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1.
Myocardial velocities in patients with congestive heart failure (CHF) were studied using pulsed wave Doppler tissue imaging. Velocities were recorded at the mitral and tricuspid annulus. Four sites at the mitral annuli were selected corresponding to the septal, lateral, inferior, and anterior walls of the left ventricle from apical 4- and 2-chamber views. A mean value from the above 4 sites was selected to describe the mitral annular velocities. Only one site of the tricuspid annulus was selected, corresponding to the right ventricular free wall. Three different annular velocities were recorded: the peak systolic, and the peak early and late diastolic velocities. A total of 96 patients were compared with 12 age-matched healthy participants. Patients with CHF had significantly decreased mitral and tricuspid systolic velocities compared with healthy participants (4.9 vs 9.3 cm/s, P <.001, for the mitral annulus and 10.4 vs 14.6 cm/s, P <.001, for the tricuspid annulus). The early diastolic velocity was also reduced in patients compared with healthy participants (5.9 vs 10.9 cm/s, P <.001, for the mitral annulus and 8.6 vs 12.9 cm/s, P <.001, for the tricuspid annulus). Patients with CHF had a severely depressed left ventricular ejection fraction (EF) (27%). The correlation the between systolic mitral annular velocity and EF was relatively good (r = 0.59 and P <.001). The patients with CHF were divided into 2 subgroups depending on the presence or absence of significant mitral regurgitation. There was a correlation between EF and the systolic mitral annular velocity both in patients with (r = 0.61, P <.001) and without (r = 0.59, P <.001) significant mitral regurgitation. In conclusion, compared with healthy participants, the mitral and tricuspid annular velocities are significantly decreased in patients with CHF. The correlation between EF and the systolic mitral annular velocity is relatively good irrespective of the presence or absence of significant mitral regurgitation. Measurements of annular velocities constitute a simple and useful method for evaluating patients with CHF.  相似文献   

2.
Respiratory variation of 25% or more in transmitral early diastolic filling (E) velocity is a well-recognized diagnostic feature of constrictive pericarditis (CP) that is useful for distinguishing it from restrictive cardiomyopathy. However, a subset of patients with CP do not exhibit the typical respiratory change. Recent data showed that mitral annular (E') velocity measured by Doppler tissue echocardiography (DTE) is markedly reduced in patients with restrictive cardiomyopathy whereas E' velocity is well-preserved in CP. This study evaluated the role of DTE for the diagnosis of CP when there is no characteristic respiratory variation of E velocity. From September 1999 to March 2001, 19 patients (17 men, 2 women; mean age, 57 +/- 13 years) with surgically confirmed CP underwent comprehensive echocardiography preoperatively, including pulsed wave and DTE examination with simultaneous recording of respiration. Nine (47%) of the 19 patients had less than 25% respiratory variation in E velocity. There was no significant difference in mitral inflow peak velocity, deceleration time, early-to-late ventricular filling ratio, and E' velocity between patients with and patients without respiratory variation of E velocity of 25% or more. Regardless of the presence or absence of a significant respiratory variation of E velocity, E' velocity was relatively normal (mean, 12 +/- 4 cm/s) in all patients with CP. In conclusion, E' velocity is well preserved in patients with isolated CP even when there is no characteristic respiratory variation of E velocity. Thus, when the respiratory variation in Doppler E velocity is blunted or absent during the evaluation of suspected CP in patients with restrictive mitral inflow velocity, preserved E' velocity shown by DTE should support the diagnosis of CP over a primary myocardial disease.  相似文献   

3.
心肌梗死部位对缺血性二尖瓣反流影响的研究   总被引:2,自引:0,他引:2  
目的探讨心肌梗死部位和缺血性二尖瓣反流的关系。方法应用超声心动图检测正常人前壁及下壁心肌梗死患者二尖瓣反流程度及左室、二尖瓣装置重构情况。结果下壁心肌梗死患者反流发生率高,程度重;左室和二尖瓣装置重构方面,下壁心肌梗死患者收缩功能更低,收缩末期容积指数更大;二尖瓣瓣叶闭合面积、瓣环面积、后乳头肌与二尖瓣前瓣环的距离的增加更为明显。多元逐步回归分析结果表明前壁和下壁心肌梗死患者的反流主要决定因素也不同。结论下壁心肌梗死较前壁心肌梗死反流更严重,其原因主要在于左室、二尖瓣装置重构的不同。  相似文献   

