What you need to know about pacemakers

When your heart’s natural pacemaker is not working properly, it may need help. A small electronic pacemaker can be placed inside your body to help your heart keep a steady beat.

Having a pacemaker means you will need to take certain precautions. But with proper care, you can live a healthy, active life. You may find that you are able to return to activities you have not been able to do for a while. Knowing more about your heart will help you understand how a pacemaker can help you.

Your heart has its own natural pacemaker that produces electrical signals. These signals cause the heart to contract and pump blood.

A heartbeat starts with electrical signals from a small bit of tissue called the SA node. The SA node is in the upper right chamber. Signals from the SA node tell the upper chambers to contract.

Signals from the SA node are picked up by the AV node. The AV node sends these signals to the lower heart chambers. Pathways in the muscle walls carry signals through the lower chambers. These signals tell the lower chambers to pump blood.

As long as the signals travel freely and occur at the right time, the heart pumps at a steady pace. 

When Problems Occur

Sometimes, problems develop with the heart’s electrical system, which change the normal beating of the heart. For example:

  • The SA node may send out less than the usual amount of signals. This decrease causes an abnormally slow heartbeat.
  • The SA node may send out signals that cause the heart to alternate between beating too fast and beating too slowly.
  • Signals from the SA node travel to the AV node, but the AV node may not be able to send the signals to the lower chambers.

A pacemaker may be needed if:

  • Your heart is beating too slowly.
  • Your heartbeat is irregular.
  • The pathways that carry signals through the walls of the heart become blocked.

A pacemaker often is used to correct a slow heartbeat. Your heart may beat too slowly all of the time, too slowly once in a while, or too slowly and too quickly at different times. Symptoms of a slow heartbeat are dizziness, lightheadedness, shortness of breath, fatigue and fainting spells. You may experience symptoms while you are doing something physical. But symptoms also can occur while you are resting.

What a Pacemaker Does

When your heart’s own electrical system sends a signal and your heart beats as it should, the pacemaker does not generate a signal. But when your heart’s electrical system misses a signal, the pacemaker sends a signal that causes your heart to beat.

Parts of a Pacemaker

A pacemaker is made up of two parts. The generator contains a tiny computer and a battery. It is the part of the pacemaker that generates electrical signals. Signals from the generator are carried through leads to the heart. Leads are soft wires that bend easily, so they can be placed in the right position inside the heart. A pacemaker can have one or two leads.

A single-chamber pacemaker has one lead. The lead is placed in the lower right heart chamber. A dual-chamber pacemaker has two leads, one in the upper right chamber and one in the lower right chamber. In some cases, two leads are needed to coordinate the signal from the upper chamber with the beating of the lower chamber.

Pacemaker Implantation

The process of putting a pacemaker in the body is called implantation. An incision is made in the upper chest just over a vein. A pocket is formed under the muscle where the pacemaker will be placed.

The vein just under the incision is opened. The lead is placed inside the vein and guided into the heart. If there are two leads, the second lead is guided through the vein into the heart. The generator then is attached to the lead, and the pacemaker is put inside the pocket under the skin.

Follow Up With a Doctor

A pacemaker will need to be checked periodically. Special tests may be done. A pacemaker is programmed for the individual’s needs, but those needs can change over time. If they do, the pacemaker can be adjusted. In most cases, adjustments are made from outside the body, and surgery is not needed. A pacemaker can be checked at home by sending signals through the telephone with a special transmitter.

Pacemaker batteries will be checked often and replaced when they begin to wear out. To replace batteries, the generator must be replaced. Surgery must be performed to replace the generator. The leads will be checked and replaced if they begin to wear out. Leads can be replaced without performing surgery. Most pacemakers last for nine to 10 years

Andrew Brenyo, MD, is a cardiologist specializing in cardiac electrophysiology with Carolina Cardiology Consultants

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