Typical AVNRT

Clinical Electrophysiology Conference

Anish S. Shah, MD, MS

Division of Cardiology, University of Illinois at Chicago

December 8, 2022

Objectives

  1. Understand the concepts of dual node physiology
  2. Know the requirements for typical AVNRT
  3. Evaluate the response of standard EP maneuvers in typical AVNRT

Abbr. Abbreviation
DAD delayed after-depolarization
EAD early after-depolarization
APD atrial premature depolarization
VPD ventricular premature depolarization
RAAS retrograde atrial activation sequence

Typical AVNRT

Evaluation

  1. Mode of initiation of tachycardia
  2. Atrial activation sequence during tachycardia
  3. Influence of bundle branch block on conduction and cycle length during tachycardia
  4. Requirement of atria/ventricle for initiation and maintenance of tachcyardia
  5. Effect of atrial/ventricular stimulation during tachycardia
  6. Effect of drugs or physiological maneuvers on tachycardia

Criteria for typical AVNRT

  • Initiation and termination by APD/VPD during AV nodal Wenckebach cycles
  • Dual AV nodal physiology (differential refractory curves during APD)
  • Initiation dependent on critical AH interval during slow pathway conduction
  • Retrograde atrial activation with variable VA activation in Triangle of Koch
  • Initiated, terminated, or reset without atrial activation

Sinus Rhythm

  • Normal P and R axis
  • RR = 900
  • PP = 900
  • QRS = 80
  • P = 120
  • PR = 160
  • QT = 440

Tachycardia

  • Suspected retro-grade P
  • RR = 350
  • QRS = 70
  • PR = 300
  • RP = 40

Differential…

  • Typical AVNRT
  • Orthodromic AVRT
  • Atypical AVNRT
  • Atrial tachycardia always a possibility
  • Non-reentrant junctional tachycardia (junctional ectopic tachycardia)
  • Non-paroyxsmal junctional tachycardia (d/t digitalis-induced DADs)
  • Dual AV nodal tachycardia (repetitive retrograde concealment or “linking” phenomenon)

Electrophysiology Study

Case setup

Access: RCFV x 3

Catheters:

  • CS: decapolar catheter
  • His: quadrapolar catheter
  • RV: quadrapolar catheter
  • Ablation: STSF 4 mm

Closure: collagen-plug x 3

Study plan:

  1. Baseline EP study
  2. RA and RV pacing maneuvers (including decremental pacing)
  3. His-refractory PVC
  4. Induction of tachycardia
  5. Entrainment
  6. 3D anatomical mapping (CART) with His cloud
  7. Ablation
  8. Post-ablation testing

Baseline

12 lead sinus rhythm

Baseline intervals showed AH of 82, and HV 50 at rate of 870

Criteria Status
Initiation -
Dual AV node -
Critical AH during slow pathway -
RAAS Retrograde P wave on surface
Involvement of chambers -

RA Pacing

AV Wenckebach shown at 390

AV node ERP at S1 = 600, S2 = 220

Decremental pacing to evaluate dual AV nodal physiology

Demonstrated AH “jump” at around 500 ms (not shown).

Criteria Status
Initiation -
Dual AV node AH jump >50 with decremental pacing
Critical AH during slow pathway -
RAAS Retrograde P wave on surface
Involvement of chambers -

RV Pacing

RV shows retrograde conduction with variable VA timing

RV pacing lead to AF degeneration

Para-Hissian pacing at high output (when RBB selected, S-A interval widened)

Criteria Status
Initiation -
Dual AV node AH jump >50 with decremental pacing
Critical AH during slow pathway -
RAAS Concentric CS activation
Involvement of chambers -

Tachycardia Maneuvers

Tachycardia initiation

Spontaneous initiation from APD

Increased sweep speed of APD, suspected “bump” from His catheter

TCL of 375

Tachycardia features prior to diagnostic pacing maneuvers

For typical AVNRT, there are some findings to help eliminate options.

  1. VA Relationship: any pattern, but most commonly V=A and V<A
  2. VA Interval: VA ≤ 70
  3. Atrial Activation Sequence: concentric
  4. Spontaneous Termination: end either in A or V response
  5. VA Increase with BBB: no
Criteria Status
Initiation APD leads to tach
Dual AV node AH jump >50 with decremental pacing
Critical AH during slow pathway AH interval is prolonging prior to APD
RAAS Concentric CS activation
Involvement of chambers -

His refractory VPDs

PVC placed between HV interval

PVC however affected the HH interval, thus not refractory

PVC breaks tachcyardia

Right bundle potential appears to be consistent in RV lead but direction is reversed after PVC

Criteria Status
Initiation APD leads to tach
Dual AV node AH jump >50 with decremental pacing
Critical AH during slow pathway AH interval is prolonging prior to APD
RAAS Concentric CS activation
Involvement of chambers No AP noted, VPD breaks cycle

Entrainment

Entrainment at 340 from CS ostia

Ventricular overdrive pacing (500) attempted but broke tachycardia

Ventricular overdriving pacing at 300, VAHV response limited by VPD

Criteria Status
Initiation APD leads to tach
Dual AV node AH jump >50 with decremental pacing
Critical AH during slow pathway AH interval is prolonging prior to APD
RAAS Concentric CS activation
Involvement of chambers VPD breaks, A advances with H

Conclusion

After slow pathway modification, tachycardia non-inducible with isoproterenol (2 mcg) and multi-stim protocols.

Criteria Status
Initiation APD leads to tach
Dual AV node AH jump >50 with decremental pacing
Critical AH during slow pathway AH interval is prolonging prior to APD
RAAS Concentric CS activation
Involvement of chambers VPD breaks, A advances with H

Evidence supports typical AVNRT using slow fast pathway, without AP.