Corresponding author:
Debabrata Bera. Rabindranath Tagore International Institute of Cardiac
Sciences (RTIICS), 124 Mukundapur, Kolkata. West Bengal, India. PIN-
700099.
Ph: +91-8013894181, Fax: +91-33 2426 4204.Email-
debu2000pgi@gmail.com
Key words: atypical AVNRT; fast slow AVNRT; long VA tachycardia after
slow pathway modification; polarity reversal.
Funding: None
Conflict of interest: None
Acknowledgements: None.
Word count – 1145.
Case
A 45-year-old lady presented with recurrent narrow QRS tachycardia.
Echocardiography was normal. During EP study dual AV nodal physiology
was demonstrated: with PR interval exceeding RR interval during
decremental pacing, AH jump and AV nodal echo (slow-fast). It was
followed by easily inducible typical slow-fast atrioventricular nodal
reentrant tachycardia (AVNRT, tachy1, septal VA= 0 ms) [Post
ventricular entrainment- VAHV response, Stim A - VA= 125 ms, corrected
post-pacing interval-tachycardia cycle length =116 ms ] (Fig 1A,1B).
After slow pathway (SP) modification in lower triangle of Koch,
(although only very few junctional beats were generated in 4
radiofrequency (RF) lesions, total 150 sec of RF energy), during
decremental pacing PR interval didn’t exceed RR interval, no AH jump, no
typical echo; but consistently had one and half long VA echo(Fig2A). After isoprenaline, sustained tachycardia with similar
long VA (septal VA= 144 ms) was induced (Fig 2A). Attempted ventricular
overdrive pacing (VOP) to entrain the tachycardia repeatedly terminated
tachycardia (Fig 2C) without entraining tachycardia even after 7-8
beats.