What have we learned about coronary artery disease from high-frequency epicardial echocardiography?

We have used a high frequency epicardial echocardiographic technique to visualize and measure coronary artery lumens and walls in patients undergoing cardiac surgery. A 12 MHz probe (Surgiscan, Biosound Corp.) is sterilized and placed on the exposed epicardial coronary arteries. Transverse cross-sectional views are obtained from the arteries on the anterior surface of the heart: the right coronary artery to the cardiac margin and the left anterior descending coronary artery to the cardiac apex. Numerous echocardiographic-angiographic-pathological correlations have been obtained from this work. We have validated the echocardiographic lumen and wall measurements by comparing the echo measurements to histological material from pressure-distended coronary arterial segments (from animals and fresh human autopsy specimens). We have shown by comparison with angiography that coronary arteries which appear normal or only minimally diseased by angiograms are often diffusely and severely atherosclerotic. We have also evaluated the shape of atherosclerotic lesions and demonstrated a wide range of lumen shapes (oval, circular, complex) and location within the residual coronary lumen (eccentric vs. concentric). Highly eccentric lesions are characterized by relative preservation of portions of the arterial wall, and this may preserve vasoreactivity of the atherosclerotic vessel. We have also demonstrated remodeling of atherosclerotic lesions: enlargement of the total arterial area (wall plus lumen) as a compensatory mechanism to preserve the arterial lumen in the face of encroaching atherosclerosis. High frequency epicardial echocardiography offers an accurate, real-time, in-vivo method for the anatomic and functional evaluation of coronary atherosclerosis. This dynamic, in-vivo technique supports and extends information previously obtainable only from pathologic studies. It contributes to our understanding of the pathologic anatomy of coronary artery disease.     

糖尿病与非糖尿病冠心病患者左冠状动脉主干粥样硬化性病变的对比研究

目的 利用血管内超声检测糖尿病患者与非糖尿病患者左冠状动脉主干部（左主干）,阐述两者冠状动脉粥样硬化病变的特点.方法 冠心病患者129例,其中合并糖尿病史40例,无糖尿病史89例.所有患者在进行左冠状动脉系统的介入检查和治疗时,给予左主干的血管内超声检查,并在每间隔1 mm的超声断面上测量血管外腔面积、内腔面积、斑块面积以及钙化角度,然后将所有检测断面的相应数值相加,从而得到整个左主干的外腔容积、内腔容积、斑块体积和总的钙化负荷,最后比较各检测数据在合并糖尿病组和无糖尿病组的差别.结果 不论在最小内腔面积的血管断面还是在整个左主干,血管内外腔和斑块大小在两组之间的差别无统计学意义,但糖尿病组的钙化阳性率明显高于非糖尿病组（67.5% 对 44.9%,P=0.022）;定量测量最小内腔面积的血管断面上总钙化角度,糖尿病组显著高于非糖尿病组（P=0.027）;整个左主干总的钙负荷,糖尿病组显著高于非糖尿病组.结论 糖尿病患者与非糖尿病患者相比,即使左主干的内外径和斑块的大小不存在差异,管壁的钙化情况和斑块的构成却显著不同,前者钙化出现的阳性率和钙化程度均明显高于后者.     

Assessment of the mechanical properties of coronary arteries using intravascular ultrasound: an in vivo study

The pressure-area relation of coronary arteries provides important information about the mechanical properties of these vessels. In human subjects methodological limitations have precluded measurement of instantaneous compliance and coronary stress in vivo. The purpose of this study was to assess a new method for measuring instantaneous values of coronary artery compliance and wall stress utilizing simultaneously acquired pressure and intravascular ultrasound measurements of vessel area. Ten subjects with coronary artery disease had intravascular ultrasound studies of the proximal left anterior descending or circumflex coronary arteries. Coronary luminal area was measured with a 30-MHz (3F or 3.5F) intravascular ultrasound catheter and simultaneous coronary pressure measured with a 2F micromanometer-tipped catheter. Using this technique the nonlinear pressure-area relation and mean circumferential wall stress were determined over the physiological pressure range. Coronary artery compliance at 100?mmHg ranged from 0.010 to 0.052 mm²/mmHg (mean ± SD, 0.020 ± 0.012 mm²/mmHg). Peak systolic circumferential stress ranged from 0.52 to 2.03 × 10⁶ dyn/cm² (1.09 ± 0.42×10⁶ dyn/cm²). This study describes a new method of determining coronary artery mechanical properties over the physiological pressure range. This technique may be useful in further studies of coronary artery mechanics.     

