Are changes in myocardial integrated backscatter restricted to the ischemic zone in acute induced ischemia? An in vivo animal study.

Integrated backscatter (IB) from a myocardial region, calculated from radiofrequency echocardiographic data, has been proposed as a useful parameter for investigating changes in myocardial tissue induced by ischemia. In 10 closed-chest dogs, 5 minutes of myocardial ischemia was induced by either a proximal occlusion of the circumflex coronary artery (CX) (5 dogs), resulting in extensive ischemia in the posterior wall, or by occluding the distal CX vessel (5 dogs) to produce a small localized ischemic zone in the posterior wall. High-resolution digital radiofrequency data from the whole left ventricular myocardium, in the imaging plane during one complete heart cycle, were acquired with a whole-image real-time acquisition approach. Regions in the septum and posterior wall (both ischemic tissue and, in the case of distal occlusions, tissue surrounding the ischemic zone) were chosen for analysis, and IB and cyclic variation (CV) of IB were calculated. Post occlusion, an increase in mean IB values was found in the ischemic segment. However, an increase in CV was also observed in the peri-ischemic zone for the distal CX occlusion and in the septum after proximal CX occlusion. These findings show that changes in CV are not restricted to the ischemic zone but may also occur in distal myocardium. This may be explained by changes in the regional contractile state and loading conditions of the "normal" myocardium, which are altered in response to the distal ischemia.     

Myocardial layer-specific analysis of ischemic memory using speckle tracking echocardiography

The assessment of post-systolic shortening (PSS) by speckle tracking echocardiography allows myocardial ischemic memory imaging. Because the endocardial layer is more vulnerable to ischemia, the assessment of this layer might be useful for detecting ischemic memory. Serial echocardiographic data were acquired from nine dogs with 2 min of coronary occlusion followed by reperfusion. Regional deformation parameters were measured in the risk and normal areas. Using speckle tracking echocardiography, circumferential strain was analyzed in the endocardial, mid-wall, and epicardial layers; and radial strain was analyzed in the inner half, outer half and entire (transmural) layers. In the risk area, peak systolic and end-systolic strain in the circumferential and radial directions significantly decreased during occlusion, but recovered to the baseline levels immediately after reperfusion in all layers. However, circumferential post-systolic strain index (PSI), a parameter of PSS, significantly increased during occlusion, and the significant increases persisted until 20 min after reperfusion in the endocardial and mid-wall layers. Radial PSI tended to increase after reperfusion in the inner half and entire layers but these increases were not significant compared with baseline. In the normal area, systolic strains and PSI in the radial and circumferential directions hardly changed before and after occlusion/reperfusion in all layers. In layer-specific analysis with speckle tracking echocardiography, circumferential PSS in the endocardial and mid-wall layers may be useful for detecting ischemic memory.     

Effects of instrument adjustments on quantitative echocardiographic gray level texture measures.

Quantitative echocardiographic gray level texture measures have proved useful in characterizing a variety of cardiac abnormalities, including contusion, ischemia, and cardiomyopathies. However, alterations of echocardiographic signal processing controls could potentially affect the resulting data. The purpose of this study was to assess the effect of common echocardiographic instrument adjustments on texture data. We imaged a graphite-in-gel phantom on five separate occasions, each time using 12 combinations of adjustments of transmit power, compression, and postprocessing curves over a clinically applicable range. Image texture was assessed using gray level run length and gray level difference texture measures; 42 individual measures were calculated. Significance of texture measure variations was assessed by analysis of variance. Changes in all three controls were associated with significant alterations in texture measures. Adjustments of transmit power and compression produced larger changes in texture measures than did adjustments of postprocessing curves. There were significant transmission-compression-postprocessing interaction effects (p less than 0.05) for all but eight of the texture measures. For each texture measure, there were significant transmission-compression interaction effects (p less than 0.05). In summary, instrument adjustments had significant effects on quantitative texture measures, and these effects should be considered when evaluating quantitative echocardiographic gray level texture measures.     

