SVC Mapping Using an Ultra-High Resolution 3-Dimensional Mapping System in Patients With and Without AF

Abstract Objectives This study aimed to characterize the superior vena cava (SVC) sleeve in patients with and without atrial fibrillation (AF). Background A few studies have examined the morphological characteristics of atrial myocardial extensions into the human SVC using autopsied hearts. Methods Thirty-four patients with AF and 30 without AF underwent SVC mapping during sinus rhythm using ultra-high-resolution mapping. In 18 patients with AF, SVC isolation was added, and the SVC mapping was repeated. Results The median acquisition time was 7.7 min (interquartile range [IQR]: 5.5 to 11.2 min), and 2,478 data points (IQR: 1,620 to 3,350 data points) were automatically annotated. The electrically activated SVC sleeve length was asymmetric and longest at the anteroseptal SVC (27.0 to 28.0 mm) and shortest at the posterolateral SVC (22.0 to 23.0 mm). The sleeve length at each segment was similar in patients with and without AF, however, conduction time in the sleeve was significantly longer (76.1 ± 26.4 ms vs. 61.0 ± 19.1 ms; p = 0.036) and conduction block more frequently pre-existing in patients with AF than in those without (3 of 34 vs. 0 of 30; p = 0.047). The conduction velocity from sinus node was slower in upper direction (to SVC) than in other directions. Electrical SVC isolations were successfully achieved in all 18 patients without any complications. The conventional isolation line was a median of 20 mm (IQR: 13.9 to 29.0 mm) apart from and superior to the earliest activation sites during sinus rhythm. The isolated SVC sleeve length was longest at the septal SVC (median: 19.1 mm [IQR: 11.8 to 24.2 mm]) and shortest at the anterolateral SVC (median: 6.4 mm [IQR: 0 to 11.3 mm]). Conclusions Ultra-high-resolution human SVC mapping demonstrated asymmetric SVC musculature sleeves and variations in the sleeve length in individual patients. Conduction disturbances were more prominent in patients with AF than in those without.