Your Pacemaker and You

© 1999 GUIDANT CORPORATION ALL RIGHTS RESERVED. PRINTED IN USA. 354389-008 A 4/99

Introduction

Now that you have your new electronic pacemaker, you are a member of a large and growing community. Statistics reveal that more than 250,000 people worldwide received pacemakers in a recent one-year period. People with pacemakers are found in every occupation, from office work to farming to construction. Your new Guidant pacemaker system will help you lead the full, rewarding life you desire.

Your pacemaker system is designed to help your heart meet your body’s varying need for blood. Your pacemaker stimulates your heart to beat when needed to meet your body’s requirement for blood flow. You should discuss the details of your particular situation with your physician, who will be able to answer questions about the pacemaker system that has been selected for you.

The heart is a remarkable organ. It is a muscular pump that beats more than 100,000 times per day.

Sometimes, however, the heart's electrical system malfunctions by beating too slowly. A person with this problem may frequently become tired or even feel faint. You may have had these or other symptoms before receiving your pacemaker system.

A general understanding of how the heart works should help you understand why your doctor has decided you need a pacemaker.

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Your Heart

The heart is composed of four chambers enclosed within a wall of muscle. The upper two chambers (atria) help fill the lower two chambers (ventricles) with blood. The ventricles are larger and more heavily muscled than the atria. They pump blood to the lungs and throughout the rest of the body.

Your heart rate is normally regulated by the heart’s natural pacemaker, located in the upper part of the heart. This natural pacemaker, called the sino-atrial node (S-A node), is a small cluster of specialized cells that produce electrical signals at regular intervals. The S-A node automatically increases your heart rate in response to the body’s needs -- for example, during exercise, when faster blood flow is required.

The electrical impulses sent out by the S-A node travel to the atrioventricular node (A-V node), a second cluster of cells located near the center of the heart. The A-V node then transmits the electrical signals out to the walls of the ventricles.

This natural electrical pathway is very important because when the signals reach the lower heart, both ventricles contract, pumping blood throughout the body. This contraction of your heart can be felt as your pulse.

Normally, the two ventricles contract a fraction of a second after they have been filled with blood by an atrial contraction. This proper timing sequence is called atrio-ventricular synchrony (A-V synchrony).

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Why the Heart May Need a Pacemaker

Sometimes, the S-A node stops working properly. It may improperly speed up or slow down the rate at which it sends out electrical signals. If the signal rate is too slow, the chambers of the heart do not contract often enough to supply the proper amount of blood to your body.

Problems also may occur with the electrical pathway between the upper heart and the lower heart. The natural pacemaker signals sent out by the S-A node may be delayed in the A-V node or may fail to reach the ventricles altogether. This condition is called "heart block." Although the lower heart has a natural standby system that can usually produce its own signals, these signals are often too slow. As a result, heart block often means that the ventricles pump too slowly even though the S-A node may be sending out faster signals in an effort to increase the heart rate.

Heart block may also cause a loss of A-V synchrony -- in other words, poor timing of contractions between the upper heart and the lower heart. Doctors call this condition "asynchrony." As a result, the ventricles may not fill with enough blood before contracting.

We have just discussed the most common reasons why patients need a pacemaker. There are, however, several other possible reasons. Be sure to ask your physician why you need a pacemaker.

A pacemaker alters the heart rate to help meet bodily needs. It does this by providing pacing signals that are much like the heart’s normal signals. Depending on your particular situation, your pacemaker may:

• Replace S-A node signals that are delayed or get lost along the pathway between the upper and lower heart
• Help maintain a normal timing sequence between the upper and lower heart
• Make sure the critical lower chambers of the heart always contract at an adequate rate

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Your Pacemaker System

Every pacemaker system has two parts - the pulse generator, which produces the pacing impulses, and the lead or leads, which deliver these impulses to the heart. The same leads also carry signals back from the heart. By "reading" these signals, the pulse generator is able to monitor the heart’s activity and respond appropriately.

Pacemakers operate on "demand." That is, a pacemaker will stand by until the natural rate of the upper and/or lower heart falls below the rate set for the pacemaker. Only then will it send out pacing impulses that are strong enough to make the heart chambers contract, pumping blood. Some of your pacemaker’s pacing and monitoring functions can be adjusted - or programmed - by your physician to best meet your particular needs.

The pulse generator is usually implanted below the collarbone just beneath the skin. The leads are threaded into the heart through a vein located near the collarbone. The tip of each lead is then positioned inside the heart. However, sometimes the pulse generator is positioned in the abdomen and the pacemaker leads are attached to the outside of the heart. Of course, where and how to implant your pacemaker system is determined by your physician, based on your individual needs.

If, after implant, any of your pacemaker’s programmable functions need to be adjusted, your physician can do this using an external programming device. The device works "noninvasively," from outside the body. The procedure is painless and no surgery is needed.

System Design

The pacemaker system is powered by a small battery safely sealed inside the pulse generator. The battery cannot be recharged. For this reason, the pulse generator must be replaced when the battery’s energy is used up.

The pacemaker also includes several electronic circuits. These circuits control the pacemaker’s functions, including the way it monitors the heart’s activity.

The pacemaker system monitors the heart by reading heart signals sent back to the pulse generator through the leads. This tells the pacemaker each time the heart chambers contract. For most patients, this gives the pacemaker enough information to decide when pacemaker pulses are needed.

