吉林大学学报(医学版)  2016, Vol. 42 Issue (03): 595-599

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付吉利, 王雪, 丛志斌, 于晓艳
FU Jili, WANG Xue, CONG Zhibin, YU Xiaoyan
R指数评价静息状态下动力型左室腔流出梗阻的价值及其临床意义
Value of Rindexin evaluationon dynamic intraventricular obstructionof left ventricle at rest and its clinical significance
吉林大学学报(医学版), 2016, 42(03): 595-599
Journal of Jilin University (Medicine Edition), 2016, 42(03): 595-599
10.13481/j.1671-587x.20160335

文章历史

收稿日期: 2015-09-26
R指数评价静息状态下动力型左室腔流出梗阻的价值及其临床意义
付吉利1, 王雪1, 丛志斌1 , 于晓艳2    
1. 长春中医药大学附属医院电诊科, 吉林 长春 130021;
2. 吉林大学药学院实验药理与毒理学教研室, 吉林 长春 130021
摘要: 目的: 通过常规超声心动图总结静息状态下动力型左室腔流出梗阻(DIVO)心动图特征,并根据其特点设计一个新的指标R指数(狭窄处等容舒张期流速/左室主动舒张峰速度),探讨R指数定量评价DIVO的价值。方法: 选取以胸痛、胸闷就诊的DIVD患者112例(梗阻组),同时选取50名健康者作为健康对照组。采用常规二维超声心动图获取研究对象左室收缩末径(LVESD)、左室舒张末径(LVEDD)、间隔上部厚度(U-IVS)、中部厚度(M-IVS)和左室射血分数(LVEF)。彩色多普勒超声获取左室腔流速(流出道流速、左室中部流速和左室心尖部流速)。在心脏各切面观察左室心肌运动和左室腔内彩色血流,并测量收缩末期左室腔最窄处内径,于血流汇聚处获取平静呼吸及Valsalva试验下的等容舒张峰峰速、左室主动舒张峰E峰峰速及R指数,绘制受试者工作特征曲线(ROC),计算曲线下面积(AUC),根据约登指数确定R指数的诊断界点。结果: 与健康对照组比较,梗阻组患者心率偏快,血压偏高(P<0.01)。梗阻组患者二维超声心动图特征表现为左室心肌运动活跃,心腔相对偏小,且可见几何形变;DIVO患者左室腔内正常流速梯度趋势发生改变,收缩期血流频谱呈峰值后移,于等容舒张期可见等容舒张峰,且等容舒张峰速明显快于健康对照组(P<0.01),R指数明显大于健康对照组(P<0.01)。结论: DIVO患者R指数明显增大,且R指数≥1可作为静息状态下DIVO患者特异性诊断指标。
关键词: 超声心动图    动力型左室腔流出梗阻    R指数    
Value of Rindexin evaluationon dynamic intraventricular obstructionof left ventricle at rest and its clinical significance
FU Jili1, WANG Xue1, CONG Zhibin1 , YU Xiaoyan2     
1. Department of Electrodiagnosis, Affiliated Hospital, Changchun University of Chinese Traditional Medicine, Changchun 130021, China;
2. Department of Experimental Pharmacology and Toxicology, School of Pharmacy, Jilin University, Changchun 130021, China
Abstract: Objective: To summarize the echocardigraphic characteristics of dynamic intraventricular obstruction (DIVO) of the left ventricle by traditional echocardiography at rest and to design a new index(R index,VIVR/VE) according to its characteristics,and to explore the value of R index in quantitative evaluation on DIVO. Methods: One hundred and twelve patients with DIVO were chosen as obstruction group. All patients had chest pain or dyspnea.A total of 50 healthy volunteers were used as healthy control group.The left ventricular end-systolic diameter (LVESD),left ventricular end-diastolic diameter(LVEDD),upper interventricular septum thickness (U-IVS),middle interventricular septum thickness (M-IVS) and left ventricular ejection fraction(LVEF) were obtained by two-dimensional echocardiogram.The maximal systolic velocities and gradients at the left ventricular outflow tract (LVOT),mid-ventricle and the apex of left ventricle were obtained at rest in all patients using color Doppler ultrasound.The myocardial movement and the flow of left ventricle were observed at different aspects.Then the velocity of E wave,the narrowest inner diameter,the systolic velocity,the velocity of isovolumic relaxation (VIVR) and R index of the narrowest part were obtained.The receiver operating characteristic (ROC) curve was builded and the area under curve(AUC) was calculated.An index about confirmed the diagnosis of R index point was obtained.Moreover,the specificity and sensitivity of R index for the diagnosis of DIVO of the left ventricle at rest was explored. Results: The heart rate of patients with DIVO in obstruction group was faster than that in healthy control group and the blood pressure was higher than that in healthy control group (P<0.01).The 2D echocardigraphic characteristics of the DIVO patients showed that the myocardial movement of left ventricle was enhanced.The left ventricle diameter of the DIVO patients in obstruction group was smaller than that in healthy control group,and the shape of the left ventricle was irregular.As for Doppler,the normal flow velocity gradient in the left ventricular of the patients with DIVO was changed.A Doppler spectrum with peak value moving forward was found in obstruction group,and a IVR wave was seen,and the velocity of IVR wave was faster than healthy control group(P<0.01) and the R index was enlarged obviously(P<0.01). Conclusion: The R index of DIVO patients enlarges significantly,and R index ≥1 is the specific diagnosis indicator of the DIVO patients at rest.
Key words: echocardiography    dynamic intraventricular obstruction    R index    

