Myocardial postsystolic motion in ischemic and not ischemic myocardium: the clinical value of tissue Doppler

Postsystolic motion (PSM) is a delayed ejection motion of the myocardium occurring after the aortic valve closure, during a generally prolonged isovolumic relaxation time (IVRT). In this review we analyze the physiopathologic mechanisms underlying PSM and the contribution of tissue Doppler for its understanding. By using various techniques, this phenomenon has been described in experimental observations and related to myocardial ischemia produced by gradual or abrupt coronary occlusion. In clinical studies, it is associated with recovery of regional myocardial function. Tissue Doppler, providing a velocity map of myocardial motion, allows an easy, noninvasive detection of PSM in the clinical setting. PSM, as identified by tissue Doppler, appears a hallmark of myocardial ischemia and viability but it may occur also in nonischemic conditions as left ventricular (LV) hypertrophy and volume overload, left bundle branch block and even in normal individuals. Strain and strain rate (SR), obtainable by off-line color tissue Doppler, may be useful to identify the mechanisms underlying PSM since these measurements reflect, respectively, the intrinsic rate and the percentage of deformation of a given myocardial segment, and are relatively independent of both overall cardiac movement and tethering of the neighboring LV segments. By using SR imaging, the ratio of PSM to regional systolic longitudinal strain can be used to separate ischemic from nonischemic PSM and appears the best quantitative parameter to identify ischemia during dobutamine stress. A method to detect LV wall asynchrony and immediate benefit of cardiac resynchronization therapy has been developed combining the assessment of tissue-tracking (TT) derived delayed longitudinal contraction and of SR-derived PSM.     

超声组织定征在心血管疾病诊断中的应用

超声组织定征(Ultrasonic Tissue Characterization,UTC)技术是通过检测组织的声学参数来定量描述正常和病理组织的物理(声学)特性。研究表明,背向散射积分作为组织定征的参数,可以识别缺血心肌、顿抑心肌、梗死心肌、左心室心肌肥厚及心脏移植排斥反应,评价和分析系统性疾病如糖尿病等引起的弥漫性心肌受累的状态、心腔内血栓和动脉斑块的成份等。因而UTC技术具有很大的临床价值和发展潜力,将成为常规超声心动图诊断的辅助手段。本文就超声组织定征技术在心血管疾病诊断中的应用及进展作一综述。     

缺血心肌细胞骨架损伤研究

目的建立动物心肌缺血模型，探讨心肌缺血时细胞骨架的改变。方法15只清洁级健康成年雄性Wistar大白鼠，采用左冠状动脉结扎术造成部分心肌缺血，分别于缺血30min、60min、120min时取缺血心肌组织用免疫组织化学方法观察心肌细胞骨架蛋白肌动蛋白（α-actin）、波形蛋白（vimentin）、肌球蛋白（myosin）、结蛋白（desmin）的变化，与未缺血部分心肌对比，并用计算机图像模拟分析系统计算细胞骨架蛋白量的变化。结果心肌缺血时30min时即有骨架蛋白actin、myosin的损伤，随后见desmin、vimentin受损。结论心肌缺血时可以早期导致心肌细胞的细胞骨架损伤。     

Tissue characterization with intra-arterial ultrasound: Special promise and problems

Although we are able to identify many tissue types based on the screen image in intravascular ultrasound, there is additional information in the ultrasound signal which could be of assistance in characterization and identification of tissue. Intravascular ultrasound has several special characteristics which affect tissue characterization. These include the high transducer frequency, small transducers, short and relatively uniform path to the tissue, and limited tissue types to identify. These characteristics influence the results obtained by absolute backscatter, local statistics, frequency dependent backscatter, and angle dependency of backscatter. These effects are both positive and negative, and in many cases can be observed in clinical imaging. Another area of tissue characterization which can be performed with ultrasound is measurement of arterial wall elasticity. This can be of importance in the evaluation of mechanisms of dilatation, and the potential for complications.     

