犬心肌梗死模型的制备及评价

 目的 建立犬心肌梗死动物模型并加以评价.方法 选取杂种犬14只,建立模型前进行心电图、超声及SPECT 检查;常规麻醉实验犬,开胸结扎左冠状动脉前降支,同时作心电监护;11 d后行超声心动图及SPECT检查.结果 犬冠状动脉前降支结扎后,心电监护示心率加快和室性早搏,ST段压低;11 d后超声心动图显示有室壁活动减弱,心梗区心肌变薄,射血分数(EF)、每搏量(SV)、左室短轴缩短率(FS)下降,较结扎前差异有统计学意义(P＜0.05) ;99rnTc-MIBI示:心尖部、左室前壁、室间隔明显充盈缺损.结论 该方法效果确实可靠、手术方便安全,是构建心肌梗死模型的理想方法.     

超声心动图观察高原右心室急性心肌梗死溶栓治疗效果

右心室心肌梗死的预后很差,其治疗方法不同于左心室心肌梗死,但右心室心肌梗死的诊断一直比较困难。右心室心肌梗死的诊断方法包括ECG、心导管血流动力学检查、心室核素显像和超声心动图。血流动力学检查发现右心室心肌梗死的患者右心房压升高,肺毛细血管楔压正常或减低,这种血流动力学改变可以用多普勒超声心动图进行监测。本研究旨在对超声心动图诊断高原地区右心室心肌梗死和判断溶栓治疗效果的价值进行初步探讨。作者在海拔3890m西藏日喀则,选取右心室心肌梗死患者23例(男16例,女7例),年龄(47~69)岁,平均(56.1±4.7)岁,,均有典型胸痛3…     

超声心动图诊断急性心肌梗死合并室间隔穿孔及室壁瘤1例

患者,女,73岁,维吾尔族,因反复胸闷、胸痛3 d伴呕吐加重1 d于2011-01-12急诊入院。体格检查：脉搏98/min,血压150/88 mmHg,心界扩大,心率98/min,律不齐,心电图示：V1～V5导联ST段呈弓背样抬高,T波倒置,可见深大病理性Q波,提示广泛前壁心肌梗死。彩色多普勒超声检查：全心扩大,以左房、左室明显（四腔切面左室径线102 mm×62 mm）,室间隔及左室后壁厚度正常。多切面扫查示左     

急性心肌梗死并发室间隔穿孔彩色多普勒超声心动图特征研究

目的:探寻急性心肌梗死并发室间隔穿孔(VSR)彩色多普勒超声心动图(CDE)特征.方法:应用CDE检查30例急性心肌梗死并发VSR.26例行心血管造影检查,19例行VSR封堵术介入治疗,3例行冠状动脉搭桥和VSR修复术治疗.结果:根据CDE特征对30例中老年急性心肌梗死并发VSR全部做出正确诊断.急性心肌梗死并发VSR的CDE特征明显:①二维超声心动图间接特征显示左心房、左心室内径明显增大,室间隔和/或左室壁节段运动异常,合并室壁瘤患者显示左心室下部心肌变薄,且向外膨出,呈矛盾运动;直接特征显示肌部室间隔不同大小回声失落;②彩色多普勒血流显像(CDFI)显示间接特征显示过二、三尖瓣五彩镶嵌反流束血流信号;直接特征显示过室间隔左向右五彩镶嵌反分流束血流信号;③自患者发病起CDE连续观察VSR直径在一定范围内逐渐增大;④实施VSR封堵术后CDFI仍显示过室间隔封堵器周围少量左向右五彩镶嵌分流束血流信号,但患者临床症状明显减轻.结论:急性心肌梗死并发VSR的CDE特征明显,CDE对急性心肌梗死并发VSR有特异性诊断价值.     

