背向散射积分技术在评价伴靶器官损害高血压患者心肌纤维化中的应用

目的研究背向散射积分(IBS)作为高血压患者心肌纤维化早期指标的可行性。方法根据2007年欧洲高血压学会(ESH)/欧洲心脏学会(ESC)指南中亚临床靶器官损害标准将原发性高血压患者分成两组:非靶器官损害组(1组,42例),靶器官损害组(2组,51例),健康对照组36例。用IBS技术测量对照组、1组和2组室间隔心肌、左心室后壁心肌、左心房后壁心肌及心腔的IBS指标,计算并比较各组标化背向散射积分(IBS%)值是否存在差异。结果各部位的IBS值在对照组、1组、2组呈逐渐增高趋势,2组最高。其中左心房后壁IBS%值2组[(181±48)dB]与1组[(164±27)dB]、对照组[(164±27)dB]比较差异有统计学意义(P<0.05),左心室后壁IBS%值2组[(190±43)dB]与1组[(169±36)dB]、对照组[(166±28)dB]间差异有统计学意义(分别为P<0.05,P<0.01),室间隔左心室侧1/2处心肌IBS%值在2组和对照组间差异有统计学意义(P<0.05)。结论超声IBS技术可以评价伴有靶器官损害的高血压患者左心室心肌纤维化程度,但尚不能作为高血压患者心肌纤维化的早期指标。     

卡维地洛对急性心肌梗死大鼠血流动力学和心肌胶原含量的影响

目的研究卡维地洛(Carvedilol)对大鼠急性心肌梗死(AMI)后血流动力学的影响及其与心肌组织中胶原含量的关系。方法23只AMI术后存活的雄性SD大鼠随机分为AMI对照组(n=11)和卡维地洛治疗(Carvedilol)组(n=12),另设假手术组(n=11)。给药6周后测量室间隔超声背向散射参数(平均背向散射积分标化值IBS%,背向散射积分周期变化值CVIB)及血流动力学参数、心功能指标。结果(1)与假手术组相比,AMI组大鼠SBP、DBP、LVSP及±dp/dtmax及其校正值(±dp/dtmax/LVSP)均显著降低,LVEDP显著增高,高频超声检测显示IBS%显著升高,CVIB显著降低(均为P<0.05)。(2)与AMI组相比,Carvedilol治疗组大鼠SBP、DBP及LVSP均未进一步降低(P>0.05),LVEDP显著降低,±dp/dtmax及其校正值(±dp/dtmax/LVSP)显著升高,高频超声检测显示IBS%显著降低,CVIB显著升高(均P<0.05)。结论第3代β受体阻滞剂Carvedilol的干预有助于恢复AMI大鼠受损的左室功能,这可能与其抑制非梗死区心肌胶原过度沉积有关。     

糖尿病大鼠肾脏纤维化病理检测和超声背向散射积分参数的相关性研究

目的探讨大鼠糖尿病模型肾脏纤维化的病理改变与肾脏背向散射积分（IBS）参数变化的关系,继而评价超声背向散射积分技术与传统病理检测结果的相关性。旨在为应用超声背向散射积分技术测量糖尿病肾脏纤维化提供实验依据。方法腹腔注射链脲佐菌素（STZ）诱导糖尿病大鼠模型。分别于实验4、12、24周测量糖尿病模型组及空白对照组的大鼠肾脏背向散射积分参数。同一时间,为两组进行大鼠肾脏病理检测。比较两种测量方法的对纤维化测量的结果。结果 1）肾脏纤维化各指标的变化：测量糖尿病组的系膜基质指数（Ms/Gs）（4周0.25±0.02,12周0.47±0.05,24周0.56±0.04）;肾小球胶原沉积评分（GCDS）（4周0.34±0.03,12周0.49±0.03,24周0.62±0.06）;血管周围胶原面积（PVCA）（4周0.96±0.11,12周1.65±0.18,24周2.63±0.40）;肾小管间质病变评分（TILS）（4周1.5,12周3,24周4.5）于三个时间段,皆显著高于同周龄健康对照组,差异有统计学意义（各为P〈0.05）,且随病程进展,逐渐增高（各为P〈0.05）。2）超声指标结果：糖尿病各组大鼠肾脏皮质IBS%（4周0.51±0.04,12周0.73±0.05,24周0.95±0.11）与髓质IBS%（4周0.31±0.07,12周0.58±0.03,24周0.87±0.12）于三个时间段,皆明显高于同周龄对照组（各为P〈0.05）,且随着病程进展逐渐增高（各为P〈0.05）。3）超声背向散射积分技术与糖尿病肾病纤维化各指数的相关性：肾皮质IBS%与GCDS（r=0.95）、PVCA（r=0.89）、TILS（r=0.85）、Ms/Gs（0.89）（P〈0.05）;并且肾髓质IBS%与GCDS（r=0.94）、PVCA（r=0.91）、TILS（r=0.83）、Ms/Gs（0.90）（P〈0.05）呈正相关。结论传统病理学方法可检测到糖尿病大鼠肾脏纤维化病理改变,以及各指标（GCDS、PVCA、TILS、Ms/Gs）在肾脏的表达增加;应用IBS技术可检测到,随着病程进展,肾皮质、肾髓质IBS%也都增高,提示超声背向散射积分（IBS）技术与传统病理学检验手段相关,IBS技术可能成为评价肾脏纤维化的重要方法。     

