We systematically studied double potentials in our canine model of
atrial flutter produced by right atrial
crush injury using a 64-channel computerized mapping system with 56
electrodes on the right atrium in seven mongrel dogs under
general anesthesia. Activation maps were recorded during sinus rhythm before and after
crush injury, during rapid pacing above and below the
crush injury, and during sustained
atrial flutter, entrainment of
atrial flutter, and termination of
atrial flutter induced with D-
sotalol (2 mg/kg). During sinus rhythm before
crush injury, activation was uniform, and double potentials were not recorded in any dog. After
crush injury, activation proceeded up to and around the
crush injury, and narrowly split double potentials were recorded in two of seven dogs. During rapid pacing above and below the
crush injury, double potentials were recorded in five dogs. During 14 episodes of
atrial flutter (mean cycle length, 140 +/- 16 msec), double potentials were recorded at
electrodes along the
crush injury. The activation time of the early x component of the double potentials (25 +/- 13 msec) was similar to that of adjacent
electrodes above the
crush injury (24 +/- 11 msec), and the activation time of the late y component (89 +/- 13 msec) was similar to that of adjacent
electrodes below the
crush injury (91 +/- 14 msec). The timing of the x and y components was dependent on the location of the recording
electrode, with x and y widely spaced at the end of the
crush injury near the area of earliest atrial activation during
atrial flutter, more equally timed at the center of the
crush injury, and more closely timed at the end of the
crush injury opposite the area of earliest activation. During transient entrainment, double potentials were accelerated to the pacing rate, but their activation time relative to adjacent
electrodes was maintained. During abrupt termination of
atrial flutter, the early x component of the double potential was always recorded, but the late y component was not, because of conduction block below the posterior end of the
crush injury.
CONCLUSIONS: