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 during atrial butter in a functionally determined reentrant circuit reflect activation of the reentrant wave front around an area of functional conduction block. Background. The center of the atrial butter reentrant circuit in the sterile pericarditis canine model is characterized by double potentials. Methods. We studied 11 episodes of atrial butter in eight dogs during interruption of atrial putter while pacing the atria. A multielectrode mapping system was used to record simultaneously from 190 electrodes on the right atrium (location of reentry). Results. 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 interruption of atrial butter depended an the location of the recording site relative to this area of block. Two types of response were seen. When the double potential was recorded orthodromically distal to this area of block, interruption of atrial butter was associated with disappearance of the second deflection, and continued pacing after interruption of atrial flutter was not associated with reappearance of the second potential. When the double potential was recorded at a site orthodromically proximal to the area of block, interruption of atrial flutter was not associated with disappearance of the second potential, and when rapid atrial pacing was continued, the double potential remained despite disappearance of the atrial flutter reentrant circuit. Conclusions. Double potentials represent functional conduction block in the center of the reentrant circuit, with each deflection of the double potential reflecting activation on either side of the area of functional block. The data also demonstrate that double potentials are not limited to a reentrant circuit, as they were recorded on either side of an area of block in the absence of such a circuit.