Intravascular ultrasound imaging following balloon angioplasty

Despite its long history and reliability, contrast angiography has several inherent limitations. Because it is a two-dimensional projection image of the lumen contour, the wall thickness cannot be measured and the plaque itself is not visualized. This results in an underestimation of the amount of atherosclerotic disease by angiography. An assessment of atherosclerosis could be improved by an imaging modality: (1) that has an inherent larger magnification than angiography and (2) that directly visualizes the plaque. Intravascular ultrasound fulfils these criteria. This presentation will provide evidence that intravascular ultrasound may prove complimentary or even superior to angiography as an imaging modality. Intravascular ultrasound demonstrates excellent representations of lumen and plaque morphology ofin vitro specimens compared with histology. There is very close intraobserver and interobserver variability of measurements made from intravascular ultrasound images. Phantom studies of stenoses in a tube model demonstrate that angiography can misrepresent the severity of stenosis when the lumen contour is irregular and not a typical ellipse, whereas intravascular ultrasound reproduces the cross-sectional morphology more accurately since it images the artery from within.In vitro studies of the atherosclerotic plaque tissue characteristics compare closely with the echo representation of fibrosis, calcification, and lipid material. In addition,in vitro studies of balloon angioplasty demonstrate that intravascular ultrasound accurately represents the changes in the structure of artery segments following balloon dilatation.     

冠状动脉粥样硬化的高分辨磁共振管壁成像

目的探讨高分辨MR管壁成像显示冠心病冠状动脉管壁异常的可行性。方法收集18例经冠状动脉血管造影或CT血管成像证实有冠状动脉狭窄的冠心病患者,在1.5 T MR设备中进行冠状动脉管壁黑血成像。采集狭窄段及其邻近非狭窄段的横断面管壁图像,由两位MR医师协商评估,将显示不满意的图像剔除。在显示满意的狭窄段和非狭窄段管壁图像上分别其测量管壁厚度、管腔直径及横截面积并进行对比。结果 18例患者中有15例患者顺利完成检查,经冠状动脉造影或CT血管成像证实共有26个冠状动脉狭窄段,MR管壁成像共获得显示满意的图像34幅(狭窄段和非狭窄段各17幅),与非狭窄段相比,狭窄段管壁明显增厚(P0.01),管腔直径及横截面积明显减小(P0.05),差异均具有统计学意义。在MR管壁图像上,冠状动脉狭窄段的管壁呈局限性增厚者11例(64.7%),呈弥漫性增厚者6例(35.3%)。增厚的管壁呈高信号者4例(23.5%),等信号者5例(29.4%),低信号者1例(5.9%),高低混杂信号者7例(41.2%)。结论高分辨MR冠状动脉管壁成像可显示粥样硬化的冠状动脉狭窄段管壁及管腔异常,为冠心病的诊断提供了有力的影像证据,是一种很有潜力的检查方法。     

Aortoiliac Angiography During Coronary Artery Angiography Detects Significant Occult Aortoiliac and Renal Artery Atherosclerosis in Patients with Coronary Atherosclerosis

