斑点追踪技术评价犬急性心肌缺血及再灌注心内膜下心肌和心外膜下心肌径向应变

目的应用斑点追踪技术检测犬急性心肌缺血及再灌注不同时间点心内膜下心肌和心外膜下心肌的径向应变。方法选取20只健康成年杂种犬,结扎左冠状动脉第一对角支,分别对结扎前、结扎即刻、60、120和180min及再灌注即刻、60和120min基底水平、乳头肌水平和心尖水平心内膜下和心外膜下心肌的径向应变进行比较。结果在急性缺血过程中,基底水平心肌起代偿作用,其径向应变上升;乳头肌水平和心尖水平心肌下降明显,心尖水平心肌甚至出现反向运动。在急性缺血及再灌注过程中,心内膜下心肌对缺血更加敏感。再灌注后,乳头肌水平和心尖水平心内膜下和心外膜下心肌及跨壁的径向应变仍低于基础状态。结论斑点追踪技术可以评价犬局部及整体心脏功能,并判断急性心肌缺血的透壁程度。     

应用斑点追踪技术对急性心肌缺血及再灌注心肌应变功能的研究

目的 应用斑点追踪技术(STI)检测急性心肌缺血及再灌注不同时间点心内膜下心肌和心外膜下心肌圆周应变的改变.方法 选取20只健康成年杂种犬,结扎左冠状动脉第一对角支,分别对结扎前、结扎即刻、结扎60、120 min和180 min及再灌注即刻、60 min和120min、基底水平、乳头肌水平和心尖水平心内膜下心肌和心外膜下心肌的圆周应变进行比较.结果 (1)在急性缺血过程中基底水平心肌圆周应变上升(P＜0.01).乳头肌水平和心尖水平心肌圆周应变下降(P＜0.01),心尖水平心肌甚至出现反向运动.再灌注后,基底水平圆周应变下降,无统计学意义(P＞0.05),乳头肌水平和心尖水平圆周应变上升(分别为P＜0.01,P＜0.05),但仍低于基础状态.(2)在急性缺血及再灌注过程中,心内膜下心肌对缺血更加敏感.(3)再灌注后心肌出现再灌注损伤.结论 斑点追踪技术可以客观定量局部及整体的心脏功能并判断心肌梗死的透壁程度及评价冠脉再通后的疗效.     

斑点追踪技术对研究心肌再灌注损伤的应用价值

目的：应用斑点追踪技术研究再灌注损伤对心肌收缩功能的影响。方法：将20只健康成年杂种犬左冠状动脉第一对角支下方结扎180 min并再灌注120 min，分别对结扎前、结扎即刻、结扎180 min及再灌注即刻、60 min和120 min基底水平、乳头肌水平和心尖水平心肌的圆周应变进行比较。结果：基底水平心肌再灌注即刻圆周应变下降，再灌注后上升，高于基础状态。乳头肌水平心肌再灌注后圆周应变上升，仍低于基础状态，没有显著性差异。心尖水平心肌再灌注后上升，低于基础状态且有显著性差异。结论：斑点追踪技术能够客观准确的评价再灌注损伤对心肌收缩功能的影响，为尽早解除冠脉梗阻状态及治疗方案的选择提供有效的参考指标。     

斑点追踪显像技术评价心肌缺血再灌注对心肌扭转影响的实验研究

目的 应用斑点追踪显像技术测定心肌缺血及再灌注后不同时刻的心肌扭转.方法 14只小型猪,随机分为两组:A组结扎前降支1 min,B组结扎前降支15 min.分别测定结扎前、解除结扎前及解除结扎后第1、5、30、60、90 min、1周各时间点常规心脏超声指标以及扭转数据,并进行比较.结果 缺血时A组心尖部及左室心内膜下扭转角度峰值再灌注后第1 min即恢复至基线水平;而B组相同扭转指标再灌注后30min出现一过性改善,相对于解除结扎前分别为(6.5±0.8).对(3.4±1.2).和(7.8±1.0)°对(6.1±1.1).(P均＜0.01),完全恢复则在再灌注后1周.B组心外膜下扭转角度峰值再灌注后呈逐渐上升趋势.结论 心肌缺血时间不同,再灌注前后心内、外膜下心肌扭转角度改变不尽相同.应用斑点追踪显像技术测定再灌注后心肌扭转恢复情况可以反映心肌缺血程度,从而为评价心肌缺血提供更长时间的观察窗.     

