In addition to drugs and nonsurgical procedures, several types of surgery can restore your heart’s rhythm. Implantation of a pacemaker can treat bradycardia (slow heartbeat); an internal cardioverter- de?brillator can correct more serious arrhythmias; or a procedure called maze surgery can be performed on some people with atrial ?brillation.
Pacemakers
A pacemaker is a battery-powered unit that regulates your heart’s rhythm. Most pacemakers are implanted in people whose sinoatrial node is firing too slowly as a result of age, heart disease, or heart medications; the pacemaker takes over for the sinoatrial node if it fails to start. In a person with heart block, the device replaces a blocked pathway. Today pacemakers not only “pace” your heart’s rhythm but also have a “demand” sensor that can speed up or slow down your heart rate in response to your activity level, just as your heart would naturally.
The device itself, which is about the size of a man’s watch, contains a battery and an electronic pulse generator, with either one or two leads that are threaded into your heart. The device is programmed to read whether your heart rate is within an acceptable range for you. If it is not, the pacemaker generates an electrical impulse to stimulate a heart beat at an appropriate rate. A single-chamber pacemaker has one lead that is positioned in one heart chamber, the right atrium or ventricle; a dual-chamber unit has two leads that are threaded into both the right atrium and the right ventricle. The pacemaker can remain in place for several years before the batteries require replacement.
For people with heart failure or with certain physical characteristics, a third lead may be placed in the back of the heart through a side vein. This is called biventricular pacing. While more complicated to perform than the usual insertion of a pacemaker, this procedure can make some people with heart failure feel much better by coordinating the heart’s contractions.
How a Pacemaker Is Implanted
To have a pacemaker implanted, you will need only a mild sedative and a local anesthetic in the area of your upper chest. First the doctor makes a small incision in the skin under the collarbone. The thin, coated leads are threaded through a blood vessel under your collarbone and positioned in your heart under X-ray. Then they connect the leads to the pacemaker unit and slip it under your skin, also just under your collarbone. You will notice only a small bump at the site. The proce- dure will be over in 1 to 2 hours, and complications are rare. Serious or life-threatening complications occur in less than 1 percent of cases. Infection of the pacemaker is rare but generally requires that the pace- maker be removed. Sometimes less serious complications can occur such as bleeding, collapse of a lung, or the pacemaker’s leads may need repositioning.
You will probably be able to return to your routine activities in a few days. Your doctor may tell you to avoid heavy lifting or vigorous move- ment of your arm on the side of the pacemaker.
Living with Your Pacemaker
You will need to have regular checkups. The checkups are more frequent until the pacemaker site heals com- pletely; then they occur about every 3 to 6 months, for monitoring. Your doctor will evaluate your pacemaker by moving an electronic programmer over the device. The programmer relays information about pacemaker function and the life of the battery, and it can also change the programming (pacing instructions) of the device if necessary. In addition to the of?ce checkups,
your doctor may also give you instructions for how to have some monthly evaluations done by telephone.
When the battery begins to wear down, your pace- maker will slow down somewhat, but it won’t stop sud- denly. Your doctor will be able to detect the first warnings that the battery is running down before you have any sensation of it. When the battery needs replacing, you will need surgery to implant a new device. This procedure requires local anesthetic, but because the leads usually do not need replacement, the procedure is somewhat simpler than the original implantation.
Your doctor will also give you an identification card that provides specific information about the device you have. It is important to show this card to health-care professionals and to airport security staff
Once your pacemaker is in place and the implant site has healed, you most likely can participate in all of your usual activities. You and your doctor can review any possible restrictions—such as full-contact sports— that might apply to you. Always feel free to ask your doctor about any questions you have about appliances, medical procedures, or other considerations that you
think might affect your pacemaker. In general, it’s a good idea to be aware of your surroundings and alert for any circumstances that might interfere with the electronic circuitry in your pacemaker.
Although your pacemaker is not likely to restrict your life in signif- icant ways, it is important to remember that there are many things your pacemaker cannot do. It cannot protect you, for instance, from a heart attack caused by blocked arteries. It also cannot necessarily replace your need for medications, including heart-related drugs for conditions such as high blood pressure, angina, or even other forms of arrhythmia.
Implantable Cardioverter-Defibrillators
The internal cardioverter-de?brillator (ICD) is a battery-operated unit, only slightly larger than a pacemaker, that is implanted under your skin to monitor and correct your heart’s rhythm. All current ICDs also func- tion as pacemakers. An ICD is usually placed in a person with a dam- aged heart (as from a heart attack) who has had or is at high risk of having life-threatening heart rhythms, such as ventricular tachycardia or ventricular ?brillation. It may also be used for some people with severe atrial ?brillation.
An ICD can deliver the same sort of low-energy, imperceptible pulses that a pacemaker does. Furthermore, the ICD monitors the heart using the same technology. De?brillators are different from pacemak- ers in that they also monitor for very fast heart rates as well as for bradycardia. The ICD can also deliver higher-energy pulses (shocks) to the heart when it detects more serious or sustained rapid arrhythmias. These stronger impulses are called de?brillation shocks, and they are often life-saving.
A person with an ICD can feel these stronger impulses—usually a single shock, but sometimes a series of them—and they are often described as feeling like a quick thump or kick in the chest. Depending on the level of consciousness you have at the time of the shock, it may be painful (if you are not sedated) or may not be painful (if you have received sedatives).
Like a pacemaker, an ICD has two parts: a pulse generator, including a battery and electronic circuitry, and a system of coated leads tipped with electrodes. Newer devices are as small as a pager. They are also designed to provide a controlled burst of impulses, called overdrive pacing, at the first sign of ventricular tachycardia. If that does not restore normal heart rhythms, the device delivers de?brillation shock.
