Intra-Observer Variability of Longitudinal Displacement and Intramural Shear Strain Measurements of the Arterial Wall Using Ultrasound Noninvasively in vivo

Using a recently developed high-resolution noninvasive ultrasonic method, we recently demonstrated that the intima-media complex of the common carotid artery show a bidirectional multiphasic longitudinal displacement of the same magnitude as the diameter change during the cardiac cycle. The longitudinal movement of the adventitial region was smaller, thus, we identified shear strain and, thus, shear stress, within the arterial wall. The aim of this study was to evaluate the intra-observer variability of measurement of the longitudinal displacement of the intima-media complex and the intramural shear strain of the common carotid artery in vivo using the new ultrasonic method. The evaluation was carried out by comparing two consecutive measurements on the common carotid artery of 20 healthy human subjects. According to the method of Bland Altman, we show that the systematic and random differences for the different phases of movement are acceptable in comparison to the measured displacement and no significant differences between the two measurements could be detected (p > 0.05 for all measured parameters). The coefficient of variation (CV) for measurement of the different phases of movement was ≤16%, including short-term physiologic variations. The higher variability in the measurement of the intramural shear strain (CV = 24%) has several explanations, which are discussed. In conclusion, this study shows that the present first ultrasonic method for high-resolution measurement of the longitudinal movement of the arterial wall is reliable and satisfactory for the further research of the longitudinal movement of the arterial wall in vivo. Further studies on the longitudinal movement of the arterial wall are important for developing an improved understanding of the physiology and the pathophysiology of the cardiovascular system. (E-mail: magnus.cinthio@elmat.lth.se)     

二维应变成像对冠心病患者的初步研究

目的 探讨冠心病患者心肌应变特点.方法 43例冠心病患者及35例正常人,分别获取左室短轴观二尖瓣环水平、乳头肌水平、心尖水平及心尖四腔观、二腔观,左室长轴观的高帧频图像,应用二维应变软件测量各个节段的二维应变值.结果 狭窄＜75%冠状动脉(冠脉)供血节段共96个,狭窄≥75%冠脉供血节段共147个.①狭窄≥75%冠脉供血节段与正常对照组比较,基底段、中间段及心尖段纵向收缩期峰值应变均明显减低,差异有统计学意义(P＜0.05);左室短轴(二尖瓣环、乳头肌及心尖水平)的绝大部分径向收缩期峰值应变及圆周收缩期峰值应变与正常对照组相比,差异无统计学意义(P＞0.05);②以纵向收缩期峰值应变≥-16.1%为截点值,预测冠脉狭窄≥75%的敏感性及特异性分别为78.7%和76.4%.③狭窄＜75%冠脉供血节段与正常对照组比较,纵向收缩期峰值应变、径向收缩期峰值应变及圆周收缩期峰值应变差异无统计学意义(P＞0.05).结论 当冠脉出现严重狭窄时,虽然二维超声心动图上无明显室壁运动异常,但反映心内膜下心肌功能的纵向应变已明显降低.     

速度向量成像技术早期无创性评价动脉硬化的临床研究

目的探讨冠心病组和正常对照组颈动脉运动速度、应变及应变率的变化。方法对86例冠心病患者颈动脉无斑块部位和50例健康体检者进行双侧颈动脉高频超声检查,测量颈动脉内膜．中层厚度（IMT）,应用速度向量成像（VVI）技术跟踪颈动脉的运动速度、应变、应变率,测量各项指标及肱动脉内皮依赖性舒张功能。结果冠心病组颈动脉内膜一中层厚度、弹性系数和僵硬度均高于正常对照组（P〈0．05）,冠心病组内皮依赖性舒张反应肱动脉内径变化数值低于正常对照组（P〈0．05）;冠心病组颈动脉无斑块部位长轴的收缩期径向最大运动速度、最大应变率分别低于正常对照组（P〈0．05）;冠心病组颈动脉无斑块部位短轴的径向运动速度、旋转率、周向应变及应变率均低于正常对照组（P〈0．05）。冠心病组颈动脉径向运动速度与弹性系数呈负相关（r=-0．464,P=0．002）。讨论VVI技术可检测血管壁的弹性变化,颈动脉运动的机械不一致性和不同部位的力学指标差别,有可能作为动脉硬化早期检测和定量评价指标。     

