The LAP evaluation and ASV support
The atmospheric pressure was set as 0 mmHg reference at a beginning of the procedure. After the transseptal puncture and insertion of the 15 Fr long sheath (FlexCath) in the LA, the LAP via the sheath was recorded on a digital polygraph (RMC-5000, Nihon Corden, Tokyo, Japan) (Figure 1 ). The LAP was measured over more than three consecutive respiratory cycles. The LAP during one respiratory cycle was calculated as the average of the integral LAPs during one respiratory cycle, and the LAP was defined as the average value of that over three or more consecutive cycles. The LAP during the inspiratory and expiratory phases also was defined in the same manner. The lowest LAP was the minimum LAP during those respiratory cycles. Afterward, the ASV treatment was initiated in all patients. As the setting for the ASV, an expiratory positive airway pressure of 5 cmH2O and inspiratory pressure support between 3 and 10 cmH2O were used. Following the ASV treatment and confirmation of stable breathing synchronized with the ASV, the LAP was re-measured.