速度向量成像技术在心血管疾病应用的进展

速度向量成像技术(VVI)基于斑点追踪原理,可定量检测心肌及血管壁生物力学特征,摆脱了组织多普勒成像(TDI)的角度依赖性,可识别心肌节段运动,观察心脏扭转运动,发现病变早期血管壁弹性改变及评估动脉粥样硬化斑块稳定性,对于鉴别诊断早期心血管疾病有重要意义。本文就速度向量成像技术在心血管疾病中的应用进展进行综述。     

速度向量成像技术及其临床应用进展

速度向量成像是评价心肌结构力学、分析局部心功能的一项新技术,通过检测心脏的轴向、径向和环向运动,分析心脏扭转运动、应变及应变率以及心脏同步化收缩,从而更加全面地认识心脏的运动,现就该技术及临床应用做一综述。     

速度向量成像技术评价心肌梗死患者左室壁非同步性运动的初步探讨

目的:运用速度向量成像(VVI)技术评价心肌梗死患者左心室壁节段心肌运动的同步性。方法:对15例正常人和8例心肌梗死患者进行VVI,测量左心室局部心肌纵向运动达峰时间(TL-V)及径向运动达峰时间(TR-V),计算纵向、径向运动达峰时间差(T-SD)及最早与最迟达峰时间标准差(T-MX)。结果:①正常心脏各节段间TL-V及TR-V差异无统计学意义。②心肌梗死节段TL-V、TR-V较非梗死节段及对照组显著延长(P<0.05);与对照组比较,心肌梗死组纵向运动T-SD和T-MX、径向运动T-SD和T-MX均显著增大(均P<0.05)。结论:VVI技术有望成为评价心肌梗死患者左心室壁非同步性运动及判断梗死节段的有效方法。     

定量组织速度成像与应变率成像评价急性前壁心肌梗死患者心功能的应用价值

目的:观察急性前壁心肌梗死患者心肌速度(V)、应变率(SR)的变化特点,探讨定量组织速度成像(QTVI)及应变率成像(SRI)技术定量评价急性心肌梗死(AMI)患者的左室局部梗死心肌功能的临床应用价值。方法:应用QTVI及SRI对20例AMI患者和30例正常人左室前壁及前间壁节段纵向收缩期(S)、舒张早期(E)及房缩期(A)的峰值速度(VS、VE、VA)、峰值应变率(SRS、SRE、SRA)进行测定,并以冠脉造影结果为标准进行对比分析。结果:VS:AMI组心梗室壁的不同水平均较正常对照组显著性减低;VE:除前间隔的心尖水平外,心梗室壁较正常对照组显著性减低;VA:前壁的不同水平及前间隔的心尖水平AMI组较对照组显著性减低;SRS、SRE:AMI组不同水平左室心梗室壁较对照组显著性减低;SRA:前壁的不同水平及前间隔的基底水平AMI组较对照组显著性减低(分别P<0.01和P<0.05)。结论:QTVI及SRI技术是临床无创、定量评价急性心肌梗死局部心肌功能的有效方法。     

心肌应变率成像——定量评价局部心肌功能的新技术

心肌应变率成像（strain rate imaging,SRI）是在组织速度成像（tissue doppler imaging,TDI）基础上发展起来的一种定量评价局部心肌功能的超声技术.1998年,Heimdal等[1]首次报道采用实时超声应变率显像来评价左心室功能,从而为SRI在心脏超声领域的应用开辟了新窗口,至此SRI的应用一直是国际心脏超声的研究热点.现就近年来国内外这方面的研究进展及应用现状作一综述.     

组织多普勒心肌速度梯度的研究现状及临床应用进展

组织多普勒成像 (TissueDopplerimaging ,TDI)技术问世以来 ,广泛用于测量心肌的运动速度 ,评估左室收缩及舒张功能。但由于多普勒技术检测探头方向上的速度 ,必然受到心脏整体运动及多普勒入射角的影响 ,使得定量评价左室功能的准确性受到限制。1　心肌速度梯度 (Myocardialvelocity gradient,MVG)的基本概念1 .1 　MVG及测量方法由于心肌各层的运动速度并不一致 ,1 994年Fleming等〔1〕首次提出用MVG的概念 (国内有学者将其称为心肌速度阶差 ) ,MVG指心内膜与心外膜速度之差与室壁厚度 (L)的比值 ,用公式表示为 :MVG =(Vend-Vep…     

