Module 1
Topic 5
Lesson 17

Infra-hisian block

Acknowledgement
Helmut Pürerfellner
EHRA President 2025-26

What will you learn?

  • what happens with conduction signal in type 2 second degree AV block
  • how prolonged HV interval looks like
  • how to recognise ventricular escape rhythm

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WARNING! Let's see if you are ready to rescue the patient when unexpected happens. Be sure that it's more common than you think.

Your task for this lesson

  • Measure basic AH and HV and compare it to one from previous Lesson
  • Determine CL at which a block occurs
  • What is the last signal at His channel during the block

About this scenario

  • Prolonged HV interval indicates infrahisian conduction abnormality.
  • During the non-conducted P wave both an A as well as an H can be expected on the HIS catheter.
  • In such patients you can expect spontaneous or mechanically induced complete AV block.
  • 3rd degree AV block can be recognised by A V dissociation (V is independent from A)
  • In case of AV block (or any other asystole) an escape rhythm can be observed. Ventricular escape rhythm is characterised by a bright QRS morphology and rate about 40bpm.
  • To avoid asystole related symptoms you should start ventricular pacing i.e. RVA. Atrial pacing will not help due to obvious reasons :)

What can be interesting

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