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首页> 外文学位 >Investigation into Mechanisms of Functional Mitral Regurgitation by Advanced Echocardiographic Technologies - Dyssynchrony and Beyond.
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Investigation into Mechanisms of Functional Mitral Regurgitation by Advanced Echocardiographic Technologies - Dyssynchrony and Beyond.

机译：先进的超声心动图技术对功能性二尖瓣反流的机制的研究-不同步和超越。

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摘要

Cardiac resynchronization therapy (CRT) is an established therapy for patients with advanced congestive heart failure and prolonged QRS duration, aiming at correcting dyssynchrony in the left ventricle (LV). Apart from the beneficial effects on cardiac function and LV reverse remodeling, reduction in functional MR has been observed by Doppler echocardiography after CRT. On the other hand, functional mitral regurgitation (MR) in fact varies over the cardiac cycle that a biphasic pattern has been reported, i.e. early- and late-systolic peaks with a mid-systolic decrease in regurgitant flow. Nevertheless, it remains to be explored whether (1) the improvement of MR leads to a greater extent of LV reverse remodeling; (2) the different components (i.e. early- and late-systolic) of MR improve and their predictors if any.;We performed echocardiography with TDI and 2DSTE in 147 patients of both ischemic and non-ischemic etiologies with LV systolic dysfunction (defined as LV ejection fraction 50%) and 45 normal controls. MR severity, displacement of papillary muscle, mitral annular dilation and dysfunction, mitral leaflet tenting, LV remodeling and function were assessed by 2D and Doppler echocardiography. LV mechanical dyssynchrony indices were derived from TDI velocity. Myocardial strain (i.e. amount of deformation) in longitudinal, circumferential and radial directions and torsion (opposite rotational movement between apex and base of the heart) were measured by 2DTSE.;The main findings were as follows: LV global systolic dyssynchrony served as an independent predictor for the presence of significant functional MR in patients with LV systolic dysfunction. Although mitral valvular tenting area was the most powerful predictor, LV global systolic dyssynchrony added incremental value to mitral valve tenting area in predicting the presence of significant functional MR.;Despite comparable ejection fraction, higher degree of functional MR was associated with further impairment in short-axis myocardial deformation (circumferential and radial), but not with long-axis myocardial deformation. The degree of LV basal rotation was also lower in the MR patient group. Furthermore, the decrease in myocardial deformation was associated with greater extent of LV remodeling.;The improvement of functional MR was an independent predictor of LV reverse remodeling after CRT. The extent of LV reverse remodeling (reduction of LV end-systolic volume) was greatest in patients with improvement of MR, followed by those with "mild or no" MR at baseline, and was least in those without improvement of MR. CRT reduced functional MR by reducing both its early- and late-systolic components in heart failure patients. The reductions in LV end-systolic volume and dyssynchrony were related to the improvement of early-systolic MR, while the improvement of late-systolic MR was attributable to the reductions in mitral leaflet tenting and LV dyssynchrony.;In conclusion, LV global mechanical dyssynchrony play a role in determining the severity of functional MR in addition to mitral leaflet tenting in patients with LV systolic dysfunction. Functional MR is associated with further impairment of myocardial deformation, but with differential change in individual component of myocardial deformation. CRT reduces functional MR in both early- and late-systolic phases, by way of improvement in LV remodeling, LV dyssynchrony and mitral leaflet tenting. Meanwhile, the improvement of MR contributes to LV reverse remodeling after CRT. (Abstract shortened by UMI.)
机译：心脏再同步疗法（CRT）是针对晚期充血性心力衰竭和QRS持续时间延长的患者的既定疗法，旨在纠正左心室（LV）的不同步。除了对心脏功能和左室逆向重构的有益作用外，CRT后多普勒超声心动图还观察到功能性MR降低。另一方面，功能性二尖瓣关闭不全（MR）实际上在已报道双相模式的心动周期上有所变化，即收缩期早期和收缩期高峰，而收缩期血流减少。然而，是否（1）MR的改善会导致更大程度的LV反向重塑尚待探索。 （2）MR的不同组成部分（即收缩早期和晚期）改善及其预测指标（如果有）。我们对147例患有LV收缩功能障碍（定义为LV）的缺血性和非缺血性病因的患者进行了TDI和2DSTE超声心动图检查左室射血分数<50％）和45个正常对照。通过2D和多普勒超声心动图评估MR严重程度，乳头肌移位，二尖瓣环扩张和功能障碍，二尖瓣小叶展张，左心室重塑和功能。左室机械不同步指数是从TDI速度得出的。通过2DTSE测量纵向，周向和径向方向上的心肌应变（即变形量）和扭转（心尖与根部之间的相对旋转运动）。主要发现如下：LV整体收缩不同步是独立的左室收缩功能不全患者中重要功能性MR的存在的预测因子。尽管二尖瓣帐篷区是最有力的预测指标，但LV全球收缩期不同步增加了二尖瓣帐篷区的增加值，以预测是否存在重要的功能性MR。尽管射血分数相当，但功能性MR的较高程度与短时间内的进一步损害相关轴心肌变形（周向和径向），但不伴长轴心肌变形。在MR患者组中，LV基础旋转的程度也较低。此外，心肌变形的减少与左室重构的程度更大有关。功能性MR的改善是CRT后左室重构的独立预测因子。在MR改善的患者中，LV反向重塑的程度（LV收缩末期容积的减少）最大，其次是基线MR为“轻或无”的患者，而在未改善MR的患者中则最小。 CRT通过减少心力衰竭患者的收缩期早期和晚期成分来降低功能性MR。左室收缩末期容积和不同步性的降低与早期收缩期MR的改善有关，而收缩末期MR的改善归因于二尖瓣小叶形成和左室不同步性的减少。左室收缩功能不全的患者，除二尖瓣小叶张开术外，在确定功能性MR的严重性方面也起着作用。功能性MR与心肌变形的进一步损害有关，但与心肌变形的各个组成部分的差异性变化有关。 CRT通过改善LV重塑，LV不同步和二尖瓣小叶展张降低了收缩期早期和晚期的功能性MR。同时，MR的改善有助于CRT后左心室反向重构。 （摘要由UMI缩短。）

著录项

  • 作者

    Liang, Yujia.;

  • 作者单位

    The Chinese University of Hong Kong (Hong Kong).;

  • 授予单位 The Chinese University of Hong Kong (Hong Kong).;
  • 学科 Health Sciences Medicine and Surgery.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 193 p.
  • 总页数 193
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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