Real-time myocardial blood flow imaging in normal human beings with the use of myocardial contrast echocardiography.

Triggered myocardial contrast echocardiography (MCE) has been used successfully to quantify myocardial blood flow and assess coronary stenosis in animal models, but practical considerations have limited its broad clinical use. Real-time MCE may have practical advantages to assess perfusion and real time myocardial blood flow in human beings. We compared real-time MCE with triggered imaging in 23 normal human volunteers by using an investigational ultrasound contrast agent (DMP-115) and a commercially available ultrasound platform (Acuson Sequoia). Peak myocardial opacification (reflecting myocardial blood volume) after contrast infusion was quantified digitally in gray scale units (GU). In 13 subjects, myocardial blood flow reserve was assessed during dipyridamole infusion with the use of intermittent destruction-replenishment techniques. Real-time MCE resulted in a 30- to 45-GU increase from baseline compared with a 20- to 70-GU increase with triggered imaging. Real-time MCE showed no statistical difference in opacification (P = .131 by analysis of variance) among any of the myocardial regions of interest. Triggered imaging resulted in heterogeneous opacification among the regions of interest (P < .05 by analysis of variance). Dipyridamole did not significantly change peak myocardial opacification (myocardial blood volume) for either technique. Quantification of flow reserve revealed that myocardial blood flow reserve for the dipyridamole group was 3.6 +/- 0.4 (mean +/- 1 standard error of the mean). Real-time MCE is feasible in normal human volunteers and provides homogenous opacification of the myocardium. Furthermore, quantification of myocardial blood flow with real-time MCE in normal human beings produces results that are consistent with the known physiology of the coronary microcirculation.     

Assessment of coronary flow reserve with transthoracic Doppler echocardiography: comparison among adenosine, standard-dose dipyridamole, and high-dose dipyridamole.

Coronary flow reserve (CFR), defined as a ratio of hyperemic-to-basal coronary flow velocity, provides important information about the functional aspect of coronary circulation. However, it usually is determined by invasive methods during catheterization. Recent studies have shown that transthoracic Doppler echocardiography (TTDE) may be useful in the measurement of coronary flow velocity in the distal portion of the left anterior descending coronary artery (LAD). The vasodilators used for hyperemia are adenosine and dipyridamole. However, the coronary vasodilative response and systemic hemodynamic effects of the two agents have not been directly compared with TTDE. We assessed blood flow velocity and vascular resistance in the distal LAD by TTDE during an intravenous 2-minute adenosine infusion (140 microg/kg/min) and low- (0.56 mg/kg) and high-dose dipyridamole (0. 84 mg/kg) infusion in 25 patients with patent LAD. Coronary flow velocity was successfully recorded in 20 patients (80%) during baseline and the consecutive vasodilator-infusion period. Compared with low-dose dipyridamole, adenosine infusion induced a higher CFR (3.7 +/- 0.87 vs 2.73 +/- 0.65; P <.05) and a lower coronary resistance index (0.31 +/- 0.04 vs 0.35 +/- 0.08; P <.05). But by increasing the dipyridamole dose to 0.84 mg/kg, the values of the CFR and coronary resistance index became comparable to those of adenosine infusion (2.85 +/- 0.78 vs 3.03 +/- 0.7, P = not significant [NS]; 0.33 +/- 0.04 vs 0.32 +/- 0.09, P = NS; respectively). We conclude that adenosine seems to be a favorable vasodilator for the measurement of CFR with TTDE.     

Real-time myocardial contrast echocardiography for pharmacologic stress testing: is quantitative estimation of myocardial blood flow reserve necessary?