Texture analysis in digitally-acquired echocardiographic images: the effect of JPEG compression and video storage

The analysis of texture in video-stored echocardiographic images is an established method to characterize myocardial pathologies. We investigated whether or not texture parameters calculated from video-stored images and those derived from the joint photographic expert group (JPEG) format compressed data are equivalent to those calculated from uncompressed digital images. Texture parameters were calculated using uncompressed digital data, images stored on videotape, and three forms of compressed digital data (baseline JPEG, JPEG 2000 and lossless JPEG 2000). Video storage heavily affected most texture parameters. Although first-order texture parameters derived from JPEG-compressed images were generally equivalent to those derived from the uncompressed data, several second-order parameters differed significantly. We conclude that texture of video-stored images is not comparable to that of digitally-stored images and that JPEG compression changes important second-order texture parameters. This observation should be taken into account when analyzing texture of modern image data (uncompressed or compressed) and comparing the results with earlier studies utilizing video-stored data.     

超声速度向量成像技术评价急性心肌缺血犬左心室心内膜下心肌力学状态

目的采用超声速度向量成像技术评价急性心肌缺血犬左心室收缩期心内膜下心肌力学变化规律。方法对12只健康比格犬结扎冠状动脉左前降支制作急性心肌缺血模型，采集缺血前后左心室二尖瓣口水平、乳头肌水平、心尖水平动态二维灰阶动态图像；获取左心室不同水平各节段缺血前后心内膜下心肌周向应变、径向应变、旋转角度与径向位移；分析同一节段心肌周向和径向应变与旋转角度的相关性，及两个相邻节段心肌周向应变差值（Acs）与相应节段心肌旋转角度和径向位移的相关性。结果缺血前左心室心内膜下心肌同一室壁周向应变、旋转角度从基底段到心尖段依次增大，缺血后这一力学状态发生改变，其中前间隔基底段周向应变大于心尖节段（P〈0．05），后间隔中段周向应变大于心尖节段（P〈0．05）；后壁基底段旋转角度大于中段（P〈0．01）、下壁中段旋转角度小于心尖节段（P〈0．05）、前间隔中段旋转角度小于心尖节段（P〈0．05）。缺血前心尖水平切面相邻两个节段心肌ACS与其相应节段心肌的旋转角度呈线性相关（r=0．609～0．739，P〈0．05或P〈0．01）；缺血前左心室心内膜下心肌同一室壁乳头肌水平节段与基底水平节段心肌△CS与其乳头肌节段心肌的径向位移呈线性相关（r=0．657～0．852，P〈0．05或P〈0．01），缺血后相关性消失。结论缺血前左心室心内膜下心肌相邻两个节段间的△CS与对应节段心肌旋转角度、径向位移的线性相关提示，相邻丽个节段心肌间的△CS与心尖节段旋转运动以及左心室心腔向心性收缩密切相关。急性心肌缺血状态下，左心室心内膜下心肌应变状态异常改变是左心室重构的重要力学基础。     

高压氧预适应对老龄大鼠急性全脑缺血的影响

目的 观察高压氧预适应对老龄大鼠急性全脑缺血后认知功能的影响.方法 24只老龄雄性SD大鼠分为正常对照组、高压氧组、缺血组、高压氧预适应缺血组,每组6只.缺血组、高压氧预适应缺血组采用改良Pulsinelli四血管闭塞法建立急性全脑缺血模型,高压氧组和建模前高压氧预适应缺血组给予连续5 d、每天1 h 2个标准大气压(2.0 ATA)高压氧处理,各组大鼠分别行横断位及冠状位T1WI、T2WI扫描;Morris水迷宫试验测试学习记忆功能:逃避潜伏期和目标象限游泳时间百分比.结果 正常对照组、高压氧组大鼠大脑未见明显缺血梗死灶,缺血组双侧皮质区可见明显弧形缺血梗死区,高压氧预适应缺血组双侧皮质区也可见弧形缺血梗死区,面积较缺血组小.缺血组逃避潜伏期长于高压氧预适应缺血组(P＜0.05),高压氧预适应缺血组潜伏期长于正常对照组、高压氧组(P＜0.05),后两者之间差异无统计学意义(P＞0.05).缺血组目标象限游泳时间百分比较高压氧预适应缺血组短(P＜0.05),高压氧预适应缺血组短于正常对照组、高压氧组,后两者之间差异无统计学意义(P＞0.05).结论 给予连续高压氧预适应,能减少老龄大鼠急性全脑缺血后超急性期大脑皮质缺血梗死面积,提高全脑缺血后的认知功能水平.     

