1. 14 yr old boy Ebstein’s anomaly Marked displacement of septal tricuspid leaflet. RA/RV moderately dilated. Mild TR Recurrent paroxysmal palpitations Inputs from Martin Green and Chandrashekhar

2. Comment. One thing I have always taught my fellows is beware the Ebstein's who does not have wide RBBB. In Ebsteins anomaly if the ECG shows absence of RBBB, we should always think of right free wall AP

3. Analyse- Normal intervals 40 ms

4. CS pacing- comment During CS pacing the wavefront reaches the AV node earlier than the right free wall AP. Hence RBBB is evident

5. RA pacing – comment. Now the wavefront goes predominantly through the AP, hence there is more preexcitation. Note the decremental AP conduction (Stim-QRS gets longer as preexcitation increases)

6. Analyse- RBBB during CS pacing, disappears during sinus rhythm

7. Interpret- Concentric and decremental VA conduction

8. Tachy initiated- describe. With CS pacing RBBB appears then it gets blocked in the AV Node and goes through the right free wall AP, initiating an antidromic tachycardia - LBBB with superior axis

9. Intracardiacs during tachy- discuss. IC EGMs showing the WCT- A in His catheter is not clearly seen. There is no RV catheter to say whether V at RV apex is earlier when compared to His V. Also RB potentials are not recorded

10. Tachy termination- any further insight? The HISP records A and H in sinus rhythm. During tachy, the H is buried in the V and the A in His is the earliest. The tachy terminates in the AV node.

11. J Cardiovasc Electrophysiol.J Cardiovasc Electrophysiol. 1998 Sep;9(9):1012-4. Preexcited tachycardia in a patient with Ebstein's anomaly: is the preexcitation manifest during sinus rhythm? Vora AM Vora AM 1, Lokhandwala YY.Lokhandwala YY

12. Isoprenaline-discuss. AP automaticity is enhanced

13. Diagnosis confirmed? Yes. A late (His-refractory) RA APD advances ( ) the next QRS and resets ( ) the tachycardia

14. Again… same thing is shown

15. Signal at RF site- Mahaim potential (M) M

16. RF site-LAO 40. SR2 sheath used.

17. RF site-PA view

18. RF energy-Voila! As the AP is eliminated, RBBB appears.

19. No tachy inducible after this Final diagnosis: Ebstein’s anomaly. Mahaim-like right lateral atriofascicular AP with ADT. Successful RF ablation.