Pacemaker Sensing and Pacing
Pacemaker sensing and pacing are two terms that are the basis for how a pacemaker works. We often take it for granted that everybody knows exactly what we mean in clinic when we say things like V pacing or V sensing. I just wanted to put a short post together so you know exactly what the two terms mean.
The Fundamentals of Pacing
“An implantable cardiac pacemaker is a device used to treat this range of heart conditions by assisting the natural conduction system when it falters. The pacemaker achieves this by being able to see when the heart is beating (sensing) and making the heart beat when it does not (pacing).
A series of electrical changes in the heart’s muscle cells is the trigger for each and every heartbeat. This is the basis for the humble ECG/EKG. During an ECG/EKG this electrical energy is sensed by the ECG machine before a representation of the activity is drawn on some graph paper.
Pacemaker leads are also able to sense the heart’s electrical activity. As the heart tissue (that the tip of the pacemaker lead is in contact with) contracts, the electrical energy generated, travels up the lead and to the pacemaker. If the pacemaker receives an electrical signal, it will be satisfied that the heart has just contracted (beat). If the pacemaker does not receive one of these electrical signals, it will assume that the heart has failed to beat when it should have.
The ability of the pacemaker to detect whether or not the heart is beating, is called sensing.
In the event that the pacemaker does not sense a heartbeat, it will initiate one. To do so, the pacemaker will deliver a very small electric charge down the pacemaker lead. This is enough of an electrical charge to trigger a heartbeat.
When the pacemaker initiates a heartbeat this process is referred to as ‘pacing’.
Hopefully this short post clears up any confusion over pacemaker sensing and pacing.