1. 24 yr old man Recurrent tachy episodes Normal echo Inputs from Tahmeed and Chandrashekhar

2. AP location? Right anteroseptal

3. Any further insight into AP location? Continuous activity in His area

4. Rapid atrial pacing. Interpret. Mild increase in preexcitation, since basally there is marked preexcitation.

5. Go for the AP or leave it alone? The AP is close to the AV node-His region. On the other hand: AF short run; shortest preexcited RR interval as 240 ms making it a high risk pathway. So go ahead only after informed consent about chance of AV block.

6. Intracardiacs… Underlying AF; in non-prexcited beats, His seen in the His distal; continuous activity seen in pre-excited complexes.

7. Detailed interpretation: initiation of tach after block in pathway (ORT) and alternans. Intermittent RBBB; CL almost same.

8. Tachy initiation: Extra-stimulus blocks in pathway and then initiates ORT. Alternans in First three beats followed by RBBB. VA time longer after RBBB=Right sided pathway. There is a compensatory shortening of the AV, hence TCL remains almost the same

9. As expected? Yes. VA longer during RBBB.

10. Route of VA conduction? No definitive decrement despite short coupling; likely pathway.

11. Signal in right anteroseptal area. What next? Good signal at His D location with continuous electrical activity with local V earlier than the surface delta. Map endocardially, in sinus rhythm and during ORT. If the earliest site has a His signal during ORT, map the R coronary sinus to look for good signal and ablate safely or else we can superior to the His catheter location and look for good signal away from the His and ablate.

12. The best endocardial site was close to the His area. Hence the aortic sinuses were mapped…

13. RAO 30. Early V in aortic sinus (NCS-RCS junction)- Test RF pulse for 5 sec unsuccessful

14. LAO 40

15. Went back to the endocardial early site, using a SR0 sheath for stability…

16. Successful site-LAO 40

17. Successful site- RAO 30

18. The catheter was not stable during ORT, despite the sheath.

19. RF test pulse in sinus rhythm for 3 seconds- AP disappears temporarily Went ahead with a 30 sec energy after this. Watch for junctionals & PR prolongation.

20. VA conduction after ablation

21. Adenosine after ablation