彩色多普勒超声检测长期吸烟者的肱动脉内皮功能

目的多普勒超声检测长期吸烟者的肱动脉内皮细胞功能。方法采用超声显像法对29例长期吸烟者和22例正常对照组作肱动脉测定基础状态下血管内径、反应性充血时的内径及舌下含服硝酸甘油后的血管内径。结果长期吸烟者反应性充血诱发的肱动脉内径变化百分率明显低于对照组P<0.01。服药后诱发血管扩张内径变化百分率也低于对照组P<0.01。结论长期吸烟者血管内皮功能受损,硝酸甘油诱发的扩血管反应也有所下降。     

Non-invasive Vascular Radial/Circumferential Strain Imaging and Wall Shear Rate Estimation Using Video Images of Diagnostic Ultrasound

The aim of this work was to develop a convenient method for radial/circumferential strain imaging and shear rate estimation that could be used as a supplement to the current routine screening for carotid atherosclerosis using video images of diagnostic ultrasound. A reflection model-based correction for gray-scale non-uniform distribution was applied to B-mode video images before strain estimation to improve the accuracy of radial/circumferential strain imaging when applied to vessel transverse cross sections. The incremental and cumulative radial/circumferential strain images can then be calculated based on the displacement field between consecutive B-mode images. Finally, the transverse Doppler spectra acquired at different depths along the vessel diameter were used to construct the spatially matched instantaneous wall shear values in a cardiac cycle. Vessel phantom simulation results revealed that the signal-to-noise ratio and contrast-to-noise ratio of the radial and circumferential strain images were increased by 2.8 and 5.9 dB and by 2.3 and 4.4 dB, respectively, after non-uniform correction. Preliminary results for 17 patients indicated that the accuracy of radial/circumferential strain images was improved in the lateral direction after non-uniform correction. The peak-to-peak value of incremental strain and the maximum cumulative strain for calcified plaques are evidently lower than those for other plaque types, and the echolucent plaques had higher values, on average, than the mixed plaques. Moreover, low oscillating wall shear rate values, found near the plaque and stenosis regions, are closely related to plaque formation. In conclusion, the method described can provide additional valuable results as a supplement to the current routine ultrasound examination for carotid atherosclerosis and, therefore, has significant potential as a feasible screening method for atherosclerosis diagnosis in the future.     

空吞咽与食团吞咽对健康人咽期吞咽功能的影响

摘要 目的：探讨通过使用高分辨率咽腔测压,分析空吞咽与不同黏度食团吞咽对健康人咽部和上食管括约肌功能的影响。 方法：使用高分辨率测压系统,分别测量34例健康志愿者[平均（24.29±5.926）岁]在空吞咽与进食三种不同黏度（5ml水,5ml浓流质,5ml糊状物）的食团情况下,咽部收缩压力峰值,咽部收缩持续时间,咽部压力上升速率,上食管括约肌（UES）松弛残余压,UES松弛持续时间,UES开放前峰值以及UES开放后峰值。使用重复测量的方差分析研究空吞咽与食团吞咽对这些参数的影响。 结果：食团吞咽与空吞咽时,咽部收缩压力峰值差异无显著性意义。而空吞咽时,UES松弛残余压、开放前压力峰值、咽部收缩持续时间和咽部压力上升速率明显高于食团吞咽,而UES松弛持续时间与UES开放后峰值明显低于食团吞咽。而不同黏度的食团吞咽之间的参数差异无显著性意义。 结论：不同的吞咽类型会影响健康人咽部与UES的压力和持续时间。明确空吞咽与不同黏度食团吞咽健康人的咽期吞咽生理学变化,为进一步探究吞咽障碍的生理与病理提供了研究基础。     

Effect of an acute increase in afterload on left ventricular regional wall motion velocity in healthy subjects.

We recorded left ventricular (LV) wall motion velocities before and after angiotensin II infusion by pulsed tissue Doppler imaging in 20 healthy subjects, and evaluated the responses of systolic and diastolic LV function along the long and short axes during an acute increase in afterload. Angiotensin II was administered intravenously to obtain a 30% increase in mean blood pressure. After angiotensin II infusion, LV end-systolic dimension and end-systolic circumferential wall stress increased significantly, and the percentage of LV fractional shortening decreased significantly. Peak first systolic LV wall motion velocity (Sw1 ) along the long axis decreased markedly compared with that along the short axis, and peak second systolic LV wall motion velocity (Sw2 ) along the short axis decreased significantly compared with that along the long axis. Early diastolic LV wall motion velocities along both the long and short axes decreased significantly, whereas atrial systolic LV wall motion velocity did not change. In conclusion, an acute increase in afterload caused a significant decrease in longitudinal fiber shortening during the isovolumic contraction phase (Sw1 along the long axis), circumferential fiber shortening during the ejection phase (Sw2 along the short axis), and LV relaxation during early diastole (early diastolic LV wall motion velocities along both axes) in healthy subjects. Pulsed tissue Doppler imaging may be useful for detecting the effect of various loading conditions on LV wall motion velocities along the long and short axes.     