心肌缺血与心肌梗死的磁共振研究

随着临床和实验研究的深入，MR在心脏方面的应用越来越受到重视。本文着重介绍近年来心肌缺血和心肌梗死的MR研究，就其形态学、运动功能、心肌灌注和能量代谢物水平变化作一综述。     

实时三维超声心动图评价心肌梗死所致心衰患者左室收缩不同步

心肌梗死后由于局部心肌收缩能力减低甚至丧失,导致左室整体收缩不同步,进而引起心室整体形态的重构和功能的受损,而且不同部位的心肌梗死对左室整体功能和预后的影响可能也存在差异,因此,本研究旨在应用实时三维     

心肌梗死与心绞痛心肌缺血发作时间的研究

目的 观察心肌梗死后和稳定型心绞痛病人在心肌缺血发生时间上的差异。方法 以动态心电图监测系统分别对心脏梗死和稳定型心绞痛病人进行了24h动态检查。结果 在心肌梗塞组的65次心肌缺血发作中,白天31次,夜间34次(P>0.05);稳定型心绞痛组的34次心肌缺血发作中,白天21次,夜间13次(P<0.05)。结论 心肌梗塞后病人心肌缺血发生时间无明显差异;稳定型心绞痛病人心肌缺血多发生在白天,其原因可能与白天心肌耗氧量增加有关。     

超声引导下急性缺血性左室舒张功能障碍并二尖瓣反流犬模型的构建

 目的 探讨超声引导下急性缺血性左室舒张功能障碍并二尖瓣反流犬模型的构建。方法 (1)二尖瓣反流模型的建立:比格犬15条,经左颈动脉穿刺并送入动脉鞘。在超声引导下,将动脉鞘送入左室,鞘前端置于二尖瓣前叶边缘,经动脉鞘将内镜活体取样钳置于二尖瓣尖下,钳断二尖瓣腱索。经胸心脏超声证实存在二尖瓣反流。(2)急性缺血性左室舒张功能障碍模型的建立:在超声引导下,外撤动脉鞘使其前端置于左冠状动脉窦内,间歇多次注射塑料微球于左冠状动脉窦内,微栓塞冠状动脉,左室舒张末压升高≥5 mmHg定义为建模成功,形成急性缺血性舒张功能不全。结果 (1)15条比格犬制作二尖瓣反流模型全部成功;14条犬形成中度二尖瓣反流,1条比格犬造成重度二尖瓣反流。多普勒频谱测量二尖瓣反流,V max为(483.0 ±1.1) m/s,PG max为(162.7± 1.8) mmHg。(2)15条二尖瓣反流比格犬进行急性缺血左室舒张功能障碍模型构建,成功12条,3条未成功。12条成功模型的左室舒张末压升高、最大左室压力下降速率(-dP/dtmax)降低、左室松弛时间常数(Tau)延长。结论 超声引导下,经颈动脉鞘管送入活检钳钳夹二尖瓣腱索制造二尖瓣反流(MR)、间歇多次注射微球入左冠状动脉窦构建急性缺血性舒张功能障碍比格犬模型,具有操作简便、方法可靠、成功率高等优点。     

心肌缺血预适应对急性心肌梗死影响的观察

目的：观察心肌缺血预适应对急性心肌梗死的保护作用。方法：将急性心肌梗死80例，根据梗死前有无心绞痛发作史分为缺血预适应组48例和无缺血预适应组32例，将两组临床资料进行对比分析。结果：缺血预适应组小面积心肌梗死的发生率明显高于无缺血预适应组，而心律失常、心衰、心源性休克和再梗死等发生率和病死率明显低于无缺血预适应组。结论：心肌缺血预适应对AMI具有保护作用，可限制梗死范围扩大，维护心功能，降低心律失常等并发症的发生率及住院病死率。     

The determination of myocardial viability using Gd-DTPA in a canine model of acute myocardial ischemia and reperfusion

