Assessment of myocardial viability after myocardial infarction

Conclusions  The data presented above suggest that assessment of myocardial viability after MI, particularly in those patients with severe LV dysfunction, is important for the identification of those with the highest risk, in whom revascularization can be of clinical benefit. There is growing and consistent evidence that patients with relatively large areas of dysfunctional but viable myocardium after MI have improved function, symptoms, and survival with prompt revascularization compared with medical therapy alone. Most importantly, long-term survival with revascularization in these patients is comparable with that achieved with cardiac transplantation. There are several methods available to the clinician with which to investigate the presence of tissue viability, and the evidence suggests that the scintigraphic approaches are the most sensitive. These observations suggest that noninvasive investigation of the amount of ischemic myocardium should be an important component of the diagnostic evaluation of patients with severe LV dysfunction after MI. This approach will likely enhance the often difficult process of selecting patients with poor cardiac function in whom revascularization will likely improve both the quality and quantity of life.     

Nitrate-augmented myocardial imaging for assessment of myocardial viability

²⁰¹Tl myocardial perfusion imaging is presently done by several possible strategies. Stress/delayed redistribution, stress/redistribution/reinjection, and rest/redistribution imaging can be useful in the clinical assessment of myocardial viability. Unfortunately, the extent of myocardial viability may still be underestimated even by ²⁰¹Tl reinjection imaging, compared with ¹⁸F-fluorodeoxyglucose positron emission tomography. ^99mTc-labeled sestamibi imaging provides results similar to those of ²⁰¹Tl imaging in the detection of coronary artery disease, but several previous studies suggest that stress/rest ^99mTc-labeled sestamibi imaging significantly underestimates myocardial viability. Recently it has been reported that the administration of nitrates, before ²⁰¹Tl reinjection, improves detection of defect reversibility. Several studies also suggested that administration of nitrates before the injection of ^99mTc-labeled sestamibi significantly improved detection of reversibility with this agent, whereas additional studies showed further that this combination improves the predictive accuracy for recovery of left ventricular function and perfusion after coronary revascularization, compared with a standard rest ^99mTc-labeled sestamibi study. Nitrate administration before the injection of ²⁰¹Tl and ^99mTc-labeled sestamibi may thus be a potentially attractive alternative for the evaluation of myocardial viability. Although the available results are encouraging, further studies are needed to evaluate the clinical value of ²⁰¹Tl and ^99mTc-labeled sestamibi imaging, in combination with nitrates, for predicting recovery of left ventricular dysfunction.     

急性心肌梗死心肌血流再灌注评价技术

TIMIFlow作为评价再灌注的方法自20世纪80年代起就一直应用于临床。TIMIFrameCount是较TIMI血流分级更为客观、更具可重复性的联系性变量指标。TMBG和TMP从心肌微血管水平对再灌注进行评价。冠脉内多普勒血流频谱变化常作为造影过程中的附加检查指标评价血管再通及心肌再灌注。同时心肌声学造影、连续心电图ST段监测、核素心肌灌注显像和心肌增强磁共振成像作为无创性的评价方法也显示出其应用价值。     

Assessment of regional myocardial function by ECG-gated myocardial SPECT]