BACKGROUND: Little is known about the diagnostic accuracy of quantitative real-time myocardial contrast echocardiography (MCE) as an adjunct to stress testing. This study was performed to evaluate the agreement between MCE and technetium 99m-sestamibi single photon emission computed tomography (SPECT) for detection of perfusion defects and to investigate whether quantitative assessment of myocardial perfusion can increase the diagnostic value of MCE. METHODS: MCE was performed at rest and during peak adenosine stress in 50 unselected patients undergoing SPECT imaging. Concordance between the 2 methods was assessed using kappa statistics. MCE images were analyzed quantitatively, measuring peak intensity (A) and maximal rise of signal intensity (beta). Myocardial blood flow reserve was estimated by calculating the ratios of A(adenosine)/A(baseline) (A reserve), beta(adenosine)/beta(baseline) (beta reserve), and A x beta(adenosine)/A x beta(baseline) (A x beta reserve). RESULTS: Visual analysis of MCE agreed well with SPECT (kappa = 0.67) with sensitivity of 64%, specificity of 97%, and overall accuracy of 87%. Quantitative analysis showed that peak signal intensity A significantly increased under adenosine stress in SPECT-normal segments (2.6 +/- 1.9 vs 3.0 +/- 1.6 dB, P <.0001), tendencially decreased in reversible (3.0 +/- 2.0 vs 2.4 +/- 1.2 dB, P =.07) and remained unchanged in fixed (0.9 +/- 0.9 vs 0.8 +/- 0.9 dB) defects. beta Increased markedly under adenosine in normal segments (0.4 +/- 0.4 vs 1.4 +/- 1.3, P <.0001) but not in segments with reversible or fixed defects. Receiver operating characteristic showed that beta reserve and A x beta reserve, but not A reserve, are sensitive parameters for detecting perfusion defects with areas under the curve of 0.84, 0.85, and 0.61, respectively. Cut-off values of 1.9 and 2.3, respectively, for beta and A x beta reserve yielded sensitivity rates of 79% and 80%, specificity rates of 75% and 78%, and overall accuracy rates of 76% and 79%, respectively. CONCLUSION: Quantitative estimation of myocardial blood flow reserve by MCE parameters corresponds to the evaluation of myocardial perfusion by nuclear imaging and can increase the sensitivity but not the overall accuracy of contrast echocardiography.     

Assessment of coronary stenoses of graded severity by myocardial contrast echocardiography.

BACKGROUND: Myocardial contrast echocardiography (MCE) has potential value in the assessment and quantitation of myocardial perfusion defects. However, the severity of stenosis detectable by MCE and its diagnostic accuracy remain undefined. Thus, we produced coronary stenoses of variable severity and quantified their effect on MCE. METHODS AND RESULTS: Three grades of left anterior descending (LAD) obstructions were produced in 7 open-chest swine. The stenoses were nonflow-limiting at rest, but decreased coronary hyperemia by 31.3% +/- 4.7%, 69.9% +/- 5.3% and 98.9% +/- 1.1%, respectively. Regional myocardial blood flow (RBF) was measured with fluorescent microspheres and was expressed as the ratio of LAD and control (LCx) beds. MCE was performed with 0.3 mg/kg intravenous AF0150 during ECG-gated harmonic imaging in short-axis view. Background-subtracted peak intensity (PI) was expressed as the ratio of LAD/LCx beds. Both RBF and PI ratios progressively decreased with increasing grades of stenosis. MCE showed a significant correlation with RBF (r = 0.74; P <.0001). Ratios of both PI and RBF differed significantly from baseline when coronary hyperemia was reduced more than 50%. An LAD/LCx ratio less than 0.6 by MCE yielded 61% and 83% sensitivity and 85% and 76% specificity with stenosis that reduced coronary hyperemia more than 50% and more than 75%, respectively. CONCLUSION: MCE with intravenous AF0150 during vasodilation correctly depicted the progressive reduction of flow ratios produced by graded coronary stenoses. A significant reduction of PI ratio was observed with stenosis causing more than 50% reduction of coronary hyperemia. An MCE ratio in stenosed/control beds could be selected, which exhibited good sensitivity and specificity in the identification of coronary stenosis.     

The myocardial performance index during low-dose dobutamine echocardiography in control subjects and patients with a recent myocardial infarction: a new index of left ventricular functional reserve?

