慢性缺血性功能异常心肌血管重建术后跨壁收缩的背向散射研究

目的利用超声背向散射（IBS）技术研究慢性缺血性功能异常心肌在血管成功再灌注后跨壁收缩的变化特征。方法分别在血管重建术前、术后3d、术后6～8周，检测58例慢性冠心病伴有左室壁节段性功能障碍患者（共88个异常心肌节段，43个正常心肌节段）相关心肌节段心内膜下层心肌及心外膜下层心肌的IBS周期变化幅度（cycle variation of IBS，CVlB），并在常规超声下测量相应心肌节段的室壁增厚率（WT）。结果正常心肌节段心内膜下心肌CVIB明显高于心外膜下心肌CVIB（P〈0．001）。血管重建术前，慢性缺血性功能异常心肌节段心内膜下和心外膜下心肌的CVIB均减低，以前者为著，二者间无显著性差异（P=0．067）。成功再灌注后，心内膜下心肌CVIB恢复较心外膜下慢，出现“心内膜下顿抑”。术后WT的恢复与心内膜下心肌层CVIB的恢复相平行（r=0．816，P〈0．0001），而与心外膜下心肌CVIB的恢复无明显相关性（r=0．125，P=0．056）。结论CVIB可以无创检测心肌的跨壁收缩性。在慢性缺血心肌的再灌注恢复过程中，心内膜下心肌跨壁收缩性的变化与心脏收缩功能的恢复密切相关。

Investigation of Integrated Backscatter on Myocardial Transmural Contraction in Patients with Chronic Ischemic Dysfunctional Myocardium

Objective To investigate the characteristics of myocardial transmural contraction in chronic ischemic dysfunctional myocardium before and after revascularization using integrated backscatter technique(IBS).Methods The magnitudes of the cardiac cycle variation of integrated backscatter(CVIB) in subendocardium and subepicardium were measured in fifty-eight patients with chronic coronary heart disease with left ventricular segmental dysfunction(totally 88 abnormal myocardial segments and 43 normal myocardial segments) before,3 days and 6-8 weeks after intervention and the wall thickening(WT) percents were calculated with conventional echocardiography.Results In normal myocardial segments,CVIBs were greater in the subendocardium than in the subepicardium(P<0.001).In chronic ischemic dysfunctional myocardial segments,CVIBs of subendocardium and subepicardium were all significantly decreased before revascularization,and the former was more prominent than the latter with no statistic differences(P=0.067).After successful reperfusion,the recovery of the CVIB in subendocardium was slower than in subepicardium,showing subendocardial stunning.Moreover,the recovery of WT after revascularization was parallel to that of the subendocardial CVIB(r=0.816,P<0.0001),but it had no obvious correlation with that of the subepicardial CVIB(r=0.105,P=0.053).Conclusions CVIB,as a noninvasive method could detect myocardial transmural contraction.The change of myocardial contractibility in subendocardium had obvious correlation with the recovery of cardiac contraction function after successful reperfusion in chronic ischemic myocardium.