【作者】 陆景；

【导师】 尹立雪； 王志刚；

【作者基本信息】 重庆医科大学 ， 影像医学与核医学， 2010， 硕士

【摘要】 目的:应用超声三维斑点追踪成像技术评价并比较不同位点心室单点双极起搏对健康犬左心室壁机械同步性和左心室功能的影响,为临床优化人工心脏起搏位点提供基础实验数据。材料与方法:分别采集10只健康开胸比格犬基础状态和右心室心尖、左心室心尖、左心室侧壁起搏状态一个完整心动周期的左心室全容积实时图像;同步记录左心室压力变化时间曲线并获取左心室射血压力和收缩期压力最大上升速率。用超声三维斑点追踪分析软件分别提取不同状态左心室壁径向三维应变图、左心室壁径向三维应变峰值和左心室收缩末期容积、舒张末期容积、射血分数、每搏输出量、心输出量。定性观察并比较不同状态左心室壁不同心肌节段的径向三维应变同步性。采用相应的参数检验或非参数检验方法比较不同状态同类定量参数;不同状态左心室壁整体径向三维应变峰值分别与左心室容量参数、压力参数之间进行直线相关分析。结果:(1)定性观察结果:①基础状态左心室壁16个不同心肌节段的径向三维应变的时空变化并非完全同步,表现为“有序不同步”。②各个不同起搏状态左心室壁16个心肌节段的径向三维应变的时空变化均失去基础状态的“有序不同步”特征,且左心室心尖或侧壁起搏状态左心室壁不同心肌节段的径向三维应变不同步程度较右心室心尖起搏状态明显。(2)定量分析结果:①与基础状态比较:右心室心尖起搏状态左心室壁基底后间隔和基底下壁的径向三维应变峰值减低(P<0.05);左心室心尖起搏状态整个左心室壁心尖部、中后壁、中侧壁、中前壁、中前间隔和中后间隔等9个心肌节段的径向三维应变峰值减低(P<0.05);左心室侧壁起搏状态整个左心室壁心尖部、中后壁、中侧壁、中前壁、中前间隔和基底前壁等9个心肌节段的径向三维应变峰值减低(P<0.05);各个不同起搏状态左心室壁部分心肌节段的径向三维应变峰值较基础状态略有增高,但差异无统计学意义(P>0.05)。②左心室心尖或侧壁起搏状态左心室壁径向三维应变峰值较基础状态显著减低的心肌节段数多于右心室心尖起搏状态(均为9/16对2/16, P<0.05)。③左心室心尖或侧壁起搏状态左心室壁整体径向三维应变峰值和左心室每搏输出量、射血分数、心输出量均低于右心室心尖起搏状态(P<0.05)。不同起搏状态间左心室压力参数差异无统计学意义(P>0.05)。④不同状态左心室壁整体径向三维应变峰值分别与左心室每搏输出量、射血分数、心输出量呈线性正相关(P<0.05),但未能与左心室压力参数建立直线相关关系(P>0.05)。结论:基于超声三维斑点追踪成像技术的左心室功能评价结果提示:(1)不同位点心室单点双极起搏均会破坏健康犬左心室壁各心肌节段的机械同步性,且左心室心尖或侧壁起搏的破坏作用较右心室心尖起搏明显。(2)不同位点心室单点双极起搏均导致左心室壁部分心肌节段收缩功能减低,且左心室心尖或侧壁起搏导致左心室壁节段收缩功能减低的范围较右心室心尖起搏广。(3)左心室心尖或侧壁起搏对健康犬左心室功能的损害超过右心室心尖起搏。(4)超声三维斑点追踪成像技术为医学工作者洞察左心室功能状态提供了新视窗,有望在心脏疾病电生理治疗的基础研究和临床应用方面发挥作用。更多还原

