A 32-year-old female, with a surgically corrected complete atrioventricular septal defect, developed an atrial tachycardia (Figure, ECG after adenosine in Panel A, bottom) after a mitral prosthetic valve implant. An ablation procedure was scheduled. A 24-pole catheter (Orbiter V R ; Bard Medical) was placed around the right-sided part of the common atrioventricular valve with its distal part within the coronary sinus. Post-pacing intervals along the coronary sinus matched the tachycardia cycle

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... ength. Left atrial activation map (Figure, Panel A, top; EnSite TM Precision TM navigator) showed a clockwise rotation around the left-sided part of the common atrioventricular valve. As left atrial electrograms comprised only 50% of the cycle length, the right atrium was also mapped. Panel B displays concealed entrainment and post-pacing intervals similar to the tachycardia cycle length, from the lateral ends of both right-sided (top) and leftsided (bottom) parts of the common atrioventricular valve (entrainment from points #1 and #2 in Panel A, respectively). With the diagnosis of macroreentrant atrial tachycardia around the native common atrioventricular valve (online supplementary video shows propagation map), a line of ablation along the theoretical cavo-tricuspid isthmus was performed (red spheres in Panel A), successfully terminating the arrhythmia.