斑点追踪显像技术评价心肌扭转与心肌梗死范围相关性的实验研究

目的 应用斑点追踪显像技术评价急性心肌梗死(AMI)再灌注前、后左室心肌扭转,借以比较多个常规扭转指标与梗死范围的相关性,找出最能反映梗死范围的扭转指标.方法 小型猪15只,结扎左前降支120 min,分别检测结扎前、结扎后120 min、解除结扎后30 min、60 min、90 min、12 h各时间点常规超声指标以及扭转数据并进行比较.氯化硝基四氮唑蓝染色后计算心肌梗死范围.结果 AMI后心尖及左室各旋转/扭转角度指标均显著下降,再灌注12 h无明显改善.AMI即刻,左室整体扭转角度峰值及心尖整体旋转角度峰值与梗死范围的相关性明显优于同期其他扭转指标,相关系数分别为-0.81和-0.69(P均＜0.01);再灌注12 h相关性依然较好.结论 在AMI即刻及再灌注12 h内,左室整体扭转角度峰值及心尖整体旋转角度峰值是反映心肌梗死范围最敏感的扭转指标.

Abstract：

Objective To investigate the most sensitive markers of left ventricular(LV) torsion which can reflect infarct size by assessing the relationship between routine markers of LV torsion and infarct size using speckle tracking imaging (STI).Methods Fifteen open-chest pigs underwent 120 minutes of left anterior descending (LAD) ligation followed by 12 hours of reperfusion.Rotation and torsion of LV were obtained by STI before LAD occlusion,LAD occlusion immediately,and 30,60,90 minutes and 12 hours after reperfusion.Infarct size was measured by nitrotetrazolium blue chloride staining.Results LAD ligation resulted in a dramatic decrease in both subepicardial and subendocardial peak apical rotation or peak LV torsion.Twelve hours after reperfusion,all of the peak rotation and torsion remained significantly reduced (P ＜ 0.01 versus AMI).At AMI,peak bulk LV torsion and peak bulk apical rotation inversely correlated with infarct size (r = - 0.81,P ＜0.01; r = - 0.69,P ＜0.01).There existed the good relationship at 12-hour follow-up after reperfusion.The relationship was superior to that of other torsion markers.Conclusions Peak bulk LV torsion and peak bulk apical rotation are the most sensitive markers of LV torsion which can reflect infarct size.     

应变及应变率成像评价急性缺血再灌注局部心肌收缩功能的实验研究

目的：本实验旨在探讨用应变及应变率成像评价缺血再灌注心肌局部功能的可行性。方法：14只健康杂种犬麻醉后开胸，于第一对角支起点以下套扎冠状动脉左前降支，结扎后30min，再灌注120min，建立缺血再灌注模型。分别于结扎前、结扎后30min，再灌注后30min、60min、120min，采集连续3个心动周期组织速度图，用应变及应变率软件分析左室前壁各节段应变及应变率曲线。Simpson’s双平面法测量左室射血分数（LVEF），舒张末（EDV）及收缩末容积（ESV）。结果：14只犬中12只成功建立缺血再灌注模型。结扎后30min，左室前壁缺血节段收缩期峰值应变（εpeak），应变率（SRpeak）明显降低（P<0.05），再灌注30min后缺血节段εpeak及SRpeak进一步减低，再灌注60min及120min后εpeak 及SRpeak有所恢复，但仍未达到结扎前水平。LVEF，EDV，ESV于冠脉结扎前后差异无显著意义（P>0.05）。结论：应变及应变率能定量评价局部心肌运动异常。可以做为评价局部心肌缺血再灌注心肌功能的指标。     