4.
Although alteration in pulmonary venous flow has been reported to relate to mitral regurgitant severity, it is also known to vary with left ventricular (LV) systolic and diastolic dysfunction. There are few data relating pulmonary venous flow to quantitative indexes of mitral regurgitation (MR). The object of this study was to assess quantitatively the accuracy of pulmonary venous flow for predicting MR severity by using transesophageal echocardiographic measurement in patients with variable LV dysfunction. This study consisted of 73 patients undergoing heart surgery with mild to severe MR. Regurgitant orifice area (ROA), regurgitant stroke volume (RSV), and regurgitant fraction (RF) were obtained by quantitative transesophageal echocardiography and proximal isovelocity surface area. Both left and right upper pulmonary venous flow velocities were recorded and their patterns classified by the ratio of systolic to diastolic velocity: normal (>/=1), blunted (<1), and systolic reversal (<0). Twenty-three percent of patients had discordant patterns between the left and right veins. When the most abnormal patterns either in the left or right vein were used for analysis, the ratio of peak systolic to diastolic flow velocity was negatively correlated with ROA (r = -0.74, P <.001), RSV (r = -0.70, P <.001), and RF (r = -0.66, P <.001) calculated by the Doppler thermodilution method; values were r = -0.70, r = -0.67, and r = -0.57, respectively (all P <.001), for indexes calculated by the proximal isovelocity surface area method. The sensitivity, specificity, and predictive values of the reversed pulmonary venous flow pattern for detecting a large ROA (>0.3 cm(2)) were 69%, 98%, and 97%, respectively. The sensitivity, specificity, and predictive values of the normal pulmonary venous flow pattern for detecting a small ROA (<0.3 cm(2)) were 60%, 96%, and 94%, respectively. However, the blunted pattern had low sensitivity (22%), specificity (61%), and predictive values (30%) for detecting ROA of greater than 0.3 cm(2) with significant overlap with the reversed and normal patterns. Among patients with the blunted pattern, the correlation between the systolic to diastolic velocity ratio was worse in those with LV dysfunction (ejection fraction <50%, r = 0.23, P >.05) than in those with normal LV function (r = -0.57, P <.05). Stepwise linear regression analysis showed that the peak systolic to diastolic velocity ratio was independently correlated with RF (P <.001) and effective stroke volume (P <.01), with a multiple correlation coefficient of 0.71 (P <.001). In conclusion, reversed pulmonary venous flow in systole is a highly specific and reliable marker of moderately severe or severe MR with an ROA greater than 0.3 cm(2), whereas the normal pattern accurately predicts mild to moderate MR. Blunted pulmonary venous flow can be seen in all grades of MR with low predictive value for severity of MR, especially in the presence of LV dysfunction. The blunted pulmonary venous flow pattern must therefore be interpreted cautiously in clinical practice as a marker for severity of MR.  相似文献   

5.
目的 该文旨在探讨急性心肌梗塞后二尖瓣返流的发生机制。方法 用彩色多普勒超声对91 例急性首次心梗入院3 天内患者按半定量法测定二尖瓣返流。结果 发现伴二尖瓣返流患者左室容积大、球形度大、下壁室壁异常运动积分高。亚组分析发现在前壁梗塞患者中也有类似表现;而在下壁梗塞的患者中,返流组的下壁室壁异常运动积分高,而其它指标差异均无显著意义。Logistic 逐步回归分析发现左室舒张末期球形度和下壁室壁异常运动积分是二尖瓣返流的独立相关因素。结论 左室球形度增大,使乳头肌向两侧移位,以及乳头肌附近的心室壁梗塞或缺血导致的运动障碍是心梗急性期二尖瓣返流的重要机制。  相似文献   

