CHARACTERIZATION OF DOUBLE POTENTIALS IN A FUNCTIONALLY DETERMINED REENTRANT CIRCUIT - MULTIPLEXING STUDIES DURING INTERRUPTION OF ATRIAL-FLUTTER IN THE CANINE PERICARDITIS MODEL

Objectives. We tested the hypothesis that double potentials recorded d uring atrial butter in a functionally determined reentrant circuit ref lect activation of the reentrant wave front around an area of function al conduction block. Background. The center of the atrial butter reent rant circuit in the sterile pericarditis canine model is characterized by double potentials. Methods. We studied 11 episodes of atrial butte r in eight dogs during interruption of atrial putter while pacing the atria. A multielectrode mapping system was used to record simultaneous ly from 190 electrodes on the right atrium (location of reentry). Resu lts. Interruption of atrial butter occurred when the orthodromic wave front from the pacing impulse blocked in an area of slow conduction in the reentrant circuit. The response of the double potential with inte rruption of atrial butter depended an the location of the recording si te relative to this area of block. Two types of response were seen. Wh en the double potential was recorded orthodromically distal to this ar ea of block, interruption of atrial butter was associated with disappe arance of the second deflection, and continued pacing after interrupti on of atrial flutter was not associated with reappearance of the secon d potential. When the double potential was recorded at a site orthodro mically proximal to the area of block, interruption of atrial flutter was not associated with disappearance of the second potential, and whe n rapid atrial pacing was continued, the double potential remained des pite disappearance of the atrial flutter reentrant circuit. Conclusion s. Double potentials represent functional conduction block in the cent er of the reentrant circuit, with each deflection of the double potent ial reflecting activation on either side of the area of functional blo ck. The data also demonstrate that double potentials are not limited t o a reentrant circuit, as they were recorded on either side of an area of block in the absence of such a circuit.