Epicardial mapping of reentrant activation during ventricular fibrillation. An experimental study

Introduction and objectives. High-resolution epicardial mapping was used in an experimental model to analyze reentrant activation during ventricular f ibrillation. Methods. In 30 isolated Langendorff-perfused rabbit hearts, recordings were made of Ventricular fibrillation activity using an epicardial multiple ele ctrode, in the activation maps with reentrant activation patterns, determin ations were made of the number of consecutive rotations, the maximum length of the central core, the area encompassed by the core and two electrodes s urrounding it, and the cycle defined by reentrant activation. Results. Most of the activation maps analyzed showed complex patterns with two or more wave fronts that either collided or remained separated by funct ional block lines (514 maps, 86%). In 112 maps (19%) activation patterns co mpatible with epicardial breakthrough of the depolarization process were ob served. Reentrant activity was recorded in 42 maps (7%) - the maximum numbe r of consecutive rotations being 3 (mean = 1.3 +/- 0.5). The maximum length of the central core ranged from 3 to 7 mm (mean = 5 +/- 1 mm), while the a rea encompassed by the central core plus two electrodes surrounding it rang ed from 35 to 55 mm(2) (mean = 45 +/- 6 mm(2)). The reentrant cycle length (mean = 47 +/- 18 ms) showed a linear relation to the maximum length of the central core reentry (cycle = 4.52 x length + 24.6; r = 0.7; p < 0.0001). Conclusions. a) Epicardial mapping allowed the identification of reentrant activation patterns during ventricular fibrillation in the experimental mod el used; b) the reentrant activity detected is infrequent and unstable, and c) a linear relation exists between the duration of the cycles defined by reentrant activity and the maximum length of central core reentry.