Some patients benefit by having a pacemaker that automatically increases the pacing rate to meet the body’s changing needs, such as when walking up stairs. Pacemaker systems for these patients use extra sensors to monitor the body’s need for blood flow. By analyzing this additional information, the pacemaker knows when it should be prepared to pace faster, just in case the heart’s natural rate does not increase enough to keep up with the body’s increased level of activity. You may be able to feel your heart rate increase when this happens.

Pacemaker Type

There are two basic types of pacemakers - single-chamber and dual-chamber. Both types constantly monitor the heart and send out pacing signals when necessary to meet the body’s need for blood.

You should discuss with your doctor which kind of pacemaker you have and why it has been selected for you.

Single-Chamber

A single-chamber pacemaker usually has one lead to carry signals to and from one chamber of your heart - either the right atrium or, more commonly, the right ventricle.

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This type of pacemaker often is selected for a patient whose S-A node sends out signals too slowly but whose electrical pathway to the lower heart is in good condition. In this example, the tip of the lead is usually placed in the right atrium.

A single-chamber pacemaker also may be selected if the S-A node is working, but the pathway to the lower heart is partly or completely blocked. In this example, the tip of the lead is usually placed in the right ventricle. Additionally, patients in chronic atrial fibrillation require a lead in the right ventrical only.

Dual-Chamber

A dual-chamber pacemaker usually has two leads, with the tip of one lead positioned in the right atrium and the tip of the other lead located in the right ventricle. As you might expect, this type of pacemaker can monitor and deliver impulses to either or both of these heart chambers.

A dual-chamber pacemaker may be selected for many different reasons. In some patients, the S-A node’s signals are too slow, plus the electrical pathway to the lower heart is partly or completely blocked. A dual-chamber pacemaker can help treat both problems. In other patients, the timing of atrial and ventricular contractions is uncoordinated (asynchronous) and a dual-chamber pacemaker is needed to restore a normal timing sequence (A-V synchrony).

These are only two possible reasons why a patient might receive a dual-chamber pacemaker. If you have this type of pacemaker, your physician can explain why it was selected for you.

Your Pacemaker and You

With your new pacemaker system and your physician’s guidance, you will soon return to normal activities. Your pacemaker will help you enjoy as active and productive a life as your overall health allows.

Under your doctor’s direction, you should take your pulse rate for a full minute each day. Your doctor will show you the correct way to determine your pulse rate.

Your heart rate may vary, but it should not drop below the minimum rate set for your pacemaker. Report to your doctor any drop in rate below the prescribed level.

The pacemaker has a replacement indicator that helps the doctor determine a desirable replacement time. Your doctor or clinic will establish a schedule for checking this indicator, either by telephone or office visits.

Guidant encourages you to discuss your case with your physician to develop a good understanding of your particular situation. Things you should discuss include medication, rest, returning to work, possible sources of pacemaker interference, and exercise. Your physician can help you determine how much exercise you should get. The proper amount of exercise should help you feel better physically and more alert mentally.

You should avoid activities that could lead to rough contact in the area around your pacemaker. Also, avoid manipulating the pacemaker or massaging the surrounding chest area. Generally, though, you may resume the daily activities and routine that you followed before receiving your pacemaker.

• You may return to your normal routine around the house.
• You may engage in your normal sexual activity.
• You may take trips by car, boat, train or airplane.

After the implant, Guidant will mail you a wallet-sized patient identification card. (A temporary identification form can be used until you receive the permanent ID card.) Show your ID card to airport security guards if your pacemaker activates a metal detector alarm.

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External Electrical Interference

Your pacemaker is an electronic device. Although it is well shielded from the kinds of electrical interference typically encountered, certain sources of electrical interference can temporarily slow down or speed up the pacemaker.

Most household appliances and home/office equipment such as personal computers, printers and fax machines are safe and should not affect your pacemaker. Airport security devices are also safe and should have no effect on your pacemaker. However, if you have a question about whether to use a particular appliance, or if you ever develop symptoms like those you had before getting a pacemaker, contact your physician immediately.

Following are some devices that you should avoid or which require special precautions. Generally, these devices only affect your pacemaker temporarily. As soon as you move away from the device, your pacemaker will resume normal functioning.

Transmitting antennas and their power sources

Avoid linear power amplifiers and antennas. Well-shielded and properly assembled systems should cause no problems. Properly operating CB radios (5 watts) should cause no problem.

Diathermy equipment (intense heat treatment devices)

Such equipment is generally located in hospitals or clinics. Tell any new doctor or dentist that you have a pacemaker. Diathermy equipment should never be used on a pacemaker patient.

Power transmission lines

Avoid high-voltage electrical fields produced by high-power lines.

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Electrical equipment

Avoid arc welders and similar equipment.

Radiation

High-energy radiation can damage your pacemaker. If you ever need radiation therapy near your pacemaker, ask that lead shielding be placed over the implant site.

Anti-theft devices

Avoid standing near anti-theft devices in doorways of department stores and public libraries. You may walk throughout them at a normal pace.

Cellular phones

In certain cases, a cellular phone could affect your pacemaker’s operation if it is closer than six inches. This interaction is temporary, and moving the phone away from the pacemaker will return it to proper function. To reduce the chance of any interaction, follow these precautions:

• Maintain a distance of at least 6 inches between the cellular phone and your pacemaker. If the phone transmits more than 3 watts, increase the distance to 12 inches.
• Hold the cellular phone on the opposite side of your body from the pacemaker.
• Don’t carry a cellular phone in a breast pocket or on a belt if that places the phone within 6 inches of your pacemaker.

These precautions apply only to cellular phones, not to household cordless phones.

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Frequently Asked Questions