左心声学造影的临床应用进展

随着左心声学造影剂的更新,左心声学造影技术的成像质量及稳定性得到提高。由此超声心动图在静息、运动或药物负荷状态下定性和定量评价左室结构和功能的准确性有了很大提升。本文就左心声学造影技术的研究进展及其在临床中的应用综述如下。     

左心声学造影的临床应用进展

心脏声学造影是将超声心动图和声学造影技术结合的一种新型心血管造影技术，包括右心声学造影和左心声学造影。其中左心声学造影包括左室声学造影和心肌造影超声心动图，其不仅可通过造影剂增强心腔与血管腔的显像，提高心肌与心腔界面的显示效果，还能直观显示心肌灌注情况，临床应用越来越广泛。本文就左心声学造影的临床应用进展进行综述。     

左心声学造影的临床应用及指南推荐

心脏声学造影是将超声心动图和声学造影技术相结合的一项新型心血管造影技术,包括右心声学造影和左心声学造影。本文主要介绍左心声学造影,包括左室声学造影(Left ventricular opacification, LVO)和心肌造影超声心动图(Myocardial contrast echocardiography, MCE)。它通过造影剂增强心腔与血管腔的显像,从而提高心肌与心腔界面的显示效果,还能够直观提示心肌灌注情况,在临床上的运用也越来越广泛。2017年欧洲心血管成像协会(European Association of Cardiovascular Imaging ,EACVI)及2018年美国超声心动图协会(American Society of Echocardiography,ASE)都发表了相关指南更新,本文就左心声学造影的临床应用及指南推荐等方面进行总结。     

心肌声学造影的研究进展及应用

随着对心肌声学造影(MCE)技术的深入研究,MCE成像质量及稳定性得到逐步提高。MCE是用于评价心肌微循环灌注的技术,其通过分析心肌血流灌注能准确评估心肌血流量,诊断急性及慢性缺血性心脏病的病变范围及程度,评价再灌注治疗后心肌存活性及收缩功能恢复情况。MCE的研究领域扩展到基因治疗方面,可为心血管疾病的诊断和治疗提供新途径。     

急性冠脉闭塞兔心肌微循环灌注的定量研究

目的通过心肌声学造影(MCE)定量评价急性冠脉闭塞后兔心肌的微循环灌注。方法将30只日本大耳兔随机分为:冠脉结扎模型组(MI组)和假手术组(Sham组),分别于开胸前、术后30min、2h及6h行常规心脏超声及MCE检查。结果成功制备兔冠脉结扎模型,兔左心收缩功能减低,MCE方法证明MI组术后造模节段心肌血流灌注量明显低于非梗死区、Sham组(P0.05)。结论通过MCE对心肌微循环灌注的定量评价,为临床诊断心肌缺血的部位和严重程度提供一定的参考价值。     

声学造影对比心血池核素评价老年人左心室收缩功能

目的探讨左心室声学造影评价心功能的准确性。方法观察80例至少有两个以上节段心内膜显示不清的60岁以上患者,经静脉注射注射用六氟化硫微泡声学造影剂后,分别测量造影剂应用前后的左室射血分数,与核素心室显像测值相比较。结果静脉注射声学造影剂前后的左室射血分数分别为(64.30±6.45)%和(72.02±4.48)%,造影前后与核素测值的相关性分别为0.39和0.82。结论左心室声学造影改善了谐波成像低估左室射血分数的问题,能够更准确地评价左心收缩功能。     

心肌声学造影评价钾离子通道开放剂的延迟性心肌保护作用

目的利用心肌声学造影观察钾离子通道开放剂尼克地尔的延迟性心肌保护作用。方法18只犬平均分为实验对照组、尼克地尔组及格列苯脲组,经药物预处理后24h,建立动物模型,利用心肌声学造影评价再灌注后心肌梗死面积、组织灌注及功能恢复。结果尼克地尔预处理明显减少再灌注后心肌梗死面积、改善心肌组织再灌注及心功能恢复。而格列苯脲可以阻断保护作用。结论尼克地尔对犬缺血再灌注后心肌在结构和功能上具有延迟性保护作用,钾离子通道在此过程起重要作用。     

