Algorithm for the Management of SVT

Step 1 : Is there a delta wave at the ECG ?

https://litfl.com/

Yes (look at V1)

  • Positive : left sided AP (Mitral annulus), where is the most positive Delta wave
    • AVL -> post-sep
    • II/AVR -> post-lat
    • III -> ant-lat
  • Negative : right sided AP (Tricuspid annulus), where is the QRS transition
    • <V3 where is the most positive Delta wave
      • II / III -> ant-sep
      • AVL / AVR -> post-sep
    • >V3 where is the most positive Delta wave
      • II -> ant-lat
      • III -> ant-sep
      • AVR -> post-sep
      • AVL -> post-lat

El Hamriti M, Braun M, Molatta S, et al. EASY-WPW: a novel ECG-algorithm for easy and reliable localization of manifest accessory pathways in children and adults. Europace. 2022 Dec 12;25(2):600–609. doi: 10.1093/europace/euac216.

Step 2 : Is there a criteria for AP ?

  1. Is there an anterograde AP ? (especially if HV < 35 ms)
    • Left sided anterograde AP suspected -> pace CS1-2
    • Right sided anterograde AP suspected -> pace R

  2. Is there a retrograde AP  ? -> Test VA conduction
    • Where is the first activation ?
    • Is it decremental ?

      – First activation : CS1,2 + non decremental -> Left sided AP suspected
      – First activation : RA + non decremental -> Right sided AP suspected
      – First activation : CS9,10 + non decremental -> Septal AP suspected
      – First activation CS9,10 + decremental = Normal

  3. ParaHisien pacing
    • No modification of the HA -> AP highly suspected
    • Shortening of the HA with high output -> normal response

Step 3 : Is there a criteria for dual AV node ?

  1. Is there an AH jump ? (> 50 ms AH increase with 10 ms decremental in A1-A2) ?
    • AVNRT probable

  2. AH jump + Is it associated with an echo beat ?

    • AVNRT highly probable

  3. AH jump + Echo beat + Is it associated with entrainement of SVT ?
    • Definite diagnose of AVNRT

Step 4 : Inductie & Observe SVT

  1. Is there a 1:1 relationship between A and V
    • Yes : it can be AVNRT, AVRT or AT
    • Missing V : AVRT is unlikely 
    • Missing A : AVRT & AT are unlikely

  2. VA time < 61-70 ms ?

    • Exclude AVRT

  3. Where is the earliest activation ?
    • CS1-2 -> AT or AVRT likely
    • RA -> AT or AVRT likely
    • CS9,10 / His -> don’t help

  4. Spontaneous termination
    • End with an A (VAV) -> AVRT or AVNRT likely
    • End with a V (VAAV) -> AT likely

  5. Is there a variation of AA interval ?
    • HH interval predict AA interval -> AVNRT / AVRT likely
    • AA interval predicat HH interval -> AT likely

Step 5 : Ventricular pacing manoeuvres

  1. Ventricular over pacing
    • VAV response : DEFINITE AVRT or AVNRT 100%
    • VAAV response : DEFINITE AT 100%

  2. Ventricular overdrive Post-Pacing interval to differentiate between AVRT and AVNRT : PPI-CL

    • > 115 ms -> AVNRT likely

    • < 115ms -> AVRT likely

  3. PVC the same time of just before the His (refractory period)
    • If the  atrium is affected delayed -> AVRT