PURPOSES: Regional myocardial functional parameters were assessed by ECG-gated myocardial SPECT analysis in normal subjects and ischemic heart diseases. METHODS: Normal subjects (13 male and 10 female) and 51 patients with chronic ischemic heart disease underwent ECG-gated myocardial SPECT. A dose of 740 MBq of 99mTc-MIBI was injected at rest, and gated SPECT was performed 60 min later. Wall motion (WM) and systolic wall thickening (WT), % tracer uptake were evaluated by quantitative gated SPECT program (QGS). Regional parameters were obtained in the 16 segments based on the functional polar map. In the normal group, standard values were evaluated in the lateral, septal, anterior and inferior regions both in male and female subjects. In the ischemic heart disease group, sensitivity and specificity of these parameters were assessed in each segment. To estimate the ability of WM and WT in detecting regional dysfunction, decreased perfusion area, which was defined as < mean - 2SD by the normal profile, was used as a standard. The receiver operating characteristics (ROC) area analysis was also performed. RESULT: In the normal profile, % tracer uptake was decreased in the anterior segments of female group, no significant difference was observed between male and female in WM and WT. WM was decreased in the septum and increased in the lateral segment. WT didn't show any difference regional difference. Sensitivity and specificity of WM were 56%/91% in the anterior, 0%/100% in the septum, 43%/87% in the inferior, 31%/85% in the lateral. WT were 67%/93% in the septum, 67%/79% in the inferior, and 59%/81% in the septum. The area under ROC curve was WM 0.63, WT 0.85 (p < 0.005 between WM and WT) in the septum, in inferior WM 0.77, WT 0.80 (p = 0.57), in anterior WM 0.86, WT 0.87 (p = 0.095), in lateral WM 0.68, WT 0.78 (p = 0.037). CONCLUSION: In normal profile, the % tracer uptake in the anterior wall decreased in females, but WM and WT did not show significant difference in each region affected this influence. The septal WM was decreased in the normal profile and ability to diagnose regional function was also decreased compared with WT. Thus, we can conclude that WT is preferable for detecting septal functional abnormality.     

民航飞行人员冠状动脉肌桥致急慢性心肌缺血二例

长期以来 ,冠心病或急性冠状动脉事件在民航飞行人员中时有发生 ,对飞行安全威胁极大 ,其病理基础均为冠状动脉粥样硬化所致[1,2 ] 。然而 ,近年发现两例民航飞行人员的急慢性心肌缺血 ,系由冠状动脉前降支 (leftanteriordescending ,LAD)肌桥引起 ,这在以往的飞行人员心血管疾病中尚未见报道 ,值得总结 ,现报道如下。　　一、临床资料例 1　男性 ,发病年龄 4 7岁 ,MD 11航空机械师 ,总飞行时间 15 36 6h。2 0 0 0年 8月驻外飞行期间 ,某日午餐后突发胸闷、胸骨后压榨性疼痛 ,伴大汗、焦虑等。急救中发现血压下降 ,心电图 :V1V4T波高尖 …     

Quantitative evaluation of myocardial viability using Tl-201 myocardial SPECT]

In order to evaluate myocardial viability, we developed a new method for quantification of redistributed area in Tl-201 myocardial SPECT, and it was applied to 71 patients with LAD lesion. Initial image was subtracted from delayed image, and redistributed area was displayed as an unfolded map (viability map). Extent and viability score, which correspond to extent and degree of the viable area, was also calculated. In the cases with prior myocardial infarction, viability score was widely distributed and extent score was smaller, while the cases with angina pectoris had larger extent score. Visual assessment of redistribution to the infarcted area was compared with % score, which was calculated as ratio to initial defect score. When the criteria of viability was defined as % viability score greater than 36 or % extent score greater than 16, quantitative evaluation agreed with visual assessment, and corresponded to clinical course. This method was considered to be effective for evaluation of extent and degree of myocardial viability, but further evaluation need to be done in comparison with reinjection, PET study, and so on, and usefulness in multi-vessel disease.     

大鼠心肌缺血再灌注损伤中的心肌细胞凋亡

 目的 观察MIRI时心肌细胞凋亡现象及其病理组织学改变,探讨细胞凋亡在MIRI中的意义.方法 采用SD大鼠MIRI模型,用原位末端标记染色检测心肌细胞凋亡和HE染色法检测心肌病理组织学改变.结果 假手术组及MIRI大鼠左室非缺血心肌组织中均末发现凋亡细胞出现,MIRI60 min、90 min和120 min大鼠缺血心肌中均可见凋亡细胞,且凋亡细胞的个数随再灌注时间的延长而增多,分别为36.3±8.76个/视野,38.41±14.21个/视野和48.01±23.87个/视野..结论 缺血后再灌注损伤可诱发心肌细胞凋亡.     

