Advisory Committee Chair
Jack Rogers
Document Type
Dissertation
Date of Award
2024
Degree Name by School
Doctor of Philosophy (PhD) School of Engineering
Abstract
Electrical excitation and mechanical function are integral to the physiologic activity of both the heart and stomach. Electrical depolarization through the myocardium triggers contraction in the heart. When normal sequences of electrical activity are disturbed, the heart’s mechanical function may also be disturbed, affecting its ability to pump blood effectively, sometimes fatally. Similarly, electrical waves called slow waves initiate gastric peristalsis. Abnormalities in slow wave propagation patterns can disturb the stomach’s ability to mechanically process gastric contents, sometimes resulting in delayed gastric emptying, nausea, and vomiting. The relationship between mechanical function and electrophysiology is not unidirectional, though. Mechanical stimuli can also influence and alter the electrophysiology of both organs. For example, mechanical stimulation can cause ectopic beats in the heart, and preliminary evidence shows the same is true in the stomach. Electromechanical activity in both the heart and stomach is bi-directional. Recently, optical electromechanical mapping has emerged as a novel tool for studying intact organ electromechanics. Presently, though, the tool is limited to ex vivo cardiac preparations. This limitation precludes the study of the heart in its native physiologic environment with dynamic mechanical loading and under neurohormonal influence. Additionally, the study of electromechanics using this system is limited to the heart. Herein, we address these limitations with two principal aims: first, we developed and validated a method of optically electromechanically mapping an in vivo porcine heart. Furthermore, we demonstrated potential use cases, including mapping during vagal stimulation, a fibrillation/defibrillation event, and post induced ischemia. Secondly, we expanded our method from the heart to the stomach. With our new tool, we demonstrate it is capable of imaging slow wave and contraction propagation simultaneously. Additionally, we probe into the effects of non-antegrade slow wave propagation on contractile activity. In summary, this project enabled the future study of simultaneous electrophysiologic and mechanical activity of both the normal and pathologic heart and stomach in an in-vivo setting at high spatiotemporal resolution.
Recommended Citation
Patton, Haley Nesmith, "Electromechanical Mapping Of The In Vivo Porcine Heart And Stomach" (2024). All ETDs from UAB. 3842.
https://digitalcommons.library.uab.edu/etd-collection/3842