1. Epicardial Mapping from Venous Catheter Measurements, Body Surface Potential Maps, and an Electrocardiographic Inverse Solution Robert S. MacLeod, Yesim Serinagaoglu*, Bulent Yilmaz, and Dana H. Brooks* NEH Cardiovascular Research and Training Institute (CVRTI), U of Utah *Communications and Digital Signal Processing (CDSP), Northeastern U

2. Combining Information Sources Forward Inverse

3. Venous Catheter Based Mapping

4. Statistical Estimation Estimation Matrix Training Data Covariance Matrix * = Sparse Test Data Estimate

5. Estimated Activation Maps OriginalMixed RV-only LV-only Training set composition Lead selection

6. Augmented Inverse Problem Forward Inverse Torso geometry Body-Surface Potentials Sparse Epicardial Potentials Inverse Solution Epicardial Map + + +

7. Subtraction Approach KnownUnknown Inverse (Tikhonov) 1) Subtract known epicardial potentials 2) Solve reduced inverse problem

8. Epicardial Estimation t1t1 t 2 …..….t N... Estimation

9. Combined Estimation Estimation

10. Bayesian Approach Inverse (MAP) 

11. Hybrid Approach Inverse (MAP)  Estimate

12. Tank/Heart Geometry

13. Test Lead Sets Anterior Posterior 42 leads 21 leads10 leads

14. Simulation Study 490 lead measured sock data Surrogate catheter potentials –42 sites –+ Gaussian noise Torso potentials –Calculated noise-free using forward model –+ Gaussian noise

15. Leave-One-Experiment Out Protocol Training Data Dec 13, 2000 Test Data Dec 18, 2000 Dec 13, 2000 LV Paced Beats Mixed Paced Beats

16. LV Pacing (LV-23 ms) OrigSubtMAP Est EpiEst AllHybrid MAP 31: LV-MEpiP-23 ms

17. LV Pacing (LV-38 ms) OrigSubtMAP Est EpiEst AllHybrid MAP 31: LV-MEpiP-38 ms

18. LV Pacing (LV-47 ms) OrigSubtMAP Est EpiEst AllHybrid MAP 31: LV-MEpiP-47 ms

19. LV Pacing (Mixed-23 ms) OrigSubtMAP Est EpiEst AllHybrid MAP 31: LV-RV-MEpiP-23 ms

20. LV Pacing (Mixed-38 ms) OrigSubtMAP Est EpiEst AllHybrid MAP 31: LV-RV-MEpiP-38 ms

21. LV Pacing (Mixed-47 ms) OrigSubtMAP Est EpiEst AllHybrid MAP 31: LV-RV-MEpiP-47 ms

22. Relative Error (31-LV) 0102030405060708090100 0 0.2 0.4 0.6 0.8 1 1.2 1.4 Relative Error Time [ms] MAP Estim-Epi Estim-All MAP-Hybrid Subtr

23. Relative Error (31-Mixed) 0102030405060708090100 0 0.2 0.4 0.6 0.8 1 1.2 1.4 MAP Estim-Epi Estim-All MAP-Hybrid Subtr Relative Error Time [ms]

24. Estimation Findings Estimation alone: noisy, unstable results Estimation + inverse: smoothing improves stability

25. Inverse Solution Findings All solutions better than simple Tikhonov MAP usually improved with addition of catheter measurements (Hybrid MAP)

26. Role of Statistics (Training) Generally helps But can add artifacts, e.g., spurious breakthroughs or wavefronts Torso potentials can reduce artifacts

27. Conclusion More (bigger) is better….. … but not always