腺病毒介导的碱性成纤维细胞生长因子对慢性缺血冬眠心肌的保护作用

目的探讨重组腺病毒介导的碱性成纤维细胞生长因子(bFGF)对慢性缺血冬眠心肌的保护作用。方法制备猪慢性缺血冬眠心肌模型,并随机分为3组,分别心内注射腺病毒介导的bFGF(AdbFGF组)、空病毒(空病毒组)和生理盐水(空白对照组),每组7头猪,观察心肌间质胶原容积分数、心肌细胞核密度、核长度、心肌细胞直径以及心肌细胞增殖活性和凋亡的改变。结果与空病毒组和空白对照组比较,AdbFGF组冬眠心肌处心肌细胞直径和核长度明显增加,而心肌细胞核密度明显降低。而且心肌细胞的增殖活性增高,凋亡减少。结论bFGF一方面诱导心肌细胞增殖分裂,促进冬眠心肌细胞肥大;另一方面抑制细胞凋亡,减少冬眠心肌的损伤。     

乌拉地尔干预急性心肌缺血的细胞机制

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Ultrasonic characterization of porcine liver tissue at frequency between 25 to 55 MHz

AIM: To study the relation between acoustic parameters and histological structure of biological tissue and to provide the basis for high-resolution image of biological tissues and quantitative ultrasonic diagnosis of liver disease. METHODS: Ultrasonic imaging and tissue characterization of four normal porcine liver and five cirrhotic liver tissue samples were performed using a high frequency imaging system. RESULTS: The acoustic parameters of cirrhotic liver tissue were larger than those of normal liver tissue. The sound velocity was 1577 m/s in normal liver tissue and 1631 m/s in cirrhotic liver tissue. At 35 MHz, the attenuation coefficient was 3.0 dB/mm in normal liver tissue and 4.1 dB/mm in cirrhotic liver tissue. The backscatter coefficient was 0.00431 dB/Srmm in cirrhotic liver tissue and 0.00303 dB/Srmm in normal liver tissue. The backscatter coefficient increased with the frequency. The high frequency images coincided with their histological features. CONCLUSION: The acoustic parameters, especially the sound backscatter coefficient, are sensitive to the changes of liver tissues and can be used to differentiate between the normal and pathological liver tissues. High frequency image system is a useful device for high-resolution image and tissue characterization.     

胰岛素对缺血心肌细胞葡萄转运子1移位的增强作用

目的：观察胰岛素对缺血心肌葡萄糖转运子1（GLUT1）移位的增强作用。方法：用自动分析仪测定生理代谢参数,用免疫抑迹和免疫荧光法检测GLUT1。结果：胰岛素使犬在体缺血心肌细胞质膜GLUT1增加1．5倍,同时伴随葡萄糖摄取增多,缺血区心肌葡萄糖摄增加4倍。结论：胰岛素对缺血心肌细胞GLUT1移位有增强作用,并促使心肌摄取更多的葡萄糖,心肌缺血时,应用胰岛素有助于增加心肌葡萄糖的摄取和利用。     

应用计算机超声图像纹理定征法评价缺血后心肌组织变化特征

目的 :探讨计算机图像纹理分析法评估缺血心肌组织超声图像纹理的变化特征。方法 :11只犬进行左冠状动脉前降支结扎术制作急性心肌缺血模型。获取不同时间段内左室长轴与乳头肌水平短轴的二维图像 ,采用共生矩阵法经计算机脱机处理对正常与不同程度缺血心肌进行纹理分析 ,提取 4种纹理参数 :二次角矩、对比度、熵、反差矩。于左心长轴与短轴切面上 ,对室间隔在前降支结扎前和结扎后不同缺血时间内的超声图像纹理参数进行比较。结果 :在左心长轴切面上 ,各缺血时间段 4种纹理参数与正常基础状态比较 ,缺血 30min后即出现差异 ,P <0 .0 5。在短轴切面上 ,与正常心肌比较 ,二次角矩、熵、反差矩在缺血 30min后的心肌图像纹理上出现差异 ,P <0 .0 5。对比度在心肌缺血 1h后呈现差异 ,P <0 .0 5。结论 :计算机超声图像纹理定征法在评价缺血后心肌组织变化特征方面具有一定的潜在应用价值 ,值得深入研究     

血管生成素相关蛋白2对大鼠缺血心肌促血管生长作用的初步观察

目的观察和评价血管生成素相关蛋白2(angiopoietin-related protein 2,ARP2)基因移植于大鼠急性缺血心肌后的促血管新生作用,探讨其促血管新生机制。方法建立急性心肌缺血大鼠模型,将42只大鼠随机分为3组:缺血区域心肌内注射ARP2重组腺病毒组(Ⅰ组,n=14);注射ARP2空腺病毒组(Ⅱ组,n=14)和注射磷酸缓冲溶液组(Ⅲ组,n=14),注射后28天行心脏彩色超声检查、心肌声学造影,并取注射点心肌切片作常规病理HE染色、VB染色、Ⅷ因子相关抗原免疫学检测。结果Ⅰ组大鼠心脏功能及心肌灌注较Ⅱ、Ⅲ组明显改善,免疫组织化学检测显示Ⅰ组心肌高度表达ARP2蛋白,心肌纤维间毛细血管数目明显增多。结论ARP2能通过促进大鼠缺血心肌血管新生,从而改善心脏功能。     

