Baseline electrophysiological study
The procedure was performed in fasting state, under general anesthesia
in 5 patients (standard procedure in one center) for which propofol and
atracurium were used during the study. In the remaining procedures,
patients were under conscious sedation with propofol and remifentanil
and monitored with bispectral index (BIS®). Three right femoral vein
punctures allowed introduction of a 7F diagnostic decapolar catheter in
the coronary sinus, a 6F diagnostic quadripolar catheter at His location
and one 8.5F SL1® sheath (Abbot Inc.) Baseline electrophysiological
study was performed using a multichannel cardiac recorder for bipolar
intracardiac electrograms with filtered signals at 30-300 Hz (EP
WorkMate Claris System®, Abbott Medical and LabSystem Pro®, Boston
Scientific), displaying 3 surface ECG leads (DII, aVF and V1) and with
programmed digital stimulation (EP-4® Cardiac Stimulator, Abbott Medical
and Qubic Stim, Biotronik). Baseline intervals were measured, and
sinoatrial node function was evaluated by measuring RR intervals and AV
node function was assessed by measuring Wenckebach cycle length (WBCL)
(atrial decremental stimulation at which Wenckebach AV block occurs).