血浆心肌细胞损伤标志物检测急性心肌梗死患者心肌损伤的临床研究

目的 探讨血浆心肌细胞损伤标志物在检测急性心肌梗死（AMI）患者心肌损伤中的价值。 方法 采用放射免疫分析法测定184例AMI患者和60名健康体检者（正常对照组）血浆心肌肌钙蛋白I（CTnI）、TNF-α、高敏C反应蛋白（hs-CRP）和β₂微球蛋白（β₂-MG）水平,并进行比较性分析。同时测定它们诊断AMI的特异度、阳性、阴性预测值、准确率以及入院后3、6、9 h时的灵敏度。 结果 184例AMI患者血浆CTnI、TNF-α、hs-CRP和β₂-MG水平较正常对照组均显著升高（t_CTnI=6.384,P＜0.001;t_TNF-α=2.136,P＜0.05;t_hs-CRP=5.109,P＜0.001;t_β2-MG=3.185,P＜0.01）,以血浆CTnI和hs-CRP水平升高最为显著。血浆CTnI、TNF-α、hs-CRP和β₂-MG水平对AMI患者诊断的特异度分别为96.67%、51.67%、65.00%和48.33%。入院后3、6和9 h时对AMI患者诊断的灵敏度:血浆CTnI分别为21.74%、92.93%和98.37%;血浆TNF-α分别为17.93%、65.76%和69.02%;血浆hs-CRP分别为16.30%、78.26%和79.89%;血浆β₂-MG分别为21.20%、69.57%和74.46%;以血浆CTnI为最高。阳性、阴性预测值和有效率亦以血浆CTnI为最高,分别为89.67%、88.33%、89.24%。 结论 心肌细胞损伤标志物CTnI不仅是早期诊断AMI的有效指标,而且具有治疗随访的临床价值。     

急性心肌梗死再灌注治疗前后心肌血流和代谢的变化及临床意义

目的　探讨急性心肌梗死患者行经皮冠状动脉腔内成形术 (PTCA)和支架术后心肌血流、脂肪酸代谢及糖代谢的变化及其临床意义。方法　 2 2例急性心肌梗死患者 ,于发病后 4周行延迟PTCA ,术前 (急性期 )及术后 (慢性期 )分别行2 0 1 Tl、1 2 3I β 甲基碘苯脂十五烷酸 (BMIPP)SPECT显像及1 8F 脱氧葡萄糖 (FDG)PET心肌显像。将左心室分成 13个节段 ,采用 4级评分法对2 0 1 Tl、1 2 3I BMIPP显像放射性分布进行视觉评价 ,两者得分差为2 0 1 Tl BMIPP不匹配。在血流减低部位 ,定量测定1 8F FDG摄取。慢性期复查冠状动脉造影。结果　急性期心肌血流 脂肪酸代谢不匹配的节段 ,1 8F FDG摄取率明显高于匹配节段 [(76 .5± 10 .6 ) %和 (4 5 .8± 8.6 ) % ,P <0 .0 1],慢性期两者无明显差异。冠状动脉非再狭窄患者其慢性期2 0 1 Tl BMIPP不匹配 (0 .2 5± 0 .4 2 )及1 8F FDG摄取率 [(5 2 .1± 8.1) % ]较急性期 [0 .36± 0 .5 1和 (72 .8± 9.8) % ]明显降低 (P均 <0 .0 1) ;冠状动脉再狭窄患者其慢性期与急性期比较 ,2 0 1 Tl BMIPP不匹配及1 8F FDG摄取率无明显变化。结论　观察急性心肌梗死PTCA前后心肌血流 脂肪酸代谢及糖代谢的变化 ,可间接预测PTCA后再狭窄。     

