Division of Functional Diagnostics, Department of Health Sciences, Osaka University Graduate School of Medicine, Suita, Osaka, Japan.
JACC Cardiovasc Imaging. 2012 Jan;5(1):1-11. doi: 10.1016/j.jcmg.2011.09.019.
The aim of this study was to evaluate which regional myocardial parameters derived from speckle tracking echocardiography could demonstrate myocardial ischemic memory in a brief ischemia-reperfusion dog model.
Myocardial ischemic memory imaging, denoting the visualization of abnormalities provoked by ischemia and sustained even after restoration of perfusion, can convey important clinical information. We previously reported that post-systolic shortening (PSS) remains in the risk area after recovery from brief ischemia. However, it is still unclear whether abnormalities in other regional deformation parameters persist after relief from brief ischemia.
Echocardiographic data were chronologically acquired from 11 dogs during 2 min of coronary occlusion followed by reperfusion. Regional systolic and diastolic deformation parameters, including parameters related to PSS, were measured from radial and circumferential strain and from strain rate analyzed in the risk and normal areas. Strain imaging diastolic index (SI-DI), which had been proposed as a parameter for assessing ischemic memory, was also calculated.
Peak systolic strain, end-systolic strain, and peak systolic strain rate decreased in the risk area during occlusion but recovered to the baseline level immediately after reperfusion. Strain rate during early diastole decreased during occlusion; however, the decrease did not persist after reperfusion. Post-systolic strain index (PSI) and time-to-peak strain index, which are parameters of PSS, increased during occlusion. These increases persisted until 10 to 20 min after reperfusion (circumferential PSI: 0.02 ± 0.04 [baseline] vs. 0.08 ± 0.04 [20 min], p < 0.05). SI-DI did not show a significant change during occlusion because of a large variation.
Although abnormalities of PSS-related parameters alone persisted after recovery from 2-min occlusion, abnormalities of other deformation parameters, such as strain rate during early diastole, did not. These data suggest that assessment of PSS by speckle tracking echocardiography is useful for detecting myocardial ischemic memory.
本研究旨在评估斑点追踪超声心动图得出的哪些区域性心肌参数可在短暂缺血-再灌注犬模型中显示心肌缺血记忆。
心肌缺血记忆成像，即显示缺血引起的异常并在灌注恢复后持续存在，可提供重要的临床信息。我们之前的研究报告称，在短暂缺血恢复后，风险区的收缩后缩短（PSS）仍然存在。然而，在短暂缺血缓解后，其他区域性变形参数的异常是否持续存在仍不清楚。
在 11 只犬中，从冠状动脉闭塞后 2 分钟开始连续采集超声心动图数据，随后进行再灌注。从径向应变和圆周应变以及应变率分析中测量风险区和正常区的局部收缩期和舒张期变形参数，包括与 PSS 相关的参数。还计算了作为评估缺血记忆的参数的应变成像舒张指数（SI-DI）。
在闭塞期间，风险区的峰值收缩应变、收缩末期应变和峰值收缩应变率降低，但在再灌注后立即恢复到基线水平。在收缩末期应变指数（PSI）和达峰应变指数（time-to-peak strain index）增加，这些增加持续到再灌注后 10 到 20 分钟（圆周 PSI：0.02 ± 0.04[基线]与 0.08 ± 0.04[20 分钟]，p<0.05）。由于变化较大，SI-DI 在闭塞期间没有显示出明显的变化。
尽管在恢复 2 分钟闭塞后，仅与 PSS 相关的参数异常持续存在，但早期舒张期应变率等其他变形参数的异常并未持续存在。这些数据表明，斑点追踪超声心动图评估 PSS 有助于检测心肌缺血记忆。
