Wang Dian, Sun Jing Ping, Lee Alex Pui-wai, Ma Gen Shan, Yang Xing Sheng, Yu Cheuk-man, Ding Jian Dong, Liu Nai Feng
Department of Cardiology, Zhongda Hospital, Southeast University School of Medicine, Nanjing, China.
Division of Cardiology, Institute of Vascular Medicine, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong, China.
J Am Soc Echocardiogr. 2015 Jun;28(6):674-82. doi: 10.1016/j.echo.2015.02.012. Epub 2015 Mar 18.
To understand the influence of myocardial bridging (MB) on left ventricular (LV) function, myocardial function was studied in patients with MB of the left anterior descending coronary artery (LAD) using three-dimensional speckle-tracking echocardiography (STE).
Left anterior descending coronary artery MB was diagnosed by coronary angiography in 82 subjects. Patients were divided into three groups according to the percentage of systolic narrowing of the compressed segment: 30% to 49% was defined as group I (24 patients), 50% to 74% as group II (28 patients), and ≥75% as group III (30 patients). Thirty gender- and age-matched normal subjects were included as controls. Left ventricular myocardial deformation was estimated by three-dimensional STE.
Left ventricular ejection fractions were normal in all patients, but diastolic function was impaired in groups II and III (E/E' ratio, 9 ± 3 and 10 ± 3, respectively). The amplitudes of longitudinal strain (LS) and area strain (AS) of the LAD territory was significantly reduced in groups II and III compared with controls and group I (LS, -15 ± 2% and -12 ± 1% vs -19 ± 2% and -18 ± 2%; AS, -22 ± 2% and -13 ± 2% vs -33 ± 4% and -33 ± 3%; P < .0001), but the amplitudes of circumferential and radial strain showed no intergroup differences. Longitudinal strain and AS were significantly lower in patients with fractional flow reserve < 0.75 than in those with fractional flow reserve ≥ 0.75 (P < .0001), with relative preservation of circumferential and radial strain. The severity of LAD compression was significantly associated with AS and LS of the LAD territory (r = -0.92 and r = -0.84, respectively, P < .0001), but the correlations with circumferential and radial strain were modest (r = -0.36 and r = -0.32, respectively, P < .05).
With the increasing severity of systolic compression of the mural coronary artery, LV diastolic function and regional systolic deformation (AS and LS) of the MB perfusion territory were reduced. Three-dimensional STE can detect subtle myocardial dysfunction in patients with MB.
为了解心肌桥（MB）对左心室（LV）功能的影响，我们使用三维斑点追踪超声心动图（STE）对左前降支冠状动脉（LAD）存在心肌桥的患者的心肌功能进行了研究。
通过冠状动脉造影在82名受试者中诊断出左前降支冠状动脉心肌桥。根据受压节段收缩期狭窄百分比将患者分为三组：30%至49%定义为I组（24例患者），50%至74%定义为II组（28例患者），≥75%定义为III组（30例患者）。纳入30名年龄和性别匹配的正常受试者作为对照组。通过三维STE评估左心室心肌变形。
所有患者的左心室射血分数均正常，但II组和III组的舒张功能受损（E/E'比值分别为9±3和10±3）。与对照组和I组相比，II组和III组LAD区域的纵向应变（LS）和面积应变（AS）幅度显著降低（LS：-15±2%和-12±1% vs -19±2%和-18±2%；AS：-22±2%和-13±2% vs -33±4%和-33±3%；P<.0001），但圆周应变和径向应变幅度在组间无差异。血流储备分数<0.75的患者的纵向应变和AS显著低于血流储备分数≥0.75的患者（P<.0001），圆周应变和径向应变相对保留。LAD受压的严重程度与LAD区域的AS和LS显著相关（r分别为-0.92和-0.84，P<.0001），但与圆周应变和径向应变的相关性较弱（r分别为-0.36和-0.32，P<.05）。
随着壁冠状动脉收缩期受压程度的增加，LV舒张功能以及MB灌注区域的局部收缩期变形（AS和LS）降低。三维STE可检测出MB患者细微的心肌功能障碍。
