Although the heart has its own natural pacemaker that sets its rhythm, the term “pacemaker” most commonly refers to an artificial electronic device that is implanted in the chest to regulate the heart’s rhythm. Generally, pacemakers correct an abnormally slow heartbeat by sending electrical impulses to one or more chambers of the heart. These signals make the heart contract in a more regular rhythm than the chamber would otherwise.

Pacemakers are implanted into the patient’s chest during a minor surgical procedure. A short stay in the hospital may be required, and some patients may need to take medications afterward that help the heart maintain a normal rhythm (antiarrhythmics). Once the pacemaker is in place, it runs on batteries that last for about 5 to 10 years. Pacemaker batteries will not run out unexpectedly. Physicians can detect when the battery is running low during a routine office visit.

Nearly 200,000 pacemakers are implanted annually in the United States. People with pacemakers enjoy significant improvement in their quality of life. However, caution is advised in certain situations. While the risk of a life-threatening problem is small, people with pacemakers are encouraged to:

• Avoid walking through a metal detector, or spending any length of time near store security gates or entrances.
• Avoid magnetic resonance imaging (MRI) machines and tests.
• Hold cell phones at least 6 inches from the pacemaker at all times, even if the phone is turned off. Use and store the cell phone on the side of the body opposite the location of the pacemaker.
• Avoid any areas or equipment that generate strong electrical or magnetic fields, such as slot machines, remote-control toys, amusement park rides and attractions, power plants, junk yards that use large magnets, stereo speakers (when held close to the pacemaker), or poorly shielded car engines.
• Avoid working on car engines while they are running.
  

What is a pacemaker?
Although the heart has its own natural pacemaker that sets its rhythm, the term “pacemaker” most commonly refers to an artificial electronic device that is implanted in the chest to regulate the heart’s rhythm. Pacemakers are designed to treat cardiac conditions that involve bradycardia (an abnormally slow heartbeat). Following a permanent pacemaker insertion, most patients with these conditions report significant improvements in their quality of life. The underlying heart conditions include the following:

• Sinus node dysfunction. Also called sick sinus syndrome, this occurs when the body’s natural pacemaker sends out electrical impulses too slowly.
• Heart block. A delayed or complete lack of communication between the upper and lower chambers of the heart. Heart block is commonly the result of degeneration of the heart’s normal conduction system. The term “conduction system” refers to the heart’s natural mechanism for transmitting the electrical impulses that make the heart beat. This may result in an inability to conduct electrical impulses between the upper and lower chambers of the heart, resulting in a slow heartbeat. This is one reason why people are more likely to need pacemakers as they age. In fact, most of the nearly 200,000 pacemakers implanted annually in the United States are in patients ages 65 or over.
• Carotid sinus hypersensitivity. A hyperactive reflex causing the heart rate to drop sharply when pressure is applied to the neck.
• Arrhythmias arising from ablation. Ablation is a minimally invasive procedure that could result in bradycardia.

The pacemaker consists of three parts:

• Generator
• Leads
• Electrodes

The generator is a small box, usually about 2 inches wide and around 3 ounces in weight. Some generators are even smaller, measuring 1 inch in diameter and weighing about half an ounce. They are battery-powered, and most use lithium batteries that last for 5 to 10 years. When the battery runs out, the entire generator is replaced. The generator is responsible for generating the electric impulses that correct the slow heartbeat.

Attached to the generator are one or more leads, or wires, generally made of platinum with an insulating coating of either silicone or polyurethane. The leads carry the electrical impulses from the generator.

At the tip of each lead is a tiny device called an electrode that delivers the necessary electrical impulses to the heart. Thus, the electric impulses are created by the generator, carried by the leads and delivered by the electrodes to the heart.

What happens during a pacemaker insertion?
Temporary pacemakers are usually performed while the patient is in the hospital for a related heart condition (e.g., following a heart attack). The procedure may take place in the patient’s hospital room or in a minor surgery room. After a local anesthetic and a sedative (if necessary) have been administered, a small tube (catheter) is inserted into the skin, usually in the chest, neck or groin area. Wires from the external pacemaker are then threaded through this tube and into the heart. The external pacemaker is either hung on an IV pole by the bedside, or pinned to the bed sheets. Patients should not touch the unit and should limit their activity while the temporary pacemaker is in use.

Permanent pacemaker insertion is more invasive, and is considered minor surgery. It can be performed either as an inpatient or an outpatient procedure. Permanent pacemaker insertion takes places in a cardiac catheterization lab, electrophysiology lab, hospital operating room or outpatient surgical facility.

