Abstract 2352: Intramural Reentry in Ventricular Fibrillation: Insights From Transmural Needle Mapping in Human Langendorff Model
Background Intramural reentry has not been well characterized in human ventricular fibrillation (VF). Activation mapping and custom software were used to assess the presence and magnitude of intramural reentry in cardiomyopathic hearts.
Methods In six human Langendorff hearts, 11 episodes of VF (20 second fragments) were studied. 25 plunge needles (with 4 electrodes spaced 2 mm apart) were deployed over the left ventricular free wall such that there were 100 unipolar intramural electrodes. We assumed that intramural reentry would mostly be represented by non-linear multi-directional intramural conduction. Global VF cycle length was computed by an automated algorithm. To detect reentry at the 4 electrode levels separately, we used the following 4 criteria at the central grid of 9 needles which had neighbours all around: activations present at a needle electrode and atleast 75% of its’ neighbours; activations spanning greater than 85% of VF cycle length; continuity of local activation times; constant increments or decrements in local activation time. Transmural reentry was defined as reentry detected at all 4 electrodes in a needle. In one heart, phase mapping protocols were done across needles to look for intramural rotors.
Results Of the 14.3% instances of reentry satisfying all 4 criteria in the central grid of 9 needles, 5.8% satisfied criteria for transmural reentry. Activation mapping revealed non-linear multi-directional patterns in 19.3% (53/225) needles. These patterns therefore overestimated the incidence of intramural reentry. Statistical analysis revealed no significant difference between the number of intramural reentries at the endocardial, subendocardial, subepicardial and epicardial levels. We visualized one intramural rotor during a ventricular fibrillation episode thus validating the presence of intramural reentry.
Conclusions Transmural reentry exists in human VF, but is rare, with no significant difference between the number of reentries at 4 intramural levels. Identifying locations and patterns of reentry in VF could help develop targeted strategies of treatment including catheter ablation.