高压氧预适应对老龄大鼠急性全脑缺血的影响

目的 观察高压氧预适应对老龄大鼠急性全脑缺血后认知功能的影响.方法 24只老龄雄性SD大鼠分为正常对照组、高压氧组、缺血组、高压氧预适应缺血组,每组6只.缺血组、高压氧预适应缺血组采用改良Pulsinelli四血管闭塞法建立急性全脑缺血模型,高压氧组和建模前高压氧预适应缺血组给予连续5 d、每天1 h 2个标准大气压(2.0 ATA)高压氧处理,各组大鼠分别行横断位及冠状位T1WI、T2WI扫描;Morris水迷宫试验测试学习记忆功能:逃避潜伏期和目标象限游泳时间百分比.结果 正常对照组、高压氧组大鼠大脑未见明显缺血梗死灶,缺血组双侧皮质区可见明显弧形缺血梗死区,高压氧预适应缺血组双侧皮质区也可见弧形缺血梗死区,面积较缺血组小.缺血组逃避潜伏期长于高压氧预适应缺血组(P＜0.05),高压氧预适应缺血组潜伏期长于正常对照组、高压氧组(P＜0.05),后两者之间差异无统计学意义(P＞0.05).缺血组目标象限游泳时间百分比较高压氧预适应缺血组短(P＜0.05),高压氧预适应缺血组短于正常对照组、高压氧组,后两者之间差异无统计学意义(P＞0.05).结论 给予连续高压氧预适应,能减少老龄大鼠急性全脑缺血后超急性期大脑皮质缺血梗死面积,提高全脑缺血后的认知功能水平.     

Echocardiographic visualization of acute myocardial ischemia--in vitro study

To evaluate whether myocardial texture changes resulting from acute ischemia can be visualized with satisfactory spatial resolution, short axis compound echo images (CEI) (B-scan) were obtained from 12 excised canine hearts in vitro. Seven had myocardial ischemia produced by open chest ligation of the left anterior descending coronary artery (LAD) for 15-30 min prior to excision. The CEI were constructed by compounding 60 simple linear B-scans. Hearts were sectioned after scanning, and gross morphological changes were recorded. Microscopic comparison between grossly abnormal and normal regions were recorded. The CEI from the ischemic group revealed altered myocardial texture seen as bright coarsely granular echoes in the regions normally perfused by the ligated LAD artery. Corresponding anatomic sections revealed increased redness in these regions. Microscopically these regions revealed interstitial and intercellular edema as compared to the normal regions. Acute myocardial ischemia can be visualized in CEI and these regions have significantly increased backscatter, decreased attenuation, and decreased speed of ultrasound relative to normal regions in the same hearts. Myocardial edema is probably responsible for these changes.     

