Discussion
Anatomically, the myocardial sleeves extended from the RA into the SVC. Simultaneous isolation of both the RSPV and SVC implied that the anterior aspect of the SVC had poor myocardial sleeves in the present case. The posterior aspect of the SVC was close to the anterior aspect of RSPV. The anatomical distance between the RSPV ostium and SVC was significantly correlated with the conduction delay of the SVC potentials produced during the RSPV isolation with the cryoballoon ablation. A distance between the RSPV ostium and SVC of < 4 mm has been demonstrated to have a significant effect on the RA-SVC junction during cryoballoon application.6 The distance between the RSPV ostium and SVC was just 1 mm in the patient presented here. Despite the relatively mild cryoballoon application (150 s and nadir -44°C), the SVC isolation had persisted for over a year. A small anatomical distance between the RSPV ostium and SVC may be the main factor for persistent SVC isolation following cryoballoon application.