Vascular wall lesion and disorder of endothelial vasoregulating function in patients with ankylosing spondylitis

Diseases accompanied by endothelial lesion are associated with elevation of mortality. Nowadays, data on endothelial dysfunction in ankylosis spondylitis (AS) are practically absent, while the disease creates "favorable" conditions for endothelial lesion and the development of endothelial dysfunction. The purpose of this work was to evaluate the degree of lesion of the endothelium and vascular wall vasoregulating function in patients with AS. The subjects of the study were 36 AS patients (mean age 36.4 +/- 1.38 years). Exclusion criteria were clinical manifestations of coronary artery disease, arterial hypertension, and other comorbidities during exacerbation period. Signs of vascular wall lesion in a form of an increase in the number of circulating endothelial cells were detected in AS patients. The study revealed disorder of the vasoregulating function of the endothelium in AS patients. Reactive hyperemia test revealed disorder in brachial artery sensitivity to tension in the patients vs. healthy controls. The study demonstrated associations between these disturbances and such factors as system inflammation (fibrinogen), smoking intensity, external respiration disorder, parameters of left ventricular remodeling, and right ventricular diastolic dysfunction.     

Pulsed tissue Doppler imaging of left ventricular systolic and diastolic wall motion velocities to evaluate differences between long and short axes in healthy subjects.

Our objective was to evaluate in healthy subjects the left ventricular (LV) wall motion velocities along the long and short axes by means of pulsed tissue Doppler imaging (TDI) to clarify the differences in the LV systolic and diastolic function between both axes. Wall motion velocities were recorded at the mid-wall portion of the middle site of the LV posterior wall in the parasternal long-axis view, and at the subendocardial portion of the middle site of the LV posterior wall in the apical long-axis view by pulsed TDI in 35 healthy subjects (mean age 26 +/- 10 years, mean heart rate 72 +/- 7 bpm). In all subjects, the LV pressure curve, its first derivative (dP/dt), the LV wall motion velocity, the phonocardiogram, and the electrocardiogram were simultaneously recorded. The systolic wave of the LV posterior wall motion velocity exhibited 2 peaks: the first and second systolic waves (Swl and Sw2, respectively). The diastolic wave also exhibited 2 peaks, the early diastolic and atrial systolic waves. The Swl along the long axis was greater than either the Sw1 and Sw2 along the short axis or the Sw2 along the long axis. The peak Sw1 along the long axis coincided with the peak dP/dt and was slightly earlier than the peak Swl along the short axis. The onset of Sw1 along the long axis coincided with the onset of the first heart sound. The Sw2 along the short axis was greater than that along the long axis. The early diastolic wave along the short axis was greater than that along the long axis, whereas the atrial systolic wave along the long axis was greater than that along the short axis. Thus, in healthy subjects, shortening of the longitudinal fibers predominated over that of the circumferential fibers during early systole, whereas shortening of the circumferential fibers predominated over the longitudinal fibers during the ejection phase. During diastole, the circumferential fibers predominated in the LV wall expansion at early diastole, whereas the longitudinal fibers predominated at atrial systole. In conclusion, pulsed TDI provided information that is useful in understanding the characteristics of LV wall motion along the long and short axes.     

肾动脉狭窄患者相关危险因素分析

目的探讨动脉粥样硬化性肾动脉狭窄(ARAS)患者的相关危险因素及与肾功能的关系。方法选取ARAS患者64例,分析其临床资料,并选取36例肾动脉正常者为对照。结果肾动脉狭窄组与对照组相比,冠心病、冠状动脉多支病变、外周血管疾病、肾功能不全的发病率增高(P<0.05),年龄、脉压、肌酐、尿素氮水平明显升高(P<0.01)。结论高龄、冠心病、冠状动脉多支病变、宽脉压、外周血管疾病及肾功能不全为ARAS患者的危险因素;严重的肾动脉狭窄可导致肾功能不全。     

The effects of posture and isoproterenol on the velocity of left ventricular contraction in man: The reciprocal relationship between left ventricular volume and myocardial wall force during ejection on mean rate of circumferential shortening

