\E Induction of Meandering Functional Reentrant Wave Front in Isolated Human Atrial Tissues by Takanori Ikeda, Lawrence Czer, Alfredo Trento, Chun Hwang, James J. C. Ong, Dustan Hough, Michael C. Fishbein, William J. Mandel, Hrayr S. Karagueuzian, and Peng-Sheng Chen Circulation Volume 96(9):3013-3020 November 4, 1997 Copyright © American Heart Association, Inc. All rights reserved.

Electrode location and mapping procedure. Electrode location and mapping procedure. Electrode array was built at bottom of tissue chamber. It has 21 columns and 24 rows, with a total of 477 electrodes. Interelectrode distance was 1.6 mm and interpolar distance 0.5 mm. Tissue was placed endocardial side down on mapping electrode array. Tissue was continuously superfused with oxygenated Tyrode’s solution. Takanori Ikeda et al. Circulation. 1997;96:3013-3020 Copyright © American Heart Association, Inc. All rights reserved.

Endocardial surface of left atrium. Endocardial surface of left atrium. Figure is from patient 4. Black box indicates site of recording electrode array, corresponding to that shown in Fig 1. White arrow in center of figure shows direction of impulse propagation during reentrant excitation in Figs 5 and 6. Takanori Ikeda et al. Circulation. 1997;96:3013-3020 Copyright © American Heart Association, Inc. All rights reserved.

Morphological examination. Morphological examination. Picture from tissue samples of patient 2. A, Low-power transmural section of right atrial free wall. Bar=5 mm. Thinnest portion of epicardium measured ≈1 mm, and thickness of pectinate muscles is >5 mm. B, High-power view of same tissue. Myocardial fiber orientation is nonuniform and complex. Takanori Ikeda et al. Circulation. 1997;96:3013-3020 Copyright © American Heart Association, Inc. All rights reserved.

Patterns of activation during baseline (S1) pacing. Patterns of activation during baseline (S1) pacing. Example from patient 4, who had a history of chronic atrial fibrillation. When an activation is registered, electrode shows red. Color then becomes yellow, green, light blue, and blue before becoming background color (black) again. Each of first five colors persists for 10 ms. Background color persists until next activation occurs. A through D, Propagation of impulses from pacing site in A to rest of tissue without evidence of conduction delay. Onset of S1 stimulus artifact is at time zero. E, Location of electrodes that registered activations in F. Takanori Ikeda et al. Circulation. 1997;96:3013-3020 Copyright © American Heart Association, Inc. All rights reserved.

Meandering functional reentrant wave front. Meandering functional reentrant wave front. Example from patient 4. Reentry was initiated by a premature stimulus (S2) and propagated in clockwise direction. Onset of S2 was used as time zero. Arrows indicate direction of wave-front propagation. Reentrant wave front did not propagate smoothly. For example, time difference between D and E was 54 ms, and between J and K 52 ms. During these 54 or 52 ms, impulse propagated only a very short distance, indicating that propagation probably did not occur at mapped surface. Comparing with Fig 2, wave front was propagating across a large pectinate muscle when delay occurred. Wave front shown in K probably was initiated by an activation wave front from epicardial side and not by direct propagation from endocardial surface to right of these electrodes. Letters a through l indicate electrode in leading edge of wave front closest to core (corresponding to tip of spiral). Trajectory of tip is shown in Fig 6. Takanori Ikeda et al. Circulation. 1997;96:3013-3020 Copyright © American Heart Association, Inc. All rights reserved.

Meandering functional reentry causing rapid and irregular activations. Meandering functional reentry causing rapid and irregular activations. Same episode of functional reentry as in Fig 5. A, Points a through l represent location of red dots closest to core of reentry in A through L of Fig 5, respectively. Trajectory of functional reentry represented by these points shows that reentry meanders in a clockwise direction. Dotted line connecting points j and k indicates that activations at these points were not continuous (see Fig 5 legend). B, Actual activations registered at these recording electrodes. Arrows indicate direction of wave-front propagation. These bipolar electrograms show that atrial activations were rapid and irregular, similar to that registered during atrial fibrillation. C, Actual bipolar recordings made by electrodes m, n, o, p, q, and r. Arrows point to double potentials when electrodes are within area encircled by trajectory. Takanori Ikeda et al. Circulation. 1997;96:3013-3020 Copyright © American Heart Association, Inc. All rights reserved.