PURPOSE: Peripheral atherosclerosis (renal and aortoiliac localizations) are frequently detected in aged patients with concomitant coronary artery disease (CAD): the risk of finding peripheral disease is increased in patients with CAD. Angiography of the aortoiliac vessels performed at the time of coronary angiography may detect any occult renal artery stenosis and atherosclerotic involvement of the aortoiliac segment. We sought to determine utility of performing angiography of aortoiliac and renal arteries during coronary arteriography in patients with known or suspect coronary atherosclerosis. METHODS: Medical records of all patients undergoing combined coronary and aortoiliac angiography between May 1998 and December 2002 was retrospectively reviewed. Moderate to severe arterial stenosis (>50% stenosis), vessel occlusion, aneurismal vessels were noted as significant angiographic findings. Contrast-induced nephropathy was defined as a rise in serum creatinine of > or =25% form baseline. RESULTS: In the study period 112 patients (81 males, mean age 68.4+/-7.8 years) with known or suspected CAD underwent combined cardiac catheterization and aortoiliac angiography. Pretreatment with 0.45% saline at a rate of 1 ml/kg/h for 12 h was administered to all patients. Significant findings were reported in 37 (33%) patients including 14 renal artery stenoses, 8 aortic aneurismal disease, and 15 aortoiliac lesions. Most patients with significant findings had 2 and 3-vessel CAD. A strong correlation was found between the number of risk factors and the frequency of angiographic findings (r = 0.92). Complications include six contrast-induced nephropathy: no case required renal replacement therapy. CONCLUSIONS: Aortoiliac and renal atherosclerosis is frequently associated to multivessel CAD. In selected patients undergoing cardiac catheterization aortoiliac angiography may be practical in detecting occult renal or aortoiliac artery lesions. Further clinical outcome studies are strongly required to support this strategy.     

Detection and characterization of vascular lesions by intravascular ultrasound: an in vitro study correlated with histology.

High-frequency intravascular ultrasound (30 and 40 MHz) was applied to study 112 human vascular specimens. The ultrasound images were compared with histologic cross-sections. In 44 out of 58 of the histologically classified muscular arteries, a hypoechoic middle layer was seen in the vessel wall, giving it a three-layered appearance. In 10 arteries, fibrous degeneration of the muscular media resulted in a homogeneous appearance of the vessel walls, whereas atherosclerotic plaque precluded the visualization of the arterial media in four of the arteries. A three-layered appearance was seen in seven of nine histologically classified transitional arteries, and a homogeneous arterial wall was seen in two of the nine. None of the 33 elastic arteries, veins, venous bypass, and Goretex conduits showed a hypoechoic medial layer. Histologically proved fibrous intimal thickening was echographically detected in 32 of 48 specimens (67%). It was noted that these intimal lesions were easier to detect with 40 MHz than with 30 MHz transducers. Hypoechoic areas of lipid deposition were detected in 32 of 36 specimens (89%) and could be distinguished from fibrous plaques. Histologically evident calcium deposits were detected with intravascular ultrasound in 35 of 36 specimens (97%). Measurement of plaque area was only possible in cross sections with a three-layered appearance. Quantitative analysis showed a significantly larger lumen area measured from ultrasonic images (26.3 +/- 21.3 mm2) than from histologic cross-sections (21.8 +/- 16.6 mm2, p less than 0.001), probably because of tissue shrinkage during processing for histology. A significant correlation (r = 0.96, p less than 0.001) between ultrasonic and histologic measurements of lumen areas was observed, with and a negligible interobserver and intraobserver variability. Plaque area and medial thickness correlated well with histology (r = 0.87, p less than 0.001 and r = 0.93, p less than 0.001, respectively). It appears from this in vitro study that intravascular ultrasound is an accurate technique for detection and characterization of atherosclerotic lesions. Vessel lumen area can be measured in most instances, whereas plaque area and medial thickness can only be reliably assessed in muscular arteries in which the hypoechoic media serves as a reference, and shadowing by calcium or attenuation by fibrous plaque components is absent.     

血管内超声检测在体粥样硬化冠状动脉的代偿性扩张及其与斑块性质的关系

取血管内超声检测的粥样硬化冠状动脉血管段图像共25帧，测量血管总面积、管腔面积、管腔最大、最小径。将图像分为软、硬斑块两组。计算斑块面积及管腔狭窄程度。结果：血管总面积随斑块面积扩大而增加。软斑块组血管总面积与斑块面积呈明显正相关（r＝0．83，p＝0．003，b＝1．44），硬斑块组亦有相关关系（r＝0．64，p＝0．01，b＝0．65）。结论：粥样硬化冠状动脉存在代偿性扩张；具软斑块者呈过度代偿性扩大，硬斑块者代偿不全。     

Non-invasive measurement of coronary plaque from coronary CT angiography and its clinical implications

Coronary CT angiography (CTA) is increasingly used worldwide for direct, non-invasive evaluation of the coronary arteries. Advances in computed tomography (CT) technology over the last decade have enabled such reliable imaging of the coronary arteries. Beyond arterial stenosis, coronary CTA also permits assessment of atherosclerotic plaque (including plaque burden) and coronary artery remodeling, previously only achievable through invasive means. It has been shown that coronary plaque volumes for non-calcified and mixed plaques and the arterial remodeling index, correlate closely with invasive intravascular ultrasound. Several studies have also shown a strong relationship of adverse plaque features imaged by coronary CTA with acute coronary syndrome, all-cause death, major adverse cardiovascular events and myocardial ischemia. The aim of this review is to summarize current methods for quantitative measurement of atherosclerotic plaque features from coronary CTA and to discuss their clinical implications.     

