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[摘要] 目的 探讨血管内超声(IVUS)对冠状动脉造影(CAG)临界病变治疗的指导意义。方法 对经选择性CAG提示冠状动脉临界病变的150例150处病变进行IVUS检查,分析动脉粥样硬化斑块类型、性质及其狭窄程度。结果 150处病变中,软斑块98例(65.3%),硬斑块33例(22.0%);偏心斑块85例(56.7%),向心斑块46例(30.7%);4例检测结果正常。斑块面积平均狭窄率为(59.4±10.7)%。对IVUS示斑块面积狭窄大于70%的62例、小于70%的16例但有典型临床症状者,以及15例有斑块破裂或夹层者行进一步介入治疗。4例患者在IVUS检查过程中出现冠状动脉痉挛现象,经处理后不良反应立即消失。所有患者随访6个月以上,未出现严重心脏缺血事件。结论 IVUS能进一步明确冠状动脉临界病变的性质和狭窄程度并能指导临床治疗,安全性高。�
[关键词] 血管内超声;临界病变;冠状动脉造影术�
[中图分类号] R541.4
[文献标识码] A
[文章编号] 1671-7562(2009)04-0284-04
Role of intravascular ultrasound in determining the treatment strategy for �intermediate coronary stenosis
ZHANG Xiao-guo,CHEN Ji-yuan,TANG Cheng-chun,DING Jian-dong,SHEN Cheng-xing,DAI Qi-ming,�CHEN Zhong,LUO Dan,TONG Jia-yi,WANG Ren-min,WANG Hui-ping, FENG Yi,MA Gen-shan
(Department of Cardiology,Zhongda Hospital,Southeast University,Nanjing 210009,China)
Abstract:Objective To evaluate the role of intravascular ultrasound(IVUS) in determining the treatment strategy for intermediate coronary stenosis.Methods IVUS was performed in 150 patients who had lesions of intermediate severity(40%～70% diameter stenosis) in coronary angiography(CAG).The characteristics of the atherosclerotic plaques were analyzed and severity of stenosis was evaluated.Results In all 150 patients,there were 98(65.3%) who had soft plaque in the lesion.There were 85(56.7%) who had eccentric plaque and �46(30.7%) concentric plaque in the lesions.Normal finding was made in 4 patients.The average of percent area stenosis was (59.4±10.7)% in the lesion.Percutaneous coronary intervention was performed in
62 patients who had lesions with percent area stenosis>70%, 16 patients with
percent area stenosis 1.2 方法�
1.2.1 CAG 应用飞利浦FD 10平板机或SIEMENS AngioStar心脏介入X线系统,将造影导管分别送到左、右冠状动脉开口,注射造影剂并同步记录影像,对任何冠脉病变至少选择2个或2个以上相互垂直的投照体位。取狭窄程度最严重的体位,供测量分析用。�
1.2.2 IVUS检查 应用IVUS成像仪(美国Jomed公司产品),在CAG后即刻于动脉鞘内推注肝素�6�000 IU,将5F、频率为25MHz的Eagle eye超声导管探头在指引导管口去除伪影后,透视下沿导引钢丝送入狭窄病变血管远端,缓慢回撤超声导管进行超声检查并记录,直至回撤到血管近端起始处中止。�
