Troubleshooting difficult SVT ablation

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Raja Selvaraj

Professor of Cardiology, JIPMER

General

  • Do not ablate without making a diagnosis
  • Do not ablate without mapping completely
  • Do not ablate unless you are sure you can recognize and avoid AV block
  • Except specific situations, high power ablation does not succeed where low power fails
  • Do not ablate for cosmetic reasons

AVNRT

Left sided ablation

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VA block during ablation

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Accessory pathways

RF parameters to identify effective ablation

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Safest ablation is the one that you avoid !

Young male. preexcitation and atypical symptoms

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Atrial S1S2 - 600/290 ms

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Parahisian pacing

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AF induced

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Young boy with preexcitation

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Mapping approaches - Rhythm

Mapping approaches

  • Earliest ventricular activation during maximum preexcitation with atrial pacing *
  • Earliest atrial activation during ventricular pacing *
  • Earliest atrial activation during orthodromic reentrant tachycardia
  • Intermediate preexcitation during sinus rhythm / slow pacing

(*) May not recognise AV conduction injury

Septal pathways - Ablate during tachycardia

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Left sided pathways - Entrain and ablate

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Unipolar EGM

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Mapping and ablating in AF

Young male, RHD MS with left sided AP, preexcited AF

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Mapping during AF

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Ablation during AF

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Using the "bump"

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Pathway slant

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Implications

  • Map for earliest A, not shortest VA
  • Atrial and ventricular insertions may not correspond
  • May be preferable to ablate medial to atrial insertion, where AP potential is observed

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LA - CS potentials

Endocardial AP

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Epicardial AP

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Unusual locations

Female with left sided AP

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A-V separated in CS

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LAA pathway

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CS Diverticulum

Preexcited AF - note leads II and V6

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Venogram

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Ablation at ventricular insertion

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Successful location at neck with CSE potential

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Atrial tachycardia

Activation mapping

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Summary

  • AVNRT - Ablation within CS / left sided ablation
  • AVNRT - VA block in some atypical AVNRT
  • AT - Activation mapping. P onset in relation to fixed reference
  • AP - Dont ablate when not needed
  • AP - Choose rhythm to map and ablate carefully
  • AP - When mapping for atrial insertion, map like AT constrained to the annulus
  • AP - When mapping the ventricular insertion, Use unipolar EGMs
  • Mechanical bump can help to map
  • Consider unusual locations - appendages / away from annulus / within CS