Fig. 1.

(A) Twelve-lead electrocardiogram and (B–E) activation maps during the BiAT. The activation wavefront propagated from the inferior to anterior MA counterclockwise, then from the anterior MA to the high RA septum via the upper interatrial connection and returned to the inferior MA via the lower interatrial connection just at the transseptal puncture site. The yellow solid and dotted arrows represent the endocardial and interatrial conduction in the BiAT circuit, respectively, and the white arrows represent the endocardial conduction outside the BiAT circuit. The black and white tags and numbers on the maps indicate the conduction block, entrainment pacing sites, and PPI interval minus the TCL, respectively.

Abbreviations: IVC, inferior vena cava; LAA, left atrial appendage; LIPV, left inferior pulmonary vein (PV); LSPV, left superior PV; MA, mitral annulus; RIPV, right inferior PV; RSPV, right superior PV; SVC, superior vena cava; TA, tricuspid annulus.