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Safety and use information

Safety and Use

Find important safety and use information for our implantable devices.

Frequently Asked Questions (FAQs)


Find answers to your questions about cardiac arrhythmias.

What Is a Pacemaker?

A pacemaker is an implantable, battery-powered minicomputer that sends electrical pulses to your heart whenever it detects a slow heartbeat or no heartbeat at all. When it senses an arrhythmia or lack of a heartbeat, it then sends electrical impulses to restore or establish a normal rhythm. A pacemaker also stores important information that your doctor can use to program your pacemaker so you can receive the best possible therapy.

Some pacemakers also treat heart failure by resynchronizing electrical impulses in the heart’s four chambers, improving the heart’s ability to pump blood to the body effectively and efficiently.

How pacemakers work

Pacemakers with leads

Most pacemakers have two components: a pulse generator (sometimes called a can) and pacemaker leads. Another important part of pacemaker treatment is an external programmer (computer) that programs the pulse generator.

Pulse generator

The pulse generator is quite small, weighing approximately 17 to 25 grams. This device contains a battery, as well as circuitry that sends electrical impulses to the heart, stimulating it to beat at a normal rhythm. The pulse generator is usually implanted under the skin of the upper chest, although it is sometimes implanted under the skin of the abdomen.

Pacemaker leads

Leads are thin, flexible insulated wires that run from the pulse generator to the heart. A lead detects your heart’s rhythm and transmits this information to the pulse generator, which responds in a way that is appropriate, given that rhythm.

Pacemaker programmer

In addition to a pacemaker’s two components, a pacemaker programmer is an important tool for adjusting your pacemaker to your particular needs. It is an external desktop computer that your doctor uses to download the information stored on your pacemaker, and to change your pacemaker’s settings, if necessary. This allows your doctor to adjust your therapy without requiring additional surgery. Newer pacemakers may also have the ability to communicate wirelessly with your hospital or clinic, conveying information for your doctor to read through remote monitoring without your having to leave home.

The St. Jude Medical commitment to safe, reliable and effective pacemakers

Since the first implantable pacemaker was developed in 1958, millions have benefited from pacemaker therapy. The remarkable story of the first cardiac pacemaker is embedded in St. Jude Medical’s history, and today, St. Jude Medical continues its commitment to revolutionizing arrhythmia management. The Assurity MRI™ pacemaker and Endurity MRI™ pacemaker are two examples.

Assurity MRI™ Pacemaker

Learn more details about the Assurity MRI™ pacemaker.

Endurity MRI™ Pacemaker

Learn more details about the Endurity MRI™ pacemaker.