超声背向散射积分技术定量评价糖尿病性心肌病的临床研究

目的　探讨背向散射积分技术在评价糖尿病患者心肌病变方面的应用价值。方法　采用 HP Sonos-5 5 0 0型超声诊断仪配置的 AD-IBS软件 ,对比测定 33例 2型糖尿病患者和 2 2例健康志愿者心肌组织的 IBS% (背向散射积分均值的校正值 )和 CVIBS%(背向散射积分周期变异率的校正值 )。结果　 1糖尿病组室间隔及左心室后壁 IBS%较对照组增大 ( P值分别 <0 .0 5和 <0 .0 1) ,CVIBS%较对照组减小 ,但无统计学差异 ;2左心室收缩功能参数 EF(射血分数 )和 FS(短轴缩短率 )两组间无统计学差异 ;舒张功能参数 TVI-E/ TVI-A(二尖瓣口舒张期血流 E峰和 A峰时间速度积分比值 )糖尿病组显著低于对照组 ( P<0 .0 5 )。结论　糖尿病患者心肌组织特征与健康者显著不同 ,背向散射积分测定可以定量评价糖尿病患者早期心肌病变     

螺内酯对原发性高血压大鼠左心室功能的影响

目的用超声评价螺内酯对原发性高血压(高血压)大鼠(SHR)心肌组织胶原含量和心功能的影响。方法20只雄性高血压大鼠随机分为螺内酯组(n=10)和安慰剂组(n=10),另设WKY组(n=7)。螺内酯组螺内酯用双蒸水溶解后以20 mg.kg-1.d-1灌胃;安慰剂组和WKY组用等容积双蒸水灌胃,连续16周。超声心动图观察大鼠左心房内径,室间隔和后壁厚度,射血分数,背向散射积分(IBS);背向散射积分周期变化(PPI)。取心肌标本,称取左心室重量,计算左心室质量指数,制备心肌组织石蜡切片,天狼猩红饱和苦味酸染色,观察心肌胶原容积分数(CVF)和血管周围胶原面积(PVCA)。结果与WKY组比较,安慰剂组大鼠心肌肥厚指标:左心室质量指数室,室间隔及左心室后壁厚度增加;心脏功能指标:左心房内径、射血分数增大,E/A比值减少;纤维化指标:胶原容积分数、血管周围胶原面积增加,声学密度指标背向散射积分升高,背向散射积分周期变化降低,差异有统计学意义(P<0.05)。治疗16周,与安慰剂组比较,螺内酯组上述指标均有改善,差异有统计学意义(P<0.05)。结论高血压大鼠左心室胶原沉积、心肌肥厚、舒张功能减退,收缩功能受损。螺内酯治疗能减少高血压大鼠局部胶原沉积,改善左心室功能。     