BACKGROUND: Wall-motion analysis during low-dose dobutamine echocardiography (LDDE) is a semiquantitative measure of left ventricular contractile reserve after myocardial infarction (MI). The Doppler echocardiographic myocardial performance index (MPI) is a quantitative measure of combined left ventricular systolic and diastolic function. We sought to characterize the changes in MPI during LDDE in control subjects and patients with MI, and to describe the relation of these changes to changes in regional systolic function. METHODS: MPI was obtained at rest and during LDDE (10 microg/kg/min) in 25 healthy volunteers (group 1) and 50 patients with a recent MI. Patients were divided into two subsets; those with (n = 23; group 2A) and those without (n = 27; group 2B) a contractile reserve defined as an improvement of wall motion in more than two contiguous infarct-zone segments during LDDE. DeltaMPI was defined as the change from rest to LDDE. RESULTS: MPI decreased significantly during LDDE in groups 1 and 2A, whereas MPI increased in group 2B (DeltaMPI = 0.12 +/- 0.04 and 0.10 +/- 0.08 vs -0.03 +/- 0.08, P <.0001). On multivariate analysis, Deltawall-motion score index predicted DeltaMPI (beta = 0.65, P <.0001) independently of age, sex, and the dobutamine-induced change in heart rate and systolic blood pressure. CONCLUSIONS: Data suggest that the change in MPI during LDDE may provide a simple and quantitative measure of overall left ventricular functional reserve in patients with a recent MI.     

Evaluation of myocardial glucose metabolism before and after recovery of myocardial function in patients with tachycardia-induced cardiomyopathy

BACKGROUND: We assessed left ventricular (LV) function and myocardial glucose metabolism by fluoro-18-deoxyglucose (18F-FDG) positron emission tomography (PET) in patients with tachycardia-induced cardiomyopathy (TC). METHODS: The subjects were 42 patients with heart disease, consisting of 7 patients with TC (61.4 +/- 19.0 years, LVEF 34.1%+/- 10.6%) and 35 with ischemic heart disease (IHD) (63.1 +/- 10.8 years, LVEF 49.9%+/- 13.5%). Five volunteers with normal ECG were the control group. All of the patients underwent 18F-FDG PET and echocardiography, and all of the patients with TC underwent 18F-FDG PET and echocardiography before and 6 months after antitachycardia therapy. Six patients underwent radiofrequency catheter ablation (RFCA) and 1 patient was medically treated with antitachycardia therapy. Myocardial glucose metabolism was assessed semiquantitatively by using the % dose uptake of 60 kg of BW (% dose uptake). RESULTS: Mean % dose uptake of the control group was 5.52 +/- 0.54%. After antitachycardia therapy, LVEF significantly improved (34.1 +/- 10.6% vs 54.3 +/- 13.6%, P < 0.01), and % dose uptake also significantly improved (1.26 +/- 0.55% vs 1.49 +/- 0.62%, P < 0.05). Patients with IHD showed higher % dose uptake than those with TC before antitachycardia therapy (3.18 +/- 1.36 vs 1.26 +/- 0.55%, P < 0.01), controls showed higher value of % dose uptake than TC before antitachycardia therapy (5.52 +/- 0.54% vs 1.26 +/- 0.55%, P < 0.01). CONCLUSION: Semiquantitative analysis of 18F-FDG PET showed that antitachycardia therapy improved myocardial glucose metabolism in patients with TC.     

Coronary flow vasodilator reserve in patients with type 2 diabetes mellitus-associated arterial hypertension

