Abstract
Non-invasive electrocardiographic imaging has been developed to overcome the challenges and limitations of the standard 12-lead ECG and invasive cardiac mapping. It utilizes high density body surface ECG signals and patient specific heart-torso geometry to reconstruct cardiac electrical activity. Body surface ECG signals are contaminated with different types of noise such as baseline wander, line frequency noise, and high frequency artifacts that impact the inversely reconstructed cardiac electrical activity. In addition, inevitable missing electrodes due to electrode disconnection, applying defibrillation pads, and/or applying CARTO electrode patches affect the inverse reconstruction of cardiac electrical activity. This thesis aims to study the impact of different filtering techniques that comply with international recommendations for ECG diagnostic and medical devices on the inverse reconstruction of cardiac electrical activity. In addition, the impact of using different interpolation methods including the hybrid method that is developed in this thesis on the reconstructed cardiac electrical activity is evaluated. Furthermore, this thesis compares between different methods of estimating the activation time including the temporal and spatiotemporal methods from the reconstructed electrograms.Although there was no substantial difference in the inverse solution between the filter that has a bandwidth of 0.5 – 150 and notched at 50 Hz and the filter with a bandwidth of 0.5 – 40 Hz, it is recommended to use the former because the latter resulted in smoother reconstructed electrograms and a shifted activation time map.
The developed hybrid interpolation method estimated the missing data in body surface ECG signals better than other interpolation methods. The ECG median CC values were
0.992, 0.979, and 0.977 for the hybrid interpolation, Laplacian interpolation, and PCA interpolation respectively. However, the Inverse forward interpolation performed best when the reconstructed cardiac electrical activity was considered for comparing the performance especially when the missing electrodes has low peak-to-peak amplitudes. The median CCEGM increases from 0.619 without interpolation, to 0.656 when interpolating 11 electrodes using the IF interpolation.
The spatiotemporal method performed better than the temporal method in estimating the activation times from the reconstructed electrograms. The CC values increased from 0.81 to 0.9 in Utah2. The same trend was noticed in the rest of the datasets. In addition, in the spatiotemporal method, using only the QRS part for estimating the activation time resulted in a better estimation as compared with using the whole beat.
| Date of Award | Oct 2021 |
|---|---|
| Original language | English |
| Sponsors | INTERREG IVA administered by the SEUPB. |
| Supervisor | Jim McLaughlin (Supervisor) & Dewar Finlay (Supervisor) |
Keywords
- ECG imaging
- IF interpolation
- Laplacian interpolation
- hybrid interpolation
- body surface potential mapping
- inverse electrocardiography