冠脉CT血管成像斑块定量参数预测冠心病患者心肌缺血事件的临床价值

  目的  分析冠脉CT血管成像（CTA）斑块定量参数预测冠心病患者心肌缺血事件的临床价值。  方法  纳入2020年1月~2022年6月256例初诊冠心病患者作为研究对象,均行冠脉CTA检查,检测斑块定量参数,根据血流储备分数检测结果将患者分为心肌缺血组和非心肌缺血组,比较两组冠脉CTA斑块定量参数,采用多元线性回归分析斑块定量参数与心肌缺血性损伤的关系,采用ROC曲线评估斑块定量参数对心肌缺血性损伤的预测价值。  结果  心肌缺血组总斑块体积、非钙化斑块体积、低密度非钙化斑块（LDNCP）体积、斑块长度、直径狭窄度均大于非心肌缺血组（P < 0.05）,钙化斑块（CP）体积及血流储备分数小于非心肌缺血组（P < 0.05）;多元线性回归分析显示,总斑块体积、LDNCP体积为冠心病患者心肌缺血的独立影响因素（P < 0.05）;ROC曲线显示,总斑块体积、LDNCP体积联合预测心肌缺血性损伤的敏感度、特异性、曲线下面积分别为94.30%、77.80%、0.948。  结论  冠脉CTA斑块定量参数变化与冠心病患者心肌缺血性损伤有关,其中总斑块体积、LDNCP体积可作为心肌缺血事件的预测指标。      

Usefulness of echocardiography and Doppler in the detection of segmental myocardial ischemia

Echocardiography and Doppler was performed in 20 patients during percutaneous transluminal coronary angioplasty of a right coronary artery to evaluate the usefulness of echocardiography and Doppler in the detection of segmental myocardial ischemia. Wall motion analysis was also compared to the occurrence of chest pain in relation to electrocardiographic and hemodynamic changes. Even in the case of small segmental myocardial ischemia, the two-dimensional echocardiographic evaluation of wall motion is superior to all other measured parameters. Contrary to this, the Doppler examination of transmitral flow is not sensitive enough in the detection of such small segmental myocardial ischemia, induced by right coronary artery occlusion.     

Acute regional myocardial ischemia identified by 2-dimensional multiregion tissue Doppler imaging technique.

BACKGROUND AND OBJECTIVE: Tissue Doppler echocardiography (TDE) is a promising method for the assessment of regional myocardial function, but pulsed TDE does not provide quantitative data from multiple regions simultaneously. This feature is important for the objective assessment of regional differences in myocardial function. In the present study, we investigated a new off-line TDE method that provides quantitative pulsed velocity data from an unlimited number of regions selected within a 2-dimensional (2D) image. The goal of the study was to determine the ability of this new approach to quantify regional myocardial function during acute myocardial ischemia induced by balloon angioplasty. METHODS: Twenty-two patients undergoing angioplasty of the left anterior descending coronary artery (LAD) were studied. Left ventricular longitudinal wall motion was assessed by 2D TDE from the apical 4-chamber view before, during, and after angioplasty. Images were sampled at a rate of 69 +/- 15 frames/s, and the off-line analysis allowed simultaneous measurement of velocities in multiple myocardial segments. RESULTS: There were 3 major alterations in the systolic velocity pattern during LAD occlusion. Peak early systolic velocities along the apical septum were significantly reduced during LAD occlusion (2.8 +/- 1.2 cm/s to 0.6 +/- 1.7 cm/s, P <.001). Myocardial velocities in mid systole suggested paradoxical wall motion (1.0 +/- 1.2 cm/s to -0.8 +/- 0.9 cm/s, P <.001). When comparing the ischemic regions of the left ventricle with the nonischemic regions, each patient demonstrated lower myocardial systolic velocities in the ischemic region. Furthermore, during early diastole, the wall motion of the ischemic segments showed a postsystolic contraction pattern with velocities changing from -0.9 +/- 1.0 cm/s to 1.9 +/- 1.3 cm/s (P <.001). CONCLUSION: This new 2D TDE approach is able to quantify detailed myocardial velocity profiles from multiple regions simultaneously. Single-beat comparisons of ischemic and nonischemic regions might enhance the sensitivity for diagnosing ischemic heart disease. Reversed systolic wall motion during midsystole and marked positive velocity during early diastole might be new and important markers of myocardial wall ischemia.     