The patient is given a local anesthetic, at which time the patient’s heart rate and blood pressure are monitored for the duration of the procedure. The insertion site will be cleaned and shaved. Then one of two methods will be used, depending on where the pacemaker is to be inserted:

• If the pacemaker is to be inserted into the chest (an endocardial implantation), then a small cut (incision) is made in the chest wall just below the collarbone to create a small surgical pocket. The wires (leads) from the pacemaker are then passed through a vein in the upper chest and placed in the right atrium or right ventricle, with the visual guidance of x-rays. The lead is then attached to the inner surface of the heart chamber using small screws or tines. If there is more than one lead, then the process is repeated. The main body of the pacemaker is then inserted into the surgical pocket created under the collarbone. Following insertion, the skin is closed with stitches (sutures). The entire procedure takes about an hour.
• Occasionally, leads are placed on the outer surface of the heart in a process known as epicardial implantation (outside the heart). When this procedure is used, the surgeon opens the chest wall, the leads are placed onto the heart’s surface and the pacemaker is inserted under the skin of the upper abdomen. This alternative is only used when the veins are unsuitable for passing the wires through in order to reach the inner heart (due to, for example, some types of congenital heart disease or if the patient is a child).

What happens after the pacemaker insertion?
Shortly after the insertion, a chest x-ray will be taken to confirm the proper placement of the device. Patients will rest for several hours and their vital signs will be monitored. Pain medications may be administered. The pacemaker’s programming may be adjusted using a magnetic wand that is passed over the chest. The patient should not feel anything during this process.

Depending on the patient’s age and overall health, a short hospital stay may be recommended following permanent pacemaker insertion. The physician will provide specific instructions regarding the patient’s appropriate activity level immediately following the procedure. If there are no complications, complete recovery from the procedure will take about two to three weeks. During that time, the wires will firmly take hold where they were placed. In order to help keep the wires from becoming dislodged, patients should avoid contact sports, heavy lifting or vigorous movements of the arm on the side of the pacemaker.

Patients should not be alarmed if a hard ridge forms where the incision was closed. This will fade away as the wound heals. However, any signs of infection (e.g. fluid leakage) should be reported to one's physician immediately. A warm compress can be used to reduce any pain in the area. Patients can bathe or shower normally, being careful to gently wash the incision area with mild soap and then pat the area dry.

A follow-up visit at the physician’s office is usually scheduled for one to two weeks after the implantation. At that time, the sutures or staples are removed (if necessary), the incision site is inspected for signs of infection. The patient will receive further instructions for living with his or her pacemaker. This includes carrying a pacemaker ID card at all times in case of emergency. There will be a follow-up visit to the physician about two months later, and then every six to 12 months, to ensure that the pacemaker is working properly.

In between visits, pacemaker checks may take place over the telephone, through transtelephonic monitoring. Through a special device, information from the implanted pacemaker can be sent over the telephone. A trained medical professional then evaluates the information and relays findings to the patient and physician. These transtelephonic checks are scheduled every two to three months. If programming adjustments are needed or battery replacement is necessary, an appointment for an office visit will be made.






What are the risks during or after pacemaker insertion?
As with any surgical procedure, there is a risk of infection with permanent pacemaker insertion. Surgical risks are higher if the patient has high-risk characteristics such as the following:

• Advanced age
• High level of stress
• Obesity (more than 20 pounds over one’s ideal weight)
• History of smoking
• Use of various medications

Serious complications are rare, occurring in 1 to 2 percent of cases. They may include the following:

• Severe bruising or bleeding
• Formation of blood clots
• Tearing of a blood vessel
• Puncturing of the lung or heart muscle
• Stroke
• Heart attack
• Introduction of air into the space between the lung and chest wall (which could lead to an embolism)
• An electrode dislodging from the heart
• Infection
• Pacemaker malfunction

Furthermore, some people face the risk of developing pacemaker syndrome, in which the implanted pacemaker is no longer synchronized with the heart’s own rhythm and attempts to pump blood through a closed valve. This restricts the flow of blood from the heart, causing dizziness and fatigue in the patient. It occurs in one of four users of the single chamber pacemaker (one that stimulates one chamber of the heart), but there is no risk of this syndrome for users of the double-chamber pacemaker (which stimulates two chambers of the heart).

Patients should immediately report the following symptoms to their physician:

• Redness, warmth, tenderness or swelling of the incision site, alone or with a fever
• Drainage of liquid from the incision site, alone or with a fever
• Swelling (edema) of arms, legs, wrists or ankles
• Increased shortness of breath, prolonged hiccuping or difficulty breathing
• Prolonged weakness or fatigue
• Fainting, lightheadedness or dizziness
• Fast or pounding heartbeat (palpitation)
• Muscle twitches
• Chest pain
• Any return of symptoms experienced before the implantation

A recent study suggests that up to 20 percent of patients with pacemakers or other implanted devices may be at higher risk of developing bacterial blood infections. Sometimes the device itself is the cause of the infection. Depending on the situation, physicians may elect to either treat the infection with antibiotics, or remove the pacemaker.