A study was performed in five normal men in whom left ventricular volume was measured by thermodilution in the supine and 60 degrees head-up postures, in the control state, and then during steady-state response to isoproterenol. The mean rate of circumferential shortening of the left ventricle was calculated for each of the postures in both inotropic states and was found to remain constant in the control state at 12.5 +/-0.6 cm/sec in the supine posture and 13.3 +/-0.5 cm/sec in the tilted posture. Similarly, mean rate of circumferential shortening remained constant in response to the positive inotropic effect of isoproterenol at 20.9 +/-0.5 cm/sec in the supine position and 20.7 +/-0.5 cm/sec in the tilted posture. It is concluded that the constancy of mean rate of circumferential shortening over the relatively broad physiologic range of left ventricular end-diastolic volume and mean force of ejection during a given state of myocardial contractility represents the coupled reciprocal influences of ventricular wall tension and myocardial fiber length on the velocity of ventricular wall shortening. Unlike stroke work, stroke power, and mean rate of left ventricular ejection, which are volume-dependent parameters of myocardial performance, the mean rate of circumferential shortening appears to be a reasonable index of left ventricular contractility, which in steady-state conditions is independent of left ventricular end-diastolic volume and mean ventricular wall force of ejection. In this study, changes in mean rate of circumferential shortening associated with changes of heart rate were small and variable.     

速度向量成像技术评价冠状动脉粥样硬化性心脏病患者颈总动脉管壁形变特征

目的应用速度向量成像(VVI)技术评价冠状动脉粥样硬化性心脏病患者颈总动脉管壁形变特征。方法选择冠状动脉粥样硬化性心脏病患者(冠状动脉粥样硬化性心脏病组)和健康体检者(健康对照组)各30例。采集并存储颈总动脉长轴及短轴二维动态灰阶图像。应用VVI技术分析2组受检者颈总动脉管壁纵向收缩期峰值应变(LS)、纵向收缩期峰值应变率(LSR)及周向收缩期峰值应变(CS)、周向收缩期峰值应变率(CSR)。将颈总动脉长轴后壁3个感兴趣点LSR的平均值定为平均纵向收缩期峰值应变率(mLSR);将颈总动脉短轴管壁6个节段CSR的平均值定为平均周向收缩期峰值应变率(mCSR)。分析冠状动脉粥样硬化性心脏病组患者的mLSR、mCSR与颈总动脉内中膜厚度(IMT)的相关性。结果健康对照组受检者颈总动脉短轴管壁各节段(分别为:前壁、前外侧壁、后外侧壁、后壁、前内侧壁、后内侧壁,下同)CS分别为(8.77±1.58)%、(8.76±1.46)%、(8.80±1.40)%、(8.43±1.41)%、(8.56±1.39)%、(8.54±1.38)%;冠状动脉粥样硬化性心脏病组患者颈总动脉短轴相应管壁节段CS分别为(4.68±1.02)%、(5.23±1.13)%、(4.79±0.99)%、(5.14±1.01)%、(5.08±1.00)%、(4.99±1.03)%,2组受检者颈总动脉短轴管壁相应节段CS比较,差异均有统计学意义(t=10.68、5.23、7.54、6.53、6.38、8.54,P均<0.01)。健康对照组受检者颈总动脉短轴管壁各节段CSR分别为(0.55±0.11)s-1、(0.54±0.11)s-1、(0.53±0.10)s-1、(0.46±0.08)s-1、(0.49±0.09)s-1、(0.51±0.13)s-1;冠状动脉粥样硬化性心脏病组患者颈总动脉短相应管壁节段CSR分别为(0.33±0.14)s-1、(0.32±0.11)s-1、(0.31±0.10)s-1、(0.29±0.09)s-1、(0.29±0.07)s-1、(0.30±0.08)s-1,2组受检者颈总动脉短轴管壁相应节段CSR比较,差异亦均有统计学意义(t=8.03、8.26、8.31、9.23、10.11、7.58,P均<0.01)。健康对照组受检者颈总动脉后壁3个感兴趣点(近心点、中点、远心点,下同)LSR分别为(0.48±0.11)s-1、(0.51±0.09)s-1、(0.53±0.13)s-1,冠状动脉粥样硬化性心脏病组患者颈总动脉后壁相应各点LSR分别为(0.24±0.07)s-1、(0.21±0.09)s-1、(0.23±0.10)s-1,2组受检者颈总动脉后壁相应各点LSR比较,差异均有统计学意义(t=11.12、13.69、15.33,P均<0.01);健康对照组受检者颈总动脉后壁各感兴趣点LS分别为(4.82±1.19)%、(4.68±1.54)%、(4.76±1.33)%,冠状动脉粥样硬化性心脏病组患者颈总动脉后壁相应各感兴趣点LS分别为(4.36±1.79)%、(4.23±1.43)%、(4.48±1.55)%,2组受检者颈总动脉后壁相应各感兴趣点LS比较,差异均无统计学意义(t=1.43、2.25、3.11,P均>0.01)。冠状动脉粥样硬化性心脏病组患者mCSR及mLSR与颈总动脉IMT均呈显著负相关,相关系数分别为-0.864和-0.853(P<0.0001)。结论 VVI技术可以评价冠状动脉粥样硬化性心脏病患者颈总动脉管壁形变特征。冠状动脉粥样硬化性心脏病患者颈总动脉管壁形变能力减弱,其减弱的程度与颈总动脉IMT相关。     