The devices make decisions on what type of therapy to give based on how fast the heart rate is. The devices are also equipped to regulate bradycardia (slow heartbeat) if that occurs. They also have a memory to record arrhythmic episodes and do some internal electrophysiologic testing.
In a person who has experienced prolonged ventricular arrhythmia, the ICD is more effective than antiarrhythmic drugs at preventing sudden death. The device may also similarly prevent cardiac arrest in a person who is considered at high risk of developing such arrhythmias. Before you are considered as a candidate for an ICD, your doctor must rule out other causes of the arrhythmia, such as a heart attack, myocar- dial ischemia (inadequate blood ?ow to the heart; see page 161), or chemical imbalance and drug reactions, which can be treated in other ways.
How an ICD Is Implanted
The procedure for placing an ICD is very similar to that for a pacemaker (see page 273). At the hospital, you will be given a sedative and then a local anesthetic. The cardiologist or surgeon will make an incision in the skin and then tunnel the leads through blood vessels into your heart, or onto its surface. Then he or she will tuck the ICD into a pouch of skin under the collarbone or somewhere above the waistline. The leads will be attached to the pulse generator. Electrophysiologic testing will be done to check out the device. The entire procedure takes about 2 hours.
You will probably stay in the hospital overnight. You may be prescribed some antiarrhythmic medications, too. These drugs may lessen the need for high-energy shocks from your ICD. The recovery time, the pain after the procedure, and risks of the procedure are very similar to those of a pacemaker.
After Implantation
After your ICD is installed, you will need to return to the doctor’s of?ce for monitoring every 1 to 3 months. Your doctor can evaluate the ICD function electronically by moving a programming wand over your chest. By this means, he or she can determine what kinds of impulses have been delivered, whether they worked, whether they need modi?- cation, and how much energy is left in the battery. When the energy level in the battery is down to a predetermined level, you will be scheduled for replacement surgery. The battery usually lasts from 3 to 5 years, depending on how many shocks it delivers. Usually, replacement surgery is somewhat simpler than the original implantation because the leads do not need to be replaced. Some ICDs can also be checked periodically by telephone.
Many people feel some apprehension about the possibility of receiv- ing unexpected de?brillation shocks. You may need to continue to take antiarrhythmia medications to reduce the risk of needing a shock from the implanted device. Some shocks are small, and some people don’t notice them. When you do receive a stronger shock, it may feel like a jolt, thump, or blow to the chest. Some people black out during periods of ?brillation, so they don’t feel the shock; see “Living with an ICD,” next section, on driving if you have an implanted ICD. If someone is touching you during the shock, he or she may feel a tremor, but will not be harmed by it in any way.
You and your doctor can discuss what to do if your ICD delivers a shock. Your doctor may tell you to call him or her if you feel a shock, or if you feel ill after the shock.
Apart from the discomfort of a sudden de?brillation shock, possible side effects of ICD placement include some sensitivity at the site of the implant, especially in very slender people; very rare problems with infection; and some cosmetic issues (the device is visible under the skin). If you feel apprehension about the shocks or concern about your need for an ICD, ask your doctor about a support group, where you can talk with other ICD “users” and medical staff.
You will also be given an identi?cation card that provides speci?c information about your ICD. Carry it with you at all times, and show it to health-care professionals and airport security.
Living with an ICD
As with a pacemaker, your ICD can interact with some devices in your environment with electromagnetic or radiofrequency ?elds. Review the interactions with implantable devices (see page 276), and talk to your doctor in detail about how devices in your environment, medical proce- dures, or your activities might affect your ICD.
Driving is a major consideration for a person with an ICD. Your ICD may take an interval of 5 to 15 seconds or longer to detect arrhythmias and deliver treatments, during which you might feel dizzy or even faint. Therefore, you are usually advised to avoid driving, and other activities, such as piloting or scuba diving, that would put you and others at risk if you were to lose consciousness. In some states, these restrictions are law. Review this issue with your doctor carefully. Some people who go for long periods without shock or symptoms are allowed to return to driving, but only with the advice of a doctor.
Maze Surgery
In some people with chronic atrial ?brillation, an operation called the maze procedure involves making a series of incision lines within the heart to create a maze that blocks electrical pathways through the heart muscle. This surgery is done in a person for whom medications, a pace- maker, or other treatments have not been effective. A likely candidate might be a person with uncontrolled atrial ?brillation, for whom the chief danger is that blood will pool in the upper chambers of the heart (the atria); this pooling increases the tendency of the blood to clot, which could lead to a stroke. The surgery may be performed with cer- tain other types of heart surgery to prevent atrial ?brillation after the operation.
The procedure is major surgery, done with the patient under general anesthesia. The surgeon must split the breastbone to expose the heart and transfer the functions of the heart and lungs to a heart-lung machine during the procedure.
The surgeon makes a number of small incisions in both the left and right atria. These incisions form a pattern that will direct the heart’s electrical impulses into the ventricles and block extra impulses. As the incisions heal, scar tissue forms that cannot conduct electrical impulses,
so the new pathways are permanently established. The surgery takes about 3 hours. Sometimes a pacemaker is implanted, too.
Recovery from maze surgery requires about 1 week in the hospital. You may need diuretics to prevent ?uid accumulation, and antiplatelet medication such as aspirin to prevent blood clots. You may experience pain from the chest incision, and fatigue for 2 to 3 months after surgery. Most people can go back to normal activities, including work, in about 3 months.
The maze procedure has been adapted to a less invasive technique, similar to a catheter-based ablation technique for atrial ?brillation. The technique allows the radiofrequency to be directed to the outside of the heart. This technique is complementary to less-invasive catheter-based ways to perform ablation of atrial ?brillation through the veins.