The coronary flow vasodilator reserve (CFVR) in the proximal segment of the anterior descending coronary artery was studied in 50 patients with diabetes mellitus (DM), by Doppler study via transesophageal approach. Group 1 included 39 patients with DM concurrent with Stages 1-2 arterial hypertension (AH), of them 14 patients were documented as having coronary heart disease (CHD) in the presence of coronary atherosclerosis (Subgroup 1A) and CHD was excluded in the remaining 25 patients (Subgroup 1B). Group comprised 11 patients with normal blood pressure (BP). For comparison, 6 healthy individuals were examined. CFVR was calculated as a ratio of the peak diastolic coronary flow (CF) velocity during infusion of dipyridamole (0.56 mg/kg) to the baseline CF. CDVR was significantly decreased as compared with the controls (2.07 +/- 0.73 in Subgroup 1A, 2.15 +/- 0.67 in subgroup 1B, 1.78 +/- 0.33 in Group 2, and 3.68 +/- 0.26 in the controls), this decrease being due to low CF velocities in hyperemia in the majority of patients in Subgroup 1A and Group 2 and to higher baseline CF velocity in most patients from Subgroup 1B. In Group 1 patients, CFVR was not linear with age, the duration of the disease, BP and HbA1 levels, but it was related to the carotid distensibility coefficient (rho = 0.60, p = 0.004) and to the blood level of total cholesterol (rho = -0.43, p = 0.0107). In Group 2 patients, the least CF velocities in the presence of vasodilatation were detectable in older patients and in patients with hypercholesterolemia. An all the patients with left ventricular hypertrophy (LVH) had decreased CFVR whose values with the myocardial mass index above 130 g/m2 were significantly less than those in the absence of LVH. Thus, the limited reserve of coronary vasodilatation was detectable in patients with DM irrespective of BP levels and the status of epicardial arteries and it was most pronounced in LVH and hypercholesterolemia. The impaired elastic properties of peripheral arteries in the presence of cholesterolemia may be regarded as a marker of the low reserve of coronary vasodilatation in patients with DM concurrent with AH.     

脉冲多普勒超声心动图对高血压病人冠脉血流储备的测定

目的　应用经胸脉冲多普勒超声心动图 (PDE)测定高血压病人的冠脉血流储备功能 (CFR)。方法　 2 0例正常人和 3 5例无并发症的轻中度原发性高血压病人经静脉注射潘生丁 ,测量用药前后左冠状动脉主干舒张期峰值速度 ,计算其比值作为冠脉血流储备指标。结果　高血压病人无论是否伴有心肌肥厚均伴有冠脉血流储备指标D/RPDV的减低 ,差异显著 (P <0 .0 1)。结论　原发性高血压病人均存在冠脉血流储备减低     

实时心肌超声造影评价X综合征患者心肌冠状动脉血流储备

目的 应用实时心肌超声造影评价X综合征患者心肌冠脉血流储备.方法 选择X综合征患者10例,对照组7例,应用超声造影剂SonoVue进行实时心肌超卢造影检查,分别测定静息状态和腺苷负荷后造影剂微泡达到峰值的最大声强度(A),再充盈平均速度(β)及A×β,并测定冠脉血流储备(负荷前后A×β的比值).结果 X综合征患者静息时A与对照组相比差异无统计学意义(P>0.05),β值和A×β值低于对照组(P<0.01),X综合征患者冠状动脉血流储备值明显低于对照组,差异有统计学意义(P<0.01).结论 X综合征患者心肌微血管功能受损,实时心肌超声造影可评价X综合征患者心肌冠脉血流储备.     

Sensitive detection of myocardial viability in chronic coronary artery disease by ultrasonic integrated backscatter analysis.