颈动脉与冠状动脉粥样硬化的病理对比分析

目的探讨颈动脉粥样硬化与冠状动脉粥样硬化病变之间的关系。方法应用图象分析对17例尸检患者的272段颈动脉和冠状动脉血管进行测量,比较内容包括动脉壁厚比值腔面积/截面积比值和狭窄血管支数比值。结果颈动脉和冠状动脉粥样硬化病变血管支数的比值呈正相关(r=0.79,P<0.01),其余比值无相关性。结论颈动脉粥样硬化病变的存在可以预示冠状动脉有病变,但二者病变的严重程度无明确的相关性。     

Noncalcified Plaque in Cardiac CT: Quantification and Clinical Implications

Coronary computed tomography angiography (CTA) is being increasingly used for direct, noninvasive evaluation of the coronary arteries. Beyond stenosis, coronary CTA also permits assessment of atherosclerotic plaque (including total and noncalcified plaque burden) and coronary artery remodeling, previously only measurable through invasive techniques. It has been shown that coronary plaque volume for noncalcified and mixed plaques and the arterial remodeling index correlate closely with corresponding measures from invasive intravascular ultrasound. Several studies have also shown a strong relationship between adverse plaque features imaged by coronary CTA and acute coronary syndrome, major adverse cardiovascular events, and ischemia. The aim of this review is to summarize current methods for quantitative measurement of atherosclerotic plaque features from coronary CTA and to discuss the clinical implications of noncalcified plaque as detected by CTA and reported in the current literature.     

Intravascular probe for detection of vulnerable plaque.

PURPOSE: Coronary angiography defines geometry of lumen of artery. However, perhaps 70% of heart attacks occur when minimally obstructive thin capped fibroatheroma rupture, causing thrombus and arterial occlusion. We have developed an intravascular imaging detector to identify vulnerable coronary artery plaque. PROCEDURE: Detector measures beta or conversion electron emissions from plaque-binding radiotracers. Detector assembly fits into a 2-mm diameter catheter and overcomes technical constraints of size, sensitivity, and conformance to intravascular environment. RESULTS: Device was tested by stepping test point sources past detector to verify function. System resolution is 6.7 mm and sensitivity is 400 cps/microCi one mm from detector. CONCLUSION: This prototype is a first step in imaging of labeled vulnerable plaque in coronary arteries. This type of system may assist in development of targeted and cost effective therapies to lower incidence of acute coronary artery diseases (CAD) such as unstable angina, acute myocardial infarction, and sudden cardiac death.     

室壁分区运动分析及全方位M型超声心动图无创评价室壁运动状态与冠脉造影检查的相关性

目的应用自动室壁分区运动分析（ASAM）及全方位M-型超声心动图（FAM）技术评价室壁运动状态，并与冠脉造影作对照，探讨其应用价值。 方法用ASMA—FAM技术和冠脉造影在同一条件下用盲法分别检查36例临床冠心病，对比分析二者的相关性。 结果ASMA—FAM检测36例冠心病均存在程度不同的节段性室壁运动障碍（RWMA），冠脉造影发现与超声检测对应供血部位的血管狭小或阻塞，二者相关性较好（r=0．538，P〈0．01）。 结论ASMA及FAM技术评价室壁运动状态直观准确，为诊断冠心病提供了一种新的手段。     

In vitro examination of the coronary artery wall after balloon angioplasty using intracoronary ultrasound