6.
目的探讨心肌跨壁速度梯度(MVG)评价急性心肌梗死(AMI)患者再灌注后存活心肌的可行性及对心功能恢复的预测价值.方法获取20例AMI患者和18例健康志愿者前间隔、下壁和后壁的中段心内、外膜侧心肌运动速度和相应室壁厚度,计算收缩期、舒张早期和舒张晚期的跨壁速度梯度(MVGS、MVGE和MVGA),并分析AMI患者急性期MVG改变与2~5个月时心功能恢复之间的关系.结果①AMI患者急性期梗死节段MVGS显著低于正常对照组;②随访时室壁运动改善组和未改善组比较,急性期MVGS降低程度后者显著大于前者;③以急性期MVGS为0或与正常值相反为区分不可逆性和可逆性节段的标准,MVGS预测左室局部运动改善或恢复的敏感性为89.1%,特异性为75.0%,准确性为81.8%.结论 MVG可准确定量评价左室局部运动,有望作为临床评价AMI患者存活心肌、预测可逆性左心功能障碍恢复的新指标.  相似文献   

7.
Doppler tissue imaging allows the measurement of tissue motion velocity in real time. However, tissue velocities are affected by translational motion and by the angle of Doppler interrogation. The myocardial velocity gradient and myocardial wall thickening velocity, determined by color Doppler tissue imaging, can be used to evaluate regional wall thickening and thinning motion independent of translational motion. To determine the control values for myocardial velocity gradient and myocardial wall thickening velocity for the interventricular septum and posterior wall, we studied 120 healthy children (mean age: 7.8 +/- 5.0 years). Peak values of myocardial velocity gradient and myocardial wall thickening velocity at each cardiac phase were measured: systole, early diastole, and atrial contraction. The peak values of myocardial velocity gradient and myocardial wall thickening velocity were higher in the posterior wall than those in the interventricular septum, suggesting that thickening and thinning are more dynamic in the posterior wall. Linear regression analysis demonstrated that absolute values of myocardial velocity gradient at systole, early diastole, and atrial contraction, and wall thickening velocity at atrial contraction decreased with body surface area (BSA). On the other hand, absolute values of myocardial wall thickening velocity at systole and early diastole increased with BSA, and myocardial wall thickening velocity at early diastole in interventricular septum did not change. Myocardial velocity gradient at systole and early diastole, and myocardial wall thickening velocity at systole were strongly related to BSA. In contrast, myocardial velocity gradient and myocardial wall thickening velocity at atrial contraction strongly correlated with time interval between 2 consecutive QRS complexes. Because myocardial wall thickening velocity at early diastole in the interventricular septum did not correlate with BSA or time interval between 2 consecutive QRS complexes, it might evaluate diastolic function of interventricular septum independent of body size or heart rate.  相似文献   

8.
目的 应用组织多普勒(tissue Doppler imaging,TDI)心肌运动速度梯度(myocardial velocity gradient,MVG)评价胎儿左、右心室心肌动力学.方法 对孕龄22~40周的30例正常胎儿取横位四腔心切面进行组织多普勒成像,采集3个心动周期的动态图像,获得心肌速度分布图.测量左、右心室游离壁基底段心内膜和心外膜收缩期及舒张期峰值速度及心肌厚度,计算MVG.分析左、右心室心肌收缩期及舒张期心内膜、心外膜速度及MVG与孕周的关系.结果 剔除图像质量较差的3例后,共有27例胎儿纳入分析.收缩期及舒张期左、右心室心内膜运动峰值速度均高于心外膜运动峰值速度(P<0.01).收缩期及舒张期左室游离壁、右室游离壁心肌运动速度与孕周呈正相关,而左室游离壁、右室游离壁MVG与孕周呈负相关.结论 TDI技术测量MVG能够用于评价胎儿心室心肌动力学,可以了解胎儿心室壁运动速度在中、晚孕期的生理变化特点及规律,有助于更加准确可靠地评估胎儿心功能的相应变化.  相似文献   

9.
急性心肌梗死患者二尖瓣返流的预后意义   总被引:1,自引:0,他引:1  
目的:探讨急性心肌梗死(AMI)患者二尖瓣返流(MR)的预后意义。方法:对142例AMI患者住院早期(7天内)行超声心动图检查,以彩色多普勒定量测定其MR。并对MR组及无MR组的临床资料、超声心动图指标及预后进行对比分析。结果:90例无MR(63.38%),轻度MR43例(30.28%),中、重度MR9例(6.34%)。MR组较无MR组患者年龄更大、既往心肌梗死发病率及高血压发病率更高(P<0.05)。MR返流组脉冲多普勒E峰、E/A显著高于无MR组(P均<0.05)。MR组30天及1年病死率均显著高于无MR组(P均<0.05)。结论:超声心动图证实的MR对AMI患者的预后具有预测价值。  相似文献   