BACKGROUND: Myocardial viability is not synonymous with contractile reserve and identifiable in a significant percentage of dysfunctional myocardial segments without contractile reserve. The usefulness of ultrasonic tissue characterization by the phase-corrected magnitude of cyclic variation of integrated backscatter (MVIB) in chronic coronary artery disease is not fully validated. Thus, whether MVIB predominantly reflects the contractile reserve or myocardial viability of chronically dysfunctional myocardium was determined. METHODS: The MVIB of severely dysfunctional interventricular septum or posterior wall was measured in 34 consecutive patients with previous myocardial infarction. Dobutamine stress echocardiography and fluorine-18 fluorodeoxyglucose positron emission tomography were used as the standards of contractile reserve and myocardial viability, respectively. RESULTS: Among 44 dysfunctional segments, only 15 were judged as having contractile reserve and 29 were judged as not by dobutamine stress echocardiography, whereas 26 segments showed myocardial viability using fluorine-18 fluorodeoxyglucose positron emission tomography and 18 did not. MVIB was greater in segments with than in those without contractile reserve (4.7 +/- 2.2 vs -1.4 +/- 4.9 dB, P < .0001), but there was considerable overlap between the groups. On the other hand, MVIB of segments with and without myocardial viability (4.1 +/- 2.6 vs -4.3 +/- 3.3 dB, P < .0001) was distinctly different and predicted myocardial viability with a sensitivity of 92% and a specificity of 94%. CONCLUSIONS: For patients with chronic coronary artery disease, MVIB better reflects myocardial viability than it does contractile reserve. Ultrasonic tissue characterization, in concordance with fluorine-18 fluorodeoxyglucose positron emission tomography, is a sensitive method for detecting myocardial viability.     

The flow-function relationship in patients with chronic coronary artery disease and reduced regional function: a Doppler transesophageal and bidimensional transthoracic echocardiography study

Background: Infra-low dose dipyridamole allows one to selectively explore myocardial viability. Transesophageal echocardiography Doppler measurement of left anterior descending coronary artery flow at baseline and following dipyridamole is an efficient tool to assess coronary flow response. Aim of this study was to determine the flow-function relationship during coronary vasodilatory stress in patients with coronary artery disease and baseline dysfunction. Methods and results: Twelve patients with resting dyssynergies and 6 controls underwent assessment of regional function and of left anterior descending blood flow velocity. Flow and function were evaluated at rest and following infra-low dose dipyridamole (0.28?mg/Kg over 4?min). Controls showed a normal function at rest and after dipyridamole. Six patients (‘Responders’) with resting dyssynergies showed an improvement in segments of left anterior descending artery territory, whereas the other six ones (‘Non-responders’) showed no functional change. Controls and ‘Responders’ had similar values of resting peak diastolic left anterior descending artery flow velocity both at rest and after dipyridamole, whereas ‘Non-responders’ showed a blunted flow response to dipyridamole. Conclusion: Myocardial segments with a resting dysfunction and a contractile reserve more often exhibit a residual flow response, whereas segments with fixed pattern show a flat flow response during coronary vasodilator stress.     

Peak negative myocardial velocity gradient and wall-thickening velocity during early diastole are noninvasive parameters of left ventricular diastolic function in patients with Duchenne's progressive muscular dystrophy.

Myocardial velocity gradient and wall-thickening velocity were measured in the interventricular septum and left ventricular posterior wall (LVPW) by color-coded M-mode Doppler tissue echocardiography in patients with Duchenne's progressive muscular dystrophy (DMD) with a normal shortening fraction (n = 14) and age-matched control subjects (n = 40). In the LVPW, peak myocardial velocity gradients during systole and early diastole were significantly lower for patients with DMD than in control subjects (P <.0005, and P <.0001, respectively). Peak myocardial wall-thickening velocities of the LVPW during systole and early diastole were also lower for patients with DMD (P <.0005 and P <.0001, respectively). Mitral peak atrial to early filling velocity ratio was not significantly different between the 2 groups. The cut-off values of peak myocardial velocity gradients and wall-thickening velocities of the LVPW during early diastole for differentiation between patients with DMD and control subjects were -5.8/s and -6.0 cm/s, respectively (sensitivity/specificity: 93%/93% and 93%/85%, respectively). In conclusion, wall thinning during early diastole is frequently abnormal in patients with DMD, even when conventional echocardiographic findings are normal.     

Assessment of diastolic function by tissue Doppler echocardiography: comparison with standard transmitral and pulmonary venous flow.