1992年Pellikka等[1]首次报道了负荷状态下的非肥厚型心肌病的动力型左室流出梗阻(dynamic intraventricular obstruction,DIVO)的概念,该梗阻可发生在心腔中部、心尖部或流出道部。该类患者以中老年患者居多,多数有心衰的症状,然而射血分数测量值却是正常或偏高,故往往易被忽略。目前研究[2, 3, 4, 5, 6, 7, 8, 9]多关注负荷状态下的DIVO,对静息状态下的DIVO研究较少。本研究对静息状态下的DIVO超声心动图进行分析,探讨等容舒张峰峰速/左室主动舒张峰E峰速(简称R指数)评价DIVO的价值,为其作为DIVO临床特异性诊断指标提供依据。

1 资料与方法 1.1 研究对象

收集112例2009年1月—2012年12月以胸痛、胸闷为首发症状在本院就诊的DIVO患者作为梗阻组,其中男性70例,女性42例,年龄40~73岁,平均年龄(59±11)岁。所有患者心电图检查均为窦性心律,有胸闷、胸痛、劳累性呼吸困难或晕厥、心功能不全等症状,常规超声心动图检查中左室射血分数(left ventricular ejection fraction,LVEF)>55%,平静呼吸下见左室腔内最快流速大于150 cm·s-1或Valsalva试验下室腔流速大于250 cm·s-1。排除标准:①有心肌梗死病史;②有瓣膜疾病;③有心室收缩功能障碍且LVEF <50%;④有肥厚性心肌病;⑤正在应用正性肌力药物和β受体阻滞剂者;⑥安装人工起搏器者;⑦完全性左束支传导阻滞者;⑧有心脏外科手术史;⑨有阵发性心房颤动、心房扑动、Ⅱ度或Ⅲ度房室传导阻滞者;⑩超声图像不清晰者。健康对照组为50名健康志愿者,其中男性29名,女性21名,年龄40~72岁,平均年龄(57±12)岁。纳入标准:①无冠心病家族史;②心电图正常,心率60~100min-1,无心律不齐;③心脏X线、超声心动图正常;④血压<140/ 90 mm Hg (18.62/11.97 kPa);⑤能耐受剧烈体力运动。排除标准:① 有冠心病家族史;② 心电图异常;③X线提示心脏形态改变者;④超声图像不清晰者。

1.2 主要检查仪器和检查方法

采用GE Vivid7彩色多普勒超声检查仪,探头型号M3S,探头频率1.5~4.3 MHz,系统内置工作站,可存储原始资料,并可行图像分析和后处理。研究对象取仰卧位或左侧卧位,同步连接心电图,胸骨旁左室长轴切面获取左室收缩末径(left ventricular end-systolic diameter,LVESD)和左室舒张末径(left ventricular end-diastolic diameter,LVEDD)。胸骨旁左室短轴切面获取舒张末室间隔上部厚度(upper interventricular septum thickness,U-IVS)和中部厚度(middle interventricular septum thickness,M-IVS)。心尖四腔心切面下Simposon法获取LVEF。在心尖五腔心切面获取左室流出道流速,心尖四腔心切面获取左室中部和左室心尖部流速。在心尖四腔切面、五腔切面、三腔切面和两腔切面观察左室心肌运动,测量收缩末左室腔最窄处内径。启动彩色血流显示,仔细观察左室腔内彩色血流,将取样容积置于诸切面左室腔收缩末最窄处血流汇聚处,获取平静呼吸和Valsalva试验下狭窄处脉冲血流频谱,分别测量该处的收缩期峰值流速、等容舒张峰峰速、左室主动舒张峰E峰峰速、左房主动收缩峰A峰峰速及R指数,并取平均值。

1.3 统计学分析

采用SPSS 19.0 统计软件进行统计学分析,所有分析数据均采用正态性检验,数据均符合正态性分布。各参数取5个心动周期的平均值并以x±s 表示。基础临床特征参数、常规二维和多普勒超声心动图参数组间比较采用t检验。以敏感度为纵坐标、1-特异度为横坐标构建受试者工作特征曲线(receiver operating characteristic curve,ROC),计算曲线下面积 (area under curve,AUC),根据约登指数(敏感度+特异度-1 )最高的临界点确定R指数的诊断界点。