Ultrasonic tissue characterization and Doppler tissue imaging in the analysis of left ventricular function in essential arterial hypertension: a preliminary study

It is not known if diastolic abnormalities are independent of systolic dysfunction in arterial hypertension. We studied three groups of 10 male subjects of comparable mean age (31.6 +/- 3.5 years), weight, and height: Athletes (A) (cyclists), essential hypertensive patients (H), and controls (C). Ultrasonic myocardial integrated backscatter signals (IBS) of the septum and the posterior wall were analyzed, while the systo-diastolic variation of the backscatter was considered as a cyclic variation index (CVI(ibs)). Myocardial velocities across the left ventricular major axis were sampled at septum and lateral wall levels by pulsed-wave Doppler tissue imaging (DTI). CVI(ibs) at the septum and the posterior wall were significantly lower in the hypertensive group in comparison with athletes and controls, who were comparable. Early diastolic myocardial velocity (E(m)) of the lateral wall and of the septum were significantly lower in hypertensives, while the late diastolic myocardial velocity (A(m)) was significantly higher in hypertensives in comparison with athletes. The E(m)/A(m) at the septum level was significantly lower in hypertensives in comparison with athletes and controls. Significant correlations were found between CVI and DTI parameters: CVI(ibs) and E(m)/A(m) septum (r = 0.50, P < 0.002). Furthermore, significant correlations were found between mean arterial pressure (MAP) and E(m)/A(m) septum (r = - 0.65, P < 0.001). Ultrasonic tissue characterization with the intrinsic contractility study and the evaluation of the regional diastolic function should, therefore, represent a new integrated diagnostic modality for the evaluation of left ventricular hypertrophied intramyocardial function. This study demonstrated that diastolic abnormalities of left ventricular function, in arterial hypertension, are related and progress with systolic intrinsic dysfunction.     

组织多普勒腺苷负荷超声心动图定量评估心肌缺血的应用

目的 评价定量腺苷负荷超声心动图技术诊断冠心病的准确性.方法 40例患者行常规剂量(140μg·ks-1·min-1持续6 min静脉滴注)腺苷负荷超声心动图试验以评估心肌缺血.基于常规二维图像之上的组织多普勒成像采集基线状态和药物负荷状态下的心肌运动图像(美国GE VIVID7超声诊断仪),在ECHOPAC软件上进行后处理分析测量16节段心肌运动速度、应变、应变率.结果 以冠状动脉造影或CT冠状动脉成像为标准,共有缺血节段159个节段,非缺血节段465个.腺苷负荷峰值后,除缺血心肌的舒张早期应变(Se)无明显变化外,缺血心肌和非缺血心肌的收缩期速度(Sm)、舒张早期速度(Em)、舒张晚期速度(Am)和收缩期应变(Smax)以及收缩期应变率(SRs)、舒张早期应变率(SRe)、舒张晚期应变率(SRa),以及非缺血心肌的舒张早期应变(Se)均明显增加(P＜0.05).缺血心肌的基线Sm和Em均显著低于非缺血心肌[分别为(3.16±1.20)cm/s和(4.03±1.27)cm/s,P＜0.01;(3.75±1.67)cm/s和(4.66±1.70)cm/s,P＜0.05],峰值负荷下,两组间Sm和Em差异更加显著[分别为(3.98±1.63)cm/s和(5.07±1.52)cm/s;(4.51±2.32)cm/s和(6.52±2.56)cm/s;均P＜0.01];缺血心肌的收缩期应变(Smax)和舒张早期应变(Se)均明显低于非缺血心肌(分别为16.91%±3.35%和19.56%±5.47%,P＜0.01;9.53%±2.89%和13.06%±4.63%,P＜0.001).操作者工作特性(ROC)曲线所得曲线下面积以负荷峰值的Se最大(曲线下面积=0.740,敏感性为67%,特异性为83%).结论 组织多普勒负荷超声心动图参数可定量评估心肌缺血,是临床非创伤性诊断冠心病准确可靠的方法.     