【Abstract】 Objective: To evaluate and to compare the effects of the one point dipolar pacing at various ventricular sites on the mechanical synchrony of left ventricular wall and its effects on the left ventricular function using echocardiographic three-dimensional (3D) speckle tracking, so as to provide basic experimental database for optimizing the sites of the artificial cardiac pacing in clinic conditions.Method: The open-chest modes for cardiac pacing were prepared in 10 healthy beagles. The full volumetric real-time images of the left ventricle in one completed cardiac cycle were acquired respectively during baseline (BASE) and at the right ventricular apex pacing (RVAP), the left ventricular apex pacing (LVAP), the left ventricular lateral wall pacing (LVLP) states. The left ventricular pressure-time curves were recorded simultaneously for achieving left ventricular ejection pressure and the maximal upstroke velocity of left ventricular systolic pressure. The radial 3D strain maps and the peak radial 3D strain of the left ventricular wall, as well as the left ventricular end systolic volume, end diastolic volume, stroke volume, ejection fraction, cardiac output at different states were extracted respectively using echocardiograic 3D speckle tracking analysis software. The radial 3D strain synchrony of left ventricular wall during different states was qualitatively observed and compared. The pertinent parameter test and non-parameter test were applied for comparing the same kind quantitative parameters of the various states; and the linear correlation analyses were applied respectively between the peak global radial 3D strain of the left ventricular wall and the left ventricular volumetric parameters, as well as the pressure parameters.Results: (1) The results of the qualitative observation:①The temporospatial changes of the radial 3D strain in the 16 myocardial segments of the left ventricular wall was not completely synchronic at the BASE, and embodied the characteristic of“orderly asynchrony”.②The“orderly asynchrony”in the 16 myocardial segments of the left ventricular wall disappeared at all the various pacing states. Further more, the temporospatial asynchrony in the different myocardial segments of the left ventricular wall was worse at the LVAP or the LVLP state than that of the RVAP state. (2) The results of the quantitative analysis:①To be compared with the BASE: The peak radial 3D strain decreased significantly in the left ventricular basal post-septum and the basal inferior wall at the RVAP state (P < 0.05). The peak radial 3D strain decreased significantly in 9 myocardial segments of the left ventricular wall at the LVAP state; including the whole left ventricular apex, the middle-post wall, the middle-lateral wall, the middle-anterior wall, the middle anterior-septum, and the middle post-septum (P<0.05). The peak radial 3D strain decreased significantly in 9 myocardial segments of the left ventricular wall at the LVLP state; including the whole left ventricular apex, the middle-post wall, the middle-lateral wall, the middle-anterior wall, the middle anterior-septum, and the basal anterior wall (P<0.05). The peak radial 3D strain in some myocardial segments of the left ventricular wall increased at various pacing states, but has no statistical significance (P>0.05).②There were more parafunctional myocardial segments,which peak radial 3D strain decreased significantly, within the left ventricular wall at the LVAP or the LVLP state than those of the RVAP state (both comparisons are 9/16 vs 2/16,P<0.05).③To be compared with the RVAP state; the peak global radial 3D strain of the left ventricular wall and the left ventricular stroke volume, ejection fraction, cardiac output decreased at the LVAP or the LVLP state (P<0.05). But the comparisons of the left ventricular pressure parameters between various pacing states has no statistical significance (P>0.05).④There were statistic significant linear correlations between the peak global 3D strain of the left ventricular wall with the left ventricular stroke volume, and the ejection fraction, as well as the cardiac output in different states (P<0.05); but the linear correlation with the left ventricular pressure parameters was not established in all states (P>0.05).Conclusion:The study results of the left ventricular function, which based on the echocardiographic 3D speckle tracking technique, hint that: (1) All the one point dipolar pacing modes at the various ventricular sites in our study have destructive effects on the mechanical synchrony of the left ventricular wall, and the destructive effects of the LVAP or the LVLP are stronger than those of the RVAP. (2) All the one point dipolar pacing modes at the various ventricular sites have negatively affects on the systolic function of some myocardial segments within the left ventricular wall, and the region of pacing-induced dysfunction within the left ventricular wall is wider during the LVAP or the LVLP than that of the RVAP. (3) AS far as the destructive effects on the left ventricular function of healthy canine are concerned, the LVAP or the LVLP mode is more harmful than the RVAP mode. (4) Echocardiographic 3D speckle tracking technique provides medical workers with new visual pathway for insighting the left ventricular function, and may contribute its advantages to the electrophysilogical therapy of heart diseases at the scope of basic studies and clinical applications.更多还原