Basic/Translational Science -> Intact Heart Electrophysiology (includes Pharmacology and Optical Mapping) D-PO04 - Poster Session IV (ID 15) Poster

D-PO04-056 - Noninvasive Tracking Of Repolarization Gradients As A Substrate For Ventricular Fibrillation (ID 391)


Background: Heterogeneous repolarization can provide a substrate for ventricular fibrillation (VF), but it is poorly characterized from body surface.
Objective: Validate a novel metric of VF complexity progression from body surface maps (BSMs) in relation to repolarization dispersion.
Methods: VF was induced by programmed stimulation in 5 Langendorff pig hearts suspended in a human-shaped torso tank. Simultaneous BSMs (256 electrodes) and epicardial electrograms (108 electrode sock) were recorded with/without repolarization gradients created by local perfusion of dofetilide (late) and/or pinacidil (early) through distinct coronaries. VF complexity was measured by the nondipolar component index (NDI), i.e. the energy non-preserved by an equivalent 3D dipole from BSMs. NDI ability to assess distinct levels of complexity at each drug state was validated by differential cycle length (ΔCL) between sock electrograms at differently perfused sites and number and speed of short- (<2rotations) and long-lasting reentrant drivers (ΔRD) from phase mapping.
Results: Low NDI described more organized VF at early stage (Panel A). This was confirmed invasively by a uniform spatial distribution of CL (B) and RD properties (C-D), regardless of their life span. Drug-induced changes in electrical recovery were responsible for increased body surface complexity with higher NDI (E, p<0.0001), correlating with more pronounced differences between early and late repolarizing zones in terms of CL and RD number and speed. With drug washout, all parameters returned to starting values.
Conclusion: NDI may be used to noninvasively assess the impact of repolarization heterogeneity on VF complexity.