Title:
New methods for quantifying the synchrony of contraction and relaxation in the heart

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dc.contributor.advisor Oshinski, John N.
dc.contributor.author Fornwalt, Brandon Kenneth en_US
dc.contributor.committeeMember Fyfe, Derek A.
dc.contributor.committeeMember León, Angel R.
dc.contributor.committeeMember Skrinjar, Oskar
dc.contributor.committeeMember Taylor, W. Robert
dc.contributor.department Biomedical Engineering en_US
dc.date.accessioned 2008-09-17T19:52:58Z
dc.date.available 2008-09-17T19:52:58Z
dc.date.issued 2008-06-12 en_US
dc.description.abstract Synchronous contraction and relaxation of the myocardium is required to optimize cardiac function. Regional timing of contraction and relaxation is dyssynchronous in many patients with heart failure. Cardiac resynchronization therapy (CRT) is a highly successful treatment for dyssynchronous heart failure. Patients are currently selected for CRT using surface electrocardiogram QRS duration as a measure of dyssynchrony. However, up to 30% of patients selected for CRT show no improvement. This poor response rate may in part be explained by the poor correlation between mechanical dyssynchrony and QRS duration. Thus, better methods to quantify mechanical dyssynchrony in the heart may improve the poor CRT response rate. The overall goal of this project was to develop better methods to diagnose dyssynchrony in the left ventricle (LV). We developed two new methods with different approaches. The first method improved upon existing tissue-Doppler based echocardiographic diagnosis of dyssynchrony by utilizing a cross-correlation (XC) function to quantify dyssynchrony during post-processing as opposed to the quantitatively simplistic time-to-peak analysis that is currently utilized. The second method utilized standard cine cardiac magnetic resonance (CMR) images to quantify the dyssynchrony in the flow of blood within the LV, which may represent a more direct, physiologically relevant measure of dyssynchrony. Specific aim 1 demonstrated that the new XC delay parameters can be quantified accurately with a stationary region of interest and therefore require significantly less post-processing time to calculate compared to the time-to-peak dyssynchrony parameters. Specific aim 2 showed that XC delays are superior to existing time-to-peak dyssynchrony parameters at discriminating patients with LV dyssynchrony from those with normal function. The time-to-peak parameters showed dyssynchrony in approximately half of the normal, healthy volunteers while the XC delay parameters had nearly perfect diagnostic accuracy. The results of specific aim 3 showed that XC delays could diagnose acute, pacing-induced dyssynchrony in young, healthy children with 79% accuracy while the time-to-peak parameters showed accuracies of 71%, 57% and 57%. Specific aim 4 showed that CMR-based quantification of LV internal flow can be used to discriminate patients with dyssynchronous heart failure from normal controls with 95% accuracy. en_US
dc.description.degree Ph.D. en_US
dc.identifier.uri http://hdl.handle.net/1853/24800
dc.publisher Georgia Institute of Technology en_US
dc.subject Tissue doppler en_US
dc.subject Echocardiography en_US
dc.subject Heart failure en_US
dc.subject Magnetic resonance imaging en_US
dc.subject Ventricular asynchrony en_US
dc.subject Ventricular dyssynchrony en_US
dc.subject Cardiac resynchronization en_US
dc.subject.lcsh Coincidence
dc.subject.lcsh Heart beat
dc.subject.lcsh Heart Contraction
dc.subject.lcsh Diastole (Cardiac cycle)
dc.subject.lcsh Cardiac pacing
dc.subject.lcsh Heart Left ventricle Diseases Treatment
dc.title New methods for quantifying the synchrony of contraction and relaxation in the heart en_US
dc.type Text
dc.type.genre Dissertation
dspace.entity.type Publication
local.contributor.advisor Oshinski, John N.
local.contributor.corporatename Wallace H. Coulter Department of Biomedical Engineering
local.contributor.corporatename College of Engineering
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relation.isOrgUnitOfPublication da59be3c-3d0a-41da-91b9-ebe2ecc83b66
relation.isOrgUnitOfPublication 7c022d60-21d5-497c-b552-95e489a06569
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