心肌肥厚大鼠超声背向散射积分与细胞外基质重塑的相关性

目的探讨心肌肥厚大鼠背向散射积分的变化情况,并结合心肌细胞外基质的病理改变及其重要影响因子基质金属蛋白酶(MMP-9)和其生理性抑制剂(TIMP-1)在蛋白和基因水平的表达,探讨其相互关系.方法 SD大鼠腹腔注射去甲肾上腺素(1.06 mg/kg*d×15 d)建立心肌肥厚的动物模型,测定室间隔中部心肌的背向散射参数,并应用免疫组化和逆转录-聚合酶链反应法(RT-PCR)方法检测心肌总体胶原、Ⅰ型和Ⅲ型胶原的改变,及MMP-9、TIMP-1蛋白和mRNA的表达,与超声测定的结果进行对比研究.结果 (1)实验组大鼠心肌胶原成分及MMP-9、TIMP-1蛋白和mRNA的表达显著高于健康对照组(P<0.01).(2)超声背向散射积分(IBS%)在实验组较对照组增高(P<0.01),与心肌胶原、MMP-9和TIMP-1蛋白和mRNA的表达之间存在相关性.结论大鼠心肌肥厚时IBS%升高与胶原的过渡沉积密切相关,而MMP-9和TIMP-1可能是引起心肌细胞外基质重塑的重要机制之一.     

超声背向散射积分量化犬心肌缺血再灌注致心肌纤维化程度的研究

目的应用超声背向散射测定结合胶原代谢物评估犬心肌缺血再灌注致心肌纤维化程度。方法 12只成年杂种犬随机分为2组:假手术组和缺血再灌注组,每组6只。测定两组血流动力学指标,于再灌注120 min后经颈内静脉采血,用超声背向散射测定技术检测室间隔和左心室后壁背向散射积分值(IBS)和背向散射积分周期变化值(CVIB)。以酶联免疫吸附法检测患者血清结缔组织生长因子(CTGF)和Ⅰ型前胶原氨基端肽(PⅠNP)。行Masson染色观察胶原纤维组织结构变化,用免疫组织化学方法检测Ⅰ型胶原蛋白表达。结果缺血再灌注组CTGF和PⅠNP水平均高于假手术组,差异有统计学意义(P0.05)。与假手术组比较,缺血再灌注组室间隔和左心室后壁的IBS明显增加,CVIB明显减小,差异有统计学意义(P0.05)。CTGF和PⅠNP水平与IBS呈正相关(P0.05),与CVIB呈负相关(P0.05)。Masson染色显示缺血再灌注组心肌纤维化明显增加。缺血再灌注组Ⅰ型胶原蛋白表达呈强阳性。结论缺血再灌注组犬超声背向散射参数IBS增加,CVIB减少,胶原代谢物CTGF和PⅠNP水平增加,心室肌纤维化参与了缺血再灌注损伤,导致心室重构。超声背向散射测定结合胶原代谢物可早期无创性检测缺血再灌注阶段心室肌纤维化程度。     

心房颤动复律前后左房结构和功能变化的超声心动图研究

目的应用超声心动图观察心房颤动(简称房颤)患者复律前后左房结构和功能的变化。方法选择房颤患者20例,按心脏复律的方式分为直流电复律组7例,药物复律组13例,分别于复律前、复律后第1天、第3天、第7天、第1个月时应用超声心动图测定左房内径和容积,记录二尖瓣血流频谱A峰流速(VA)、A峰速度时间积分(A-VTI)、心房充盈分数(AFF)和左房射血力(LAEF)。分析左房内径、容积变化与左房收缩功能的关系。应用心房肌超声组织定征技术在左房后壁心肌和心包处测量背向散射积分值(IBS)及背向散射积分周期变异幅度(CVIB)评价心肌组织的声学特征。结果房颤时所有患者均存在左房扩大,而恢复窦性心律后直流电复律组和药物复律组的左房上下径均显著降低(P<0.05或0.01)。恢复窦性心律后第1天、第3天直流电复律与药物复律组比较,左房最大和最小容积显著增大(P<0.05或0.01),VA、A-VTI、AFF和LAEF明显降低。房颤时左房心肌标化IBS较健康对照组增大,而CVIB则降低(P均<0.01),直流电复律组恢复窦性心律后第1天、第3天左房心肌标化IBS及CVIB与房颤时比较无差异(P>0.05),而药物复律组左房IBS%与房颤时和直流电复律组比较显著降低,CVIB则显著增大。恢复窦性心律后第7天、第1个月时,两组左房IBS%与房颤时比较均显著降低,CVIB显著增大(P均<0.01),两组无差异。结论两种复律方式成功复律后随时间推移均可改善房颤患者的左房结构重构和功能。     

