Key result
Mapping of isolated canine right atria during AF showed that low-amplitude transmembrane potentials occurred in 34% of activations and were primarily associated with areas of random reentry (67%).
This preclinical study demonstrates that low-amplitude transmembrane potentials during atrial fibrillation are associated with specific activation wavefront patterns, such as random reentry and functional reentry cores.
INTRODUCTION: Although computerized mapping studies have demonstrated the presence of multiple wavelets during atrial fibrillation (AF) and that action potential amplitude and duration in AF vary significantly from beat to beat, no study has correlated the single cell action potential changes with the patterns of activation during AF. METHODS AND RESULTS: We studied wavefront dynamics and single cell transmembrane potential (TMP) characteristics in 12 isolated perfused canine right atria. The endocardial surface was mapped using 477 bipolar electrodes while TMP was recorded with a standard glass microelectrode from an epicardial cell. AF was induced in the presence of acetylcholine. Successful simultaneous TMP recordings and activation maps were made during six episodes of AF and for a total of 141 activations. Large variations of TMP amplitude and duration were observed frequently; 34% of them have a low amplitude (<50% of the amplitude recorded during pacing). Low-amplitude potentials were recorded when the impaled cell was (1) in an area of random reentry (67%, n = 36); (2) within 3.2 mm of the core of organized functional reentry (22%, n = 12); (3) in the middle of two merging wavefronts (9%, n = 5); and (4) at the point of spontaneous wavebreak (2%, n = 1). CONCLUSION: Large variations of TMP are observed frequently during in vitro AF. Low-amplitude TMPs are associated with specific patterns of AF activation wavefronts.
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Athill et al. (2000) studied Atrial fibrillation (n=12). Computerized mapping and transmembrane potential recording was evaluated on Correlation of single cell action potential changes with patterns of activation during AF. Mapping of isolated canine right atria during AF showed that low-amplitude transmembrane potentials occurred in 34% of activations and were primarily associated with areas of random reentry (67%).
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