BACKGROUND: The aim of this study was to categorize the conduction patterns between the right atrium (RA) and the superior vena cava (SVC), and to determine the ideal procedure for SVC isolation using a novel high-resolution mapping system.Methods and Results: RA-SVC conduction was evaluated using the RHYTHMIA system in 113 patients (age 62.8±11.5 years, paroxysmal: 67) with atrial fibrillation (AF) after pulmonary vein (PV) isolation. In 56 patients, a line of conduction block was found to run obliquely just above the sinus node (Block group). The remaining 57 patients did not have block (Non-block group). Non-PV foci were spontaneous or provoked with isoproterenol after electrical cardioversion of pacing-induced AF. In 43 patients with SVC foci (Block group: 22, Non-Block group: 21), SVC was isolated by radiofrequency applications delivered along the line connecting the open ends of the block line (Block group) or by conventional methods (Non-block group). The Block group required fewer radiofrequency deliveries for SVC isolation than the Non-Block group (4.2±0.9 vs. 10.2±2.8 times; P<0.0001). The isolated SVC area was larger in the Block group (15.7±3.7 vs. 10.5±3.1 cm2; P<0.0001). CONCLUSIONS: We found that approximately half of patients with AF had a diagonal line of block at the RA-SVC junction that could be utilized to isolate the SVC with fewer radiofrequency deliveries.
BACKGROUND: The aim of this study was to categorize the conduction patterns between the right atrium (RA) and the superior vena cava (SVC), and to determine the ideal procedure for SVC isolation using a novel high-resolution mapping system.Methods and Results: RA-SVC conduction was evaluated using the RHYTHMIA system in 113 patients (age 62.8±11.5 years, paroxysmal: 67) with atrial fibrillation (AF) after pulmonary vein (PV) isolation. In 56 patients, a line of conduction block was found to run obliquely just above the sinus node (Block group). The remaining 57 patients did not have block (Non-block group). Non-PV foci were spontaneous or provoked with isoproterenol after electrical cardioversion of pacing-induced AF. In 43 patients with SVC foci (Block group: 22, Non-Block group: 21), SVC was isolated by radiofrequency applications delivered along the line connecting the open ends of the block line (Block group) or by conventional methods (Non-block group). The Block group required fewer radiofrequency deliveries for SVC isolation than the Non-Block group (4.2±0.9 vs. 10.2±2.8 times; P<0.0001). The isolated SVC area was larger in the Block group (15.7±3.7 vs. 10.5±3.1 cm2; P<0.0001). CONCLUSIONS: We found that approximately half of patients with AF had a diagonal line of block at the RA-SVC junction that could be utilized to isolate the SVC with fewer radiofrequency deliveries.