腺苷负荷心肌灌注显像评价心肌血流供应异常的临床研究

目的 回顾性分析腺苷负荷/静息心肌灌注显像用于评价冠心病心肌血流供应异常的准确性和临床价值.方法 1858例临床确诊或可疑冠心病患者行常规标准程序两日法腺苷负荷/静息99Tcm-甲氧基异丁基异腈心肌灌注断层显像,由2位以上核医学科医师共同阅片定性分析图像.所有患者在显像前后1个月内行冠状动脉（简称冠脉）造影检查.方法间的一致性分析用Kappa检验,Kappa＞0.45为一致性较好.结果 1858例患者中,冠脉造影有1支及1支以上冠脉狭窄≥50%的患者957例,其中单支病变506例,双支病变256例,三支病变195例;共累及冠脉1603支,其中左前降支（LAD）765支、左回旋支（LCX）399支、右冠脉（RCA）439支.腺苷负荷/静息心肌灌注显像示心肌缺血或心肌梗死者1126例,与冠脉造影对照,其诊断冠心病的灵敏度为91.54%（876/957）,特异性为72.25%（651/901）,阳性预测值为77.80%（876/1126）,阴性预测值为88.93%（651/732）,2种方法一致性好（Kappa=0.641）.对LAD、LCX和RCA病变诊断的灵敏度分别为81.31%（622/765）,56.64%（226/399）和70.62%（310/439）;对单支、双支和三支冠脉病变的灵敏度分别为87.55%（443/506）,94.92%（243/256）和97.44%（190/195）.腺苷不良反应的发生率为84.12%（1563/1858）,无严重心脏事件发生.结论 腺苷负荷心肌灌注断层显像诊断冠心病有较高的灵敏度、特异性和准确性,对评价心肌血流供应异常有重要的临床价值.     

Cesium-129 myocardial scintigraphy to quantify myocardial infarction in dogs.

The sizes of surgically induced acute myocardial infarctions were quantified in a study of 28 dogs. Four projections (right and left anterior oblique, anterior, and left lateral) were obtained with 129Cs myocardial scintigraphy. Control images, taken before surgery, were compared with images taken 24-72 hr after coronary artery ligation. From postmortem examination the size of the infarct was determined and expressed as a percentage of the total left ventricle. On a standard diagram four independent observers marked the infarcted areas in each projection, expressed the severity of involvement in each area, and determined overall infarction size as a percentage of the total left ventricle. A nonlinear least-squares method was also employed to derive the size of the infarct, using the results from each observer's diagram. There were positive correlations between each observer's percentage estimate and the autopsy results. The overall accuracy of the least-squares method was similar to that of the individual observers. In this study, Observer 3 proved that acute myocardial infarcts can be quantified accurately from multiple scintigraphic projections of the myocardium, but the other three observers had difficulty in estimating infarct size. This difficulty probably resulted from the lack of well-validated criteria to aid the observer in determining the area of infarction, the severity of involvement within that area, or the total size of a myocardial infarct. Improvement in these estimates will require the development of definitive criteria, the use of optical scanners or computer processing, and combinations of radionuclides.     

A clinical feature of myocardial stunning associated with acute myocardial infarction

We report a case of myocardial stunning after acute myocardial infarction. In the hyperacute phase of myocardial infarction, the patient’s coronary arteries showed normal features on coronary angiography during extensive ST-segment elevation observed on a standard 12-lead electrocardiogram and extensive akinesis observed on a left ventriculogram. Thallium-201 emission computed tomography revealed extensive perfusion abnormality. In the chronic phase, the perfusion abnormality was markedly improved. However, the electrocardiogram demonstrated poor R wave progression, and the left ventriculography revealed slight hypokinesis in the anterolateral wall. The acetylcholine provocation test disclosed coronary vasospasm of the left anterior descending coronary artery. About six months thereafter, left ventricular wall motion became completely normal and no poor R wave progression was observed on the electrocardiogram. The findings in this case indicate that myocardial stunning resulted from brief but severe ischemia due to vasospasm which led to cardiogenic shock, and that the recovery of findings for thallium-201 perfusion might be followed by those of electrocardiography and left ventriculography in the stunned myocardium.     