应变率成像的临床应用

现综述正常心脏应变率成像表现和局部心肌缺血的特征;应变率成像定量评价局部收缩和舒张功能的可靠性;以及应变率成像结合负荷试验鉴别心肌不同存活状态等方面问题。     

正常成人左室后壁短轴方向应变率特点的初步评价

目的研究正常左室后壁短轴方向应变率特点,并与速率比较。方法健康者54例,根据二尖瓣口血流频谱分为A组（E/A>1）和B组（E/A<1）,记录后壁基底部、中部和心尖3个水平应变率和速率曲线,测量收缩期、舒张早期和左房收缩期峰值应变率和速率,计算3个水平平均值。比较各水平之间应变率和速率的差异,对各参数与年龄之间作相关性分析,比较A,B两组之间的差异。结果应变率和速率在正常后壁的分布特点并不相同;与年龄的相关性分析和分组比较中,应变率和速率基本表现出相同的特点,与年龄显著相关,A、B组间各指标也有显著性差异。结论应变率和速率意义均与心肌功能状态有关,可用于评价心肌功能。     

实时三平面定量组织速度成像技术评价冠心病患者心室壁运动

目的探讨实时三平面定量组织速度成像技术在冠心病诊断中的临床应用价值。方法同步实时采集行冠状动脉造影检查的139例患者(分为4组)心尖四腔观、心尖两腔观和心尖左室长轴观的组织速度动态图像,测量左右心室壁基底段的收缩及舒张速度,并做对比研究。结果左室部分室壁收缩及舒张速度在组间比较有统计学意义(P<0.05或P<0.01),并与冠状动脉狭窄程度存在相关性(P<0.05或P<0.01);左室下壁舒张早期峰值速度(e)以截断值为-5.19cm/s对冠状动脉狭窄≥50%的诊断价值最高(P<0.01)。结论实时三平面定量组织速度成像技术可较准确地分析心肌缺血时收缩及舒张运动的速度变化,对评价缺血心肌的敏感性优于常规超声心动图。     

应用速度向量成像及定量组织速度成像技术评价左心室舒张功能

目的 以左心室舒张末压(LVEDP)为标准,探讨速度向量成像(VVI)与定量组织速度成像(QTVI)技术各参数在评价左心室舒张功能中的应用价值.方法 51例接受心导管检查的患者纳入研究.介入诊疗前,使用超声心动图测量二尖瓣舒张早期血流速度(E峰)、舒张晚期血流速度(A峰)、E/A比值、左室射血分数;应用VVI及QTVI分别测算二尖瓣环舒张早期平均峰值运动速度(Em),计算E/Em值.介入术中,使用猪尾导管测量LVEDP.结果 VVI及QTVI测算的E/Em均与LVEDP旱良好的线性相关,相关系数分别为:r=0.808,P<0.01及r=0.692,P<0.01;两相关系数比较,前者高于后者(Z=2.246,P=0.025).VVI及QTVI测算的Em均与LVEDP呈良好的负相关,相关系数分别为:r=-0.740,P<0.01及r=-0.567,P<0.01;两相关系数比较,前者高于后者(Z=2.595,P=0.009).常规二维超声心动图测定的E/A值和LVEDP相关性差(r=0.117,P=0.415).结论 VVI作为一种新的超卢诊断新技术,在评价左心室舒张功能上优越于QTVI.E/Em及Em均可用于评价左心室舒张功能,前者与LVEDP相关性较高,但二者差异尚无统计学意义(P>0.05).     

超声应变率显像在心功能检测中的应用

超声应变率显像是基于组织多普勒显像的一种新技术,它能够评价心肌的收缩、舒张功能,这不仅体现在该技术能够评估心脏整体功能,而且它更主要应用于评估心室局部功能,因此它在室壁心肌缺血的早期检出、心脏负荷试验中具有重要意义。另外,超声应变率显像还能够定量估测心肌病的心脏收缩、舒张功能,这有助于对限制型心肌病和缩窄性心包炎的鉴别。本文还简单地阐述了超声应变率显像的技术特点、判定标准以及该技术尚存在的缺陷。     