What are the lifestyle considerations with a pacemaker?
Following the insertion procedure, patients will be given a card providing basic information on the implanted pacemaker as well as emergency instructions. This card should be kept with them at all times. In addition, patients should memorize their pacemaker make and model number. Although mechanical problems are rare, this information will prepare patients in the event of a pacemaker recall by a manufacturer. Patients may want to wear a medical alert ID bracelet or necklace that provides information about their heart rhythms and pacemaker, as well as an access number for their medical files.

In that 10-year period, 52 Food and Drug Administration (FDA) advisories were issued, affecting more than 400,000 pacemakers and 114,000 implantable cardioverter defibrillators (ICDs). While more pacemakers were affected, investigators found that ICDs had a higher recall rates. In that same time period, the number of people in the United States with implanted heart devices increased 49 percent. Researchers speculated that increased vigilance on the part of the FDA and manufacturers might account for the increase. Changing technologies within this field may also have played a role. An advisory is not the same as a recall. However, advisories may lead to device checks and/or future recalls. The increasing frequency of advisories underscores the need to patients to memorize their pacemaker make and model number and to carry their device information card. That way, patients will be able to determine quickly if an advisory concerns their implanted device.

Patients should know the rate at which their pacemakers are set and then take their resting pulse rate for one full minute each day, contacting their physician if their pulse is five beats or more below the programmed rate. A faster rate is not a concern unless it is more than 100 beats per minute at rest. A program of daily moderate exercise is also recommended. Patients who want to exercise more strenuously will need to speak with their physician about designing a healthy exercise program. All patients should consult their physicians before starting to exercise.

Starting about two to three months after implantation, patients will have regularly scheduled pacemaker checks with their physicians every six to 12 months, depending on the model that was implanted. These visits may include a medical history update, blood pressure check, x-ray, electrocardiogram (EKG) and/or a stress test. Both the programming and the battery strength of the device will be checked by a radio transmitter that is used to communicate with the device.

What devices interfere with pacemaker operation?
There are many myths about electrical devices that could interfere with pacemaker operation. Home security systems, for example, do not pose a significant risk to people with pacemakers (although patients who are concerned can contact the system manufacturer for further reassurance). Furthermore, most common household appliances in good repair such as microwaves, cordless phones, electric blankets, electric shavers, CB and HAM radios, heating pads, televisions and remote controls, computers and hair dryers do not pose a significant risk to pacemaker operation. While some of these devices have been found to cause interference with an occasional single beat, they have not been found to change or inhibit pacing rates. Patients should discuss their concerns regarding these or other devices with their physicians. It is also vital that patients inform their health care providers about their pacemaker before any medical or dental procedure is done.

Although newer pacemakers have better insulation that makes them less susceptible to interference, some devices can still affect pacemaker operation. While this interference is rarely life threatening, caution is recommended around the following:

• Metal detectors. In airports, courthouses or other high-security areas, patients should present their identification card and request to be hand-searched. They should not walk through the metal detector or allow a hand-held wand to be waved over the chest area because it could temporarily interfere with the function of the pacemaker. Metal detectors are also used as security devices in retail stores and are sometimes not visible near doorways. While reports of problems from these devices are rare, the Food and Drug Administration recommends that individuals with pacemakers avoid leaning against or lingering near store security gates or entrances.
• Cellular phones. When held near the ear, cell phones rarely cause interference with pacemakers. In a recent study, however, the phones did interfere with about 13 percent of patients when placed directly over the pacemaker implantation site. Interference varies depending on the model types of both the pacemaker and the cell phone. The risk of interference is greater with digital cell phones and dual-chamber pacemakers. To avoid interference, patients should hold the cell phone at least 6 inches from the pacemaker generator at all times, even when the phone is turned off. It is advisable to use a cell phone with the ear on the side of the body opposite to the pacemaker.
• Magnetic resonance imaging test (MRI). The magnetic fields and radio fields generated during this diagnostic test can significantly affect pacemaker function, with potentially lethal consequences. Patients should avoid these tests and the machines that perform them.
• Strong electrical fields. Patients should avoid any areas or equipment that generate strong electrical fields. These include (but are not limited to) amusement park rides and attractions, power plants, junkyards that use large magnets, stereo speakers (when held close to the pacemaker) or poorly shielded car engines. Patients should also never work on automobile engines when they are running. Patients should discuss their concerns regarding these or other devices with their physicians.

