Thesis (M. S.)--University of Hong Kong, 2007. / Also available in print.

Thesis (M.S.)--Ohio State University, 2007. / Includes bibliographical references (leaves 70-73). Available online via OhioLINK's ETD Center

Thesis (M.S.)--Brigham Young University. Dept. of Mechanical Engineering, 2005. / Includes bibliographical references (leaves 61-64).

published_or_final_version / abstract / Surgery / Master / Master of Surgery

Thesis (Ph. D.)--University of Texas at Austin, 2003. / Vita. Includes bibliographical references. Available also from UMI Company.

The interaction between the mapping/ablation catheter and left atrial (LA) myocardium potentially affects the LA electrical and mechanical properties and impacts on ablation efficacy. Using catheters able to provide real-time contact force (CF) measurement, it has become possible to explore these relationships in vivo. In 60 persistent atrial fibrillation (AF) patients, ablation CF was higher in the right than left wide area circumferential (WACA) lines and where steerable transseptal sheaths were used. Differences were also apparent in the burden of WACA segment reconnection but did not just reflect differences in ablation CFs, suggesting factors other than CF contribute to ablation efficacy. Relationships between ablation force time integral (FTI), impedance drop and electrogram attenuation were assessed in 15 persistent AF patients. FTI significantly correlated with electrogram attenuation and impedance drop from ablation. The relationship was stronger for the former but in both cases plateaued at 500g.s, suggesting no ablation efficacy gains beyond this. Factors further affecting CF and ablation efficacy, the latter judged by impedance drop, were assessed in 30 patients. The variability of the CF waveform and catheter locational stability were both affected by factors including atrial rhythm and catheter delivery mode. Greater CF variability, catheter drift and perpendicular catheter contact were associated with reduced ablation efficacy. The relationship between CF and the electrogram was assessed in 30 patients. The size of the electrogram complexes was affected by CF increases but only where initial CF was <10g. This was also the case for electrogram fractionation measurements. Increasing CF was associated with an increasing incidence of atrial ~ 3 ~ ectopics during sinus rhythm. Spectral parameters (dominant frequency and organisation index) were unaffected by CF. Various factors affect the contact between the catheter and LA myocardium. In turn, catheter contact significantly affects the electrogram during LA mapping and the efficacy of clinical radiofrequency ablation.

Atrial Fibrillation (AF) is a debilitating heart rhythm disorder affecting over 2.7 million people in the US and over 30 million people worldwide annually. It has a high correlation with causing a stroke and several other risk factors, resulting in increased mortality and morbidity rate. Currently, the non-pharmocological therapy followed to control AF is catheter ablation, in which the tissue surrounding the pulmonary veins (PVs) is cauterized (called the PV isolation - PVI procedure) aims to block the ectopic triggers originating from the PVs from entering the atrium. However, the success rate of PVI with or without other anatomy-based lesions is only 50%-60%. A major reason for the suboptimal success rate is the failure to eliminate patientspecific non-PV sources present in the left atrium (LA), namely reentry source (a.k.a. rotor source) and focal source (a.k.a. point source). It has been shown from several animal and human studies that locating and ablating these sources significantly improves the long-term success rate of the ablation procedure. However, current technologies to locate these sources posses limitations with resolution, additional/special hardware requirements, etc. In this dissertation, the goal is to develop an efficient algorithm to locate AF reentry and focal sources using electrograms recorded from a conventionally used high-resolution multi-pole diagnostic catheter. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2019. / FAU Electronic Theses and Dissertations Collection

Not available / text

Diss. (sammanfattning) Stockholm : Karol. inst., 2006. / Härtill 4 uppsatser.

Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 113-118). Available also in a digital version from Dissertation Abstracts.