IDF
We used the BeeAT catheter and a dedicated defibrillator (Shock AT, Japan Lifeline, Tokyo, Japan). which together constituted the IDF system approved for use in Japan (Figure 1 ). The BeeAT catheter has 20 poles consisting of a distal set of 8 poles, middle set of 8 poles, and proximal set of 4 poles. The distal 8 poles are positioned in the distal CS and middle 8 poles along the lateral wall of the right atrium (RA). The proximal 4 poles are positioned in the superior vena cava (SVC) and record the SVC activity during the procedure. We selected the catheter sizes (S, M, and L) to fit the LA and RA size of the patients. Cardioversion was effective with a current delivery between those distal and middle sets of electrodes, but they were also able to record the local electrograms.
For cardioversion, a biphasic direct current was delivered between the distal set and the middle set of electrodes synchronized to the R wave of the body surface electrocardiogram. If cardioversion was not possible, we changed the lead of the body surface electrocardiogram to detect and synchronize to any R wave. We started the IDF output at 1 J and went up to 3, 5, 10, 15, 20, and 30 J. The maximum energy output was 30 J with this system. We performed IDF under deep sedation with propofol and dexmedetomidine. When the blood pressure was low, we used phenylephrine.