斑点追踪成像技术评价犬急性缺血再灌注左室功能

目的探讨二维斑点追踪成像(STI)技术测量实验犬的等容收缩期加速度指标在评价左室功能方面的价值。方法将14只健康杂种犬建立急性心肌梗死再灌注模型,分别于基础状态,结扎即刻、30 min、120 min、180 min及再灌注即刻、60 min、120 min行超声心动图检查,应用STI技术测量并计算左室心肌等容收缩期径向加速度和圆周加速度。结果缺血节段的等容收缩期圆周加速度和径向加速度自梗死30 min开始降低,且随梗死时间延长而减低(均P0.05);恢复再灌注后,各梗死节段的等容收缩期加速度逐渐升高(均P0.05)。结论二维STI技术所测等容收缩期加速度指标可定量评价犬急性缺血再灌注引起的心肌节段性室壁运动异常,为评价左室收缩功能提供有价值的信息。     

超声二维斑点追踪显像技术检测犬顿抑心肌跨壁力学状态的变化

目的 应用超声二维斑点追踪显像技术检测犬顿抑心肌心内、外膜纵向的应变变化,探讨顿抑心肌的跨壁力学变化及其随时间的变化规律。方法 12只犬左冠状动脉前降支结扎20 min,再灌注120 min,分别于结扎前、结扎期间、再灌注后即刻、30、60、90、120 min采集心尖切面图像。应用超声二维斑点追踪显像技术检测缺血及非缺血节段心内膜、心外膜、整体节段应变参数:纵向峰值应变(LS_peak)、峰值应变延迟时间(TPS_LS),并进行比较分析。结果 犬心肌左冠状动脉前降支结扎后、再灌注后即刻缺血节段心内、外膜、整体节段LS_peak明显减低,TPS_LS延长,且LS_peak以心内膜下心肌减低更明显;随再灌注时间延长,二维应变逐渐恢复,心外膜下心肌恢复更快,缺血节段整体心肌恢复正常时,心内膜下心肌仍未恢复正常。非缺血节段在左冠状动脉前降支结扎后、再灌注后即刻心内、外膜下LS_peak明显增加,TPS_LS延长,再灌注30 min恢复正常。结论 超声二维斑点追踪显像技术可检测犬顿抑心肌在缺血及再灌注阶段心内、外膜下心肌二维应变变化。     

应变率成像定量评价犬急性缺血再灌注局部心肌收缩功能的实验研究

目的探讨应变率成像(SRI)定量评价急性缺血再灌注左心室局部收缩功能变化的可行性,探求评价局部心肌功能的合理化指标。方法14只健康杂种犬,麻醉后开胸,于第一对角支起点以下套扎冠状动脉左前降支(LAD),结扎后30min,再灌注120min,建立缺血再灌注模型。分别于LAD结扎前,结扎后30min,再灌注后30min,60min,120min采集连续3个心动周期的组织速度图,用SRI软件分析左室各节段纵轴方向上收缩期应变率曲线的变化,Simpson's双平面法测量左室射血分数(LVEF),舒张末(EDV)及收缩末容积(ESV)。心肌缺血程度通过心肌特染病理切片确定。结果14只犬中12只成功建立缺血再灌注模型。结扎后30min,左室前壁缺血节段收缩期应变率明显降低(P<0.05),并出现收缩后压缩(PSC),再灌注30min后缺血节段收缩期应变率进一步降低,再灌注60min及120min后有所恢复,但仍未达到结扎前水平,LVEF,EDV,ESV于冠脉结扎前后差异无显著意义(P>0.05)。结论应变率能敏感定量评价局部心肌收缩功能的异常,可作为评价局部心肌缺血再灌注的定量指标。     

