1. 35 yr old man Recurrent tachy episodes Normal echo Inputs from Tahmeed Contractor, UCLA and Chandrashekhar, Chennai

2. Likely AP location? Right anteroseptal AP

3. During catheter placement-analys. WCT initially then narrow complex tachycardia no difference in the cycle length between the two tachycardias WCT- may be ORT with LB aberrancy - LB with inferior axis then aberrancy disappears so NCT - ORT

4. Analyse. Early V in His region. AV Continuous activity in His catheter-scary for the first year fellow.

5. Atrial pacing- analyse. Minimal increase in pre-excitation; Stim to QRS stable

6. Tachy initiation during PES. Block in pathway-initiation of ORT

7. Intracardiacs at initiation A after QRS during tachy

8. Mechanism confirmed? His synchr PVC pulls in A that delays next A-likely presence AND participation of pathway. Baseline wobble but still definite pulling in and delay

9. Again-second PVC is more fused with native QRS; A definitely pulled in. Is the next A pulled in or delayed? Assuming it is, proves presence and participation of PW.

10. The AP was mapped endocardially in sinus rhythm and during ORT. The best site was close to the His region. The aortic sinuses were mapped. The signals obtained were not very early (delta-V in sinus rhythm and retrograde A during tachycardia)

11. Earliest signals in aortic sinus- LAO 40

12. Earliest signal in aortic sinus- RAO 30

13. Anything encouraging here? Now, with a clear His signal in HISp, there is a gap between the V and A. What next? Next I will take the ablation catheter just above the His location and look for even better signals and give the RF energy initially during the tachycardia after verifying that there is no His signal in the ablation distal

14. Best signal obtained- Sinus rhythm- beware, the His could be hidden in the continuous activity

15. RF site-LAO 40

16. RF site-RAO 30

17. RF energy at this site. Always during ORT- no His in RFD, V and A fused. Tachy terminates retrogradely.

18. After ablation-no tachy inducible