Intraatrial reentrant circuit in a patient with isomerism of the left atrial appendages and atrioventricular septal defect.

An intraatrial reentrant circuit was identified using an electroanatomical mapping system and evaluation of postpacing intervals in a patient with isomerism of the left atrial appendages and atrioventricular septal defect. Intraatrial reentrant tachycardia was eliminated on the basis of our interpretation of the reentry circuit being dependent on a new anatomical obstacle consisting of a right-sided atrioventricular annulus and atrial septation patch. We must consider the possibility of arrhythmogenic obstacles changing, as a patient grows, long after congenital heart disease surgery.