## Theses

#### Abstract

Scar-related VT is caused by local \textit{short circuits} of electrical propagation formed by slow-conducting channels of surviving tissue within a scar. Catheter ablation treats scar-related VT by destroying the critical channel of surviving tissues. Its efficacy heavily relies on how well the channels critical to the formation of VT circuits can be localized. Unfortunately, in current practice, this relies on invasive catheter mapping that falls short in several critical aspects: up to 90$\%$ of the VT circuits are too short-lived to be mapped, the mapping cannot be done non-invasively prior to the ablation procedure, and the mapping is restricted to one heart surface at a time. Electrocardiographic imaging (ECGi) is a noninvasive approach that reconstructs cardiac electrical signals from a very dense body surface electrocardiogram (ECG) in combination with patient-specific geometries of the heart and torso. In this dissertation, we investigate the clinical utility of ECGi in guiding catheter ablation of scar-related VT. Specifically, we investigate two open questions that are not well-understood in the potential of ECGi for mapping VT circuits. First, instead of commonly-used epicardial ECGi, we investigate the validity of simultaneous epicardial and endocardial ECGi mapping of VT circuits, and the possibility of using information from these two surfaces to infer the morphology of 3D circuits. Second, we investigate the integration of ECGi electrical information of VT circuits with magnetic resonance imaging (MRI) of scar analysis for joint electrical and structural delineation of the substrates for VT circuits. These studies were performed on a combination of computer simulation, animal model, and human subject data. Experimental results showed that epi-endo ECGi mapping could reconstruct VT circuits, differentiate 2D versus 3D circuits, and provide information about the location of the VT circuit beneath the surface. They also showed that integrated MRI-ECGi analysis offered a quantitative characterization of the scar substrate that forms a VT circuit. These outcomes showed that simultaneous epi-endo ECGi in the combination of MRI structural scar imaging may provide a viable augmentation to the current practice of invasive catheter mapping. It may help clinicians plan for the ablation prior to the procedure by equipping them with knowledge about a VT circuit's critical components, the surfaces that are involved, and the 3D morphology of the VT circuit.

9-2021

Dissertation

#### Degree Name

Computing and Information Sciences (Ph.D.)

#### Department, Program, or Center

Computer Science (GCCIS)

Linwei Wang

Pengcheng Shi