静脉输注国产声学造影剂定量心肌血流灌注的实验研究

目的：评价应用国产左心声学造影剂“全氟星”定量心肌血流灌注的可行性。方法：建立犬前降支缺血模型，经外周静脉持续匀速输注“全氟星”，存取不同触发间隔的造影图像，通过计算造影剂再充填曲线的平台声强度及微泡再充填速率估测心肌血流量。以正常区为参照、放射微球测定心肌血流量为“金标准”，判定应用国产左心声学造影剂定量心肌血流灌注的可行性。结果：放射微球测定心肌血流量与心肌声学造影定量结果相关良好（r=0.8913，P＜0．001）。结论：静脉均速输注“全氟显”可用于估测心肌血流量。     

谐波、超谐波心肌声学造影技术评价犬急性心肌梗死

目的探讨谐波(HA)和超谐波(UH)两种心肌声学造影技术评价心肌梗死的准确性。方法10条常规开胸犬动物模型,在基础状态、结扎冠状动脉左前降支1h后,分别应用HA和UH技术采集心肌声学造影图像,目测观察充盈缺损的范围,定量计算充盈缺损的面积,并与应用TTC染色测量的梗死心肌面积对比。结果TTC染色显示心肌梗死HA面积百分率为15.8%±2.4%,应用两种心肌声学造影模式计算的充盈缺损面积与解剖学梗死心肌面积高度相似,应用HA模式为15.5%±2.9%,应用UH模式为15.5%±3.0%。两种心肌声学造影模式检测急性心肌梗死HA的敏感性、特异性及诊断准确率分别为:在HA模式为88%、100%、94%;在UH模式为100%、75%、88%。结论两种心肌声学造影技术在诊断急性心肌梗死中均具有高度的准确性。     

二次谐波经静脉左心造影剂的研究

近几年二次谐波成像技术的应用 ,使超声心动图造影检查取得了新的突破 ,而经静脉注射造影剂产生左室和心肌显像的研究产生飞跃。经静脉左心造影剂的开发和应用 ,使越来越多的人接受了这种无创、快速、准确的检测左心室结构、功能和心肌血流灌注的方法。本文从二次谐波经静脉左心造影剂的特性对左心和心肌显像的影响 ;造影剂的剂量对造影成像质量的影响 ;成像方式对造影剂的影响 ;以及造影剂的临床应用等方面概述了近几年经静脉左心造影剂研究的进展 ,并列举出一些常用的二次谐波造影剂供研究者参考     

Determination of creatine kinase isoenzyme MB activity in serum using immunological inhibition of creatine kinase M subunit activity. Activity kinetics and diagnostic significance in myocardial infarction.

This is a new method for the determination of creatine kinase isoenzyme MB activity in serum. The method uses direct activity measurement of creatine kinase B subunit activity after blocking of CK-M subunit activity by inhibiting antibodies. The test takes no longer than 15 min. The method yields an intra-serial C.V. of 2.0-12.9%, and a C.V. from day to day of 5.5%. The detection limit is 3.4 U/l creatine kinase MB. In the 95 cases with proven myocardial infarction several types of creatine kinase MB activity kinetics could be determined. The percentage of creatine kinase MB of peak CK-total is 6-25%, with a mean of 11.1%. The amount of creatine kinase MB with respect to total CK activity after reinfarction is higher than the amount after initial infarction.     

Dissociable correlates of two classes of retrieval processing in prefrontal cortex

Although substantial evidence suggests that the prefrontal cortex (PFC) implements processes that are critical for accurate episodic memory judgments, the specific roles of different PFC subregions remain unclear. Here, we used event-related functional magnetic resonance imaging to distinguish between prefrontal activity related to operations that (1) influence processing of retrieval cues based on current task demands, or (2) are involved in monitoring the outputs of retrieval. Fourteen participants studied auditory words spoken by a male or female speaker and completed memory tests in which the stimuli were unstudied foil words and studied words spoken by either the same speaker at study, or the alternate speaker. On "general" test trials, participants were to determine whether each word was studied, regardless of the voice of the speaker, whereas on "specific" test trials, participants were to additionally distinguish between studied words that were spoken in the same voice or a different voice at study. Thus, on specific test trials, participants were explicitly required to attend to voice information in order to evaluate each test item. Anterior (right BA 10), dorsolateral prefrontal (right BA 46), and inferior frontal (bilateral BA 47/12) regions were more active during specific than during general trials. Activation in anterior and dorsolateral PFC was enhanced during specific test trials even in response to unstudied items, suggesting that activation in these regions was related to the differential processing of retrieval cues in the two tasks. In contrast, differences between specific and general test trials in inferior frontal regions (bilateral BA 47/12) were seen only for studied items, suggesting a role for these regions in post-retrieval monitoring processes. Results from this study are consistent with the idea that different PFC subregions implement distinct, but complementary processes that collectively support accurate episodic memory judgments.     

