pacemaker built into it, a defibrillator also has the capability of stimulating the heart like a pacemaker, to help stop fast rhythms, at times, and to prevent the heart from getting too slow.
Are there any lifestyle limitations when these devices are implanted?
Dr. Olshansky: Yes there are limitations, though most people don't find that there are serious limitations with either type of device. There are some limitations in the first couple of weeks or months after the devices are placed until everything is healed. At any time, electrical fields or strong magnetic fields can influence the devices. People who work in power plants, or near alternators of cars, can be affected because they are exposed to heavy magnetic fields. People with pacemakers and defibrillators who use arc welding devices and other kinds of heavy energy that involve magnetism or electricity tend to have problems.
If you are an athlete, there can be some limitations regarding what you are allowed to do with a device. Implantable defibrillators, in particular, are placed to prevent death from a heart rhythm abnormality. Still, you could have an episode of a serious cardiac arrhythmia. Before the device corrects that episode, you could get dizzy, light headed, or pass out. People who have serious or recurrent problems with heart rhythm disturbances may have restrictions and may have activities such as driving curtailed. Usually, when a pacemaker is placed and it is working well, the problem has been corrected and driving is allowed. For implantable defibrillators, the issue is not so simple.
Usually you can do most activities but some things are not recommended, like heavy weight lifting, because that could crack or damage a lead (an electrical connection from the device to the heart). Very extreme upper extremity motion over a long period of time could do the same thing. People who do a lot of exercise and have defibrillators could get a shock from their defibrillators when they don't need a shock because their heart is beating too fast, but it is not due to an abnormal or life-threatening problem.
How reliable are these devices?
Dr. Olshansky: These devices are highly reliable There have been tremendous advancements and improvements in these devices over the past 20 to 30 years. Defibrillators have been around since the early 1980s and pacemakers at least 10 to 20 years before that. Both devices can malfunction, but rarely. The device often has to be programmed to the patient's needs, the medical condition and the situation.
Does insurance cover the cost of these devices and their surgical placement?
Dr. Olshansky: Cost is an issue. Some people must have a device implanted at any cost, as they most certainly would not survive without that device. In those cases, devices are placed without question. There are other situations where a device implantation may not be completely clear, necessary, or allowed by the present billing structure.
There is always the issue of risk versus the benefit when implanting a device. There might be some benefit of a device but there might be just as much risk as there is benefit. In those cases, it is not absolutely necessary to put a device in. (It may even be the wrong thing to do.)
What powers these devices?
Dr. Olshansky: There are many approaches to supply energy to these devices. In the old days you could actually recharge the devices from the outside of the body by putting a charger on them. We do not have those kinds of devices anymore. There were even nuclear devices that would last for many additional years. Those devices are not on the market anymore. The devices we now have are better than these old devices by an order of magnitude.
Right now we have a very good type of battery--it is a lithium type battery that wears out slowly. With these batteries we can really measure and determine when the battery is about to get to its end of life. There is a point before the battery fails when we have several months to decide what to do. In the old days, with mercury/zinc batteries, the units would just die suddenly. There could be a major problem because one day a pacemaker could work and the next day the pacemaker may not. This is not true anymore. The battery's energy supply does wear out, and it can vary depending on the kind of device--some devices will last maybe five years, maybe ten years, and some people get more life out of it and some get less, depending on the situation and how much they use it.
What we do when the battery reaches its end of life is we open up the pocket where the device is located, which is under the skin, and we unscrew the leads. Then we plug in a new device and close up the skin. We put in a brand new device, often a higher quality, more technologically advanced device.
During an implant procedure, will the patient be under sedation?
Dr. Olshansky: It depends on the patient's condition and type of device. A pacemaker implant can be done under local anesthesia, but most patients prefer to have sedation, so we use conscious sedation, where the patient can respond to us. We do not generally place a tube down the throat for most people unless we use general anesthesia.
For defibrillator implants we have to use larger amounts of conscious sedation because we need to test the device. We put the patient into a cardiac arrest and use the defibrillator to shock the patient to normal rhythm. That may sound scary, but in fact that is a very safe procedure. We are prepared for all consequences, and it is something necessary. It requires a deeper sedation during the time of the testing of the device. For biventricular devices, in which we place leads into the left side of the heart through a vein, the devices and the leads are more complicated to put in. The implants are more challenging and they take longer.
Will a patient ever outgrow the need for these devices?
Dr. Olshansky: For most people, the device will be needed for the rest of their life. There are specific individuals who may get a device for prophylactic purposes, or for some reason the condition resolves. That does not happen very often. If it can be determined for a fact that the problem has resolved, then occasionally we remove devices. Sometimes, patients would prefer not to live with the device, after a period of time, and the device is either pulled out or turned off, depending on the wishes of the patient. Sometimes the devices get infected and removal of the device can be somewhat risky. If we need to remove the device because of infection, we will reassess the need for a new device. Sometimes it is better to live with the problem if it is not too serious rather than to undergo the significant risk of getting a new device after an infection.
Do these devices replace heart medications?
Dr. Olshansky: We often use devices in conjunction with medications. We do not look at devices in general as a substitute for medication. On the other hand, no medication can substitute completely for an implanted defibrillator. What some people are hoping for is when they get a device put in they can come off all of their medications--this is not the case. In fact, devices usually work with medications much better than they work by themselves. For some people we try to treat life-threatening rhythm disturbances with medication first before we place a defibrillator in.