电磁脉冲辐照对大鼠心肌闰盘形态及ZO-1、Cx43蛋白表达的影响

目的探讨电磁脉冲（EMP）导致心肌闰盘（ID）改变的规律及机制,为制定EMP的卫生标准以及其医学应用提供实验依据。方法采用EMP模拟发生器,场强为200kv/m、脉冲次数为200次、脉冲间隔2s。雌性SD大鼠54只随机分为7组,其中对照组和照后12h组均为12只,其余组（照后即刻、6、24、36及48h）均为6只。将大鼠于照后即刻、6、12、24、36和48h,采用硝酸镧示踪法和透射电子显微镜观察心肌ID结构的改变。照后12h组,用免疫荧光标记法和激光共聚焦显微镜观察大鼠心肌中Zo-1和Cx40蛋白表达的变化。结果正常对照组大鼠的心肌肌膜完整,肌小节清楚,肌丝排列整齐,细胞连接结构完整,ID连接紧密未见镧颗粒沉积。照后即刻组和6h组的心肌ID间隙增宽不明显,仅见其间隙有少量镧颗粒;照后12h组的心肌ID间隙增宽最明显,ID间隙中充满着大量镧颗粒;照后24h组较照后12h组明显好转,照后48h组已基本恢复正常。照后12h组和对照组的心肌细胞连接处Zo-1、Cx43均有表达,但辐照组两种蛋白的平均荧光强度值均有下降的趋势,且无移位表达。结论EMP辐照可诱导心肌ID间隙时相性增宽及Zo-1和Cx43蛋白的表达下降。     

肥厚型心肌病与高血压性心脏病心肌超声组织定征的鉴别诊断

目的探讨肥厚型心肌病、高血压病患者与正常人左室后壁、室间隔心肌声学特性是否存在差异,以期将超声组织定征作为鉴别诊断的指标之一. 方法将被检者分成3组肥厚型心肌病组(HCM组)、高血压性心脏病组(EH组)及正常对照组,分别测定各组左室后壁、室间隔部位的心肌背向散射参数.结果左室后壁心肌HCM组与EH组的IBS、CVIB无显著性差异(P>0.05),而与正常对照组均有差异(P<0.05);室间隔部位3组IBS、CVIB均有显著性差异(P<0.05);HCM组室间隔、左室后壁均存在IBS、CVIB的跨壁梯度,而EH组、正常对照组则无上述异常存在.结论 HCM患者左室后壁心肌的声学特性与正常对照组有差异,室间隔与左室后壁均存在IBS、CVIB的跨壁梯度.因此背向散射参数测定可作为鉴别肥厚型心肌病和高血压性心脏病的一项指标.     

Prediction of the no-reflow phenomenon with ultrasonic tissue characterization in patients with anterior wall acute myocardial infarction

The no-reflow phenomenon after acute myocardial infarction seems to be related to ischemic injury before reperfusion. Analyzing cardiac cycle-dependent variation of integrated backscatter (IBS) is a unique method to assess myocardial viability. In this study, the ability of ultrasonic tissue characterization with IBS to predict the no-reflow phenomenon was investigated in 90 patients with first anterior wall infarction who underwent successful primary percutaneous coronary intervention. IBS images were recorded on admission (before reperfusion), and the magnitude of the cyclic variation of IBS within the infarct zone was expressed as phase-corrected magnitude (PCM) by giving positive and negative values when it showed synchronous and asynchronous contraction, respectively. Myocardial contrast echocardiography was performed soon after reperfusion, and 21 patients showed substantial no-reflow. They had smaller PCM before reperfusion than patients without no-reflow (-1.6 +/- 1.9 vs 0.7 +/- 2.7 dB, respectively; p = 0.0002). Multivariate logistic regression analysis revealed that PCM before reperfusion and the number of Q waves were the independent predictors of no reflow. Using -1.0 dB as the cut-off point, PCM predicted no reflow with 66.7% sensitivity and 81.2% specificity. These results indicate that the analysis of myocardial IBS could predict the no-reflow phenomenon before reperfusion.     