The objective of this study was to determine the utility of Doppler tissue echocardiography in the evaluation of diastolic filling and in discriminating between normal subjects and those with various stages of diastolic dysfunction. We measured myocardial velocities in 51 patients with various stages of diastolic dysfunction and in 27 normal volunteers. The discriminating power of each of the standard Doppler indexes of left ventricular filling, pulmonary venous flow, and myocardial velocities was determined with the use of Spearman rank correlation and analysis of variance F statistics. Early diastolic myocardial velocity (E(m)) was higher in normal subjects (16.0 +/- 3.8 cm/s) than in patients with either delayed relaxation (n = 15, 7.5 +/- 2.2 cm/s), pseudonormal filling (n = 26, 7.6 +/- 2.3 cm/s), or restrictive filling (n = 10, 7.4 +/- 2.4 cm/s, P <.0001). E(m ) was the best single discriminator between control subjects and patients with diastolic dysfunction (P =.7, F = 64.5). Myocardial velocities assessed by Doppler tissue echocardiography are useful in differentiating patients with normal from those with abnormal diastolic function. Myocardial velocity remains reduced even in those stages of diastolic dysfunction characterized by increased preload compensation.     

经胸超声心动图评价系统性红斑狼疮患者冠状动脉血流储备

目的 研究经胸超声心动图评价系统性红斑狼疮(SLE)患者冠状动脉(冠脉)血流储备的价值.方法对24例SLE患者(SLE组)和18例健康志愿者(对照组)行经胸超卢心动图检查,获得冠状窦的内径和血流频谱,计算血流量,静脉注射潘生丁诱导冠脉扩张充血.冠状窦充血状态与基础状态血流量的比值即为冠脉血流储备.比较SLE组与对照组冠脉血流储备的差异.结果经胸超声心动图可测得两组受检者冠状宴血流量.SLE组冠脉血流储备为1.55±0.21.对照组冠脉血流储备为2.51±0.33,SLE组低于对照组,差异有统计学意义(P＜0.01).结论经胸超声心动图可用于评价SLE患者冠脉血流储备,冠脉血流储备受损提示SLE患者可能存在亚临床型冠脉疾病.     

Quantification of transmural gradient of blood flow in myocardial ischemia with real-time myocardial contrast echocardiography and dipyridamole stress test

Transmural redistribution of myocardial blood flow (MBF) is the earliest sign of myocardial ischemia. We aimed to evaluate the ability of real-time myocardial contrast echocardiography (MCE) combined with dipyridamole stress to quantify the transmural gradient of MBF during graded coronary stenosis. Real-time MCE was performed in 14 open-chest dogs at seven experimental stages: baseline; hyperemia induced by 6-min infusion of dipyridamole; 50%, 75% and 90% reduction of hyperemic flow after constriction in each stage for 10 min; reperfusion for 10 min; and subtotal occlusion of the left anterior descending coronary artery (LAD) for 90 min. We obtained MCE perfusion parameters from subendocardial (A-endo, beta-endo and A x beta-endo) and subepicardial (A-epi, beta-epi and A x beta-epi) layers of the ventricular septum and calculated their transmural gradients (A-EER, beta-EER and A x beta-EER) and systolic wall thickening (SWT). The sensitivity and specificity of each parameter for predicting 75% reduction of hyperemic flow, which was defined as mild myocardial ischemia, were derived by receiver operating characteristic (ROC) curve analysis. No transmural gradients were found at baseline; during maximal hyperemia and 50% reduction of hyperemic flow. beta-endo, A x beta-endo, beta-EER and A x beta-EER decreased significantly when the hyperemic flow was reduced by 75% or more. In contrast, SWT remained unchanged until the hyperemic flow was reduced by 90%. Among all parameters measured, beta-EER and A x beta-EER had the highest and SWT the lowest sensitivity and specificity in predicting mild myocardial ischemia. In conclusion, real-time MCE combined with dipyridamole stress allows for quantification of the transmural gradient of MBF. beta-EER and A x beta-EER are more sensitive than SWT and other MCE parameters in detecting mild myocardial ischemia.     

