Miyasaka Yoko, Haiden Mio, Kamihata Hiroshi, Nishiue Takashi, Iwasaka Toshiji
Cardiovascular Division, Department of Medicine II, Kansai Medical University, 10-15 Fumizono-cho, Moriguchi, Osaka 570-8507, Japan.
Int J Cardiol. 2005 Jul 10;102(2):225-31. doi: 10.1016/j.ijcard.2004.05.027.
Tissue Doppler imaging-derived systolic myocardial velocity can detect subtle alterations in contractility during dobutamine stress. However, increased cardiac translation and tethering during dobutamine stress may affect measurements.
To examine the hypothesis that regional ischemic myocardium can be sensitively detected during dobutamine stress using myocardial strain rate, a new indicator of regional myocardial contraction that is independent of cardiac translation and tethering, we studied seven closed-chest pig confirmed chronic ischemic models produced by placing an ameroid constrictor on the left circumflex artery. Left ventricular short-axis tissue Doppler imaging was obtained at baseline and during dobutamine stress (10 and 30 microg/kg/min). Peak systolic myocardial velocity and peak systolic myocardial strain rate in anterior and posterior segments were derived offline at each stage.
In peak systolic myocardial velocity and peak systolic myocardial strain rate, repeated-measures analysis of variance showed significant interaction between nonischemic and ischemic segments during dobutamine stress. Statistical significance between nonischemic and ischemic segments was reached at baseline, 10 microg/kg/min dobutamine, and 30 microg/kg/min dobutamine in peak systolic myocardial strain rate, and at 30 microg/kg/min dobutamine in peak systolic myocardial velocity. By receiver operating characteristic (ROC) analysis for predicting ischemic segments at 30 microg/kg/min dobutamine, a cutoff value of peak systolic myocardial strain rate was 4.84, with a sensitivity of 100% and a specificity of 100%. Peak systolic myocardial velocity was the less discriminating parameter (cutoff, 6.46; sensitivity, 86%; specificity, 86%).
Myocardial strain rate imaging might represent an accurate parameter for clinical recognition of regional ischemic myocardium during dobutamine stress echocardiography.
组织多普勒成像得出的收缩期心肌速度可检测多巴酚丁胺负荷试验期间收缩性的细微改变。然而，多巴酚丁胺负荷试验期间心脏平移和牵拉增加可能会影响测量结果。
为检验使用心肌应变率（一种独立于心脏平移和牵拉的局部心肌收缩新指标）在多巴酚丁胺负荷试验期间能灵敏检测局部缺血心肌的假设，我们研究了7只通过在左回旋支动脉放置阿霉素环缩器建立的慢性缺血闭胸猪模型。在基线状态和多巴酚丁胺负荷试验（10和30微克/千克/分钟）期间获取左心室短轴组织多普勒成像。在每个阶段离线得出前壁和后壁节段的收缩期心肌峰值速度和收缩期心肌峰值应变率。
在收缩期心肌峰值速度和收缩期心肌峰值应变率方面，重复测量方差分析显示多巴酚丁胺负荷试验期间非缺血节段和缺血节段之间存在显著交互作用。收缩期心肌峰值应变率在基线、10微克/千克/分钟多巴酚丁胺和30微克/千克/分钟多巴酚丁胺时，以及收缩期心肌峰值速度在30微克/千克/分钟多巴酚丁胺时，非缺血节段和缺血节段之间达到统计学显著性。通过对30微克/千克/分钟多巴酚丁胺时预测缺血节段的受试者工作特征（ROC）分析，收缩期心肌峰值应变率的截断值为4.84，敏感性为100%，特异性为100%。收缩期心肌峰值速度是区分能力较差的参数（截断值，6.46；敏感性，86%；特异性，86%）。
心肌应变率成像可能是多巴酚丁胺负荷超声心动图期间临床识别局部缺血心肌的准确参数。
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