Electroanatomical mapping and ablation of upper loop reentry atrial flutter.

Upper loop reentry is a rare type of non isthmus-dependent atrial flutter with a reentry circuit around the superior vena cava. We present a case of atrial flutter of this type in a 75-year-old man with concomitant sick sinus syndrome. The diagnostic approach used three-dimensional electroanatomical mapping with the upgraded ENSITE 3000 system. This is the first case to be described where, apart from non-contact mapping, the circuit was also tracked in detail with three-dimensional contact mapping. The reentry circuit followed a clockwise course around the superior vena cava and passed through a conduction gap in the crista terminalis. Radiofrequency ablation of this region successfully eliminated the tachycardia.