As time has gone by, we have learned more and more about the safety and effectiveness of implanted defibrillators. We have moved toward using devices more than anti-arrhythmic drugs, specifically, to try to lower the risk of an arrhythmia and its consequences. This is because many of the anti-arrhythmic drugs have side effects and some toxicity. But that does not mean that we stop the other drugs used--such as drugs used to lower cholesterol, or drugs to help the heart condition.
For pacemakers, occasionally we do use medication to keep the heart going faster, but that generally is not the best approach. There are some cases when we use medications to prevent fast rhythms in conjunction with a pacemaker or a defibrillator. For biventricular pacemakers, if the heart function improves enough, we can stop some of the medications that appeared to be necessary before.
What information should I have in order to make a decision about these devices?
Dr. Olshansky: It is always good to get as much information as possible about the need for the device because there are risks and benefits for any device. There are specific conditions in which a device needs to be placed. In some cases, a second or third opinion may be necessary.
There are places to get more information. One place is the American Heart Association and the American College of Cardiology guidelines.
There are conditions where most doctors agree that a pacemaker should be placed. These would be called a Class I condition. There is a similar classification for defibrillators. For a Class I condition, the device is clearly indicated no matter what. These are generally agreed-upon criteria.
There are Class II indications--IIa and IIb. In this classification some doctors would go ahead and place the device and others would not. For a IIa condition there is a lot of evidence to suggest that a device is needed and for a IIb condition there is less evidence in that regard.
For Class III conditions devices are generally not indicated, which means they are not supposed to be placed.
For each person there often is some judgment as to what the right thing is to do. Based on those guidelines then there is no way you can tell everyone what the right thing is, it requires some judgment. If there is any concern, consider getting another opinion.
How do I know my doctor is proficient at this procedure?
Dr. Olshansky: There are various types of doctors who put in different devices, and there are different kinds of devices requiring different kinds of expertise.
Cardiac electrophysiologists who are board certified through the American Board of Internal Medicine would be considered in most cases qualified to implant most heart rhythm devices. There are other doctors who are not board certified cardiac electrophysiologists but are cardiologists who have a wide range of experience with device implants. Some of them have more experience with one type than another. Most cardiologists do not have much experience with implantable defibrillators or biventricular pacemaker defibrillators. Nevertheless, for a straight-forward pacemaker implant, they might be very good. On the other hand one has to recognize that a doctor who is not attuned to the needs of the patient based on their education might be able to place the device but might not understand which would be the right device for the patient. Other types of doctors implant cardiac devices including, nephrologists, pulmonologists, and others who may be less well trained in the procedure.
With respect to experience, certainly experience would help the doctor better understand the risks and benefits and help to minimize the risks of implanting a device. For a doctor to implant devices safely and effectively, continuous practice doing so is needed. The person who places more devices generally does a better, safer job than the person who replaces an occasional device. There are limits to what is necessary. In other words, if a doctor were to place 2,000 devices in a year, that doctor would be unlikely to be any better than the doctor who implants perhaps 100 pacemakers in a year. However, if the doctor only implants two pacemakers in a year, chances are that doctor would not have the type of expertise that you would want to be assured that you are getting the best service.
The American Heart Association and the American College of Cardiology have specific recommendations for the number of devices a doctor needs to place to be considered competent. This also goes for specific types of devices. If a doctor is very good at implanting pacemakers and might implant several hundred pacemakers in a year, they might never implant a biventricular pacemaker or a defibrillator, so they should not be considered qualified to implant every single type of device.
What kind of change will I see with one of these devices on board?
Dr. Olshansky: Let's take a look at three different scenarios:
The first is a patient who needs a pacemaker. The reason most people need pacemakers is that their heart is going too slow. When their heart is going too slow they get fatigued and pass out, feel weak, and just have no energy. With a pacemaker they feel much better. The goal is to make the patient feel better, and that generally happens when the indications for the device are correct. Once in a while that doesn't happen. Sometimes a pacemaker is placed when a patient does not have a symptom, but that is rare. Usually pacemakers are implanted because of symptoms, and we usually get improvement of the symptoms because of the pacemaker. There are some kinds of pacemakers that are programmed poorly and sometimes make this worse. So that might require specific program changes.
Biventricular pacemaker/defibrillators are life saving devices because they can reduce the risk of sudden death. They also can improve the function of the heart. They can improve the ability of the heart to pump blood efficiently and can provide an individual who has one to have more energy and do more with less shortness of breath. In short, the device can improve the ability to become more functional. Some of our patients who have biventricular pacemakers and biventricular pacemaker-defibrillators have not improved. The majority in whom we have placed these devices have improved tremendously.
We had one patient who had no chance otherwise to leave the hospital alive. There was no hope for him. We placed the biventricular device, and now he has been fine for over two years. He travels all over the country with his children and grandchildren with no problem whatsoever. This excellent improvement can and does happen. Generally you do see a marked improvement with the biventricular devices.
With the implanted defibrillators alone (without the capability of bi-ventricular pacing) we don't normally see a marked improvement in the quality of life because these devices act only as protection. They are not necessarily designed to improve the way the heart works. Some people actually get worse with these devices because they do not like to get a shock. The shock may be painful, and it may limit the patient's amount and type of activity. There are some quality-of-life issues of concern for these patients. It has been my experience that an implanted defibrillator alone has a minor effect on quality of life, but it has general lifesaving benefits. For some people, though, an implant can be a real problem.