Abstract 12257: Interplay Between Temporal and Spatial Dispersion of Repolarization in the Initiation and Perpetuation of Torsade De Pointes Arrhythmias

IntroductionVentricular arrhythmias, consisting of single ectopic beats (sEB), multiple EB (mEB), and Torsade de Pointes (TdP, defined as >5 beats with QRS vector twisting around isoelectric line) can be reproducibly induced in the anesthetized chronic AV-block (CAVB) dog by dofetilide (DIKr-blocker) infusion. The role of temporal dispersion of repolarization, quantified as short-term variability (STV), and its interplay with spatial dispersion of repolarization (SDR), in the initiation and perpetuation of these arrhythmias remains unclear.Methods5 inducible (>3 TdPs/10 min) CAVB dogs were observed for 10 minutes from the start of D infusion (0.025mg/kg, 5min) and received an intracardiac decapolar electrogram (EGM) catheter and extensive mapping with 30 intramural cardiac needles containing 120 unipolar electrodes in the left ventricle (LV). STVLV, ARI was derived from 31 consecutive activation recovery intervals (ARI) on the intracardiac EGM at the LV apex, using the formula Σ