The partition coefficient of Gd-DTPA was thought to vary with the amount of cellular membrane damage after an acute myocardial infarction. The relationship between the partition coefficient of Gd-DTPA (λ) and the uptake of ²⁰¹TI (as a marker of tissue viability) was studied 2 h to 3 weeks after reperfusion of a 2-h occlusion to the left anterior descending coronary artery in a canine model. Gd-DTPA was infused as a bolus followed by a prolonged constant infusion, and this infusion protocol was optimized such that the concentration of Gd-DTPA was directly related to λ. After this infusion, MR images of excised hearts showed regions of increased signal intensity corresponding to increased Gd-DTPA concentration. At all time points, λ and ²⁰¹TI uptake were strongly negatively correlated indicating that λ is an accurate indicator of myocardial viability. Furthermore, λ in the infarcted regions was increased relative to normal regions after 2 h of reperfusion and stayed elevated up to 3 weeks. At all time points, λ in the infarcted and normal regions were significantly different. As well, this data showed a trend that λ in infarcted regions decreased monotonically from 1 day to 3 weeks. This trend was confirmed with MR imaging by examining the change in signal intensity of in vivo images from 4 days to 3 weeks in two animals. These results suggest that MRI with Gd-DTPA could be used to measure the extent of myocardial damage after an acute myocardial infarction.     

Proton NMR spectroscopy in canine myocardial infarction

Proton NMR spectroscopy was used to study the relationship between proton relaxation times and other resonances in the proton spectra, such as lipids, creatine, and choline/carnitine in subacute (8-day-old) myocardial infarctions. Eight mongrel dogs received operative ligation of the left anterior descending coronary artery (four were permanently occluded, four were occluded for 1 h and reperfused) and were sacrificed 8 days later so that tissue samples could be prepared for NMR spectroscopy. The results of this study indicate that (for the core of infarcted tissue) the lipids do not contribute directly to the increased bulk relaxation times associated with myocardial infarction and that the lipid peaks (2.3, 1.2, 0.8 ppm) and creatine peak (3.0 ppm) are more specific to the kind of infarct than to the relaxation times. Therefore, analysis of the proton spectrum of myocardial tissue may serve as a method for tissue characterization.     

Prevalence and prognostic significance of silent myocardial ischemia in patients after myocardial infarction

BACKGROUND/AIM: Silent myocardial ischemia (MI) can be detected in subjects with any symptoms, in patients after myocardial infarction and in coronary patients who have episodes of symptomatic, as well as of silent MI. This study was carried out to evaluate the frequency, characteristics and prognostic significance of silent MI detected in stress echocardiography test in patients after myocardial infarction. METHODS: In 210 patients within three months after myocardial infarction exercise test was performed. In those patients with ischemic ST depression on exercise electrocardiogram, in order to confirm MI stress echocardiography was additionally performed. To assess the incidence of major cariovascular events, all the patients were followed at least five years after the first myocardial infraction. RESULTS: Out of 210 patients 88 (42%) had ischemic response during stress echocardiography test. Out of 88 patients with MI 54 (61%) had anginal pain (patients with symptomatic MI), while 34 (39%) were free of symptoms (patients with silent MI). Level of exercise test, heart rate, time to the onset of ST segment depression, and the magnitude of ST segment depression were similar in both subgroups of the patients with MI. Duration of exercise test was longer in patients with silent MI (p < 0.05). Wall motion score index during stress echocardiography was higher in patients with symptomatic MI (p < 0.05). Coronary angiography findings were similar in patients with silent and those with symptomatic MI. During a five-yearsfollow-up period the occurrence of major cardic events (cardiac mortality and recurrent myocardial infarction) was similar in both subgroups of the patients with MI. CONCLUSION: In more than one third of patients after myocardial infarction silent MI during stress echocardiography was detected. The patients with silent ischemia had longer duration of exercise test and smaller wall motion score index on stress echocardiography. There was no difference in coronary angiography finding between patients with silent and those with symptomatic MI. The incidence of major cardiac events during a five- years- follow-up was similar in the patients with silent and those with symptomatic MI.     

