Rick Schreurs

113 Left and right ventricular response to CRT dP/dt max in the measurements was reached with a short A-LV (50ms) and A-RV (90ms). LV pre-excitation led to a larger increase in LV dP/dt max than RV pre-excitation during all measurements and simulation, with an optimal LV pre-excitation range of 10-50ms. For RV dP/dt max , all LV pre-excitation pacing settings led to a decrease up to 33% in the experiment and 18% in the simulations, while RV pre-excitation caused little change compared to baseline (RV-only) pacing. LV TAT (ms) Effect of changing VV-delay Effect of changing AV-delay 50 50 90 90 130 130 170 170 210 210 50 210 90 170 130 130 170 90 210 50 A-LV A-RV (ms) (ms) Increase in AV-delay LV first | RV first 70 90 100 80 60 40 80 0 -20 20 -40 VEU (ms) RV TAT (ms) A-LV (ms) 50 230 A-LV (ms) 50 230 A-LV (ms) 50 230 A-RV (ms) 50 230 A-RV (ms) 50 230 A-RV (ms) 50 230 100ms 66ms 75ms 39ms 27ms -43ms LV TAT (ms) ff t f i - l ff t f i - l VEU (ms) RV TAT (ms) Figure 3. Changes in electrical dyssynchrony indices during variation in pacing delay in the animal experiments. The left column shows the effect of increasing AV-delay during simultaneous RV+LV pacing; the middle column shows changes in VV-delay (yellow, from LV pre-excitation to RV pre-ex- citation) and the heat maps on the right are the results for all pacing setting (mean of 6 dogs, bars represent standard errors of the mean). From top to bottom: Total activation time (TAT) of the total LV (free wall and septum), RV free wall (RVFW) and VEU (ventricular electrical uncoupling). The green square in each heat map indicate the baseline pacing setting. 6