Distribution of Dyssynchrony in Subjects with No Known Cardiac Disease and Comparison of Velocity Vector Imaging to Color‐Coded Tissue Doppler Imaging

Data on the distribution of dyssynchrony in subjects with normal ejection fraction (EF) and normal QRS are scarce. We studied 100 subjects with no known cardiac disease (52% male, mean age 60 ± 17 years) using velocity vector imaging (VVI). Seventeen percent had septal to lateral (S–L) wall longitudinal delay >75 msec, 63% of subjects had S–L wall radial delay >75 msec, and 25% had a circumferential opposing wall delay >100 msec. Those with circumferential opposing wall delay of >100 msec had a lower EF (57 ± 5% vs. 62 ± 5%, P < 0.05). In an additional group of 33 patients, we compared the longitudinal dyssynchrony parameters as assessed by VVI and tissue Doppler imaging (TDI) and found them to be comparable. In conclusion, we find significant variation in time to peak velocities in subjects with no known cardiac disease, who had a normal left ventricular ejection fraction and QRS duration. VVI is comparable to TDI.     

Regional Diastolic Function in Microvascular Angina Studied by Pulsed-Wave Doppler Tissue Imaging

Objectives: Diastolic dysfunction is an early finding during myocardial ischemia. However, regional diastolic function has not been studied in patients with microvascular angina (MA). The purpose of this study was to assess the regional diastolic function in patients with MA through use of the new echocardiographic technique, pulsed-wave Doppler tissue imaging (DTI). Methods: Regional diastolic function was studied by DTI in 81 myocardial segments of seven patients with MA and in 54 segments of six healthy control subjects. Results: Myocardial segments in patients with MA had, in comparison with controls, an increased regional isovolumetric relaxation time (126 ± 34 vs 99 ± 34 msec, P < 0.0001), a higher e/a ratio (1.1 ± 0.7 vs 0.8 ± 0.3, P = 0.0048), and a lower peak velocity of the late diastolic wave a (6.9 ± 2.9 vs 8.4 ± 1.7 cm/msec, P = 0.0009). Moreover, peak velocity of systolic wave s was higher in patients with MA (5.8 ± 1.4 vs 5.3 ± 1.2 cm/msec, P = 0.0424). Conclusions: Patients with MA have an impaired regional diastolic function (an increased regional isovolumetric relaxation time and a lower a wave) and a higher velocity of the regional systolic wave s. These findings may have physiopathological implications .     

Tissue Doppler Myocardial Velocity Imaging in Infants and Children—a Window into Developmental Changes of Myocardial Mechanics

In adults, tissue Doppler myocardial velocity imaging (TDI) is a recommended component of routine echocardiography and particularly useful to assess diastolic function of the left ventricle. In contrast, color and pulsed‐wave TDI velocities are less accepted in pediatrics, perhaps due to their strong age dependence in children. This review discusses the strengths and limitations of TDI velocity imaging in the pediatric age group. Myocardial velocities increase during normal childhood heart development, starting from fetal life, and these changes vary by cardiac segment. TDI velocity maturation opens an interesting window into the normal development of myocardial mechanics in childhood, but makes it difficult to interpret data in an individual child. Moreover, there is a wider range of normal for any given pediatric age than in adults. Still, TDI has been useful to monitor systolic heart function in children with cardiomyopathy or after heart transplantation. TDI studies revealed diastolic dysfunction in obese children and in cancer survivors with preclinical anthracycline cardiomyopathy. There is a growing body of studies using TDI to assess right heart function in children with congenital heart disease or pulmonary hypertension. Another potential strength of TDI velocities is the study of myocardial dyssynchrony where color TDI is well suited for rapid pediatric heart rates, even on fetal echocardiogram. Quantitative stress echocardiography with TDI is an emerging application in children that already offered insight into heart function in children with tetralogy of Fallot. Therefore, TDI velocity imaging should become part of the routine assessment of heart function in children.     