How long will a pacemaker last?
Since the battery of the pacemaker is sealed within the generator chamber, the entire chamber is replaced when the battery is low. Most modern pacemakers use lithium batteries that need to be replaced every five to 10 years, depending on how dependent the heart is on the pacemaker.

Pacemaker batteries will not run out unexpectedly. When a battery is running low, the elective replacement indicator (ERI) is activated. Physicians can detect this activation during a routine office visit. In addition, the battery status and the general functioning of the pacemaker can be tested over the telephone. This is generally done every one to two months. Pacemakers will continue to function for approximately six months after the ERI is activated, allowing ample time to schedule an elective replacement procedure.






What is in the future for pacemakers?
The areas in which pacemakers have shown benefit continue to expand, while the design and function of pacemakers continue to improve. Following are some of the areas being explored:

• Sleep apnea. Their role in correcting bradycardia (slow heartbeat) may make pacemakers effective for persons with sleep apnea. Sleep apnea is characterized by repeated, brief episodes of interrupted breathing during sleep. It can be due to the tonsils or tongue blocking the airway (obstructive apnea), or by the respiratory system itself (central apnea), where the nervous system slows down breathing too much when the body is at rest. By setting the pacemaker to make the heart beat at a slightly higher resting rate, researchers found that sleep apnea was improved. For reasons not understood, the pacemaker provided relief in obstructive apnea as well.
• Falls in the elderly. Unexplained falls and blackouts in the elderly may not simply be due to aging. Rather, they may be a sign of unrecognized heart problems that could be corrected with a pacemaker. Recent research suggests that the use of a pacemaker in these patients may reduce the risk of blackouts or falls. Elderly individuals who suffer unexplained falls may find it helpful to see a cardiologist for testing.
• Damage to ventricles. Research is currently evaluating the possibility of pacemaker implantation as a treatment for diseases that damage the ventricles, causing them to pump inefficiently. These conditions include congestive heart failure, heart attack, viral infections and high blood pressure (hypertension).
• Biatrial pacing. A new strategy to control the electrical activity of the atrium, Biatrial pacing delivers electrical impulses to the right atrium and to the coronary sinus (the area of the heart that receives the cardiac veins and opens into the right atrium). Research suggests that biatrial pacing can reduce the number of episodes of atrial fibrillation.
• Pacemakers with defibrillators. Devices that combine pacemakers with defibrillators are being developed to detect and treat both abnormally fast and abnormally slow rhythms in the same patient.
• Biventricular pacemaker. This new pacemaker designed specifically to treat congestive heart failure received approval from the Food and Drug Administration (FDA) in 2001. Also called a ventricular resynchronizer, this device uses an extra wire (lead) to synchronize the lower chambers of the heart so that they pump together. The resynchronizer is implanted in the chest in the same manner as a pacemaker. The early results from the biventricular pacemaker as a treatment for heart failure have been very encouraging.
• Magnetic Resonance Imaging (MRI). Currently, MRIs are not possible for patients with pacemakers and other implanted devices because the electromagnetic fields generated to conduct the test can interfere with device functions. Scientists are examining potential methods of shielding devices during an MRI or creating wireless devices that would not be affected by the MRIs magnetic fields. Such devices might temporarily take over some or all of the pacemaker's functions while the pacemaker is turned off for the MRI test.
• Transtelephonic monitoring. New methods of sending the data that pacemakers gather to physicians are also being examined. In October 2001, the Food and Drug Administration (FDA) approved a new pacemaker that transmits data to a cell-phone like device carried by the patient. The phone sends the information to a customer service center, which then faxes it to the patient's physician. This new form of transtelephonic monitoring differs from traditional checks because the data can be transmitted at any time and the process does not require patient involvement. It can be programmed to perform checks as often as needed, from once a day to once month. Current methods require that the patient call in every two to three months for a transtelephonic transmission of their pacemaker data.

Single-chamber vs. dual chamber pacemakers
For many years after pacemakers were first introduced in the 1960s, the only form of the internal device was the single-chamber pacemaker (also referred to as a single-lead or simple pacemaker). A single chamber pacemaker can be placed in either an atrium or ventricle and stimulates one chamber of the heart.

In the early 1990s, the use of the dual-chamber (or dual-lead) pacemaker became more common. The dual-chamber model sends electrical leads to both an atrium and a ventricle, stimulating both chambers. In addition, the dual-chamber model has the ability to synchronize the contraction of the atrium and ventricle to more closely resemble the natural action of the heart, which is why it is often preferred by physicians. However, single-chamber pacemakers have been found to last about six months longer than the more complex models. They are also less expensive and easier to implant and maintain.

Although there is some controversy over whether the newer dual-chamber pacemakers are better than the single-chamber versions, most physicians believe that dual chamber pacemakers are preferred for most patients (except for those in chronic atrial fibrillation).