1.2.3 IVUS图像分析 主要观察动脉粥样硬化斑块的类型、性质及其狭窄程度。(1)斑块类型。用偏心指数(eccentricity index,EI)表示。EI=(最大斑块加中膜厚度-最小斑块加中膜厚度)/最大斑块加中膜厚度。若EI≤0.5为偏心斑块,EI>0.5为向心斑块。(2)斑块性质。将动脉粥样斑块分为软斑块(脂质斑块)、硬斑块(纤维斑块、钙化斑块和混合斑块)。斑块主要成分的回声低于血管外膜回声者为软斑块,接近或者等同于血管外膜回声者为纤维斑块,钙化病变的特点为强回声伴后方声影,若斑块成分有多种回声则视为混合斑块。(3)斑块破裂。指斑块内膜的纤维帽破裂,完整性被破坏。(4)定量分析。包括测定动脉粥样硬化斑块处外弹力膜横截面积、管腔横截面积、斑块面积、斑块负荷(斑块面积/外弹力膜横截面积×100%),即面积狭窄程度。(5)冠状动脉重构。用重构指数(remodeling index,RI)表示。RI=(靶病变处外弹力膜横截面积/近远端参考血管外弹力膜横截面积)的平均值。RI>1.05为正性重构,0.95～1.05为无重构,[1]。�
1.2.4 治疗方案 对斑块面积狭窄程度大于70%,斑块面积狭窄程度50%～70%的偏心性软斑块、斑块破裂及夹层患者行经皮冠状动脉内介入(PCI)治疗,其余则行药物治疗。介入治疗按标准方法行冠脉内支架植入术,术后冠脉直径残余狭窄≤20%且无并发症为介入治疗成功的判断标准。�
2 结果�
2.1 IVUS检查结果�
150例患者共有150处冠状动脉临界病变,以软斑块、偏心斑块多见;正性重构多见,钙化较少。其中软斑块98例(65.3%),硬斑块33例(22.0%),血管开口斑块17例(11.3%),钙化斑块13例(8.7%),偏心斑块85例(56.7%),向心斑块46例(30.7%),15处病变有斑块破裂及夹层。正性重构70例(�46.7%),无重构52例(34.7%),负性重构28例(18.6%),面积狭窄率(59.4±10.7)%。4例检查结果无狭窄,CAG的阳性结果系血管迂曲造成的假象。�
2.2 IVUS指导介入治疗�
对于IVUS显示斑块面积狭窄程度大于70%的62例患者,均植入了支架;虽斑块面积狭窄程度[2]。其次,CAG仅能提供血管内腔长轴的二维图像,而无法获得斑块内部组织结构的特征等信息,这就给临界狭窄病变PCI治疗指征的判断带来了极大困难。研究表明,CAG轻中度狭窄多数具有不稳定性斑块的结构特点,这些特点导致轻中度狭窄者容易发生急性冠脉综合征(ACS)[3]。IVUS克服了CAG的不足,通过血管360 °横截面图像,除可显示管腔形态外,还可清晰显示血管壁及粥样硬化斑块的组织形态学特征,精确测量血管的直径及横截面积[4],对临界病变进行精确的定量分析,以确定其狭窄程度及病变类型,给临界病变PCI的治疗选择提供依据。�
CAG检查血管狭窄程度≥75%为目前公认的PCI治疗指征,但对于冠脉临界病变采用何种治疗手段往往使医生难以确定。应用IVUS指导PCI治疗指征的判断,目前尚无统一标准。Bartunek等[5]建议以冠脉血流储备分数(FFR)[6]。研究发现,IVUS测定的指标与FFR之间有很好的相关性[7],在IVUS检查中当面积狭窄程度达到60%和70%时,其检出FFR IVUS还可以指导进一步的PCI治疗,通过IVUS可以发现在支架置入后CAG未能显示的支架贴壁不良和(或)扩张不对称等情况。本研究行支架置入的93例中有29例(31.2%)支架植入后CAG显示扩张尚好,但IVUS发现支架扩张不充分,经进一步加压扩张后IVUS才显示满意的管腔直径和面积以及良好的支架贴壁。因此,IVUS有助于指导理想的支架植入。研究显示IVUS检查存在1%～3%的并发症[8],主要为一过性冠脉痉挛。本研究IVUS检查过程中,有4例患者出现冠脉痉挛(2.7%),冠脉内注射硝酸甘油后痉挛立即解除,未见夹层或血管闭塞等其他并发症,说明IVUS检查本身是安全的。�
总之,对CAG显示直径狭窄40%～70%的临界病变行IVUS检查,通过其准确判断动脉粥样硬化斑块的类型、性质和精确测量狭窄的程度,可安全有效地指导PCI治疗,包括PCI适应证选择和手术效果的评价。�
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[收稿日期] 2009-02-27
