Pacemaker Components

Pacemakers are implantable devices used to control heart rate and rhythm, and a pacemaker system, at its simplest, comprises body tissue and these components:Screenshot (4)

  • Pulse Generator
    • Power source
    • Computer system
  • Leads
    • Deliver the pulse to the electrodes
  • Electrodes
    • Anode (positive)
    • Cathode (negative)temporary_1470908044601.png

The pulse generator is the main body of the pacing system. It contains the:

  • Casing/Can
    • Titanium – lightweight, biocompactible, stronger than steel
  • Connector/header
  • Battery
    • Largest single component
    • Lithium Iodide
  • Circuitry components


  • Low self-discharge rate
  • LiI battery
    • Long shelf life/ high energy density

In single chamber pacing, longevity sits at circa 7 – 12 years.

Dual chamber is 6 – 10 years

Reducing the output voltage of the battery by half, can increase the battery life of the device by up to 2x

Leads and Electrodes

Screenshot (5)

  • Impulse delivery to the heart
  • Sensing of depolarisation

Leads are characterised based on their;

  • Positioning
    • Endocardial/transvenous
    • Epicardial
      • Applied exteriorly
  • Fixation mechanism
    • Active/Screw-in
      • Screw helix extends into endocardial tissue
      • Can be placed anywhere within the heart’s chamber
    • Passive/Tined
      • Tines become lodged in endocardial trabeculae
  • Shape
    • Straight
    • “J-shaped”
  • Insulator
    • Silicon
    • Polyurethane
  • Polarity
    • Unipolar
    • Bipolar

Lead electrodes come in many varieties, some examples of which are given below.


A. Epicardial, active fixation. Suture pad that elutes steroids B. Epicardial, barbed “fish hook”. C. Helical screw, active fixation D. Tined, passive fixation


Screenshot (8)