Posterior offset of inferior caval vein and its impact on cavotricuspid conduction block difficulty during...

Anatomic factors influencing the difficulty of achieving cavotricuspid isthmus (CTI) conduction block during cryoablation for common-type atrial flutter remain unclear.

This study aimed to investigate these factors and their impact on procedural parameters.

We enrolled 100 consecutive patients who underwent CTI cryoablation. We evaluated associations among anatomic factors measured via preoperative computed tomography scans. The CTI was defined as the line connecting the midpoints of the tricuspid annulus (TA) and the inferior vena cava in the horizontal view. The CTI rotation (CR) angle was defined as the angle between the vertical line passing through the midpoint of the TA and the CTI line, with a larger CR angle indicating a greater posterior offset of the inferior caval vein. Procedural parameters, including freezing characteristics and procedure time from the start of CTI ablation to final confirmation of conduction block, were assessed.

The CR angle was positively associated with procedure time (B = 0.369, P < .001), whereas other anatomic factors showed no significant associations. Patients were stratified into 2 groups based on the median CR angle. Those in the larger CR angle group had significantly longer procedure times (P = .005) and longer times to reach nadir freezing temperature at both the TA-side (P = .031) and middle-side segments (P = .038) of the CTI than those in the smaller CR angle group.

A larger CR angle may be associated with increased difficulty achieving CTI conduction block during cryoablation, potentially complicating catheter positioning.