After autopsy 12 human coronary arteries were investigated by intracoronary ultrasound in order to measure the vessel wall dimensions and to detect damage on the vessel wall architecture after balloon angioplasty. Histology revealed artherosclerosis in 11/12 arteries. A total of 41 representative coronary segments were selected for further off-line ultrasound and histological analysis. Intracoronary ultrasound and histological measurements of the vessel wall thickness after balloon dilatation demonstrated a good correlation between the maximum thickness of the intima (histology 0.62 mm vs. intracoronary ultrasound 0.65 mm, r = 0.87) and the intima-media complex (0.80 mm vs. 0.83 mm, r = 0.87), in contrast to a weak one between the minimum thickness (r = 0.46 and r = 0.37). A total of 21 cases of damage occurred during angioplasty; intracoronary ultrasound detected 17. Further analysis showed that it imaged 10 of 11 cases of damage involving more than 30° of the vessel circumference and 7 of 10 cases of damage involving less than 30° of the vessel circumference. After balloon angioplasty of diseased coronary arteries, intracoronary ultrasound is therefore reliable in measuring the maximum wall thickness and in imaging damage involving more than 30° of the vessel wall circumference.     

Angiographically undetected plaque in the left main coronary artery

The absence of angiographic findings despite significant coronary artery disease has been previously described. Possible explanations for the limitation of plaque detection by angiography include compensatory vessel enlargement in face of intracoronary plaque formation, the lack of reference segments in diffuse atherosclerosis as well as technical limitations. Intracoronary ultrasound (ICUS) imaging provides the possibility of direct plaque visualization. We studied angiographically normal left main coronary arteries (LMCA) in 72 patients prior to diagnostic angiography or therapeutic interventions using ICUS (30 MHz). ICUS images were continuously recorded and recalled from memory for morphometric analysis. Lumen area, plaque area and the total vessel area were determined by computer software. ICUS imaging revealed atherosclerotic plaque in 55 of the 72 patients with angiographically normal LMCA (76%). The average plaque area stenosis was 22±12% (range 3–44%). Total vessel area showed a significant direct correlation with plaque area, indicating compensation of coronary plaque formation. The average percent change in plaque area (difference between maximal and minimal plaque area within the LMCA) was 11±19%, indicating a diffuse pattern. Measurement of change in lumen area (difference between maximal and minimal lumen area within the LMCA) revealed an average value of 6±7%. Lumen area of the LMCA was 15.9±3.2 mm² in patients with and 17.2±1.9 mm² without atherosclerotic plaque (n.s.). Thus, the lack of angiographic changes despite advanced plaque formation in the LMCA could be explained by compensatory vessel enlargement and by diffuse distribution of plaque in the vessel; true lumen narrowings overlooked by angiography seem not to account for the failure of angiography to detect plaque.     

二维彩色多普勒超声筛选冠状动脉搭桥术桥血管的价值

目的：探讨冠状动脉搭桥术前胸廓内动脉和桡动脉用作桥血管的可能性。方法：应用二维彩色多普勒超声对50例冠状动脉搭桥术前患者的98例胸廓内动脉和81条桡动脉血管内径、管壁、管腔及血流状况进行检测。结果：不适合作为桥血管的胸廓内动脉为2．04％,桡动脉为8．64％。结论：二维彩色多普超声是筛选胸廓内动脉及桡动脉及桡动脉作为冠六动脉搭桥术桥血管的首选和可靠的方法。     

应变成像检测冠心病局部心肌径向舒张异常的价值

目的:探讨应变成像(SI)检测冠心病局部心肌径向舒张异常的临床应用价值。方法:应用SI技术获取53例冠心病患者(冠心病组)和42例正常对照者(正常对照组)左心室不同水平前间隔与后壁径向应变曲线,测量快速充盈期、心房收缩期各节段应变的变化幅度△εE、△εA和△εE/△εA比值。对比分析冠心病组狭窄冠状动脉供血节段(狭窄节段)和正常对照组相应正常节段(正常节段)的各项参数。结果:冠心病患者狭窄节段快速充盈期的径向应变下降幅度明显变小、消失,甚至倒置。冠心病组前间隔与后壁狭窄节段的△εE及△εE/△εA均较对照组相应节段明显减低,而两者的△εA差异无统计学意义。结论:SI技术可无创、定量检测冠心病局部心肌径向舒张功能异常。     