超声速度向量成像技术评价急性心肌缺血犬左心室心内膜下心肌力学状态

目的采用超声速度向量成像技术评价急性心肌缺血犬左心室收缩期心内膜下心肌力学变化规律。方法对12只健康比格犬结扎冠状动脉左前降支制作急性心肌缺血模型，采集缺血前后左心室二尖瓣口水平、乳头肌水平、心尖水平动态二维灰阶动态图像；获取左心室不同水平各节段缺血前后心内膜下心肌周向应变、径向应变、旋转角度与径向位移；分析同一节段心肌周向和径向应变与旋转角度的相关性，及两个相邻节段心肌周向应变差值（Acs）与相应节段心肌旋转角度和径向位移的相关性。结果缺血前左心室心内膜下心肌同一室壁周向应变、旋转角度从基底段到心尖段依次增大，缺血后这一力学状态发生改变，其中前间隔基底段周向应变大于心尖节段（P〈0．05），后间隔中段周向应变大于心尖节段（P〈0．05）；后壁基底段旋转角度大于中段（P〈0．01）、下壁中段旋转角度小于心尖节段（P〈0．05）、前间隔中段旋转角度小于心尖节段（P〈0．05）。缺血前心尖水平切面相邻两个节段心肌ACS与其相应节段心肌的旋转角度呈线性相关（r=0．609～0．739，P〈0．05或P〈0．01）；缺血前左心室心内膜下心肌同一室壁乳头肌水平节段与基底水平节段心肌△CS与其乳头肌节段心肌的径向位移呈线性相关（r=0．657～0．852，P〈0．05或P〈0．01），缺血后相关性消失。结论缺血前左心室心内膜下心肌相邻两个节段间的△CS与对应节段心肌旋转角度、径向位移的线性相关提示，相邻丽个节段心肌间的△CS与心尖节段旋转运动以及左心室心腔向心性收缩密切相关。急性心肌缺血状态下，左心室心内膜下心肌应变状态异常改变是左心室重构的重要力学基础。     

Myocardial layer-specific analysis of ischemic memory using speckle tracking echocardiography

The assessment of post-systolic shortening (PSS) by speckle tracking echocardiography allows myocardial ischemic memory imaging. Because the endocardial layer is more vulnerable to ischemia, the assessment of this layer might be useful for detecting ischemic memory. Serial echocardiographic data were acquired from nine dogs with 2 min of coronary occlusion followed by reperfusion. Regional deformation parameters were measured in the risk and normal areas. Using speckle tracking echocardiography, circumferential strain was analyzed in the endocardial, mid-wall, and epicardial layers; and radial strain was analyzed in the inner half, outer half and entire (transmural) layers. In the risk area, peak systolic and end-systolic strain in the circumferential and radial directions significantly decreased during occlusion, but recovered to the baseline levels immediately after reperfusion in all layers. However, circumferential post-systolic strain index (PSI), a parameter of PSS, significantly increased during occlusion, and the significant increases persisted until 20 min after reperfusion in the endocardial and mid-wall layers. Radial PSI tended to increase after reperfusion in the inner half and entire layers but these increases were not significant compared with baseline. In the normal area, systolic strains and PSI in the radial and circumferential directions hardly changed before and after occlusion/reperfusion in all layers. In layer-specific analysis with speckle tracking echocardiography, circumferential PSS in the endocardial and mid-wall layers may be useful for detecting ischemic memory.     

Differentiation of transmural and nontransmural infarction using speckle tracking imaging to assess endocardial and epicardial torsion after revascularization

Assessment of transmural extent (TME) of necrosis after acute myocardial infarction (MI) remains a major problem in clinical practice. The study sought to determine whether speckle tracking imaging (STI) could differentiate transmural from nontransmural acute MI by assessment of endocardial and epicardial torsion. TME of infarct was measured by contrast-enhanced magnetic resonance imaging. Patients were divided into two groups according to TME (transmural MI group [TME ≥ 50 %, n = 36] and nontransmural MI group [TME < 50 %, n = 35]). As a control group, 30 subjects without evidence of structural heart disease were included. Conventional echocardiography and STI were done in controls and patients before and 1 month after percutaneous coronary intervention. Compared with control subjects, endocardial and epicardial torsion in patients with transmural and nontransmural MI were all extremely decreased (all P < 0.01). One month after percutaneous coronary intervention, there was no significant increase in endocardial and epicardial torsion in transmural MI patients. However, apical rotation and left ventricular torsion resumed slightly but significantly in the epicardium (but not endocardium) in patient with nontransmural MI (3.11 ± 0.81 vs. 4.37 ± 1.15°, P < 0.01; 3.69 ± 1.07 vs. 5.52 ± 1.89°, P < 0.01, respectively). The combined evaluation of endocardial and epicardial torsion by STI may be used to differentiate transmural from nontransmural MI after revascularization.     