心肌声学造影评估X综合征患者心肌血流量的临床研究

目的 探讨应用实时心肌声学造影(MCE)评估X综合征患者心肌血流量(MBF)的临床应用价值.方法 选择X综合征患者35例,对照组32例,分别在静息状态和多巴酚丁胺药物负荷试验后进行MCE检查,测量平台期心肌显影强度(A),曲线上升平均斜率(β)及A×β(MBF),并测定冠状动脉血流储备(CFR).结果 负荷前后两组β值和A×β值均较负荷前增加,差异有统计学意义,X综合征患者负荷前后(0.83±0.13 vs 1.34±0.26,(17.66±3.12) dB vs (31.42±3.98) dB;对照组负荷前后β值1.68±0.16 vs 1.89±0.19;A×β值负荷前后(31.06±3.25) dB vs (99.97±4.35) dB(P＜0.05),且负荷后X综合征组β值和A×β值低于对照组(P＜0.05),X综合征患者CFR降低,1.49±0.30 vs 3.63±0.28(P＜0.01).结论 实时心肌声学造影能定量分析MBF,可用于评价微循环灌注异常的X综合征患者.     

Simultaneous analysis of wall motion and coronary flow reserve of the left anterior descending coronary artery by transthoracic doppler echocardiography during dipyridamole stress echocardiography.

BACKGROUND: Coronary flow reserve (CFR) can be measured in the left anterior descending artery (LAD) by dipyridamole transthoracic Doppler echocardiography (DTTDE). This information may critically improve the diagnostic accuracy of dipyridamole stress echocardiography, which is limited by moderate sensitivity. OBJECTIVE: We sought to assess the feasibility and accuracy of value of DTTDE. METHODS: We evaluated 752 consecutive patients (478 men; mean age, 64.7 years) referred for dipyridamole stress echocardiography. The diastolic velocity in the LAD was continuously monitored with pulsed Doppler at baseline and during hyperemia induced by the infusion of 0.84 mg/kg of dipyridamole. CFR was calculated as the ratio of maximal and basal diastolic velocity; a value < 2 was considered to indicate decreased CFR. Wall motion was assessed semiquantitatively. Coronary angiography was performed in 132 patients the week after DTTDE. RESULTS: Adequate tracings were obtained in 95% of patients studied (715 of 752). In the subset of 132 patients undergoing coronary angiography, 71 patients (group A) showed a nonsignificant (<70%) and 61 patients (group B) a significant stenosis of the LAD. In group A, 65 had a normal wall-motion response (91.5% specificity) and 19 patients showed a decreased CFR (73.2% specificity; P =.1). In group B, new wall-motion abnormalities were seen in 42 patients (68.8% sensitivity), whereas CFR was decreased in 52 patients (86.8% sensitivity; P <.02). CONCLUSION: Simultaneous assessment of wall motion and CFR of the LAD with DTTDE was highly feasible and safe. The information about CFR had a significantly higher sensitivity than the analysis of wall motion during dipyridamole stress echocardiography.     

心肌造影超声心动图对糖尿病大鼠心肌微循环的评价

目的 研究心肌造影超声心动图(MCE)技术结合潘生丁负荷试验是否能够早期检测糖尿病(DM)大鼠左室心肌微循环的功能障碍.方法 雄性SD大鼠18只,腹腔注射链脲菌素复制DM模型,另12只体质量匹配的雄性SD大鼠腹腔注射生理盐水作为对照.分别在静息状态和潘生丁负荷后,对两组大鼠(12周)乳头肌水平左室短轴行MCE检查,测定各室壁感兴趣区域峰值声学强度(PI)、造影剂灌注速率(β)及声学强度达峰时间(TTP)等指标,计算心肌血流量(MBF)和心肌血流储备(MFR).MCE检查完毕后,对心肌组织分别行~(99m)Tc-MIBI核素摄取量及毛细血管密度测定.结果 无论静息状态还是负荷后,同组大鼠后壁的MBF较前壁、侧壁和室间隔的MBF显著减低(P<0.05);取前壁心肌进行组间比较,静息状态和负荷后,DM组的PI、MBF和MFR均较对照组显著减低(P<0.05).潘生丁负荷后,DM组β也较对照组显著减低,TTP显著延长(P<0.05).DM组各室壁的核素摄取量和毛细血管密度均显著减低(P<0.05).结论 MCE检测的PI、β、TTP、MBF及MFR等指标可以敏感地检测出DM早期的心肌微循环功能障碍.     

