PO-05-006 MECHANISMS UNDERLYING ALTERNANS AND OSCILLATION DURING SUSTAIN VT: INSIGHTS FROM HIGH DENSITY MAPPING OF THE ISTHMUS

The mechanism of perturbations and spontaneous variations during monomorphic VT are unknown. We performed high density mapping the isthmus that exhibited alternans oscillation in morphology rate to characterize attributable components reentrant circuit. purpose this study is delineate patterns activation change human circuit exhibit morphologic and/or oscillations tachycardia cycle length. analyzed retrospectively 19 patients who underwent a high-density map with QRS TCL (tachycardia length) oscillation. For each episodes, maps were reconstructed different waveforms or same QRS. distance between breakout sites difference TCL, measured compared two groups: group (Figure). Patients 67±6.0 years old, male(78.9%), had structural heart disease (NICM 52.6%, ICM 31.5%, ARVC 15.8%). A total 46 evaluated for VTs simultaneous endocardial epicardial on 4 them. All shared part isthmus. Nine showed shift all 9 VTs, but no was observed (distance 16±4.8mm vs 0mm P<0.05). significantly shorter than (22.3±33.7ms 61.0±33.8ms Shared slight alternans/oscillation successfully visualized both Differences exit region contribute changes intra-isthmus conduction characteristics.