超声组织定征对顿抑心肌各层损伤程度的实验研究

目的：探讨超声组织定征对顿抑心肌各层损伤程度的意义。方法：使用HP 5500型彩超仪及S8探头,各项设置在试验中保持一致,犬13条,麻醉后开胸,结扎冠状动脉左前降支近端,15min后再灌注,检测基础状态。结扎 15min,再灌注后心内,外膜下心肌的背向散射积分周期变化幅芳和室壁增厚率的变化。结果：结扎15min后,周期变化幅度均减少或消失,尤以心内膜下心肌为显著,室壁增厚率明显降低;再灌注后,心外膜下心肌的周期变化幅度恢复最快,心仙膜下心肌次之,室壁增厚率最慢,结论：顿抑心肌各层的损伤程度不一样,心内膜下心肌损伤较重。     

Nitroglycerin and Heterogeneity of Myocardial Blood Flow REDUCED SUBENDOCARDIAL BLOOD FLOW AND VENTRICULAR CONTRACTILE FORCE

The effects of both intracoronary and intravenous administration of nitroglycerin on transmural distribution of blood flow in the left ventricle after partial coronary artery occlusion was investigated using two independent methods. In 16 open chest, anesthetized dogs, tubing supplying the cannulated left coronary artery was partially occluded. Strain gauges sutured paralled to superficial and deep fibers of the myocardium separately recorded the contractile force of each layer. With occlusion set so that depression of the deep contractile force was imminent. 12 mug intracoronary nitroglycerin in seven dogs depressed only the deep contractile force without changing systemic hemodynamics. Intravenous administration of 180 mug nitroglycerin in nine dogs resulted in a decrease of deep contractile force and aortic pressure often associated with an increase in superficial contractile force. Distribution of myocardial blood flow during peak coronary flow after intracoronary administration of nitroglycerin or during a decrease in aortic pressure after intravenous nitroglycerin administration was determined by the tissue uptake of an intracoronary bolus of rubidium-(80). This was compared with the uptake of potassium-(42) injected before nitroglycerin. Intravenous or intracoronary administration of nitroglycerin caused a significant reduction in subendocardial blood flow with a decrease in the subendocardial/subepicardial ratio of isotope.These experiments suggest that under conditions of acute partial coronary occlusion, the autoregulatory response results in more fully dilated subendocardial vessels causing them to be less responsive to nitroglycerin. Nitroglycerin may then reduce the vascular resistance in the subepicardial more than the subendocardial vessels, resulting in a "steal" of blood flow from deep to superficial myocardium.     

超声二维斑点追踪技术评价急性期川崎病患儿左室扭转

目的探讨超声二维斑点追踪技术评价急性期川崎病（KD）患儿左室扭转运动的临床价值。方法选取39例急性期KD患儿（KD组）和31名正常患儿（对照组）,采集基底水平左室短轴清晰二维图像并存储,用QLab软件进行脱机分析,计算两组内膜旋转峰值、外膜旋转峰值、平面旋转峰值及跨壁扭转峰值,并进行比较。结果与对照组比较,KD组内膜旋转峰值、外膜旋转峰值、跨壁扭转峰值、平面旋转峰值均显著下降,差异有统计学意义（P〈0.05）。结论超声二维斑点追踪技术可评价急性期KD患儿左室扭转运动,为临床早期干预KD患儿心功能损害及预防心血管并发症提供了较敏感的指标。