Epicardial pacing wires are inserted after cardiac surgery. Often ventricular, sometimes ventricular AND atrial. Off-pump surgeries often do not have wires.

Key principles:

• Wire types
  • Older pacing wires are bipolar
    • single wire, 2 poles along it, fixed distance apart, negative pole in myocardium
    • require more energy
    • MUST be inserted the correct way into the block (distal pole = negative)
  • Newer wires are unipolar
    • paired wires
    • each wire has a pole on the end of it
    • each attached near the other in the myocardium
    • doesn’t matter which is negative and which is positive
• Electrical flow
  • remember electrical current is made up of electrons
  • electrons are negatively charged
  • therefore the energy flows FROM the negative terminal, TO the positive terminal
  • the largest transfer of current to the myocardium will therefore occur at the NEGATIVE pole
• Skin Lead
  • represents the ‘ground’ or the ‘receiver’ of the current, is therefore the POSITIVE pole of the circuit

Technique:

1. Pinch a piece of skin up (in subxiphoid region) and push a needle through & through.
   • 18G or smaller
   • longer is better (easier to get in to the pacing block) but really any length >25mm should do
2. insert the point of the needle into the positive terminal of the pacing block and lock it in place
3. attach the appropriate epicardial pacing wire pin to the negative terminal of the pacing block
   • for Bipolar wire – must be the negative lead
   • for unipolar wire, try each to determine which works better
4. pace at maximum output energy to ensure capture, then assess thresholds once patient is stabilised.