99锝m N-2-巯基吡啶-N-氧化物与99锝m-甲氧基异丁基异腈对犬急性心肌梗死模型的对照研究

Objective The purpose of the present study is to compare the pharmacokinetic and biodistribution properties of 99Tcm N-mercaptopyridine-N-oxide (99 Tcm N-MPO) with 99 Tcm-sestamibi (99 Tcm-MIBI) in normal dogs, and to investigate the potential of 99TcmN-MPO as a myocardial perfusion agent in canines with acute myocardial infarction. Methods Twelve healthy mongrel dogs were injected intravenously with 99TcmN-MPO (n = 6) or 99Tcm-MIBI (n = 6). Tracer kinetics in body fluids were determined by collecting blood of 1 ml via a femoral vein catheter at 30 s, 1,2,3,4,5, 10, 20, 30, 40, 60and 90 min post-injection (p. i.). The collected blood samples were weighed and counted for radioactivity in a γ-counter. Anterior and posterior planar γ-camera images were collected at 10, 20, 30, 60, 90, and 120 min after injection, with organ uptake quantified by region-of-interest (ROIs) analysis. For comparison, 99Tcm-MIBI was also evaluated in the same twelve dogs. Canine infarct models were set up by micro-invasive interventional embolization. SPECT images in the canine infarct model were collected 24 hours after myocardial infarction at 30 min and 60 min after the administration of 99Tcm N-MPO (n = 5) or 99Tcm-MIBI (n = 5). Results Both of 99Tcm N-MPO and 99Tcm-M1BI had a rapid blood clearance with less than 50% of initial radioactivity remaining at 1 min [99TcmN-MPO: (35. 77 ± 6. 31)% ID/mg ,99Tcm-MIBI (34. 46 ± 6. 83) % ID/mg] and less than 5% at 30 min p. i. [99Tcm N-MPO(3. 11 ± 1.44) % ID/mg,99Tcm-MIBI (2.93 ±0. 39)% ID/mg] . After injection, 99TcmN-MPO showed significant accumulation in the myocardium and prolonged retention. This rapid liver clearance of 99TcmN-MPO led to favorable heart-to-liver ratios, reaching values of 0. 54 ±0. 06 at 10 min, 1.02 ±0. 06 at 30 min, and 1.38 ±0. 06 at 60 min p. i.In contrast, the heart/liver ratio of 99Tcm-MIBI remained low at all time points (0. 46 ± 0. 03 at 10 min,0. 63 ±0. 03 at 30 min, and 0. 62 ± 0. 12 at 60 min p. i.). SPECT imaging studies in canines with acute myocardial infarction indicated that good visualization of the left ventricular wall and perfusion defects could be achieved at 30 min after administration of 99TcmN-MPO, but not 99Tcm-MIBI. Conclusion The combination of high heart uptake and rapid liver clearance makes 99TcmN-MPO a promising new radiotracer for myocardial perfusion imaging.     

99锝m N-2-巯基吡啶-N-氧化物与99锝m-甲氧基异丁基异腈对犬急性心肌梗死模型的对照研究

Objective The purpose of the present study is to compare the pharmacokinetic and biodistribution properties of 99Tcm N-mercaptopyridine-N-oxide (99 Tcm N-MPO) with 99 Tcm-sestamibi (99 Tcm-MIBI) in normal dogs, and to investigate the potential of 99TcmN-MPO as a myocardial perfusion agent in canines with acute myocardial infarction. Methods Twelve healthy mongrel dogs were injected intravenously with 99TcmN-MPO (n = 6) or 99Tcm-MIBI (n = 6). Tracer kinetics in body fluids were determined by collecting blood of 1 ml via a femoral vein catheter at 30 s, 1,2,3,4,5, 10, 20, 30, 40, 60and 90 min post-injection (p. i.). The collected blood samples were weighed and counted for radioactivity in a γ-counter. Anterior and posterior planar γ-camera images were collected at 10, 20, 30, 60, 90, and 120 min after injection, with organ uptake quantified by region-of-interest (ROIs) analysis. For comparison, 99Tcm-MIBI was also evaluated in the same twelve dogs. Canine infarct models were set up by micro-invasive interventional embolization. SPECT images in the canine infarct model were collected 24 hours after myocardial infarction at 30 min and 60 min after the administration of 99Tcm N-MPO (n = 5) or 99Tcm-MIBI (n = 5). Results Both of 99Tcm N-MPO and 99Tcm-M1BI had a rapid blood clearance with less than 50% of initial radioactivity remaining at 1 min [99TcmN-MPO: (35. 77 ± 6. 31)% ID/mg ,99Tcm-MIBI (34. 46 ± 6. 83) % ID/mg] and less than 5% at 30 min p. i. [99Tcm N-MPO(3. 11 ± 1.44) % ID/mg,99Tcm-MIBI (2.93 ±0. 39)% ID/mg] . After injection, 99TcmN-MPO showed significant accumulation in the myocardium and prolonged retention. This rapid liver clearance of 99TcmN-MPO led to favorable heart-to-liver ratios, reaching values of 0. 54 ±0. 06 at 10 min, 1.02 ±0. 06 at 30 min, and 1.38 ±0. 06 at 60 min p. i.In contrast, the heart/liver ratio of 99Tcm-MIBI remained low at all time points (0. 46 ± 0. 03 at 10 min,0. 63 ±0. 03 at 30 min, and 0. 62 ± 0. 12 at 60 min p. i.). SPECT imaging studies in canines with acute myocardial infarction indicated that good visualization of the left ventricular wall and perfusion defects could be achieved at 30 min after administration of 99TcmN-MPO, but not 99Tcm-MIBI. Conclusion The combination of high heart uptake and rapid liver clearance makes 99TcmN-MPO a promising new radiotracer for myocardial perfusion imaging.     

