Abstract 5338: Intramural Activation Patterns During Human Ventricular Fibrillation
Intramural activation in human ventricular fibrillation (VF) has not been studied. It is unknown if fixed intramural reentry is present and is the driving source in human VF. We fabricated unipolar plunge needles to study transmural activation pattern during VF in a human Langendorff model.We assumed that intramural reentry would mostly be represented by non-linear multi-directional intramural conduction. In six human Langendorff hearts, 25 plunge needles (with 4 electrodes spaced 2 mm apart) were deployed over the entire the left ventricle such that there were 100 unipolar intramural electrodes. In each heart, we studied 3 episodes of VF analyzed as 20s fragments at the onset and at 180s. In total, 6 fragments of VF were studied per heart. The transmural activation pattern was taken as the pattern seen atleast 3 seconds after VF onset. Electrodes which had transmural activation times less than 10 milliseconds along one needle were defined as having simultaneous transmural activation. Transmural activation detection and direction of VF spread could be accurately computed in 78.67% (59/75) of needles. The commonest pattern of activation was simultaneous activation of all the transmural electrodes in a single needle in (38/59, 64.41%) followed by endocardial activation before epicardium (7/59, 11.86%) followed by epicardium activated before endocardium (4/59, 6.78%). The non-linear multi-directional conduction patterns included varying sequences of initial or later epicardial, transmural and endocardial activations. These were seen in 16.95% (10/59) needles. The mean transmural conduction velocity vector across all episodes of VF was computed to be 0.20m/sec. The rare non-linear multi-directional atypical transmural conduction patterns may suggest that intramural re-entry if present is rare in human VF. In addition, our findings point to a linear source(s) parallel to the transmural needle, pointing to the presence of transmural scroll waves in human VF.