narrow QRS tachycardia diagnostic pacing maneuvers

simplified approach to different pacing maneuvers to reach to the diagnosis of narrow QRS tachycardia

1. Narrow QRS tachycardia diagnostic maneuvers Ahmed Taha Abdelwahed MD Cardiology, EHRA-certified EP-specialist Fellowship of Cardiac electrophysiology-Tampere Finland

2. features

3. AVNRT simple D.D SVT has : a septal VA interval <70 ms ( excluding AVRT ) HH interval changes precede and predict AA interval changes the SVT stops with a nonpremature terminal atrial electrogram ( excluding AT, repetitively and reproducibly ) --> slow pathway can be targeted for ablation

4. VOP Overdrive pacing from the right ventricle (RV) at a cycle length (CL) that is 10–40 ms shorter than the TCL provides a rapid tool: a post-VOP response that is atrial-atrial-ventricular (A-A-V) rules in AT. a post-VOP response that is atrial-ventricular ( A-V) rules out AT (effectively ruling in AVRT or AVNRT ).

5. Post VOP: V-A-A-V

6. AT post VOP

7. AVRT

8. AVNRT

9. cPPI -TCL ~“ AVRT<115ms<AVNRT ” Decremental pacing of VA with VOP

10. SA-VA < 85 ms SA-VA > 85 ms Stimulus-A: ventricle-A

11. Differential entrainment The PPI-TCL interval was longer at the base than at the apex in AVNRT The PP-TCL interval shorter at the base than the apex in AVRT

12. Differential entrainment The SA-VA interval shorter at the base than the apex in AVRT The SA-VA interval was longer at the base than at the apex in AVNRT

13. Differential entrainment The PPI–TCL interval was longer at the base than at the apex in AVNRT but shorter at the base than the apex in AVRT

14. PVC-His refractory

15. results Termination of Tachycardia by block in A -> AVRT Atrial activation is delayed without a change in the atrial activation sequence -> AVRT employing decremental AP. Atrial activation is advanced without a change in the atrial activation sequence -> AVRT No change in the A sequence or timing -> rule out AVRT “AP” “but not confident”

16. AOP AT vs. AVNRT VA linking

17. APC-His refractory affects the timing of the next His potential in any way (i.e. that advances or delays the next His potential, or that terminates the SVT) is consistent with a diagnosis of -> AVNRT

18. APC-His refractory Slow P. FAST P. AVNRT JT Focal

19. In VOP response Pitfalls

20. Non-interpretable The main shortcoming of this pacing maneuver is that, in 50–80% of cases of AT, the atria are not accelerated to the pacing CL ( the ventricles are dissociated from the tachycardia), “VA dissociation” so the response is technically not interpretable (though this particular response still excludes AVRT ).  AT is most common diagnosis

21. Pseudo- V-A-A-V response

22. Pseudo- V-A-A-V response the HV interval exceeds the HA interval in AVNRT.

23. IsoRhythm When the pacing CL is not short enough , or when the TCL shortens “accelerate” just before or during pacing , so that 1:1 VA conduction during pacing is not present the tachycardia and the pacing train are just isorhythmically dissociated from each other.

24. Overcome 1) performing the maneuver repeatedly and decrementing the pacing CL by 10–20 ms after each apparently successful attempt to accelerate the atria to the pacing CL. 2 ) checking to see that after pacing has stopped, the TCL immediately returns to the longer pre-pacing TCL, or at least a CL that is longer than that to which the atria were accelerated during pacing.

25. Don’t be Tachy Thank You