Salvage of acutely ischemic myocardium by emergency coronary artery bypass grafting

After cardiac catheterization a 53-year-old patient developed widespread myocardial ischemia that produced electromechanical dissociation and cardiogenic shock. The administration of methylprednisolone, the initiation of cardiopulmonary bypass and hypothermia within 40 min of the onset of ischemia, and reperfusion within 90 min of the onset of ischemia were sufficient to salvage a major portion of the ischemic myocardium.     

Interstitial pH value in the myocardium as indicator of ischemic stress of cardioplegically arrested hearts

Summary The influence of different cardioplegic methods (Bretschneider, Cardiac Surgery in Hamburg, Kirklin, St. Thomas' Hospital in London) on the progressive myocardial acidosis during global ischemia of up to 24 hours' duration was investigated in arrested, nonperfused canine hearts (n=36). The increasing acidosis of the ischemic heart muscle was continuously measured and registered with the aid of interstitial pH measurement (pH_i) using glass implant electrodes. With various buffered and unbuffered cardioplegic solutions there were relatively wide fluctuations of the pH_i courses in the myocardial extracellular space. The critical interstitial pH values (pH_crit) relative to a defined myocardial ATP concentration (4 mol/g ww) vary between 6.10 (Bretschneider) and 5.6 (Kirklin) (p<0.001). These striking results cannot be attributed solely to different total myocardial lactate concentrations, but variations in a cellular and an extracellular factor must also be taken into account.Measurement of interstitial pH for intraoperative monitoring of myocardial ischemic stress can therefore be used only within limits and with knowledge of the specific protective procedure applied. The method continues an important tool in basic investigations of partial or global ischemia of organs, particularly as regards the spectrum of metabolic, morphological and functional parameters.Dedicated to Prof. Dr. J. Koncz on the occasion of his 65th birthday     

Use of cyclic variation of integrated backscatter to assess contractile reserve and myocardial viability in chronic ischemic left ventricular dysfunction

The detection of viable myocardium has important implications for management, but use of stress echocardiography to detect this is subjective and requires exposure to dobutamine. We investigated whether cyclic variation (CV) of integrated backscatter (IB) from the apical views could provide a resting study for detection of contractile reserve (CR) and prediction of myocardial viability in 27 patients with chronic ischemic left ventricular (LV) dysfunction. Repeat echocardiography was performed after 6.7 +/- 3.8 months of follow-up; 14 patients underwent revascularization and 13 were treated medically. Using a standardized dobutamine echocardiography (DbE) protocol, images from three apical views were acquired at 80-120 frames/sec at rest and during stress. CR was identified if improvement of wall motion was observed at low dose (5 or 10 microg/kg/min) DbE. Myocardial viability was characterized by improvement at follow-up echocardiography in patients with revascularization. CVIB at rest and low dose dobutamine were assessed in 194 segments with resting asynergy (severe hypokinesis or akinesis), of which 88 (45%) were in patients who underwent revascularization. Of these, CVIB could be measured in 190 (98%) segments at rest and 185 (95%) at low dose dobutamine. Sixty-two (33%) segments had CR during low dose DbE and 50 (57%) segments showed wall-motion recovery (myocardial viability) at follow-up echocardiography. Segments with CR had significantly higher CVIB at rest (P < 0.001) and low dose dobutamine (P = 0.005) than segments without CR. Using optimal thresholds of CVIB (> 8.2 dB) at rest, the accuracy of CVIB for detecting CR was 70%. Compared with nonviable segments, viable segments had significantly higher CVIB at rest (P < 0.001) and low dose dobutamine (P < 0.001). Using optimal thresholds of CVIB (> 5.3 dB) at rest, the accuracy of CVIB for detecting myocardial viability was 85%, which was higher than that in conventional DbE (62%, P < 0.01). Thus, assessment of CVIB from the apical views is a feasible and accurate tool for detecting CR and predicting myocardial viability in chronic LV dysfunction.     

