Atypical form of biatrial tachycardia using an interatrial connection in the superior septum: Detailed analysis from 2 single-loop biatrial tachycardias

Figure 1. Intracardiac electrocardiogram and 3-dimensional mapping of biatrial tachycardia (BiAT1). A: Intracardiac electrocardiogram during BiAT1. Red arrows show a chevron activation pattern in the coronary sinus (CS). B: Activation map and results of entrainment pacing during BiAT1 in both atria. The post-pacing interval (PPI) minus the tachycardia cycle length (TCL) from the superior septum, fossa ovalis (FO), and left posterior wall is <30 ms (white circle), whereas the PPI-TCL from the distal and proximal CS exceeds 30 ms (white cross). Red arrows indicate interatrial connections and white arrows depict the propagation pattern in the atria. The earliest activation site in the right atrium (RA) is marked with a yellow star. C: Histogram showing local activation times in both atria. AP = anterior to posterior; AT = atrial tachycardia; LA = left atrium; LAO = left anterior oblique; LAT = local activation time; PA = posterior to anterior; SVC = superior vena cava; TA = tricuspid annulus.

Figure 2. Fluoroscopy and intracardiac echocardiography of effective ablation sites during biatrial tachycardia (BiAT1). The ablation targets the breakthrough site at the superior septum in the right atrium (RA, left panel) and the left atrium (LA, right panel) during BiAT1. The lower panels depict the intracardiac echocardiography, illustrating the ablation sites from both the RA and LA septa. The interlesion distance between the ablation sites in the RA and LA measures 8.7 mm. Ao = aorta; NCC = noncoronary cusp; PPI = post-pacing interval; RAO = right anterior oblique; RCC = right-coronary cusp; TCL = tachycardia cycle length.

Figure 3. Intracardiac electrocardiogram and 3-dimensional mapping of biatrial tachycardia (BiAT2). A: The intracardiac electrocardiogram during BiAT2. Red arrows exhibit a proximal to distal activation sequence in the coronary sinus (CS). B: The post-pacing interval (PPI) minus tachycardia cycle length (TCL) at the fossa oval (FO), the distal and proximal CS, the left atrial roof, and the left anterior wall are <30 ms (white circle). The activation map depicts counterclockwise-rotating mitral isthmus-dependent BiAT. The interatrial connections are identified as Bachmann’s bundle (BB) and the FO (red arrows). White arrows indicate the propagation within both atria. The earliest activation site in the right atrium (RA) is marked by a yellow star. The orange dotted line demonstrated the liner ablation sites from left superior pulmonary vein to mitral valve anulus. C: Histogram displaying the local activation times during BiAT2. AP = anterior to posterior; AT = atrial tachycardia; LA = left atrium; LAA = left atrial appendage; LAO = left anterior oblique; LAT = local activation time; SVC = superior vena cava; TA = tricuspid annulus.

Supplemental Figure.