18F-氟脱氧葡萄糖符合线路诊断心肌梗死后的心肌活力

目的利用^18F-氟脱氧葡萄糖（^18F-FDG）符合线路空腹，糖负荷代谢显像和^99mTc-甲氧基异丁基异腈（^99mTc-MIBI）来判断心肌梗死后心肌的活力。方法24例心肌梗死患者进行血管造影、^99mTc-MIBI负荷和（或）静息血流灌注检查、^18F-FDG符合线路心肌代谢显像（空腹-葡萄糖负荷显像一日法）。结果^99mTc-MIBI灌注显像发现的27个缺血节段在空腹和糖负荷均有^18F-FDG的摄取，心肌存活；22个缺血节段在空腹和糖负荷显像后没有^18F-FDG的摄取，心肌没有活力。空腹状态心肌对^18F-FDG摄取较少，有活力的心肌缺血节段显示特别清晰，图像质量较差；葡萄糖负荷后活力心肌摄取^18F-FDG，图像质量有明显改善。结论空腹和糖负荷都可判断心肌活力，空腹显像时图像的质量稍差，糖负荷能够提高图像质量。     

核素心肌灌注显像和CT冠状动脉造影检测冠状动脉心肌桥所致心肌血液供应异常

目的利用SPECT／CT完成同机核素MPI和CTCA,探讨冠状动脉（简称冠脉）心肌桥（MB）对心肌血液供应的影响。方法回顾性分析2008年3月至2013年3月间294例以胸闷、胸痛或心悸为主要症状、接受MPI及同机CTCA检查的患者资料,筛选出冠脉MB患者49例[男26例,女23例,年龄32～85（55．4±16．6）岁]。统计MB和缺血发生部位;将MPI和CTCA图像进行融合,对融合图像上MB．壁冠脉穿行心肌缺血区域、且CAG证实该区域供血冠脉不存在粥样斑块所致管腔狭窄者,判定心肌缺血为MB所致。利用z。检验比较不同部位MB引发心肌缺血改变的发生率差异。结果49例冠脉MB患者中,MB位于前降支近段3例,前降支中段34例,前降支远段4例,间隔支3例,回旋支远段2例,中间支I例,右冠脉近中段2例;MPI显示心肌缺血41例（缺血部位46处）,其中心尖部3例,前壁心尖部5例,前壁中部17例,间隔心尖部4例,前间隔中部3例,前侧壁中部2例,下侧壁中部2例,下侧壁基底段4例,下壁近心尖部3例,下壁基底段3例;融合图像示MB引发的心肌缺血有32例,其中23例由前降支中段MB所致。MB位于好发部位组（前降支中段,34例）与非好发部位组（15例）的心肌缺血发生率分别为67．6％（23／34）和60．0％（9／15）,差异无统计学意义（x2=0．27,P〉0．05）。结论左冠脉前降支中段是MB的好发部位,不同部位的MB引发心肌缺血的发生率无显著差异。MPI／CTCA融合影像可同时探测心肌缺血和冠脉MB的部位,判断MB对心肌血液供应的影响。     

用双核素心肌断层显像评价Q波和非Q波心肌梗死存活心肌

目的利用^99Tc^m-甲氧基异丁基异腈(MIBI)/^18F-脱氧葡萄糖(FDG)双核素心肌断层显像评价Q波和非Q波心肌梗死(MI)患中存活心肌的情况。方法45例MI患分为无Q波MI(NQMI，n=17)和有Q波MI(QMI，n=28)2组。均行^99Tc^m-MIBI SPECT门控心肌灌注显像、^18F-FDG SPECT心肌代谢显像和冠状动脉造影。根据心肌血流灌注、代谢和门控信息等比较2组患存活心肌的情况。结果NQMI组的缺血存活心肌节段数明显高于QMI组，非存活心肌节段数明显低于QMI组(P值分别为0．001和0．005)；左室射血分数(LVEF)明显高于QMI组(t=4．603，P：0．000)。门控分析所得室壁增厚率和缺血存活心肌间存在良好相关性(r=0．671，P=0．000)，NQMI组室壁增厚率降低的节段数明显低于QMI组(t=4．183，P=0．000)。结论对NQMI患采取更积极的治疗策略有助于挽救更多的缺血存活心肌，改善其预后。