99锝m N-2-巯基吡啶-N-氧化物与99锝m-甲氧基异丁基异腈对犬急性心肌梗死模型的对照研究

目的 在正常和心肌梗死犬模型上,研究99TcmN-2-巯基吡啶-N-氧化物(99TcmN-MPO)的药物代谢动力学特征、生物学分布特征和对急性心肌梗死的诊断能力,并与传统示踪剂99锝m-甲氧基异丁基异腈(99Tcm-MIBI)进行对比研究.方法 正常杂种犬12只.静脉注射99TcmN-MPO,于不同时间点(30 s及1、2、3、4、5、10、20、30、40、60和90 min)静脉分别采血1 ml,经γ探测器测量其放射活性;注药后10、20、30、60、90及120 min行全身SPECT显像,并于不同器官上各取同样大小的ROI,测量其放射性计数进行定量研究.每只犬均注射相同剂量的99TcmMIBI,进行相同的实验作为对照.介入学方法构建犬急性心肌梗死模型,24 h后,静脉注入99TcmN-MPO(5只)和99Tcm-MIBI(5只),并于注药后30、60min进行心肌SPECT显像.结果 在静脉注射90 min内,99TcmN-MPO和99Tcm-MIBI均表现为快速的血液清除.两种示踪剂的初始注射剂量均为370 MBq.注射后1 min,每毫克血浆的放射活性小于初始注射剂量的50%[99TcmN-MPO为(35.77±6.31)%ID/mg;99Tcm-MIBI为(34.46±6.83)%ID/mg],30 min时＜5%[99TcmN-MPO:(3.11±1.44)%ID/mg;99Tcm-MIBI:(2.93±0.39)%ID/mg].99TcmN-MPO在心脏的浓聚明显,且存留时间很长,由于其在肝脏清除的速度较快,因此可获得良好的心/肝摄取比值,注射后10 min为0.54±0.06,30 min为1.02±0.06,60 min上升到1.38±0.06.相比之下,99Tcm-MIBI的心/肝摄取比值上升较为缓慢(注射后10 min为0.46±0.03,30 min为0.63±0.03,60 min为0.62±0.12).犬心肌梗死后SPECT心肌断层扫描显示,在注射99TcmN-MPO 30 min后,心脏与肝脏分界清楚,可清楚显示心肌缺血、梗死灌注缺损区域、范围和程度;而99Tcm-MIBI注射后60 min,心脏和肝脏的分界依然不清,尤其是肝脏的高放射性对心脏下壁和左心室壁的影响很大,对心脏左心室壁的心肌梗死灌注缺损区域的显示不佳.结论 99TcmN-MPO具有心肌摄取量较高,肝脏代谢快的特点,是一种具有广阔临床应用前景的SPECT心肌灌注成像显像剂.

