Unipolar & Bipolar Systems

In all pacing systems, the impulse travels from the impulse generator, through the lead and the negative cathode, simulates the heart, then returns to the generator.

This system differs between uni and bipolar pacing systems, but both utilise the same basic polar elements.

  • Cathode
    • Electrode in contact with the heart
    • Negative
  • Anode
    • Receives impulse after cardiac depolarisation
    • Positive during current flow

 

Unipolar Pacing Systemstemporary_1470934328398.png

  1. Impulse begins at generator
  2. Flows through lead tip
    • Cathode
  3. Stimulates heart
  4. Returns through bodily fluid and tissue
    • Anode

Unipolar Leads

temporary_1470944952494.png

  • One electrode on the tip
  • One conductor coil
  • Smaller in diameter than Bipolar leads
  • Usually produce larger pacing artifacts on ECG than Bipolar

These can still be found in situ, but are generally considered obsolete. Bipolar leads can be programmed to operate in a unipolar fashion and they do not suffer from EMI in the way that unipolar leads do.

Bipolar Pacing System

temporary_1470934714101.png

Screenshot (7)

  1. Impulse begins at generator
  2. Flows through lead tip
    • Cathode
  3. Stimulates heart
  4. Returns to the ring electrode above the lead tip
    • Anode

Bipolar Leads

temporary_1470944542525.png

  • Creates circuit between electrode tip and ring electrode
  • Two conductor coils
  • Inner layer of insulation
  • Less susceptible to oversensing of non-cardiac signals

It is now considered standard practice to insert bipolar leads.

 

 

Heart

 

 

 

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