21 yr old ladyRecurrent tachycardia episodes

Normal echo

Inputs from Tahmeed and Chandrashekhar

During catheter insertion-D/D? Tachy initiated by PAC with prolongation of PR; P wave narrow, in ST segment; VA linking despite “wobble” in first few complexes makes AT unlikely. DD: Atypical AVNRT versus ORT

Another episode- any further information? RBBB during tachy this time. TCL longer than the previous tachy. However, difficult to draw conclusions since these are 2 separate episodes.

1400 ms 1300 ms

Intracardiacs-D/D now? Among available channels, A at His region is earlier. Same D/D as before

Another episode, 3 minutes later- any further insight? No. Spontaneous termination after V.

Analyse: VA time slightly longer with complete RBBB compared to incomplete RBBB.

Comment- Spontaneous termination, fortuitous simultaneous RV pacing spike

Route of retrograde conduction? No obvious decrement: AP likely

What next? PVC during tachycardia; either his-synchronous or entrainment from RV

Interpret: atrium entrained. Post-entrainment:-VAHV response.Corrected PPI-TCL in keeping with ORT

Consistent with the prior diagnosis? Yes. His-refractory VPD advances the next A and resets tachycardia.

Any further confirmation needed? No. Termination of tachycardia without A=ORTIf not, what next? Map the tricuspid annulus.

Signal at RF site- where is this likely to be?Likely right sided (given prior findings); away from CS os and His area.

After ablation

RF site-LAO 40

Final diagnosis:

Concealed right anterolateral AP with ORT

Successful RF ablation