冠状动脉痉挛的血管造影和血管内超声特征

目的探讨冠状动脉痉挛影像学表现的病理学基础。方法选择临床上具有静息性胸痛或胸闷但冠状动脉造影无显著狭窄的患者进行乙酰胆碱试验，对成功诱发了冠状动脉痉挛的患者进行血管内超声检查，研究其血管造影及血管内超声的特征。结果共有42例患者成功地诱发了冠状动脉痉挛，根据影像学特点可以分为节段性及弥漫性冠状动脉痉挛两种类型，冠状动脉造影除两者均为轻、中度狭窄外，前者表现为节段性血管边缘不光滑且常合并肌桥，后者则表现为弥漫性血管僵硬、突然变细及血管边缘粗糙，常见血管迂曲及血流速度缓慢。血管内超声下前者内膜增生较重而范围相对较局限，多形成偏心性纤维斑块，而弥漫性痉挛者多为病变血管以远的全程血管呈均匀的向心性纤维性增生。结论冠状动脉痉挛多发生于轻、中度血管狭窄的基础之上，病变常为稳定的纤维性增生。     

Does remodeling occur in the diseased human saphenous vein bypass grafts? An intravascular ultrasound study

Background: Coronary artery remodeling is a common phenomenon in human atherosclerotic arteries. Controversies exist concerning the presence of absence of the remodeling process in diseased human coronary saphenous vein bypass grafts. The purpose of the study was to observe the vessel and lumen dimensions in patients who had undergone saphenous vein grafting with intravascular ultrasound to find out whether the remodeling process exists in the diseased human saphenous vein bypass grafts. Methods: A total of 43 saphenous vein bypass grafts from 43 patients (39 males, 4 females, mean age 63 ± 8 years); 1–16 years (mean 9.3 ± 4.0 years) after grafting, who had not undergone previous catheter intervention, were studied using intravascular ultrasound. The vessel, lumen and plaque area were measured at the lesion segment as well as in the proximal and distal reference segments. The percent stenosis was calculated. Results: In 43 bypass grafts having severe stenosis before intervention, plaque was eccentric in 69.4% and concentric in 30.6%. No calcification was detected in 75% cases and 25% cases has mild-moderate intimal calcification. The vessel area in the lesion segment was 19.0 ± 9.7 mm², significantly larger than the proximal reference segment 12.8 ± 4.0 mm² as well as the distal reference segment 12.9 ± 3.6 mm² (p < 0.001). It was also larger than that of the average area of the proximal and distal reference segments (p < 0.001). The vessel area increased in accordance with plaque area (p < 0.001). A weak relationship existed between vessel area and percent stenosis (r = 0.37, p = 0.04). Conclusion: In contrary to previous findings, diseased human saphenous vein bypass grafts undergo focal compensatory enlargement (remodeling) in the presence of plaque formation. The underlying mechanism is probably similar to that in de novo atherosclerosis.     

血管内超声与冠状动脉造影的对比研究

目的：对89处冠状动脉血管段分别进行状动脉造影（CAG）及血管内超声（IVUS）检测,比较和探讨两种技术在冠状动脉介入诊断和治疗中的作用和价值。方法：用IVUS检测71例患者89处冠状动脉血管段总截面的最大径、最小径及血管腔的最大径、最小径,算出平均径及直径狭窄率,测量相部位CAG所显示的管腔直径、直径狭窄率。对这两种技术检测血管的斑块性质,狭窄形态及狭窄程度的测值进行比较,结果：CAG检测发现偏心性狭窄59处,向心性狭窄30处;IVUS检测发现偏心性斑块64处,向心性斑块25处,CAG无法显示管腔形态,斑性狭窄59处,向心狭窄30处,IVUS检测发现偏心性斑块64处,向心性斑块25处,CAG无法显示管腔形态、斑块性质,而IVUS可清晰显示,对手术的效果判断,CAG显示手术效果理想的血管,IVUS则显示大多数内膜撕裂严重而需进一步处理,对于病变血管的直径及直径狭窄率、CAG与IVUS两种技术测值之间的差异有显著性,CAG测重而需进一步处理,对于病变血管的直径及直径狭窄率,CAG与IVUS两种测值之间的差异有显著性,CAG测值较IVUS测值为低,结论：对于冠脉介入入手术适应症的选择、手术过程指导、手术效果评价,IVUS明显优于CAG。