Cyclic variation of the myocardial integrated backscatter signal in hypertensive cardiopathy: a preliminary study.

BACKGROUND: Ultrasound tissue characterization studies realized through integrated backscatter analysis with end-diastolic sampling in hypertensive cardiopathy have demonstrated that abnormalities in the left ventricular myocardial ultrasonic texture are present in extreme forms of left ventricular hypertrophy (LVH). Such abnormalities are not evident in the athlete's heart. The aim of the present study was to analyze the ultrasonic backscatter myocardial indexes both as peak end-diastolic signal intensity and as cardiac-cyclic variation in two models of LVH: hypertensive cardiopathy and athlete's heart. METHODS: Three groups of 10 subjects each, all men of mean age (31.6+/-3.5 years), and of comparable weight and height, were analyzed. Group A comprised 10 cyclists of good professional level, while hypertensive patients were grouped in Group H. Both groups presented a comparable left ventricular mass (LVM). Group C included 10 healthy subjects acting as controls. The men with hypertension were selected on the basis of the results of ambulatory monitoring of the blood pressure according to ISH-World Health Organization guidelines (International Society of Hypertension). A 2D-color Doppler echocardiography with a digital echograph Sonos 5500 (Agilent Technologies, Andover, Massachusetts, USA), was carried out on all the subjects in the study for conventional analysis of the LVM and function. The ultrasonic myocardial integrated backscatter signal (IBS) was analyzed with an 'acoustic densitometry' module implemented on a AT echograph. The signal was also sampled with a region of interest (ROI) placed at interventricular septum and at posterior left ventricular wall level. The systo-diastolic variation of the backscatter was also considered, as cyclic variation index (CVIibs). RESULTS: According to the inclusion criteria, the LVM was comparable in groups A and H, but it was significantly higher than group C (left ventricular mass (body surface) (LVMbs)=154.5+/-18.7 (A), 146.8+/-25.5 (H), 101.4+/-12.4 (C), p < 0.001). The end-diastolic IBS did not show significant statistical differences among the three groups. The CVI(IBS) both at septum (30.5+/-5.3 (A), 13.2+/-13.1 (H), 27.2+/-7.3(C), p < 0.002) and posterior wall level (43.7+/-9.1 (A), 16.5+/-12.1 (H), 40.7+/-9.1 (C), p < 0.001) though, was significantly lower in the hypertensive patients than in both the athletes and the control group, where the results were comparable. CONCLUSION: A significant alteration of the myocardial CVIibs (both for septum and posterior wall) was found in the hypertensive model. This was probably the expression of an alteration in the intramural myocardial function.     

Preclinical cardiac involvement in phaeochromocytoma: a study with integrated backscatter

Objective It is well known that vascular and cardiac structure may be influenced by circulating neurohormonal factors. Our aim was to study the myocardial wall texture by integrated backscatter (IBS) analysis in patients with phaeochromocytoma (PHEO). Design Fourteen patients with PHEO, 15 matched high‐normal blood pressure (BP) subjects, 15 mild essential hypertensives and 15 normotensive controls underwent two‐dimensional conventional ultrasonography and ultrasonic IBS of the myocardial wall. IBS analysis was performed at both interventricular septum and posterior wall levels. IBS values were expressed in decibels and corrected for the IBS values obtained within the pericardium (C‐IBS). The systo‐diastolic cyclical variations in IBS (CV‐IBS), an index of myocardial contractile performance, were also evaluated. Results Patients with PHEO showed C‐IBS values comparable to those of hypertensive patients, and significantly higher than those of high‐normal BP subjects and controls at both septum and posterior wall levels (P < 0·001 for all). In PHEO patients, CV‐IBS was lower than that of normotensive, high‐normal BP subjects and hypertensive patients, at both septum and posterior wall levels (P < 0·001 for all). An inverse relationship was found in the PHEO group between 24‐h urinary normetanephrine and CV‐IBS of both septum (r² = –0·29, P < 0·05) and posterior wall (r² = –0·46, P < 0·05). Conclusions Our results show that patients with PHEO have myocardial remodelling characterized by increased myocardial fibrosis, confirmed by an increase in the overall myocardial backscatter level measured. The observed decrease in the magnitude of CV‐IBS suggests an impairment of myocardial contractile performance. These results may provide insights into the role of catecholamines in left ventricular (LV) structure and function in PHEO.     

