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Determining retrograde conduction

Useful when a septal pathway is suspected

Parahisian pacing

How to perform

  • Pace ventricle at set rate (e.g., 600ms) continuously

  • Start of at very high output (e.g., 20mA @ 2ms)

  • Decrease output relatively quickly

  • Cease pacing when a change of complex is seen or LOC

  • Ensure no atrial capture (VA too short)

3 responses

  • Very broad – V only capture (parahisian)

  • Narrow/broad – His and V capture

  • Narrow with stim-V delay – selective HIS capture

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HIS & RV

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RV only

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Selective HIS

Results

V & HIS VA < paraHIS VA

-nodal

-no AP

​

V & HIs VA ~= para HIS VA

-AP present

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Differential pacing

How to perform

  • Pace ventricle at set rate (e.g., 600ms) for ~5-10 beats from RV apex

  • Repeat above, when catheter is moved to basal RV, ensuring there is no HIS or atrial capture.

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