2 结 果 2.1 2组研究对象基础临床特征

2组研究对象年龄、体质量、身高和性别比比较差异均无统计学意义(P>0.05);而血压和心率比较差异有统计学意义(P<0.01),梗阻组患者心率偏快,血压偏高。见表 1

表1 2组研究对象基础临床特征 Tab.1 Clinical features of subjects in two groups
Group n Age(year) Systolic pressure( P/mmHg) Diastolic pressure( P/mmHg) Heart rate(min-1) BMI(kg·m-2) Male ratio ( η/%)
*P < 0.01 compared with healthy control group.
Healthy control 50 57±12 108±9 76±6 70±8 24.34±2.98 60
Obstruction 112 59±11 140±21* 88±7* 82±9* 24.58±3.53 62
2.2 2组研究对象常规超声心动图二维测值

梗阻组患者左室舒张末径和左室收缩末径均小于健康对照组(P <0.01)。梗阻组患者室间隔上部和中部厚度均大于健康对照组(P<0.05或P<0.01),其中梗阻组有63例患者室间隔上部增厚明显,约占56%;而健康对照组中仅有10例,约占20%。梗阻组患者LVEF明显大于健康对照组(P<0.01)。左室心尖长轴诸切面观察显示:梗阻组患者左室心肌运动活跃,收缩末左室心腔呈几何形变,61例患者左室中部呈狭缝状,19例患者左室心尖部呈狭缝状。健康对照组研究对象收缩末左室心腔未见几何形变。见图 1(插页四)和表 2

表2 2组研究对象常规超声心动图二维测值 Tab.2 2D ecocardiography outcomes of subjects in two groups
(x±s)
Group n LVEDD (l/mm) LVESD (l/mm) U-IVS (l/mm) M-IVS (l/mm) LVEF (η/%)
*P <0.05,** P <0.01 compared with healthy control group.
Healthy control 50 45.6±6.2 27.8±5.9 9.7±2.1 9.0±1.9 63±4
Obstruction 112 40.8±4.7** 22.5±3.9** 10.8±2.1** 9.6±2.3* 70±6**
A: Healthy control group; B : Obstruction group. 图1 心尖左室四腔心切面显示2组研究对象收缩期左室心腔形态表现 Fig.1 Morphology of under apical four-chamber view of subjects in two groups.
2.3 2组研究对象常规超声心动图多普勒测值

梗阻组患者左室流出道流速和左室中部流速、左室心尖部流速均明显快于健康对照组(P<0.01);2组E峰和A峰比较差异无统计学意义(P>0.05)。健康对照组左室腔内流速呈现的趋势:左室心尖部流速<左室中部流速<左室流出道流速,彩色多普勒结果显示:左室心腔内无明显血流汇聚处;频谱多普勒结果显示:收缩期血流频谱形态较正常。而在梗阻组中该趋势多被打乱,53例患者左室中部流速最快,8例患者左室心尖部流速增快。彩色多普勒结果显示:收缩期左室心腔呈狭缝者可见明显血流汇聚处;频谱多普勒结果显示:汇聚处血流速度增快,且峰值后移,且可见明显的等容舒张峰,等容舒张峰速较健康对照明显增快(P<0.01),R指数明显增大(P<0.01)。见图 23(插页四)及表 3

A: Healthy control group; B: Obstruction group. 图2 2组研究对象等容舒张期左室心腔 Fig.2 Left ventricle in IVRT of subjects in two groups
A: Healthy control group; B: Obstruction group. 图3 2组研究对象等容舒张峰和R指数 Fig.3 Peak velocity of IVR and R index of subjects in two groups
表3 2组研究对象常规超声心动图多普勒测值 Tab.3 Doppler outcomes of coventional echocardiography of subjects in two groups
(x±s)
Group n Velocity of LVOT (cm·s-1) Velocity of mid-left ventricle (cm·s-1) Velocity of apex-left ventricle (cm·s-1) Velocity of IVRT (cm·s-1)
*P < 0.01 compared with healthy control group.
Healthy control 50 92.5±16.7 56.3±11.3 29.9±9.7 29.8±8.6
Obstruction 112 169.8±51.3* 176.7±46.2* 125.1±22.4* 175.8±52.6*
Group n Mitral E velocity (cm·s-1) Mitral A velocity (cm·s-1) R index
Healthy control 50 84.6±13.2 59.8±10.7 0.41±0.30
Obstruction 112 85.2±14.3 61.5±11.9 1.98±0.89*
2.4 研究对象的ROC