碱性成纤维细胞生长因子对兔正常和缺血心肌血管新生的影响

目的　观察碱性成纤维细胞生长因子 ( b FGF)对兔正常和缺血心肌血管新生的影响。方法　开胸结扎兔的冠状动脉左前降支 ( L AD)后 ,动物被随机分为两组 ,一组分别在兔缺血和正常的心肌内注入重组人类的 b FGF ( n=9) ,另一组分别注入生理盐水 ( n=7)。 6周后 ,观察两组兔子的缺血和正常心肌的血管新生情况。结果　注射rhb FGF后 ,缺血心肌的血管密度较注射生理盐水者有显著性增加 ,而正常心肌的血管密度未见明显增加。结论　rhb FGF能促进缺血心肌的血管生长但不能促进正常心肌的血管生长     

直流电场对兔缺血心肌组织p27~(Kip1)及增殖细胞核抗原表达的影响

目的探讨低压稳恒直流电对兔缺血心肌组织p27~(Kip1)及增殖细胞核抗原(PCNA)表达的影响及作用。方法日本大耳白兔70只,随机分为假手术组(5只)、心肌梗死组(MI组,5只)、2.0 V/cm电治疗组(2EFs组,30只)和4.0 V/cm电治疗组(4EFs组,30只)。后2组建立急性心肌梗死模型后,在冠状动脉左回旋支两侧心外膜上,缝合一对铂金电极,予电刺激30 min/d,分别于电刺激第1、3、5天、1、2和4周6个时相点,检测梗死边缘区毛细血管密度,Masson染色测心肌梗死面积,免疫组织化学检测缺血心肌组织p27~(Kip1)及PCNA的表达。结果与假手术组比较,MI组毛细血管密度和PCNA明显降低,p27~(Kip1)明显升高(P0.01);与M1组比较,2EFs组和4EFs组第5天时毛细血管密度和PCNA明显升高,心肌组织p27~(Kip1)表达下降(P0.05,P0.01),心肌梗死面积减少(P0.05);2EFs组和4EFs组各时相点比较,差异无统计学意义(P0.05)。结论低压稳恒直流电场在一定作用时间内,可能通过下调缺血心肌组织p27~(Kip1)的表达,刺激血管生成,缩小心肌梗死面积。     

硝酸异山梨酯对大鼠缺血心肌血管新生的影响

目的观察硝酸异山梨酯对急性心肌梗死(AMI)大鼠缺血心肌组织形态、梗死面积及毛细血管新生的影响。方法Wistar大鼠90只建立AMI模型后,随机分为5组,分别为正常组,假手术组,模型组,硝酸异山梨酯低剂量组(IDL组)和硝酸异山梨酯高剂量组(IDH组),每组18只。大鼠饲养7、14天后各随机处死9只,截取心肌组织,进行光镜、电镜观察,利用NBT染色法测定心肌梗死面积,应用免疫组织化学法测定Ⅷ因子,进而计算缺血心肌微血管密度(MVD),通过RT-PCR技术检测血管内皮生长因子(VEGF)及碱性成纤维细胞生长因子(bFGF)基因表达情况。结果光镜下观察,缺血区可见炎细胞浸润、心肌肿胀、梗死区纤维化。与模型组比较,IDL组和IDH组7、14天心肌梗死面积明显缩小,MVD明显增加(P<0.05);正常组、假手术组VEGF mRNA、bFGF mRNA表达有所减少,而IDH组则有所增加。结论硝酸异山梨酯可明显缩小AMI大鼠梗死面积,促进缺血心肌的毛细血管新生,对心肌缺血损伤具有保护作用。     

Serum markers of angiogenesis and myocardial ultrasonic tissue characterization in patients with dilated cardiomyopathy

BACKGROUND AND AIMS: It has been proven that a disturbance in angiogenesis contributes to the progression of myocardial interstitial fibrosis in idiopathic dilated cardiomyopathy (DCM). This study was designed to evaluate the relationship between serum activity of angiogenic factors and myocardial ultrasonic tissue characterization in patients with DCM. METHODS AND RESULTS: We studied 30 patients with DCM and 15 healthy control subjects. Serum levels of vascular endothelial growth factor (VEGF), interleukin (IL)-4 and IL-13 were measured using enzyme-linked immunosorbent assay. We determined calibrated myocardial integrated backscatter (IB) as the value of myocardial interstitial fibrosis using ultrasonic tissue characterization and also quantified the magnitude of cyclic variations in IB (CV-IB). Serum levels of VEGF and IL-13 were significantly higher in patients with DCM than in control subjects (both P<0.05). Calibrated IB was significantly higher and CV-IB was markedly lower in patients with DCM than in control subjects (both P<0.01). In patients with DCM, the levels of IL-13 significantly correlated with calibrated IB (r=0.520, P=0.018). In addition, there was a significant negative correlation between levels of VEGF and CV-IB (r=-0.611, P=0.007). CONCLUSION: The increase in serum VEGF and IL-13 may be closely related to alterations in myocardial texture in DCM.