Abstract：

Objective The purpose of the present study is to compare the pharmacokinetic and biodistribution properties of 99Tcm N-mercaptopyridine-N-oxide (99 Tcm N-MPO) with 99 Tcm-sestamibi (99 Tcm-MIBI) in normal dogs, and to investigate the potential of 99TcmN-MPO as a myocardial perfusion agent in canines with acute myocardial infarction. Methods Twelve healthy mongrel dogs were injected intravenously with 99TcmN-MPO (n = 6) or 99Tcm-MIBI (n = 6). Tracer kinetics in body fluids were determined by collecting blood of 1 ml via a femoral vein catheter at 30 s, 1,2,3,4,5, 10, 20, 30, 40, 60and 90 min post-injection (p. i.). The collected blood samples were weighed and counted for radioactivity in a γ-counter. Anterior and posterior planar γ-camera images were collected at 10, 20, 30, 60, 90, and 120 min after injection, with organ uptake quantified by region-of-interest (ROIs) analysis. For comparison, 99Tcm-MIBI was also evaluated in the same twelve dogs. Canine infarct models were set up by micro-invasive interventional embolization. SPECT images in the canine infarct model were collected 24 hours after myocardial infarction at 30 min and 60 min after the administration of 99Tcm N-MPO (n = 5) or 99Tcm-MIBI (n = 5). Results Both of 99Tcm N-MPO and 99Tcm-M1BI had a rapid blood clearance with less than 50% of initial radioactivity remaining at 1 min [99TcmN-MPO: (35. 77 ± 6. 31)% ID/mg ,99Tcm-MIBI (34. 46 ± 6. 83) % ID/mg] and less than 5% at 30 min p. i. [99Tcm N-MPO(3. 11 ± 1.44) % ID/mg,99Tcm-MIBI (2.93 ±0. 39)% ID/mg] . After injection, 99TcmN-MPO showed significant accumulation in the myocardium and prolonged retention. This rapid liver clearance of 99TcmN-MPO led to favorable heart-to-liver ratios, reaching values of 0. 54 ±0. 06 at 10 min, 1.02 ±0. 06 at 30 min, and 1.38 ±0. 06 at 60 min p. i.In contrast, the heart/liver ratio of 99Tcm-MIBI remained low at all time points (0. 46 ± 0. 03 at 10 min,0. 63 ±0. 03 at 30 min, and 0. 62 ± 0. 12 at 60 min p. i.). SPECT imaging studies in canines with acute myocardial infarction indicated that good visualization of the left ventricular wall and perfusion defects could be achieved at 30 min after administration of 99TcmN-MPO, but not 99Tcm-MIBI. Conclusion The combination of high heart uptake and rapid liver clearance makes 99TcmN-MPO a promising new radiotracer for myocardial perfusion imaging.     

A reproducible canine model of nonocclusive mesenteric ischemia

A technique for producing a reliable, clinically applicable, and highly reproducible canine model of nonocclusive mesenteric ischemia was developed. Following left thoracotomy in 10 dogs, a 1 mm diameter soft polyethylene tube was inserted into the pericardial space via a small puncture site. This tube was sealed in place with cyanoacrylate tissue adhesive. A solution of 10% Dextran 40 in saline was infused into the pericardial space until a 50% reduction (as monitored by electromagnetic flowmeter) in superior mesenteric artery flow (SMAQ) was obtained. Without additional intrapericardial infusion of the Dextran solution, SMAQ was reduced 51 +/- 4% to 54 +/- 3% of control values during a 60 minute post-tamponade observation period. During the same time. Cardiac output was depressed between 40 +/- 8% and 54 +/- 3%, and right atrial pressure remained elevated between 164 +/- 15% and 171 +/- 15%. Systemic arterial pressure initially dropped 28 +/- 5% but compensated to within 11 +/- 5% of pre-tamponade level at 60 minutes. The stability of this model is well suited for evaluating new experimental diagnostic and therapeutic procedures.