How does a pacemaker work?

There are two leads connected to most pacemakers. In some atrial fibrillation patients we only insert one lead.

 

These leads are very thin, flexible, electrically insulated wires that are inserted into the vein at the top of the shoulder and travel inside it to go into chambers on the right side of the heart. 

The leads are attached to a pacemaker box/generator that contains a battery and a small computer with some memory in it to record any heart rhythm abnormalities. The box sits in the upper left chest, below the collarbone. A pacemaker senses through its wires what the heart is doing. If it senses that the heart has slowed down or missed a beat, then it will send an electrical impulse to stimulate the heart to restore it to its normal rate.

The average lifespan of a pacemaker battery is about 6–7 years. There is plenty of warning before the battery runs out and patients are regularly checked towards the end of the battery life.

 

The procedure for changing the battery is much simpler than when pacemakers are put in. The wound is reopened and the pacemaker box is removed, but the leads stay in place. Most people go home the same day. 

At the tip of each wire are electrodes. These are the contact points between the pacemaker and the heart – where the electrical signal is delivered from the pacemaker to your heart, and where the information about your heart’s signalling action is received and carried back to the pacemaker. 

The leads are attached to the heart muscle by a tiny barb or small screw mechanism. Traditionally there will be one in the right ventricle and one in the right atrium.