Echocardiography has an prominent role in the era of CRT by virtue of its non-invasive nature with high feasibility and reproducibility. The clinical applications include not only quantification of the change in systolic function, hemodynamics, LV volume, or mitral regurgitation, but also assessment of systolic dyssynchrony. A number of new echocardiographic techniques were employed in this study, such as tissue Doppler imaging (TDI) and its post-processing modalities including strain, strain rate and displacement mappings, tissue synchronization imaging (TSI), as well as three-dimentional (3D) echocardiography. / For heart failure patients with wide QRS complexes who received CRT, LV volumes, cardiac function and synchronicity were shown to change acutely between CRT-on and CRT-off modes by both 2D and 3D echocardiography methods. Furthermore, the usefulness of 3D echocardiography and its accuracy in assessing volumetric changes / Systolic dyssynchrony, which illustrates discoordinated contraction of the heart, is relatively common in heart failure patients, in particular those with prolonged QRS complexes. It is caused by electromechanical delay in some regions of the failing heart and will result in further reduction of cardiac function. Cardiac resynchronization therapy (CRT) is a rapidly evolving pacing modality for advanced heart failure, characterized by implantation of the left ventricular (LV) lead through coronary sinus to the free wall region. It is recommended to patients who have refractory heart failure despite optimal medical treatment, LV dilatation with ejection fraction lower than 35%, and prolonged QRS duration on surface ECG. / The main findings were as followed: The Ts-SD was 17.0+/-7.8ms in normal control, 33.8+/-16.9ms in narrow QRS group and 42.0+/-16.5ms in wide QRS group, respectively. The prevalence of systolic dyssynchrony in heart failure population was 43% in the narrow QRS group, and 64% in the wide QRS group, when a Ts-SD of > 32.6 ms (+2 SD of normal controls) was used to define significant dyssynchrony. QRS duration does not have a linear relationship with systolic dyssynchrony. / TSI was useful to predict a reverse remodeling and gain in ejection fraction after CRT. Qualitative identification of the latest peak systolic contraction at the lateral wall was a quick and specific guide to predict a favorable reverse remodeling response while quantitative computation of "Asynchrony Index" from 12 LV segments in ejection phase was beneficial in the absence of lateral wall delay. In conclusion, the improvement of cardiac function and LV reverse remodeling after CRT is more obvious in heart failure patients with wide QRS complex and echocardiographic evidence of significant systolic dyssynchrony. Reverse remodeling is not only an objective measure of favorable responses, but also a prognosticator of disease outcomes. "Asynchrony Index" is a strong predictor of LV reverse remodeling response after CRT. Assessment of systolic dyssynchrony by various echocardiographic tools is promising, however, further studies are needed to compare the predictive values of different parameters objectively and prospectively. / We performed echocardiography with TDI in 200 subjects, including 67 patients with heart failure and narrow QRS complexes (≤ 120ms), 45 patients with heart failure and wide QRS complexes (>120ms), and 88 normal controls, which served as a polit study. Severity and prevalence of systolic dyssynchrony were assessed by the maximal difference in time to peak myocardial systolic velocity (Ts-dif-12) and the standard deviation (Ts-SD) of the 12 LV segments. / We recruited a group of seventy patients with chronic heart failure who fulfilled the established criteria and received CRT. Serial echocardiographic assessment with clinical evaluation was performed at baseline, predischarge, 1-month, 3-month, 6-month and long-term follow up. The objective was to demonstrate the improvement of cardiac function and dyssynchrony after CRT by echocardiographic parameters, in particular the reduction of LV end-systolic volume (LVESV) which is also known as reverse remodeling, and its relationship with the improvement in clinical status and prognosis. We also attempted to identify dyssynchrony parameters which are useful in predicting LV reverse remodeling after CRT. / Zhang Qing. / "October 2006." / Adviser: Yu Cheuk-Man. / Source: Dissertation Abstracts International, Volume: 68-09, Section: B, page: 5852. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract in English and Chinese. / School code: 1307.
| Identifer | oai:union.ndltd.org:cuhk.edu.hk/oai:cuhk-dr:cuhk_343829 |
| Date | January 2006 |
| Contributors | Zhang, Qing, Chinese University of Hong Kong Graduate School. Division of Medical Sciences. |
| Source Sets | The Chinese University of Hong Kong |
| Language | English, Chinese |
| Detected Language | English |
| Type | Text, theses |
| Format | electronic resource, microform, microfiche, 1 online resource (1 v. (unpaged) : ill.) |
| Rights | Use of this resource is governed by the terms and conditions of the Creative Commons “Attribution-NonCommercial-NoDerivatives 4.0 International” License (http://creativecommons.org/licenses/by-nc-nd/4.0/) |
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