Use of a 3-dimensional electroanatomical mapping system for catheter ablation of macroreentrant right atrial tachycardia following atriotomy.

The purpose of this study was to utilize a 3-dimensional (3D) electroanatomical mapping system (CARTO) to characterize the reentrant circuit in macroreentrant right atrial tachycardia (AT) following right atriotomy. Right atrial mapping was performed during incessant AT in a patient who had a right atriotomy for closure of an atrial septal defect. During AT, the right atrial free wall exhibited a large contiguous area of low bipolar voltage (< or =0.5 mV, 7.3 cm in length, and 6.3 cm in width). Two discrete scars, showing no electrical potential, were identified within the large low-voltage area. A larger vertical scar (thought to be from the atriotomy) and a smaller second scar (possible inferior vena cava cannulation scar) formed a narrow channel (1.5 cm in width) between these 2 scars. Right atrial activation propagated around the large upper scar, and then propagated through the channel between the 2 scars. A single application of radiofrequency current within the channel eliminated the macroreentrant AT. In conclusion, macroreentrant AT following right atriotomy was associated with 2 discrete scars and utilized the isolated channel between the 2 scars. Ablation within the channel effectively eliminated macroreentrant AT after atriotomy and eliminated the requirement for linear ablation between one or more of the scars and the tricuspid annulus.