Abstract
Animal studies show that low energy intracardiac conversion (IC) of atrial fibrillation (AF) is feasible. A lead position in the distal coronary sinus (CS) vs. right atrium (RA) showed lower energy levels for conversion than left pulmonary artery (PA) vs. RA. Cardioversion was attempted in 25 patients (pts), 15 randomized to the CS/RA lead position and 10 to PNRA. The CS group consisted of 4 females, mean age at 60.2 ± 8.2 years, left atrial diameters ranged from 54 to 71 mm with a mean of 59.2 ± 4.9 mm, AF duration was 9.5 ± 9.0 months (range 1 – 36 months). The PA group consisted of 3 females, mean age 60.5 ± 10.5 years, left atrial diameters ranged from 54 to 76 mm with a mean of 64.5 ± 6.6 mm, AF duration was 13.7 ± 22 months (0.5 – 79 months). There were no significant differences between the two groups. Biphasic shocks (3 ms ± 2 ms) were R-wave triggered and delivered in increments of 40 V from an external defibrillator (Ventritex HVS 02, Sunnyvale, CA) via two custom made catheters (6 F, Elecath Inc., Rahway, NJ) to a maximum energy of 11.1 J or successful conversion to sinus rhythm. Pts were sedated with midazolam. In the CS group conversion in 13/15 pts was achieved at a mean energy level of 3.7 ± 1.6 J, range 1.0 – 6.6 J. Mean lead impedance was 58.8 ± 7.5 Ω. In the PA group, IC was successful in 9/10 pts, the mean energy level was 4.4 ± 2.1 J, range 2.5 – 11.1 J. Mean lead impedance was 59.1 ± 10.0 Ω. No severe complications were observed in either lead position group. There was no significant difference between CS and PA. Low energy biphasic shocks delivered between RA and CS or PA are successful in conversion of AF. Positioning of the anodal electrode in the PA shows slightly higher thresholds and lead impedances than the CS position. From a practical point of view, however, the pulmonary electrode is advantageous for positioning a single balloon guided catheter with electrodes in PA and RA position; this is currently under development.
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