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.