• About
    • Login
    View Item 
    •   Institutional Repository Home
    • Electronic Theses and Dissertations
    • Electronic Theses and Dissertations
    • View Item
    •   Institutional Repository Home
    • Electronic Theses and Dissertations
    • Electronic Theses and Dissertations
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Browse

    All of Institutional RepositoryCommunities & CollectionsBy Issue DateAuthorsTitlesSubjectsDepartmentThis CollectionBy Issue DateAuthorsTitlesSubjectsDepartment

    My Account

    LoginRegister

    Measurement And Analysis Of Cardiac Tissue During Electrical Stimulation

    Holcomb, Mark Raymond
    : https://etd.library.vanderbilt.edu/etd-05232007-124842
    http://hdl.handle.net/1803/12368
    : 2007-05-30

    Abstract

    Over 300,000 deaths in the United States each year are caused by sudden cardiac death. The most common cause of sudden cardiac death is ventricular fibrillation. Once initiated, ventricular fibrillation in humans almost never terminates spontaneously. If allowed to persist, death usually occurs within minutes. The application of strong electric shocks, termed defibrillation, is a very effective and well-established method of terminating fibrillation, but the underlying dynamics are still not well understood. The goal of this research was to better understand the response of cardiac tissue to applied electric fields. The primary probes used in these studies are fluorescent dyes, whose spectra shift with changing transmembrane potential or intracellular calcium concentration. The fluorescence emitted by the dyes is collected via optical imaging techniques that yield data with high temporal spatial resolutions. Before the desired studies could be conducted, several instrumentation needs were addressed: 1. A flexible software library that can be used to control multiple high-speed CCD cameras, illumination, and electrical stimulation was developed. 2. Three microcontroller-based constant-current electrical stimulators capable of delivering complex biphasic stimulation sequences were designed and constructed. 3. A two-camera imaging system with camera calibration ability was assembled which allow simultaneous measurement of two dynamic quantities, Vm (Transmembrane Potential) and [Ca2+]i, (Intracellular Calcium Concentration) from the same spatial region. 4. A three-camera panoramic cardiac imaging system was designed, constructed, and validated to enable imaging of Vm over the entire epicardium. Many of these technological advances were used for a comprehensive study of Vm dynamics of an isolated and flattened right ventricle under field-shock conditions which produced a number of interesting observations. We observed a striking symmetric reversal of virtual anodes and virtual cathodes upon reversal of shock polarity. Clear relationships between field strength, electroporation, and virtual anodes were observed. We discovered a previously unreported dye artifact. We attempted the first reported correlation between Vm response to field shock and fiber direction obtained by diffusion tensor imaging.
    Show full item record

    Files in this item

    Icon
    Name:
    Mark_Holcomb_Dissertation.pdf
    Size:
    10.26Mb
    Format:
    PDF
    View/Open

    This item appears in the following collection(s):

    • Electronic Theses and Dissertations

    Connect with Vanderbilt Libraries

    Your Vanderbilt

    • Alumni
    • Current Students
    • Faculty & Staff
    • International Students
    • Media
    • Parents & Family
    • Prospective Students
    • Researchers
    • Sports Fans
    • Visitors & Neighbors

    Support the Jean and Alexander Heard Libraries

    Support the Library...Give Now

    Gifts to the Libraries support the learning and research needs of the entire Vanderbilt community. Learn more about giving to the Libraries.

    Become a Friend of the Libraries

    Quick Links

    • Hours
    • About
    • Employment
    • Staff Directory
    • Accessibility Services
    • Contact
    • Vanderbilt Home
    • Privacy Policy