Assessment of Regional Myocardial Function in Patients with Dilated Cardiomyopathy by Velocity Vector Imaging

Objective: To assess the left ventricular (LV) longitudinal systolic and diastolic function in patients with dilated cardiomyopathy (DCM) by syngo Velocity Vector Imaging (VVI). Methods: Digital dynamic images of 30 DCM patients and 30 healthy subjects were collected; then the longitudinal velocity, strain, and strain rate were measured in systolic early and late diastolic periods, and the time to peak systolic velocity, strain, and strain rate were measured and recorded. The parameters of the two groups were compared. Results: All of the parameters of the DCM were significantly lower than those of the normal group (P < 0.05–0.01), except that the parameter of late diastolic strain was not different between the two groups (P > 0.05). Conclusions : VVI is a novel noninvasive tool to assess quantitatively and objectively LV regional systolic and diastolic function in patients with DCM; it provides another useful modality for evaluating cardiac function.     

Pulsed Tissue Doppler Imaging to Assess Myocardial Viability by Quantification of Regional Myocardial Functional Reserve

Dobutamine stress echocardiography (DSE) is used widely to evaluate myocardial viability, but is limited by the subjective nature of test interpretation. Assessment of systolic function by pulsed tissue Doppler imaging (TDI) during dobutamine stimulation may allow a more objective evaluation of myocardial functional reserve and, thus, myocardial viability. In 30 patients (58 +/- 9 years) with prior myocardial infarction, pulsed TDI with low dose dobutamine stress (10 microg/kg/min) was performed to assess myocardial viability. Qualitative assessment of two-dimensional (2-D) DSE and positron emission tomography (PET) were used for comparison. Peak systolic myocardial velocity was measured for each left ventricular segment (16 segments) at baseline and low dose dobutamine stress using pulsed TDI. The absolute and relative increases of peak systolic velocity from rest to low dose dobutamine stress were calculated. Three hundred sixty-four segments with adequate pulsed TDI tracing were divided according to either 2-D DSE or PET findings into normal, viable (mismatch), and nonviable (match) segments. The increase of peak systolic myocardial velocity from baseline to low dose dobutamine was significantly different between segments defined as normal, viable, and nonviable by 2-D DSE (2.71 +/- 1.91 cm/sec, 1.86 +/- 2.15 cm/sec, and 0.99 +/- 1.16 cm/sec, respectively; P < 0.001). The increase of peak systolic myocardial velocity from rest to low dose dobutamine for normal, mismatch, and match segments defined by PET was 2.72 +/- 1.96, 1.01 +/- 0.96 and 0.80 +/- 1.07 cm/sec, respectively (P < 0.001). In conclusion, the increase of peak systolic myocardial velocity during low dose dobutamine stimulation determined by pulsed TDI distinguishes between different myocardial viability states. It complements the standard interpretation of stress echocardiograms.     

Pulsed Doppler Tissue Imaging for Assessment of Left Ventricular Systolic and Diastolic Synchronicity in Normal Subjects

Objectives To quantitatively analyze the longitudinal myocardial systolic and diastolic velocities and time intervals of the left ventricle in normal subjects, and to explore the value of pulsed Doppler tissue imaging (DTI) for the assessment of left ventricular systolic and diastolic synchronicity. Methods Twenty and six healthy subjects were studied by pulsed DTI. The septal and lateral, anterior and inferior walls of the left ventricle were displayed respectively, and basal and middle segments of each wall were selected for myocardial motion spectrum sampling. DTI parameters were; peak systolic myocardial velocity (s) , regional pre-ejection period (PEP), time to the peak of s wave (Ts), regional ejection time (ET); peak early diastolic velocity (e), peak late diastolic velocity (a), e/a ratio, time to the beginning of e wave (QE), time to the peak of e wave (Te) and regional isovolumic relaxation time (IVRT). Results The e and e/a were significantly different among basal segments, and s and e/a were significantly different among middle segments, with the highest value in lateral segments and the lowest value in septal segments. The s, e and a were all significandy higher in basal segments than middle segments. None of the systolic time intervals (PEP, Ts and ET) and diastolic time intervals (QE, Te and IVRT) were significantly different among basal segments and middle segments, neither were they when basal segment was compared with middle segment. Conclusions In normal subjects, the longitudinal myocardial systolic and diastolic velocities of the left ventricle are not homogeneous, but the contraction and relaxation are highly synchronized. Pulsed DTI can be used to quantitatively analyze the systolic and diastolic synchronicity of the heart.     

