As a pacing system creates an electrical circuit, it is important to be familiar with basic electrical physics.
OHM’s Law
In a standard series circuit, the relationship is explained thusly;
So consider the general set up of a packer circuit and apply these principles:
When thinking about resistance (impedance) to the current flow in a pacing circuit, one must be aware of the factors that create resistance within the system.
- Lead resistance
- Tissue impedance
- Capacitive
- Polarisation resistance
Impedance is calculated with the following:
Normal pacing impedance sits at circa 500Ω, an insulation defect is implied with an impedance of <250Ω and impedance >1000Ω indicates a lead fracture.
Ref
Barold, S., Stroobandt, R., Sinnaeve, A. (2004) Cardiac Pacemakers Step by Step. Oxford. Blackwell Publishing
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