A pacemaker is device that is implanted when the heart rate or pulse is too slow.  The pacemaker has wires that are attached to the heart muscle and in this way can deliver a small stimulus that will allow the heart to beat.

The pacemaker box has a small computer inside that can be programmed in various ways to suit the type of underlying heart rhythm abnormality.  This encourages the natural heart rhythm to be used as much as possible and the pacemaker then only paces when it is required.  The benefits of this are that the normal electrical conducting system of the heart is used and also less pacing prolongs the batter life of the pacemaker.  The programming of the pacemaker can be changed after the operation at any time.  This is done using an external computer that communicates with the pacemaker remotely using radio waves.    Once a pacemaker is implanted then it will be checked at regular intervals to see among other things if the battery is depleting.  Before the battery becomes exhausted the pacemaker will be replaced.