Two-dimensional echocardiographic image texture analysis: reduction of regional variability using polar coordinates

Factors inherent to the ultrasound imaging system can influence quantitative ultrasound image texture and may produce changes that mask or mimic those due to alterations in tissue structure. In this study, we assessed the effect of the method of image data acquisition and analysis on the variations in quantitative texture measures that occurred solely due to the position of a region of interest (ROI) within the field of view. When ROI's, which varied in range and azimuth within the image of a tissue equivalent phantom (of uniform composition), were assessed by conventional analysis of scan-converted (rectangular coordinate) data, over 50 percent of all texture measures showed significant differences. Pseudo polar analysis reduced the number of texture measures showing regional variation by 80 percent (p less than 0.01) and true polar coordinate data analysis reduced the number by 74 percent (p less than 0.01). True polar analysis completely abolished differences in texture measures between ROI's separated in azimuth. Acquisition and analysis of tissue texture data using polar coordinates should allow a more definitive identification of abnormal tissue.     

Comparison of radionuclide and contrast ventriculography for detection and quantitation of regions of myocardial ischemia in dogs.

Radionuclide and contrast ventriculography were evaluated for their ability to estimate myocardial ischemia. In 14 closed-chest, sedated dogs, a small and larger region of ischemia were produced by inflating balloon occluders on the left anterior descending coronary artery. The systemic arterial pressure, atrial-paced heart rate, global ejection fraction by radionuclide and contrast ventriculography, regional wall-motion abnormalities (as the percentage of abnormally contracting segments), and regional myocardial blood flow (using the microsphere technique) were measured during an initial control period, two separate ischemic periods, and a final control period. The regional ischemic weights based on myocardial blood flow ranged from 0 to 38.5 g and were grouped as zero, small (range 0 to less than 10 g, mean 3.40 g), and large regions of ischemia (greater than 10 g, mean 24.8 g). Regional wall-motion abnormalities were sensitive qualitative indicators of ischemia. Receiver operating characteristic analysis showed that both ventriculographic methods were highly sensitive, specific, and accurate for detecting regional ischemia. Contrast ventriculography was slightly superior for detecting small regions less than 4 g, but the methods were equal for regions greater than 4 g. The arterial pressure and heart rate were unchanged during ischemia. For small regions of ischemia, the global ejection fraction did not fall using either the contrast or radionuclide technique, but it fell significantly when large regions were produced. There was a quantitative relationship between the percentage of abnormally contracting segments and the grams of myocardial ischemia (for radionuclide ventriculography, r = 0.65, P = 0.003, and for contrast ventriculography, r = 0.75, P less than 0.001), but for many small regions of ischemia, wall-motion changes were greater than anticipated, suggesting hypofunction of the continguous normal tissue. This study demonstrated that both radionuclide and contrast ventriculography were quite sensitive and specific for detecting measured amounts of regional ischemia. The functional changes resulting from ischemia are quantitatively related to the extent of regional ischemia, small areas resulting in regional wall motion abnormalities, and large areas producing both reduced global ejection fraction and wall motion changes.     

心脏超声组织定征研究:急性缺血与再灌注过程中心肌组织回声强度变化及其与心肌收缩力的关系

目的：观察心肌组织在急性缺血与再灌注过程中回声强度的变化及其与心肌收缩力的关系。方法：用自制ＤＦＹ－Ⅰ型超声图像定量分析诊断仪对６只犬正常、缺血及再灌注过程中超声心动图局部心肌组织回声强度（ｄＢ值）及其心动周期变化幅度（ＣＶｄＢ）进行了动态定量分析,并同时测定室壁厚度和收缩期增厚率的变化。结果：冠脉阻断后２０分钟,缺血区ｄＢ值增高（Ｐ＜０．０１）,ＣＶｄＢ值降低（Ｐ＜０．０１）。再灌注后１０分钟,ｄＢ值即恢复正常（Ｐ＝ＮＳ）,ＣＶｄＢ值的恢复过程则相对缓慢,并与室壁收缩期增厚率的恢复同步且密切相关（ｒ＝０．８１,Ｐ＜０．０１）。结论：急性缺血时,心肌组织ｄＢ值增高,ＣＶｄＢ值降低;ＣＶｄＢ值与心肌组织收缩力的改变密切相关;通过定量分析超声心动图心肌组织回声强度变化,不但能区别正常与缺血心肌,同时可评估心肌组织的收缩功能。与国外学者所测背向散射积分一致。     