10.
In 422 patients admitted from the emergency department (ED) for suspected acute myocardial infarction, the hypothesis that chest pain that persists on arrival in the ED or recurs during the initial ED evaluation is a useful predictor of acute myocardial infarction (AMI) and complications of coronary ischemia was tested. Compared with patients whose chest pain spontaneously ceased before arrival in the ED, patients whose chest pain persisted or recurred during the initial ED evaluation had a 2.3 times greater risk of interventions (P less than .001), a 1.7 times greater risk of complications (P = .045), a 3.8 times greater risk of life-threatening complications (P = .04), and a 2.4 times greater risk of AMI (P = .005). A third group of patients with suspected AMI never experienced chest pain. This group of patients who never experienced chest pain had a three times higher risk of death (P = .02) compared with patients whose chest pain persisted or recurred in the ED, and a 2.1 times greater risk of intervention (P = .01), a 5.2 times greater risk of life-threatening complication (P = .015), and a 7.9 times greater risk of death (P = .025) compared with patients whose chest pain resolved before arrival in the ED. It was concluded that patients with chest pain that resolves spontaneously before arrival to the ED have a better in-hospital prognosis than any other group.  相似文献   

11.
OBJECTIVE: We sought to test the value of a simple Doppler index, the mitral/aortic flow velocity integral ratio (MAVIR), as a screening method to identify patients with hemodynamically significant mitral regurgitation (MR). METHODS: Included in the study were 91 patients (mean age 61 +/- 14 years; 54% men) with echocardiographically diagnosed MR. The cause was organic in 23 patients and ischemic/functional in 68. MR degree was assessed by 2 quantitative echocardiographic measures: the regurgitant fraction and the regurgitant orifice area. RESULTS: A good correlation was found between MAVIR and both regurgitant fraction (r = 0.75) and orifice (r = 0.60). When we divided patients into 3 groups on the basis of the regurgitant fraction, used as reference standard, MAVIR significantly increased in proportion to MR severity (0.7 +/- 0.1 for mild MR vs 1.1 +/- 0.2 for moderate and 1.4 +/- 0.3 for severe regurgitation; P <.0001). A ratio > 1 identified 28 of 30 patients with severe MR (regurgitant fraction > 60%), whereas all patients with mild MR (regurgitant fraction < 40%) had a ratio < 1. Using a regurgitant orifice >or= 40 mm(2) as threshold for severe MR, a significant difference in MAVIR was also present among patients who had severe MR compared with those having mild and moderate regurgitation (P <.0001). CONCLUSIONS: These findings suggest that MAVIR is a sensitive index, potentially widely applicable in clinical practice as a screening parameter for identifying patients with hemodynamically significant MR.  相似文献   

12.
自制曲线M型超声测定心肌运动速率阶差的应用研究   总被引:2,自引:0,他引:2  
目的 一种自制曲线解剖M型超声图像方式,用于分析心肌运动速率阶差(MVG)。方法 设计能快速获取左室短轴8个采样点的心内外膜心肌运动速率,并计算出MVG的程序,对141例各类心脏病人,26例正常人进行了观察。结果 观察到心肌梗死、冠心病、扩张性心肌病各组MVG较对照组显著降低(P〈0.01),MVG与左室每搏量、射血分数等左室收缩功能指标相关良好。结论 自制曲线解剖M型超声图像方式MVG检测方法操作简便易行、重复性较好,使复杂的MVG测定过程简化,易于临床应用。  相似文献   

13.
14.
A novel single-photon emission computed tomography (SPECT) camera was developed to evaluate dynamic myocardial perfusion flow. However, it is unclear whether myocardial flow reserve (MFR) derived by dynamic perfusion SPECT using the novel SPECT camera (D-SPECT) reflects the severity of coronary atherosclerosis. In the present study, we therefore examined the relationship between MFR using D-SPECT and severity of coronary lesions. The study population comprised 40 patients who underwent both a myocardial dynamic perfusion SPECT study and invasive coronary angiography. The severity of coronary atherosclerosis was evaluated using the Gensini score. All patients underwent a rest/stress SPECT imaging protocol using Tc-99m-sestamibi, and dynamic acquisition was performed. Stress and rest flow was evaluated, and the global and regional MFR was calculated. Global MFR showed a significant negative correlation with Gensini score (r?=???0.345, p?=?0.037). Multiple linear regression analysis showed that only global MFR was independently related to Gensini score (p?=?0.018). Regional MFR was significantly lower in regions with ?90% ≤ stenotic lesions compared with regions with <?90% stenotic lesions (p?=?0.009). Global MFR derived by dynamic perfusion SPECT using D-SPECT reflects the severity of coronary atherosclerosis. Further, regional MFR is modulated by severe coronary artery stenotic lesions.  相似文献   

