Biophysical Modeling to Determine the Optimization of Left Ventricular Pacing Site and AV/VV Delays in the Acute and Chronic Phase of Cardiac Resynchronization Therapy

Figure 1. Top row: Clinical measurements of the LV endocardium electrical activation were taken using an ENSITE balloon catheter for case 2 with (A) atrial pacing and (B) biventricular (BiV) pacing. Middle row: The model parameters were fitted to the electrical activation of the heart with (A) atrial or (B) BiV pacing. (C) The models were then used to simulate the electrical activation of the heart at a range of LV epicardium sites. Bottom row: The simulated activation wave on the LV endocardium was projected onto the 17‐segment AHA map for the different scenarios.

Figure 2. Clinical (blue) and simulated (orange) pressure volume loops for the 3 patient cases before (ACUTE) and after at least 6 months of CRT treatment (CHRONIC).

Figure 3. The motion of the cardiac models during the cardiac cycle was validated against cine MR images.

Figure 4. The area where any 1 of the 9 combinations of AV/VVD timings would give an optimal response is shown (ACUTE: gray with solid outline; CHRONIC: brown with dashed outline). Areas of no overlap between the optimal regions for CHRONIC and ACUTE models are shown as striped. Regions in the CHRONIC models where all 9 of the AV/VVD combinations would give an optimal response are shown as yellow (dotted outline) for cases 1 and 3. There were no such regions in the ACUTE model and the CHRONIC model for case 2. The locations of the multipolar LV lead (blue), RV lead (red), and scar (green) are shown for all cases. The location of the maximal response for any of the 9 AV/VVD timings is shown as stars (ACUTE: gray; CHRONIC: brown).

Figure 5. The LV free wall was paced and the AHR was simulated at 49 locations with 9 AV/VVD settings in the ACUTE and CHRONIC time points for each case. The optimal LV pacing regions were defined as the LV sites within 70% of the global maximal AHR. The percentages of the 49 sites on the LV free wall that gives an optimal response for pacing with 1–9 of the simulated AV/VVD timing settings for the ACUTE and CHRONIC models are shown for the 3 cases.