俯卧位通气对高海拔地区肺复张治疗无效急性呼吸窘迫综合征患者氧合的影响

目的 探讨俯卧位通气对高海拔地区肺复张术(RM)治疗无效急性呼吸窘迫综合征(ARDS)患者的治疗作用.方法 从海拔2260m的地区医院筛选RM治疗无效的41例ARDS患者[平均氧合指数( PaO2/FiO2)较RM前升高＜20％视为RM无效],依不同病因分为肺内源性ARDS组(ARDSp组)和肺外源性ARDS组(ARDSexp组),每组再按信封法随机分为俯卧位组和仰卧位组,即ARDSp俯卧位组(11例)、ARDSp仰卧位组(9例)、ARDSexp俯卧位组(10例)、ARDSexp仰卧位组(11例).在通气前及通气1、2、3、4h监测动脉血氧分压( PaO2)、PaO2/FiO2、静态顺应性(Cst)、气道阻力(Raw)的变化.结果 通气lh时,ARDSexp俯卧位组PaO2/FiO2( mm Hg,l mm Hg=0.133 kPa)即较通气前显著升高(157.4±40.6比129.3±48.7,P＜0.05),并随通气时间延长呈持续增高趋势,4h达峰值(219.1 ±41.1);且ARDSexp俯卧位组通气3h内PaO2/FiO2较其他3组显著增高,另3组间则差异无统计学意义.ARDSp俯卧位组、ARDSexp俯卧位组通气4h时PaO2/FiO2均较相应仰卧位组显著增高(208.8±39.7比127.4±47.1,219.1±41.1比124.9±50.8,均P＜0.05).4组通气前后Cst无显著改变,各组间差异也无统计学意义.ARDSp俯卧位组通气4h时Raw(cmH2O·L-1·s-1)较通气前显著降低(6.8±1.7比10.7±1.8,P＜0.05),且明显低于其他3组;其他3组各时间点Raw组内及组间比较差异均无统计学意义.结论 俯卧位通气作为ARDS机械通气重要策略之一,可以改善RM无效高原ARDS患者的氧合,为抢救患者赢得宝贵的时间.     

Digital imaging among medical facilities

The Department of Veterans Affairs (VA) in the USA operates a network of 172 medical centres which all utilize a hospital information system (HIS) which has been developed and is currently maintained by the VA. During the past several years, an image management and communication module has been developed, installed and clinically utilized at the Washington DC and Maryland VA Medical Centres. This image management and communication system, referred to as the decentralized hospital computer program (DHCP) imaging system, is fully integrated with a commercial picture archiving and communication system (PACS). The system is utilized to capture, archive, and display all images generated within the hospital including radiology, nuclear medicine, pathology, endoscopy, bronchoscopy, and dermatology, intraoperative photographs, ECG data, and a limited number of paper documents. The ultimate goal of the project is to have all patient text and image data available at any clinical workstation to any authorized user anywhere within the network of medical centres. Clinical requirements for an imaging workstation include ease of use, rapid and reliable access to the complete set of patient information, and images which are of acceptable quality to meet the requirements of the user and the subspecialty. Patient confidentiality and data security must be safeguarded at all times. Integration of the images with the remainder of the patient's database was found to be critical to the success of the project. The experience at the Washington and Maryland facilities suggests that an imaging system that is successfully integrated with a hospital information system can provide substantial clinical and economic benefits both within and among medical centres. Clinical acceptance and utilization of the system has been excellent, particularly in diagnostic radiology where DHCP Imaging has been interfaced to a commercial PAC system. Based upon this initial experience, the VA has begun to deploy the system throughout its large network of medical centres.     

Myocardial elastography at both high temporal and spatial resolution for the detection of infarcts