Early assessment of coronary flow reserve by transthoracic Doppler echocardiography predicts late remodeling in reperfused anterior myocardial infarction.

BACKGROUND: Microvascular integrity is an essential determinant of favorable late outcome in reperfused myocardial infarction. Coronary flow reserve (CFR) can be assessed by transthoracic Doppler echocardiography and provides a functional estimate of microvascular integrity downstream from the patent infarct-related vessel. OBJECTIVE: We sought to assess the effects of CFR in predicting late left ventricular (LV) remodeling in patients with reperfused acute anterior myocardial infarction treated with primary angioplasty. METHODS: In all, 31 patients admitted with acute anterior myocardial infarction underwent primary angioplasty of the infarct-related vessel. After angioplasty, angiographic thrombosis in myocardial infarction (TIMI) grade and myocardial blush were scored. On the first day, all underwent stress echocardiography and CFR evaluation of left anterior descending coronary artery by transthoracic Doppler. All patients had resting 2-dimensional echocardiography at 1, 3, and 6 months for assessment of LV function. RESULTS: CFR could be successfully assessed in 31 patients. After 6 months 5 patients showed LV dilatation (group I), whereas 26 patients did not show significant variation (group II). On day 1, CFR was higher (group I = 1.43 +/- 0.11 vs group II = 1.67 +/- 0.26, P =.005) and the deceleration time of diastolic left anterior descending coronary artery flow velocity was longer (group I = 212 +/- 41.4 milliseconds vs group II = 286 +/- 106.7 milliseconds, P <.02) in patients without, compared with those with LV remodeling, whereas there was no difference in angiographic parameters. CONCLUSION: Early assessment of CFR and the pattern of baseline diastolic coronary flow velocity by transthoracic Doppler echocardiography is feasible, safe, and more useful than angiographic indices in identifying patients at high risk of remodeling in spite of successful primary angioplasty.     

Value of myocardial contrast echocardiography for predicting left ventricular remodeling and segmental functional recovery after anterior wall acute myocardial infarction.

OBJECTIVE: We sought to study the value of microvascular perfusion assessed by myocardial contrast echocardiography in predicting left ventricular remodeling after anterior wall acute myocardial infarction. METHODS: In 31 patients myocardial contrast echocardiography was performed up to 48 hours after acute myocardial infarction with determination of end-diastolic and end-systolic volumes, wall-motion score index, and myocardial perfusion score index (MPSI) at rest and under dobutamine stress at 6 months. Patients were classified into remodeling group (RG) (n = 19) and non-RG (n = 12), and, according to number of segments without opacification, reflow (< or =2 segments, n = 15) and no-reflow (>2 segments, n = 16) groups. RESULTS: Wall-motion score index (1.84 +/- 0.22 vs 1.64 +/- 0.3; P =.049), MPSI (1.53 +/- 0.25 vs 1.26 +/- 0.17; P =.006), and number of segments without contrast (3.11 +/- 2.23 vs 1.08 +/- 1.38; P =.018) were higher in RG than in non-RG. End-diastolic and end-systolic volumes, and wall-motion score index, increased significantly in RG at 6 months and decreased in non-RG. MPSI increased in RG (1.53 +/- 0.25-1.66 +/- 0.21; P =.011) and was the only independent predictor of left ventricular remodeling (odds ratio = 1.8; 95% confidence interval = 1.15-2.82; P =.010). No-reflow group presented 27.8 +/- 19.9% of segments with resting functional recovery or contractile reserve, and reflow group presented 69.9 +/- 31.2% (P <.001). CONCLUSION: MPSI obtained 48 hours after acute myocardial infarction is an independent predictor of left ventricular remodeling. Patients with two or fewer segments without opacification revealed a better prognosis of resting ventricular function and contractile reserve.