(A) Representative polar maps of a normal heart before VNS (baseline) and during VNS, with and without isoproterenol infusion. Polar maps of the same animal are also shown before and after CSD. Regardless of CSD, VNS prolongs ARI in all regions. (B) During isoproterenol infusion, percentage change in global ARI with VNS is potentiated both pre- and post-CSD (*P<0.01). (C) Changes in LV and RV regional ARIs are shown for normal hearts. CSD did not lead to any regional ARI differences. No significant differences across regional ARIs are observed with VNS before vs. after CSD. However, effects of VNS on regional ARI’s are greater with isoproterenol infusion vs. without (#P<0.05). ISP=isoproterenol, RVOT=right ventricular outflow tract.