Collection of procedural variables
Transseptal access was achieved in the standard fashion using a BRK
needle (Abbott, Abbott Park, IL) and a long sheath (typically a medium
curl Agilis or SL1 [both Abbott, Abbott Park, IL]). Baseline
variables were collected before and after initial transseptal access
(“pre” ablation values). Pressure readings were made after zeroing the
pressure line with the transducer at the level of the inferior vena
cava. Ablation was performed as described above, and those in persistent
AF were cardioverted after ablation. After the waiting period just prior
to sheath removal, measurements were collected again (“post” ablation
values), including both left atrial and right atrial pressures. Mean
values over a 10 second window were used without regard to the
respiratory cycle. All patients received general anesthesia with
standard ventilation parameters. Cardiac output was calculated using
Fick’s equation and a right atrial sampling for the mixed venous oxygen
saturation.