糖尿病患者左室超声背向散射改变的初步观察

目的　了解 2型糖尿病 (T2 DM)心肌背向散射 (IBS)变化的特点及其临床意义。　方法正常对照组 5 0例 ,T2 DM组 5 0例 ,病程≤ 5年 ,糖化血红蛋白 (Hb A1c) (9.6 9± 1.78) % ,应用HP5 5 0 0型超声诊断仪 ,在胸骨旁左室乳头肌短轴切面分别测量左心室前间壁、前壁、侧壁、后壁、下壁和后间隔心肌组织的 IBS,并将其与心包 IBS的比值作为心肌 IBS的校正值 (IB% ) ;舒张末期与收缩末期的差值即 CVIB,并将其与心包 IBS的比值作为心肌 CVIB的校正值 (CVIB% )。同时测定左室等容舒张期时间 (IVRT) ,二尖瓣血流图 E峰与 A峰的比值 (E/ A )。　结果　 T2 DM组心脏左室各室壁心肌背向散射参数与正常对照组比较 IB%增大 ,CVIB减低 ,差异非常显著 (P <0 .0 0 1) ,两组IVRT、E/ A均在正常范围 (P>0 .0 5 )。　结论　 T2 DM患者左室 IBS有明显的变化且呈弥漫性改变 ,左室 IBS的变化出现在舒张功能异常 (糖尿病心肌病亚临床期 )之前 ,背向散射技术可早期发现糖尿病心肌微结构的病变     

背向散射技术与彩色室壁运动技术在高血压左室重构中的应用

目的 探讨背向散射和彩色室壁运动参数评估原发性高血压不同左室构型心肌病变程度和局部室壁运动的临床价值。方法 测定70例原发性高血压病患者和31例正常对照者室间隔及左室后壁的背向散射参数和局部室壁收缩期位移。共收入正常构型组18例，向心重构组17例，向心肥厚组23例，离心肥厚组12例。结果 高血压各组室间隔超声背向散射(IB％)均不同程度地增大，以向心性肥厚组和离心性肥厚组为著；左室后壁IB％在向心性肥厚组和离心性肥厚组增高，以离心性肥厚组为著；室间隔周期变化幅度(cvlB)在向心性肥厚组和离心性肥厚组减低；左室后壁的CVIB在离心性肥厚组显著减低；高血压各组均未出现明显的背向散射跨壁梯度的改变。室间隔和左室后壁的SEM在离心性肥厚组显著减低，其余各组间虽无明显统计学差异，但在向心性肥厚组呈现增加的趋势。在离心性肥厚组，收缩期CK色带变薄或消失，色带不完整。结论 心肌超声背向散射参数可用于判断高血压不同左室构型心肌病变的程度；彩色室壁运动技术可用于评估高血压不同左室构型局部室壁运动状态。     

急性心肌梗死超急性期的超声诊断

目的 研究急性心肌梗死(AMI)超急性期时的心肌组织超声背向散射积分(IBS)的变化及对临床诊断AMI超急性期的价值.方法 将72例AMI患者分成2组:超急性期组(梗死时间在2 h以内)30例,急性期组42例(梗死时间>2 h,有典型的心电图改变);另取正常对照组30例.用HP-5500型超声诊断仪,分别测量心肌梗死区域和非梗死区域心肌组织的心动周期时间平均背向散射积分(IBS),并将其与心包IBS的比值作为心肌IBS的校正值(IB%),舒张末期与收缩末期的IBS差值即IBS的周期变化幅度(CVIB),并将其与心包IBS的比值作为心肌CVIB的校正值(CVIB%).同时作心电图的比较对照.结果 当AMI超急性期组患者心电图还无典型变化时,心肌梗死部位的IBS值已明显大于正常人[(18.8±3.4)dB比(8.3±1.2)dB,P<0.01],而CVIB明显小于正常人[(6.3 ±0.7)dB比(7.6±1.1)dB,P<0.01].急性期组患者,其IBS明显高于正常人及患者本身非心肌梗死部位[(22.2±4.1)dB比(8.3±1.2)dB,(21.1±3.2)dB比(8.7 ±0.9)dB,P<0.01],而CVIB则明显低于正常人及患者本身非心肌梗死部位[(5.6±0.8)dB比(7.6±1.1)dB,P<0.05;(5.8±0.7)dB比(9.3±0.9)dB,P<0.01].且与心电图的变化完全一致.结论 心肌组织背向散射积分对临床上诊断AMI超急性期有很高的价值,并可判断病变心肌的范围和功能状况.     

