Browsing by Subject "Left bundle branch block"
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Item The Non-Invasive Application of Electrocardiography in the Optimization of Cardiac Resynchronization Therapy(2020-08) Harbin, MichelleCardiac resynchronization therapy (CRT) is intended to reverse electrical dyssynchrony and improve systolic function in heart failure patients. However, roughly 30% of recipients do not clinically or echocardiography benefit, despite advancements with implant techniques and pacing technology, and are considered to be non-responders (Auricchio & Prinzen, 2011). Suboptimal postoperative device programming of the interventricular and atrioventricular delays, and the left ventricular (LV) pacing vector in quadripolar leads, is thought to be a prevailing cause of this persistent non-response (Mullens et al., 2009). Device optimization of pacing configurations is highly underutilized, and research has yet to establish a standardized, patient-specific methodology that can be routinely used in outpatient heart failure clinics (Gras, Gupta, Boulogne, Guzzo, & Abraham, 2009; N. Varma et al., 2019). The use of electrocardiography in device optimization is supported by the notion that synchronous ventricular electrical activation is a requisite for adequate systolic and diastolic function (Nguyen, Verzaal, van Nieuwenhoven, Vernooy, & Prinzen, 2018). Electrocardiography has furthermore shown promise in routine CRT device optimization owning to its non-invasive, inexpensive, and practical attributes. QRS duration shortening during the paced rhythm, as well as metrics of wavefront fusion and cancellation, on 12-lead electrocardiograms have been reported to correlate with subsequent LV reverse remodeling (Gage et al., 2018; Sweeney et al., 2014; Sweeney et al., 2010). Innovations in technology allow for the application of multiple unipolar electrodes placed over the upper anterior and posterior torso (Bank et al., 2018; Johnson et al., 2017; Rickard et al., 2020). The intent of this technology, as depicted in its ability to simultaneously acquire ventricular activation from both anterior and posterior surfaces, is to provide a better assessment of electrical dyssynchrony relative to that of a 12-lead electrocardiogram. Previous reports have shown that this technology can accurately, non-invasively, and efficiently measure electrical heterogeneity in patients with CRT devices (Gage et al., 2017). The purpose of this dissertation is to use this technology to: (1) quantify how a device-based pacing algorithm improves electrical resynchronization, and (2) evaluate the therapeutic window on the corresponding potential of electrical resynchronization during left ventricular unipolar pacing.