Pacemaker Terminology and Definitions

A more detailed discussion of pacemaker technology is conducted elsewhere. This is a brief point-form summary. Some of these definitions have been asked about in the SAQs before, eg. in Question 29 from the second paper of 2013 and Question 2 from the first paper of 2016. 



  • The pacing rate, in beats per minute.
  • Usually set as a "backup rate"


  • Sensitivity of a pacemaker electrode is the minimum myocardial voltage required to be detected as a P wave or R wave, measured in mV.
  • The lower the number, the more sensitive the pacemaker.
  • The normal settings are 0.4-10mV for the atria, and 0.8-20mV for the ventricles



  • The output of a pacemaker is the current (in mA) which it produces as a brief pulse.


  • Capture is the effective stimulation of cardiac depolarisation by the pacemaker

Pacing threshold or "Capture threshold"

  • This is the minimum amount of current (in mA) required to initiate depolarization of the paced chamber.



Reade, M. C. "Temporary epicardial pacing after cardiac surgery: a practical review." Anaesthesia 62.3 (2007): 264-271.

Reade, M. C. "Temporary epicardial pacing after cardiac surgery: a practical review: Part 2: Selection of epicardial pacing modes and troubleshooting."ANAESTHESIA-LONDON- 62.4 (2007): 364.

Gammage, Michael D. "Temporary cardiac pacing." Heart 83.6 (2000): 715-720.

Sanders, Richard S. "The Pulse Generator." Cardiac Pacing for the Clinician. Springer US, 2008. 47-71.