15.
Cardiac amyloidosis has been documented to show mitral regurgitation (MR) and a thickened mitral valve (MV) due to amyloid deposits. However, the changes in the physical properties of the thickened MV tissue in cardiac amyloidosis, which may be a causative factor of the MR, have not been described. Physical properties of the tissue, which are expressed by the elastic bulk modulus, can be evaluated by tissue sound speed. If biological tissue is assumed to be fluid-like, the tissue sound speed may be given by c= square root of K/rho, where c is the tissue sound speed, K is the elastic bulk modulus, and rho is the density. A reduction in tissue sound speed indicates a reduction in the elastic bulk modulus of the tissue, assuming that there is little change in rho. This suggests that the tissue is less elastic. The purpose of this study was to assess the physical properties of MV tissue by evaluating the sound speed of the MV tissue in cardiac amyloidosis. MV specimens were obtained at autopsy from 20 control adults without cardiovascular diseases and from 20 patients with cardiac amyloidosis. An acoustic microscope operating at 450 MHz was used to measure the tissue sound speed in the tip and basal portions of the MV tissue. The density of MV tissue was measured by microgravimetry. The severity of the MR had been evaluated by Doppler echocardiography before death, and it was compared with the tissue sound speed measured after death. In cardiac amyloidosis showing mild MR, the tissue sound speed of the MV in the tip portion (1605 +/- 19 m/s) and in the basal portion (1791 +/- 64 m/s) were lower than the corresponding values in control subjects (1637 +/- 42 m/s and 1851 +/- 62 m/s). However, these differences were not statistically significant. In cardiac amyloidosis showing moderate MR, the tissue sound speed of MV in the tip portion (1563 +/- 17 m/s) and in the basal portion (1654 +/- 59 m/s) were significantly lower than the corresponding values in the control subjects (p < 0.001) and the patients with mild MR (p < 0.05). No significant differences were observed in the density of MV tissue among the three groups. Therefore, the low value of the MV tissue sound speed in patients with cardiac amyloidosis indicated a reduced elastic bulk modulus, suggesting the less elasticity of the MV tissue. Furthermore, the patients with moderate MR demonstrated the greater reduction in the tissue sound speed than the patients with mild MR. The data suggest that the changes in physical properties of the MV tissue may be one of the causes of MR in cardiac amyloidosis.  相似文献   

16.
17.
Doppler-derived left ventricular (LV) rate of pressure rise (Dop LV DeltaP/Deltat) is described as an index of LV performance in the presence of mitral regurgitation (MR). This study was designed to define more accurately the accuracy of the method in the presence of severe MR. Ten pigs were anesthetized and monitored. MR was gradually created. At each grade of MR, preload was manipulated with the intent of modifying LV end-diastolic area value within a range of +/-20%. Concurrently, the mean left atrial pressure (LAP) was recorded, MR was quantified by the mitral to aortic velocity-time integral ratio (mitroaortic VTI ratio), Dop LV DeltaP/Deltat was calculated, and peak LV dP/dt was derived from LV catheterism data. During the procedure Dop LV DeltaP/Deltat gradually underestimated peak LV dP/dt. This difference was correlated to the mean LAP (P < 10(-5)) and mitroaortic VTI ratio (P < 10(-5)) and became clinically significant when the mean LAP was superior to 21 mm Hg.  相似文献   

