Basic/Translational Science -> Intact Heart Electrophysiology (includes Pharmacology and Optical Mapping) D-BT01 - Cardiac Electrophysiology Society (CES): Lunch and Young Investigator Award Poster Session (ID 41) Special Session

D-BT01-05 - Relationship Between VF Dynamics And Repolarization-based Electrical Substrates (ID 12)

 L.R. Bear: Nothing relevant to disclose.


Background: Ventricular fibrillation (VF) dynamics in primary electrical disorders have been shown to highlight areas relating to arrhythmogenesis, but the relationship with underlying repolarization substrates is not fully understood.
Objective: To determine the impact of repolarization time (RT) gradients on VF in structurally normal hearts
Methods: Langendorff perfused pig hearts (n=5) were selectively perfused pinacidil (Pin; shortening ARI) and dofetilide (Dof; prolonging ARI) through the LAD and non-LAD coronaries respectively to produce RT gradients. VF was induced during (i) baseline (no drugs), (ii) Dof-ony and (iii) Dof+Pin perfusion using an S1S2 protocol at two S2 trigger locations. Unipolar electrograms were recorded during 30s of perfused VF from a 108 electrode sock. In sinus rhythm, Activation-reocvery intervals (ARI) were computed. In VF, cycle lengths (CL) were computed and reentrant activity evaluated using phase mapping.
Results: A baseline ARI gradient (ΔARI=59ms) between LAD and non-LAD perfusion beds increased with Dof-only (ΔARI=98ms) and Dof+Pin (ΔARI=142ms) perfusion. During the initial 10s of VF, CL decreased rapidly (SD=12ms) with the spatial distribution depending on S2 location and ΔARI. CL values for the remaining 20S (SD=1ms) with no change in driver number (p=0.1) and no longer depended on S2 location. During this period, VF was more complex for greater ΔARI, with a larger CL gradient (R2=0.70) and drivers rotated faster in the LAD than non-LAD perfusion bed (p<0.01).

Conclusion: While trigger location influences the initial stage of VF, repolarization gradient substrates impact VF dynamics throughout its duration.