Transition between different types of biatrial tachycardia during catheter ablation: Implication for ablation strategy

Key Teaching Points•Since biatrial tachycardias (BiATs) usually occur based on an electrical obstacle located in the septum, ablation to septum may provide a substrate for BiATs.•BiATs are classified into 3 types terms of tachycardia circuits: circuit containing mitral and tricuspid annuli (type 1), that right atrial annulus 2), left septa 3).•The strategy BiATs is interrupting by ablating anatomical isthmus or interatrial connection; however, creating conduction block give rise transition another type BiAT. •Since Biatrial (BiAT) atypical form (AT), which contains both atria 2 distinct connections circuit. BiAT most frequently observed patients with history open heart surgery1Namdar M. Gentil-Baron P. Sunthorn H. Burri Shah D. Postmitral valve replacement biatrial, septal macroreentrant developing after perimitral flutter ablation.Circ Arrhythm Electrophysiol. 2014; 7: 171-174Crossref PubMed Scopus (8) Google Scholar catheter fibrillation.2Mikhaylov E.N. Mitrofanova L.B. Vander M.A. et al.Biatrial following linear anterior wall reentry: incidence electrophysiological evaluations.J Cardiovasc 2015; 26: 28-35Crossref (31) 3).3Kitamura T. Martin R. Denis A. al.Characteristics single-loop diagnosed ultrahigh-resolution mapping system.Circ 2018; 11e005558Crossref (48) However, factors determine occurs remain unclear. An 82-year-old woman was referred AT. Four years prior, patient underwent aortic surgery stenosis. Since had paroxysmal fibrillation, pulmonary vein isolation cryoablation also performed during surgery. The voltage map created sinus rhythm showed extensive low-voltage area throughout atrium. No reconnection isolation. Left posterior empirically prevent roof-dependent AT, cavotricuspid peri-tricuspid Thereafter, AT (AT1) cycle length (TCL) 280 ms induced burst pacing. activation revealed lines anteroseptum atrium localized-reentrant propagated through gaps between (Figure 1A). We ablated gap connected line veins 1B). AT1 terminated ablation; (AT2) TCL 310 In map, AT2 centrifugal pattern from basal (ie, connection site Bachmann bundle). Activation then downward ventricular side clockwise direction annulus, resulting collision wavefronts inferoseptum. mapped as we suspected upward coronary ostium 2A). not reconnected. Entrainment pacing postpacing interval (PPI) similar at anteroseptum, proximal sinus, septum. considered out circuit, entrainment lateral antidromically captured PPI longer than TCL. Therefore, 3). earlier lesion extended toward complete anteroseptal 2B). Then, transitioned AT3 330 ms. counterclockwise 3A). demonstrated 2). isthmus. Finally, Although appendage delayed ablation, electrically isolated 3B). inducible procedure. recurrence any tachyarrhythmias no antiarrhythmic drugs were taken 15-month follow-up. Anticoagulation therapy continued procedure, thromboembolic event occurred.Figure 2Biatrial A: bundle (green arrow) arose conducted inferoseptum (red B: green tag indicates where CS = sinus; TA annulus. Other abbreviations Figure 1.View Large Image ViewerDownload Hi-res image Download (PPT)Figure 3Biatrial 2) tracing recorded ablation. around arrow). onset P wave potential 153 Abbreviations 2.View (PPT) this case, incomplete have provided septal-type Furthermore, extension rendered consequently hindered As result, became dominant giving Theoretically, can cause BiAT, respectively. best our knowledge, first case report proved theory direct anteroseptum. findings critical insights considering BiATs. Firstly, when ATs should be designed manner avoided much possible. occurrence could been if instead Secondly, creation appropriate some previous reports,3Kitamura Scholar,4Kusa S. Hachiya Iesaka Y. occurring mitral/tricuspid repair using superior transseptal approach: optimal site?.J 2019; 30: 1154-1155PubMed treat BiATs, targeting atria. because concerned about result bundle4Kusa Scholar; cannot Thirdly, added ablate BiAT; appendage. preserved, decided create even though already delay occurred suggesting damage. would disrupted owing remodeling. different theoretically possible but has fully described. importance design prevention treatment highlighted.