A Fibre-optic Catheter for Intracardiac Substrate Mapping and Radiofrequency Ablation Monitoring
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Open Access
Type
ThesisThesis type
Doctor of PhilosophyAuthor/s
Davey, Christopher JamesAbstract
Radiofrequency catheter ablation (RFCA) is the only curative therapy for drug refractory ventricular tachycardia (VT). The procedure is associated with suboptimal rates of arrhythmia recurrence due to inaccuracies in substrate maps and RF lesion monitoring. This thesis demonstrates ...
See moreRadiofrequency catheter ablation (RFCA) is the only curative therapy for drug refractory ventricular tachycardia (VT). The procedure is associated with suboptimal rates of arrhythmia recurrence due to inaccuracies in substrate maps and RF lesion monitoring. This thesis demonstrates that autofluorescence (AF) and diffuse reflectance (DR) spectroscopy have the potential to improve on performance of conventional electrical catheters in this space. A first study investigated used AF microscopy to quantify the composition of scarred myocardium in an ovine model of VT. AF spectral regression models determined heart tissue composition with a root mean square error (RMSE) of 14.9%, supporting the development of a novel optical catheter for in-vivo use. A novel fibre-optic catheter was deployed in the same ovine model both ex-vivo and in-vivo. Accurate (RMSE = 13.3%) quantification of tissue composition was achieved ex-vivo. An optical contact sensing algorithm was also derived for robust spectral acquisitions in-vivo in the presence of blood interference. In-vivo data was used to accurately separate scarred tissue from healthy. This study represents the first report of in-vivo AF substrate mapping, a major step towards the validation of this technology for clinical use. A third study investigated the AF depth sensitivity of the catheter ex-vivo. Detection depth of an exogenous fluorophore increased significantly with increasing excitation wavelength, reaching a maximum of 2.89 mm with 532 nm. Contact force had no effect on depth sensitivity, while that of fibre separation and fluorophore type were modest. In a final study, the optical catheter was used to investigate the effects of RF-induced thermal necrosis on tissue optics. 532 nm AF intensity was modestly correlated with RF lesion depth (R2 = 0.71). AF spectra were also capable of detecting steam pops in the absence of any electrical signal deviation, supporting further development towards a clinically feasible prototype.
See less
See moreRadiofrequency catheter ablation (RFCA) is the only curative therapy for drug refractory ventricular tachycardia (VT). The procedure is associated with suboptimal rates of arrhythmia recurrence due to inaccuracies in substrate maps and RF lesion monitoring. This thesis demonstrates that autofluorescence (AF) and diffuse reflectance (DR) spectroscopy have the potential to improve on performance of conventional electrical catheters in this space. A first study investigated used AF microscopy to quantify the composition of scarred myocardium in an ovine model of VT. AF spectral regression models determined heart tissue composition with a root mean square error (RMSE) of 14.9%, supporting the development of a novel optical catheter for in-vivo use. A novel fibre-optic catheter was deployed in the same ovine model both ex-vivo and in-vivo. Accurate (RMSE = 13.3%) quantification of tissue composition was achieved ex-vivo. An optical contact sensing algorithm was also derived for robust spectral acquisitions in-vivo in the presence of blood interference. In-vivo data was used to accurately separate scarred tissue from healthy. This study represents the first report of in-vivo AF substrate mapping, a major step towards the validation of this technology for clinical use. A third study investigated the AF depth sensitivity of the catheter ex-vivo. Detection depth of an exogenous fluorophore increased significantly with increasing excitation wavelength, reaching a maximum of 2.89 mm with 532 nm. Contact force had no effect on depth sensitivity, while that of fibre separation and fluorophore type were modest. In a final study, the optical catheter was used to investigate the effects of RF-induced thermal necrosis on tissue optics. 532 nm AF intensity was modestly correlated with RF lesion depth (R2 = 0.71). AF spectra were also capable of detecting steam pops in the absence of any electrical signal deviation, supporting further development towards a clinically feasible prototype.
See less
Date
2021Rights statement
The author retains copyright of this thesis. It may only be used for the purposes of research and study. It must not be used for any other purposes and may not be transmitted or shared with others without prior permission.Faculty/School
Faculty of Science, School of PhysicsAwarding institution
The University of SydneyShare