Myocardial elastography is a novel method for noninvasively assessing regional myocardial function, with the advantages of high spatial and temporal resolution and high signal-to-noise ratio (SNR). In this paper, in-vivo experiments were performed in anesthetized normal and infarcted mice (one day after left anterior descending coronary artery [LAD] ligation) using a high-resolution (30 MHz) ultrasound system (Vevo 770, VisualSonics Inc., Toronto, ON, Canada). Radiofrequency (RF) signals of the left ventricle (LV) in longitudinal (long-axis) view and the associated electrocardiogram (ECG) were simultaneously acquired. Using a retrospective ECG gating technique, 2-D full field-of-view RF frames were acquired at an extremely high frame rate (8 kHz) that resulted in high-quality incremental displacement and strain estimation of the myocardium. The incremental results were further accumulated to obtain the cumulative displacements and strains. Two-dimensional and M-mode displacement images and strain images (elastograms), as well as displacement and strain profiles as a function of time, were compared between normal and infarcted mice. Incremental results clearly depicted cardiac events including LV contraction, LV relaxation and isovolumetric phases in both normal and infarcted mice, and also evidently indicated reduced motion and deformation in the infarcted myocardium. The elastograms indicated that the infarcted regions underwent thinning during systole rather than thickening, as in the normal case. The cumulative elastograms were found to have higher elastographic SNR (SNR(e)) than the incremental elastograms (e.g., 10.6 vs. 4.7 in a normal myocardium, and 6.0 vs. 2.4 in an infarcted myocardium). Finally, preliminary statistical results from nine normal (m = 9) and seven infarcted (n = 7) mice indicated the capability of the cumulative strain in differentiating infracted from normal myocardia. In conclusion, myocardial elastography could provide regional strain information at simultaneously high temporal (>/=0.125 ms) and spatial ( approximately 55 microm) resolution as well as high precision ( approximately 0.05 microm displacement). This technique was thus capable of accurately characterizing normal myocardial function throughout an entire cardiac cycle, at the same high resolution, and detecting and localizing myocardial infarction in vivo.     

Guns and Knives in New Mexico: Patterns of Penetrating Trauma, 1978–1993

Objective: To identify patterns of nonfatal and fatal penetrating trauma among children and adults in New Mexico using ED and medical examiner data.
Methods: The authors retrospectively sampled in 5-year intervals all victims of penetrating trauma who presented to either the state Level-1 trauma center or the state medical examiner from a 16-year period (1978–1993). Rates of nonfatal and fatal firearm and stabbing injury were compared for children and adults.
Results: Rates of nonfatal injury were similar (firearm, 34.3 per 100,000 person-years; stabbing, 35.1). However, rates of fatal injury were significantly different (firearm, 21.9; stabbing, 2.7; relative risk: 8.2; 95% confidence interval: 5.4, 12.5). From 1978 to 1993, nonfatal injury rates increased for children (p = 0.0043) and adults (p < 0.0001), while fatal penetrating injury remained constant. The increase in nonfatal injury in children resulted from increased firearm injury rates. In adults, both stabbing and firearm nonfatal injury rates increased.
Conclusions: Nonfatal injury data suggest that nonfatal violence has increased; fatal injury data suggest that violent death rates have remained constant. Injury patterns vary by age, mechanism of trauma, and data source. These results suggest that ED and medical examiner data differ and that both are needed to guide injury prevention programs.     

手转胎头术失败的原因与分娩结局临床分析

目的 探讨手转胎头术失败的原因与分娩结局.方法 选择2008年1月至2010年12月于我院住院分娩的持续性枕横位、枕后位产妇198例,根据行手转胎头术后结果分为成功组126例、失败组72例.比较两组分娩结局,对比分析失败原因.结果 失败组胎儿体质量≥3500 g的发生率[76.4％(55/72)]明显高于成功组[31.7％(40/126)],差异有统计学意义(x2=30.177,P=0.001)、失败组宫缩乏力发生率[58.3％(42/72)]高于成功组[38.1％ (48/126)],差异有统计学意义(x2=7.569,P=0.006)、失败组骨盆临界或轻度狭窄发生率[38.9％ (28/72)]高于成功组[23.8％(30/126)],差异有统计学意义(x2 =5.030,P=0.002)、失败组手转胎头时机不当(宫口开大＜6 cm、胎头位于坐骨棘上及宫口开大8～10 cm、胎头位于坐骨棘下≥2 cm)发生率[61.1％(44/72)]高于成功组[38.9％(49/126)],差异有统计学意义(x2=9.084,P=0.003).失败组母儿并发症(产后出血、产褥病率、胎儿窘迫、新生儿窒息)发生率高于成功组(x2 =9.586,P=0.002、x2=9.334,P=0.002、x2=5.910,P=0.015、x2=5.240,P=0.022)、失败组剖宫产发生率[72.2％(52/72)]明显高于成功组[34.1 ％(43/126),x2=26.641,P=0.001)].结论 手转胎头术能使难产变顺产,降低剖宫产率,减少母儿并发症,但须积极预防、处理导致手转胎头术失败的原因,对矫正失败后继续矫正及试产应慎重.