Fig 3
A: A:V ratio of 2:1 during SVT2 after a an attempt of ventricular entrainment ( atrial CL- 255-260 ms)
B: Annotated Fig 2A showing that the APD did not engage the slow pathway as it was refractory. The H3 and next RR was unperturbed. There was a retrograde conduction locally (A3) via FP which could not produce any evident A-EGM in CS as it was prematurely captured by the APD. The same produced another beat of AVNRT (H4) beat via antegrade SP conduction. Hence the timing of next H (H4) was unperturbed. The second AT beat (A4) could capture fast pathway and terminated the AVNRT after which AT completely took over. Over next few beats the wobble got stabilised.
Appendix 1: Adenosine terminating the tachycardia.