Diagnostic maneuvers for narrow QRS tachycardia

Raja Selvaraj

JIPMER

Introduction

Narrow QRS tachycardia

  • Regular, rate > 100, QRSd < 120
  • AT, AVNRT, orthodromic AVRT
  • Clues
    • Preexcitation in sinus rhythm / with atrial pacing
    • Dual AV nodal physiology
    • Manner of induction

General approach

  • What is the situation / pattern ?
  • What are the differential diagnoses ?
  • What are the electrophysiologic differences ?
  • What pacing maneuvers can differentiate ?

Patterns

  • A = V
    • Central atrial activation, VA < 70
    • Eccentric atrial activation
    • Central atrial activation, VA > 70
  • A > V
  • V > A

NQRST, central A, VA < 70

Central atrial activation, very short VA

typical_avnrt.jpg

Differential diagnosis

  • Typical (Slow-fast) AVNRT
  • Atrial tachycardia
  • Junctional tachycardia

Which pacing maneuver ?

  • Ventricular overdrive pacing
  • Simple to perform
  • Relatively simple to interpret
  • Provides lot of information

Setting up

  • Burst pacing from right ventricle (apex / base)
  • Sync on and functional
  • Tachycardia CL - 20 / 30 ms
  • Pace until atrium entrained
  • Stop pacing

What to look for ?

  • Don't 'eyeball'
  • Was the atrium entrained ?
  • Does tachycardia continue ?
  • Which is the last entrained A ?
  • Sequence - VAV or VAAV

Response

  • Atrium not entrained - AT / AVNRT
  • VAAV - AT
  • VAV - AVNRT

Ventricular overdrive pacing

vav_avnrt.jpg

Eccentric atrial activation

Eccentric atrial activation

tachy_eccentric.jpg

Differential diagnoses

  • AVRT
  • AT

Response to VOP

  • Unable to entrain - AT
  • Identical atrial activation, VAV - AVRT
  • Different atrial activation, VAAV / failure of atrial capture - AT

Ventricular overdrive pacing

vop_eccentric.jpg

Narrow QRS tachycardia, VA > 70

NQRST with VA > 70 ms and central VA

svt.jpg

Differential diagnoses

  • AVNRT - Slow fast / slow slow / fast slow
  • AVRT
  • AT
  • VOP again most useful

Rule out (or in) AT

vav.jpg

AVNRT vs AVRT

vav_measurements_ppi.jpg

SA / VA intervals

sa_va.jpg

Sequential vs parallel activation

seq_parallel.jpg

RV pacing in narrow QRS tachycardia.

pseudoVAAV.png

Measurements

pseudo_vaav_measurements.jpg

RV pacing in AT - VAAV

VAAV.jpg

VOP always terminates tachycardia - What would you do?

05_vop_termination.jpg

Beginning of entrainment can give a clue

06_vop_onset.jpg

  1. Dandamudi … Vijayaraman. A novel approach to differentiating orthodromic reciprocating tachycardia from atrioventricular nodal reentrant tachycardia. Heart Rhythm. 2010 Sep;7(9):1326-9.
  2. AlMahameed … Michaud GF. New criteria during right ventricular pacing to determine the mechanism of supraventricular tachycardia. Circ Arrhythm Electrophysiol. 2010 Dec;3(6):578-84.

Entrainment with Isoprenaline

09_vop_iso.jpg

Other clues

Spontaneous termination

spont_term.jpg

Bundle branch block

lbbb_narrow_measurements.jpg

Bundle branch block

coumel.jpg

Summary

Approach to evaluation of tachycardia

  • eccentric atrial activation - vop
    • overdrive with same eccentric activation / VAV - AVRT
    • overdrive with different activation / VAAV - AT
    • VA diss - AT
  • central atrial activation
    • Very short VA
      • VOP - VAAV vs VAV
    • Longer VA
      • VOP - VAAV vs VAV
      • SAVA / PPI

Summary

  • VAAV identifies AT, VAV rules out
  • SA - VA and PPI - TCL are longer for AVNRT
  • Can use basal pacing if responses are equivocal
  • A entrained earlier for AVRT, entrained before His