18.
Repairing mitral regurgitation (MR) requires an understanding of its mechanism. Evaluating restricted leaflet closure in functional MR is challenging. Tenting area between leaflets and annulus in long-axis (LAX) views correlates with MR, but is positive even in control subjects; in the 4-chamber view, the incomplete mitral leaflet closure (IMLC) tenting pattern may be subtle and variable. We tested the hypothesis that leaflet concavity toward the left atrium in the LAX view, a rapid visual clue indicating abnormal tethering predominantly by intermediate chords, is a strong indicator of functional MR. We reviewed 90 patients: 40 with inferior myocardial infarction and ejection fraction > or = 50%; 40 with global left ventricular dysfunction and ejection fraction < 50%; and 10 control subjects. We assessed leaflet shape (concave or convex toward the left atrium) and maximum systolic proximal MR jet width in the LAX views. To quantify shape, we measured the leaflet concavity area between the anterior leaflet and a line connecting its ends. Conventional IMLC area was also assessed. Patients with leaflet concavity had significantly greater MR than those without this finding (jet width of 4.6 +/- 0.7 vs 0.5 +/- 0.1 mm, P <.0001), indicating mild-moderate versus trace MR, with differences comparable in those with inferior myocardial infarction and left ventricular dysfunction. Leaflet concavity area most strongly predicted MR by multivariate regression (R(2) = 0.7). Conventional IMLC area did not uniquely distinguish patients with or without MR and correlated more weakly with MR (R(2) = 0.30 vs 0.73). Mitral leaflet concavity in the LAX view provides rapid and reliable recognition of functional MR, with greater reliability than IMLC area. This shape, consistent with tethering by intermediate chords, may have implications for potential intervention.  相似文献   

19.
BACKGROUND: Doppler tissue echocardiographic myocardial velocity gradient (MVG) overcomes translational or tethered motion effects. Diagnostic applications rely on MVG numeric value, an instantaneous value calculated at peak endocardial velocity. Our aim was to test the clinical relevancy of MVG for patients with dilated cardiomyopathy (CM) at rest. Efficiency of MVG, as a marker of the underlying mechanism, ischemic or nonischemic, was compared with that of mean velocities averaged over a cycle. METHODS: Peak and mean velocities were measured and MVG calculated during ejection, and early and late diastole, in the endocardium and epicardium on color M-mode Doppler tissue echocardiographic parasternal recordings of the posterior wall, simultaneously imaged with the septum. The population consisted of 34 patients with similar clinical presentation (left ventricular ejection fraction < 40%, left ventricular end-diastolic diameter > 6 cm, and proven ischemic [14] or nonischemic [20] dilated CM) and 16 control subjects. RESULTS: Doppler tissue echocardiography data significantly differed between control subjects and all patients with CM. Between patients, the only significant differences were found at the posterior wall for mean velocities at the epicardium in systole (9 +/- 4 mm/s for ischemic vs 14 +/- 5 mm/s for nonischemic, P =.002), and at both layers in early diastole (endocardium, 14 +/- 9 vs 29 +/- 12 mm/s, P =.0004; epicardium, 12 +/- 4 vs 22 +/- 11 mm/s, P =.002; ischemic vs nonischemic CM, respectively). CONCLUSION: Specific features of CM were characterized by myocardial velocity changes studied layer by layer throughout a phase. The binary response of transient peak MVG could not reach this goal.  相似文献   

20.
Left ventricular (LV) longitudinal shortening plays an important role in cardiac contraction and is invariably affected by the presence of coronary artery disease. Third-generation tissue velocity imaging (TVI) color-maps cardiac movement by obtaining mean velocities of LV segments from the same set of beats. The goals of this study were to characterize patterns of longitudinal myocardial motion velocity in healthy subjects and to use these patterns to evaluate abnormal segments of patients with myocardial infarction (MI). Included were 20 healthy subjects and 16 patients with MI who underwent a 2-dimensional Doppler echocardiography study. Myocardial velocity profiles were taken at the anulus, basal, mid, and apical segments of the septal and lateral walls in the apical view. Segmental velocity patterns from healthy subjects were compared with abnormal segments in patients with MI. Both lateral and septal walls of healthy subjects showed significant basal-apical myocardial velocity reductions in systolic shortening (Sm) and early and late diastolic lengthening (Em and Am) and a basal-apical increase in the Em/Am ratio. The lateral wall had greater Sm and Em velocities than the septal wall. The Sm and Em velocities and the Em/Am ratio were significantly reduced in the abnormal segments in patients with MI. Latent lateral wall ischemia may have been detected in 5 of 9 patients with septal infarction, showing reduced Sm velocity in apparently normal lateral walls. In conclusion, TVI objectively quantifies directional and incremental changes in myocardial movement that are useful in evaluating global and regional myocardial function, and it may play a role in the detection of early myocardial ischemia.  相似文献   

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