Novel Application of Tissue Doppler Imaging

Tissue Doppler imaging was used with transthoracic and transesophageal echocardiography to determine its clinical usefulness beyond visualization of ventricular wall motion. Thirteen novel applications were found: acoustically difficult transthoracic studies, thrombus, mitral chordal motion, shunt detection using saline contrast, spontaneous echo contrast, intra-aortic balloon pump position and function, endocarditis (prosthetic and native), valve strands (prosthetic and native), mobile aortic atheroma, prosthetic valve motion, aortic valve motion in the presence of a calcified aortic annulus, systolic anterior motion of the mitral valve, and cardiac tumors. Tissue Doppler imaging directly affected the ability to make difficult diagnostic decisions with increased confidence and reduced the need for additional studies.     

Assessment of Right Ventricular Diastolic Function by Tissue Doppler Imaging in Patients with Acute Right Ventricular Myocardial Infarction

Background: It is known that right ventricular systolic parameters as assessed by color tissue Doppler imaging (TDI) are abnormal in patients with inferior wall ST elevation myocardial infarction (IWMI) with right ventricular myocardial infarction (RVMI). This study was undertaken to determine right ventricular diastolic function as assessed by TDI in patients with acute RVMI. Methods: Thirty‐five patients with first IWMI were studied and compared with 20 age‐matched healthy controls, and categorized into those with (14 patients) and without (21 patients) RVMI based on standard ECG criteria. Peak systolic, peak early and late diastolic velocities (Sm, Em, and Am), Em/Am ratio along with time to Sm (ECG Q‐Sm) and time to Em (ECG Q‐Em) were acquired from the apical 4‐chamber view at the lateral side of tricuspid annulus using TDI. Results: Sm, Em, and Em/Am ratio was reduced significantly in patients with RVMI as compared with those without RVMI and healthy individuals (Sm [11.1 ± 2.9] vs. [14 ± 1.9] and [14.5 ± 2.1] cm/sec, P < 0.01; Em [9.2 ± 3.5] vs. [12.9 ± 3] and [14.0 ± 2.0] cm/sec, P < 0.01; Em/Am ratio 0.53 ± 0.2 vs. 0.78 ± 0.19 and 0.8 ± 0.3 [P < 0.0001]). Among the intervals, there was significant prolongation of Q‐Em (558 ± 14.8 vs. 507 ± 16.2 and 480 ± 20 ms [P < 0.0001]) but Q‐Sm and Am were not statistically different between the groups. Conclusion: Right ventricular TDI diastolic parameters are abnormal in patients with RVMI. The method of recording the velocities and time intervals are simple and can be used to assess right ventricular diastolic function in patients with RVMI. (Echocardiography 2010;27:539‐543)     

Evaluation of Longitudinal Tissue Velocity and Deformation Imaging in Akinetic Nonviable Inferobasal Segments of Left Ventricular Myocardium by Dobutamine Stress Echocardiography

Aim: To study tissue velocity imaging (TVI) and strain rate imaging (SRI) indices in akinetic nonviable and normal left ventricular (LV) inferobasal segment and effect of dobutamine infusion on these indices in nonviable segments. Methods: The study population consisted of two groups: 25 patients (mean age 60.75 ± 8.69 years) with left ventricular akinetic inferobasal nonviable segment determined by dobutamine stress echocardiography (DSE) and 14 normal coronaries (mean age 56.67 ± 11.90 years) with normal echocardiography as control group. The following TVI and SRI parameters were measured in patient and control group: ejection phase velocity (Sm [cm/sec]), peak systolic strain (ST [%]), and strain rate (SR [per second])). Results: Ejection fraction was significantly lower in patient group (29.40%± 5.46% vs. 55.00%± 3.39%; P < 0.001). Several differences were observed in patients with nonviable inferobasal segments compared to control group: Sm was reduced (3.58 ± 1.08 cm/sec vs. 5.56 ± 1.28 cm/sec; P < 0.001); SR and ST were significantly decreased (−0.39 ± 0.20/second vs. −1.44 ± 0.64/second, and −3.86%± 4.12% vs. −17.64%± 7.44%, respectively; P < 0.001 in both). The range of SR for nonviable segments (−0.04 to −0.77/second) did not overlap with that of the normal segments (−0.80 to −3.0/second). This range for Sm and ST overlapped with those of the normal segments. Conclusion: All TVI and SRI parameters are reduced in akinetic nonviable inferobasal compared with normal segments. According to findings of this study, resting strain rate has a potential to discriminate nonviable inferobasal from normal segments.