以敏感度为纵坐标、1-特异度为横坐标绘制的ROC显示: R指数对动力型梗阻的最佳诊断界点为0.83,ROC的AUC为0.995,标准误为0.003,P=0.000,对应的敏感度为 98.3%,特异度为 90.9% 。R指数为1时敏感度为92.9%,特异度为100%。

图4 研究对象的ROC Fig.4 ROC of subjects
3 讨 论

静息状态下DIVO是指静息状态下由于左室心肌运动过强致收缩期左室心腔血流流出不畅(包括左室流出道部、左室中部和左室心尖部)。由于很多医生对DIVO的概念模糊,对超声心动图特征缺乏了解,故该类患者往往不能被正确诊断,导致治疗方向的偏差。多年来学者们对DIVO评价不一,Luria等[10]认为:DIVO偶然会发生在负荷超声心动图检查中,并认为其无临床意义。然而Henein 等[11]认为:在老年人中有些无名原因的胸闷及胸痛与DIVO相关。还有学者[12]认为:DIVO与β受体相关。本文作者更赞同后二者的观点。

关于超声下左室腔流出梗阻的定义标准也不近相同,Luria等[10]将左室流出道的峰值压差>36 mmHg定义为左室流出道梗阻的标志。而李治安[13]将其定义为左室流出道的峰值压差>50 mmHg。Dawn等[14]认为:静息状态下左室中部或流出道流速>150 cm·s-1或Valsalva试验下左室腔流速大于250 cm·s-1,且伴频谱形态的峰值后移者,当属静息状态下DIVO的范畴。本研究采用Dawn 等[14]的诊断标准作为纳入标准,该标准除流速外还涵盖了因梗阻所致的频谱形态的改变。

本研究结果显示:梗阻组患者心率偏快,超声心动图显示梗阻组患者较健康对照组研究对象左室舒张末、收缩末内径偏小,而射血分数明显偏大,即DIVO更易发生在左室内径相对较小的患者群中。左室腔的大小与容量负荷相关,该类患者左室容量负荷相对较低,为保证正常的体循环,心脏启动代偿性保护措施,心率加快,心肌收缩力代偿性增强,故射血分数偏大。吴亚峰等[15]应用多巴酚丁胺负荷超声心动图检测左心室流出道血流速度,分析负荷后左心室流出道动力型梗阻的原因及其意义,结果表明:室间隔厚度与负荷后左心室流出道血流速度呈明显相关性,以室间隔基底肥厚更为明显,室间隔基底肥厚的患者在负荷超声心动图下更易发生DIVO。Henein等[11]研究结果与其相似。上述均为负荷超声心动图下研究结果。本研究结果显示:静息状态下梗阻组患者室间隔上部增厚的患者所占比例明显多于健康对照组。梗阻组有51例患者的梗阻发生于左室流出道部,在这51例患者中有37例患者的室间隔上部增厚,且凸向左室流出道,其主动脉前壁与室间隔的夹角减小,加之左室心肌运动增强,致左室流出道流速增快,说明不仅负荷状态下室间隔上部增厚与梗阻的发生有关联,静息状态下室间隔上部增厚与左室腔上部即左室流出道梗阻的发生亦有关联。在梗阻组中有53例患者梗阻发生于左室中部,这些患者收缩末左室中下部呈狭缝状,致该处收缩期流速明显增快,其收缩期左室腔内流速梯度被打乱。等容舒张期是指心动周期中心室收缩结束、主动脉瓣关闭、心室开始舒张、房室瓣尚未打开的这段时间。此时心室压力不断下降,但心室压仍高于心房压,心室腔容积不变,此时左室腔内的血流有极微弱的流动,流速极低,故彩色多普勒即使可以看到该时期的血流信号,其颜色也是暗淡的,故用常规的脉冲多普勒检测其流速时,需调低量程,借助连接心电图或将取样容积置于左室流出血流与左室流入血流相交界处才可分辨和测及。而对于梗阻组患者,尤其是中、下部的梗阻,可以在收缩末左室腔内径最窄处测及高速的等容舒张期流速。其发生的根本原因为:正常心室的舒张顺序是错落有致的,如果心室腔在收缩末无狭窄,那么心室腔的压力会无明显差距。但有梗阻的患者收缩末心腔内径出现限局狭窄,等容舒张期左室腔容积不变,压力减低,收缩末左室腔中下部限局的狭窄致左室腔压力传递受阻,狭窄处的上下有了明显的压力阶差,致原本在等容舒张期内可能仅有轻微流动的左室内产生了高速的血流[16]

R指数为本课题组根据梗阻组患者的超声心动图特征创新设计的一个新的常规超声心动图参数,为收缩末狭窄处等容舒张峰速度与左室主动舒张E峰的比值,统计学分析显示:由于梗阻组患者等容舒张峰速明显增快,故与健康对照组比较其R指数亦明显增大。ROC分析结果显示R指数≥1是静息状态下DIVO特异性诊断的指标。

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