Mechanisms Contributing to Malignant Dysrhythmias Induced by Ischemia in the Cat

Continuously recorded bipolar electrograms were obtained simultaneously from epi-, endo-, and mid-myocardial regions of the ischemic and normal zones of cat left ventricle in vivo after coronary occlusion, analyzed by computer, and compared to regional cyclic AMP levels. Regional cyclic AMP content was used as an index of the combined local effects of: (a) efferent sympathetic nerve discharge; (b) release of myocardial catecholamines due to ischemia; and (c) circulating catecholamines. Ischemia resulted in a progressive increase in pulse width and rise time and a decrease in rate of rise of voltage (dV/dt) of the local electrograms from ischemic zones reaching a maximum within 2.4+/-0.3 min (mean+/-SE) at the time of onset of severe ventricular dysrhythmias, all of which returned toward control before the cessation of the dysrhythmia (33.5+/-1.5 min after coronary occlusion). Increases in cyclic AMP in ischemic zones preceded corresponding increases in the frequency of premature ventricular complexes (PVCs). Propranolol inhibited the increases in cyclic AMP and reduced the frequency of PVCs in animals without ventricular fibrillation. In animals with ventricular fibrillation, cyclic AMP was significantly elevated in normal and ischemic zones compared to animals with PVCs only. Electrical induction of PVCs or ventricular fibrillation in ischemic and nonischemic hearts failed to increase cyclic AMP. The results suggest that the changes in regional adrenergic stimulation of the heart may contribute to perpetuation of ventricular dysrhythmia and the genesis of ventricular fibrillation early after the onset of myocardial ischemia.     

Strain rate acceleration yields a better index for evaluating left ventricular contractile function as compared with tissue velocity acceleration during isovolumic contraction time: an in vivo study

OBJECTIVE: Our study aimed to investigate whether strain rate acceleration (SRA) during isovolumic contraction time (IVCT) could serve as a sensitive indicator of myocardial function. METHODS: A total of 8 sheep underwent occlusion of left anterior descending coronary artery or diagonal branches and 2 sheep underwent left circumflex coronary artery occlusion to create septal, apical, or basal segment myocardial ischemia 19 to 27 weeks before the study. Baseline, volume-loading, dobutamine, and metoprolol infusion were used to produce 4 hemodynamic stages for each sheep. Doppler tissue imaging was acquired using a 5-MHz probe (GE/VingMed Vivid Five, GE Medical Systems, Milwaukee, Wis) on open-chest animals using the liver as a standoff at the apex. Using software (EchoPac, GE Medical Systems), SRA during IVCT was calculated and compared with tissue velocity acceleration (TVA) during IVCT from areas located in the normal and ischemic zones. Also, invasively monitored left ventricle dP/dt was measured as reference contractile function. RESULTS: Both TVA and SRA during IVCT showed higher values for normal tissue than for ischemic area (P <.0001). SRA for normal wall segments changed significantly during the 4 stages (P =.01) with corresponding changes on high-fidelity left ventricular pressure catheters (r = 0.92). TVA over normal segments showed no significant change (P =.29) in the 4 hemodynamic stages. Both TVA and SRA of the ischemic segments showed no significant change with pharmacologic maneuvers or loading conditions. CONCLUSIONS: SRA and TVA during IVCT are both useful indicators for detecting abnormal heart wall motion. However, SRA tends to be more sensitive than TVA for differentiating the response to stress conditions.     