Use of echocardiography for predicting myocardial viability in patients with reperfused anterior wall myocardial infarction

Dobutamine stress echocardiography (DSE), myocardial contrast echocardiography (MCE), and ultrasonic tissue characterization with integrated backscatter are useful methods for assessing myocardial viability in acute myocardial infarction. In this study, we compared the potential of 3 methods for predicting myocardial viability in 38 patients with reperfused anterior wall acute myocardial infarction. We performed MCE shortly after coronary reperfusion with an intracoronary injection of microbubbles. We recorded 2-dimensional integrated backscatter images at rest and, then, performed low-dose (10 microg/kg/min) DSE 3 days later. In integrated backscatter images, we placed the region of interest in the midwall of the myocardial segment to reconstruct the cyclic variation of myocardial integrated backscatter. The myocardial segment was judged viable when it showed active contraction 3 months later. Among 74 segments analyzed, 34 were judged viable. Presence of contractile response during DSE predicted segmental viability with 91% sensitivity and 78% specificity. Intense and homogenous contrast enhancement with MCE predicted viability with 82% sensitivity and 73% specificity. The presence of synchronous contraction of cyclic variation predicted myocardial viability with 79% sensitivity and 83% specificity. There were no differences in sensitivity and specificity among the 3 methods. Thus, MCE and ultrasonic tissue characterization can predict myocardial viability as accurately as DSE in patients with acute myocardial infarction. The logistics of the methods may determine clinical application.     

Integrated backscatter for the assessment of myocardial viability

PURPOSE OF REVIEW: Ultrasonic tissue characterization is a non-invasive diagnostic method that uses myocardial integrated backscatter analysis to determine contractile performance and myocardial viability independent of wall motion. This review discusses recent clinical findings regarding the application of ultrasonic tissue characterization for the assessment of myocardial viability. RECENT FINDINGS: As this technique is non-invasive, ultrasonic tissue characterization can be used to predict the patency of infarct-related arteries in patients in the early stage of acute myocardial infarction. Several recent studies have shown that this technique is useful in identifying myocardial contractile reserve. The accuracy of ultrasonic tissue characterization for predicting functional recovery after coronary reperfusion is comparable to dobutamine echocardiography and radionuclide methods. Several studies have suggested that the cyclic variation of myocardial integrated backscatter reflects myocardial viability rather than contractile reserve. The cyclic variation of integrated backscatter is associated with myocardial viability confirmed by the integrity of the microvasculature identified by contrast echocardiography. In addition, the cyclic variation of integrated backscatter better reflects myocardial viability confirmed by the integrity of cellar metabolism than contractile reserve. SUMMARY: Ultrasonic tissue characterization with integrated backscatter is a useful non-invasive method that can provide unique information for the assessment of myocardial viability.     

Effect of harmonic imaging on the measurement of ultrasonic integrated backscatter and its interpretation in patients following myocardial infarction.

BACKGROUND: Recently, we have demonstrated that cyclic variation in ultrasonic integrated backscatter (IBS) can be used to predict patency of the infarct related artery (IRA) post-acute myocardial infarction (AMI). Second harmonic imaging has become widely available on ultrasound machines and enhances endocardial definition. The effect of harmonic imaging on the measurement and interpretation of cyclic IBS is unknown. METHODS AND RESULTS: Twenty-eight patients were studied post-AMI. Cyclic IBS was measured in myocardial segments supplied by the IRA as well as in remote segments with normal myocardial function in both fundamental and second harmonic modes. Harmonic imaging increased the measurement of cyclic IBS in IRA as well as normal myocardial territories. However, the difference in cyclic IBS between IRA and normal myocardial territories remained unchanged. CONCLUSION: Second harmonic imaging increases the measurement of cyclic IBS. However, the interpretation of these data is unchanged in the setting of AMI. It is important that repeated studies in the same patient are performed in the same mode (fundamental or harmonic) as the values are not interchangeable.