Abstract 2882: Right Atrial Substrate Characteristics in Patients with Right Atrial Arrhythmias
Introduction: Right atrial substrate characteristics may differ between patients with right atrial (RA) typical flutter (AFL), atypical AFL, and atrial fibrillation (AF).
Methods: 45 patients (males=30, age=65±16) with typical AFL (n=15), atypical RA AFL (n=15), and RA AF (n=15, no PV initiating foci) referred for 3D Ensite mapping (St. Jude Medical, USA) and ablation were included. Voltage (peak negative unipolar voltage) and activation maps were visualized during sinus rhythm (SR), atrial pacing, and tachycardia.
Results: As shown in the Table⇓, the mean voltage of the entire RA during SR was similar between the groups. However, the mean voltage during short cycle length atrial pacing was lower. Voltage mapping showed that the fixed low voltage zones (LVZs, independent of the rhythm) were located at lower crista terminalis (CT) in all patients. Functional extensions of the LVZ were observed during atrial pacing and the AFL. Activation mapping showed that the functional extensions of LVZ’s formed the borders of the conduction isthmus for the reentrant circuits. The conduction velocity within the isthmus was lower than outside (0.27±0.16 vs. 1.21±0.57 m/s, p<0.01). AF patients had more isthmuses than the typical and atypical AFL patients (Table⇓). These isthmuses were located at the CT in 31, RA free wall in 12, sinus venosa in 5, and superior vena cava to RA junction in 2, and all were ablated successfully (9.6±3.2 pulses per patient).
Conclusions: The RA AFL and AF substrate was characterized by a greater heterogeneous voltage distribution of the RA. Single and multiple slow conduction isthmuses bordered by the LVZ were critical for reentrant circuits in patients with RA AFL and AF. The conduction isthmuses could be identified by their substrate characteristics and ablated successfully.