亚低温治疗实验性脑梗死时对心脏的影响

目的　研究全身亚低温治疗实验性脑梗死时对心脏的影响。方法　 5 8只Wistar大鼠分成对照组 (n =10 )、常温组 (n =2 4)和亚低温组 (n =2 4) ,采用线栓法制作大脑中动脉 (MCA)梗死模型。监测ECG ,测定术后 12h心肌高能磷酸化合物 (ATP、ADP、AMP)、能量储备 (EC)值和心肌超微结构改变。结果　缺血后 12h时常温组和亚低温组大鼠心肌ATP、ADP、EC均低于对照组 (P <0 .0 1) ,但亚低温组的ATP和EC却高于常温组 (P <0 .0 1) ;常温组和亚低温组异常ECG发生率无明显差异 (P >0 .0 5 ) ;但亚低温组的心率明显低于常温组 (P <0 .0 1) ,有 3只大鼠的心率低于 15 0次 /min ;超微结构显示常温组和亚低温组心肌均有缺血性损伤 ,但亚低温组的损伤较常温组轻。结论　全身亚低温治疗实验性脑梗死时能改善心肌的能量储备 ,减轻脑梗死引起的心肌缺血 ,不会增加ECG异常的发生率 ,但可显著减缓心率     

Clinical potential of ultrasound tissue characterization in cardiomyopathies

Standard methods of echocardiographic analysis permit accurate categorization of cardiomyopathies into dilated, hypertrophic, and restrictive types. However, ascertainment of the cause of a particular cardiomyopathy (e.g., ischemia versus inflammation as the cause of a dilated myopathy) with ultrasound would be greatly facilitated by analysis of myocardial composition with ultrasound tissue characterization techniques. Qualitative observations have identified unusual echocardiographic image texture in hypertrophic cardiomyopathy and in amyloidosis. Quantitative observations have verified these findings and have identified increased ultrasound backscatter in regions of myocardial fibrosis, calcification, and anthracycline-induced cardiomyopathy. Although several technical problems remain unsolved and further research is needed in the mechanisms of normal and abnormal ultrasound/tissue interactions, tissue characterization with ultrasound has the potential to contribute independent information on myocardial composition in patients with cardiomyopathy.     

Echocardiographic alteration in patients with hemodynamic stroke

Echocardiography was made in 330 patients with ischemic stroke. Group 1 consisted of 72(21.8%) patients with hemodynamic stroke, the rest 258(78.2%) patients (group 2) had other pathogenetic subtypes of stroke. Chronic cardiac pathology was represented by postinfarction cardiosclerosis (38.9 and 17.8% for groups 1 and 2, respectively, p < 0.001) and continuous atrial fibrillation (15.3 and 15.1%, respectively, p > 0.05). Stroke volume of the left ventricle (LV), cardiac output and ejection fraction of the LV were significantly less than in group 2 and in control group but within normal range. The number of group 1 patients having local LV dyskinesia and transitory painless myocardial ischemia was significantly higher than in group 2 (p < 0.001). Painless ischemia correlated with local dyskinesia of the LV (p < 0.02). As transitory myocardial ischemia may deteriorate LV contractility and provoke excessive fall of blood pressure, local LV dyskinesia caused by postinfarction changes seems to be a principal and stable echocardiographic sign of developing hemodynamic stroke.     

心肌造影超声心动图评估心肌缺血程度的实验研究

本实验制作不同程度心肌缺血的动物模型，以声处理５％人血白蛋白为超声造影剂进行心肌灌注造影，探讨ＭＣＥ时间－强度曲线各指标与心肌缺血程度间的关系。结果表明：心肌显影的峰值强度和曲线下面积均与缺血程度呈显著负相关（相关系数分别为ｒ＝－０．９８，Ｐ值＜０．００５；ｒ＝－０．９４，Ｐ值＜０．０５），且能区分轻度、中度和重度三种程度的心肌缺血；而三项时间指标与心肌缺血程度间未发现显著性差异。本实验的初步结果表明，ＭＣＥ是一项活体评估局部心肌血流灌注的有效方法。