1. 30 yr old lady Recurrent paroxysmal tachycardias Normal echo Inputs from Tahmeed Contractor and Chandrashekhar

2. Basal ECG- normal

3. During catheter insertion into CS-analyse. Narrow QRS tachy, noisy baseline. No ST deviation, clear P not seen. RR irregular before termination.

4. Intracardiacs-D/D? Short VA with eccentric atrial activation; CS 3,4 before his A; DD-ORT versus Left sided AT

5. Diagnosis confirmed? Eccentric activation: but minimal decrement; likely LL pathway

6. Tachy induced again: Same as previous tachy-ORT versus AT

7. Compare this with the previous tachy ECG: The second tachy (on the left) shows significant ST depressions

8. Intracardiacs- comment. Different atrial activation pattern, A earliest in CS 78/56 D/D: AT/Atypical AVNRT/2 nd ORT. Some CL variations (the are equal).

9. Interpret- Fused PVC did not advance A-no evidence of pathway. Not able to entrain the A during V pacing indicating an AT

10. Faster speed….A never entrained to Paced CL; tachycardia continues-rules out AVRT

11. And now? What next? ORT degenerates into multifocal AT

12. RF energy- Left lateral AP conduction changes to AV nodal conduction

13. RF site- LAO 40

14. After ablation- LV pacing shows retrograde AV nodal conduction

15. Adenosine after ablation- VA block No tachy inducible after this

16. Final diagnosis: Concealed left lateral AP with ORT, successfully ablated “Secondary” and non-specific atrial arrhythmias