Plaque development, vessel curvature, and wall shear stress in coronary arteries assessed by X-ray angiography and intravascular ultrasound

The relationships among vascular geometry, hemodynamics, and plaque development in the coronary arteries are complex and not yet well understood. This paper reports a methodology for the quantitative analysis of in vivo coronary morphology and hemodynamics, with particular emphasis placed on the critical issues of image segmentation and the automated classification of disease severity. We were motivated by the observation that plaque more often developed at the inner curvature of a vessel, presumably due to the relatively lower wall shear stress at these locations. The presented studies are based on our validated methodology for the three-dimensional fusion of intravascular ultrasound (IVUS) and X-ray angiography, introducing a novel approach for IVUS segmentation that incorporates a robust, knowledge-based cost function and a fully optimal, three-dimensional segmentation algorithm. Our first study shows that circumferential plaque distribution depends on local vessel curvature in the majority of vessels. The second study analyzes the correlation between plaque distribution and wall shear stress in a set of 48 in vivo vessel segments. The results were conclusive for both studies, with a stronger correlation of circumferential plaque thickness with local curvature than with wall shear stress. The inverse relationship between local wall shear stress and plaque thickness was significantly more pronounced (p<0.025) in vessel cross sections exhibiting compensatory enlargement (positive remodeling) without luminal narrowing than when the full spectrum of disease severity was considered. The inverse relationship was no longer observed in vessels where less than 35% of vessel cross sections remained without luminal narrowing. The findings of this study confirm, in vivo, the hypothesis that relatively lower wall shear stress is associated with early plaque development.     

左室径向应变和圆周应变对冠状动脉粥样硬化性心脏病患者心肌缺血的诊断价值

目的 应用斑点追踪技术评价室壁运动正常的心肌缺血患者左室径向应变及圆周应变,探讨其检测心肌缺血的临床价值.方法 30例经冠状动脉造影证实的冠状动脉粥样硬化性心脏病（CHD）患者,28例健康者为对照组,应用二维应变软件分析左室短轴二尖瓣水平、乳头肌水平及心尖水平图像,获取左室短轴各节段心肌径向应变和圆周应变均值.结果 CHD组径向应变和圆周应变均较对照组减低（P〈0.001）;ROC曲线表明径向应变诊断心肌缺血的敏感性为89.3%,特异性为80.0%;圆周应变诊断心肌缺血的敏感性为75.0%,特异性为63.3%;径向应变诊断心肌缺血的敏感性和特异性均较圆周应变增高.结论 二维短轴应变能较敏感地发现心肌缺血,径向应变较圆周应变能更准确地评价心肌缺血.     

Steady flow in models of abdominal aortic aneurysms. Part II: Wall stresses and their implication for in vivo thrombosis and rupture.

In a continuing investigation into the mechanical factors that lead to rupture of abdominal aortic aneurysms, wall pressure and shear stress measurements are presented for steady flow through the series aneurysm models described in Part I. These models simulate in vivo aortic aneurysms of diameters from 3.3 to 7.5 cm; the flow rates through the models were dynamically matched to aortic flows under conditions ranging from rest to exercise. For all models, at all flow rates, a pressure maximum was found at the midpoint of the model bulge. This maximum increased with bulge diameter, suggesting that the largest aneurysms in vivo are exposed to the greatest pressures. When the flow was turbulent, the mean wall shear stress at the proximal end of the model bulge had magnitude 2 to 4 dynes/cm2, approximately equal to its value in an undilated tube. However, at the distal end of the model bulge the mean shear stress increased to 5 to 10 dynes/cm2, whereas the peak instantaneous shear stress exceeded the mean by an order of magnitude. When extrapolated to in vivo parameters, the maximum distal wall shear stress reached levels near those capable of disrupting endothelium. This suggests that turbulence in in vivo aneurysms may precipitate thrombus formation. Subsequent decreased luminal diameters in the presence of thrombus would then lessen the likelihood of turbulent flow and reduce the strength of any turbulence that did occur. It would also reduce the pressure in the aneurysmal bulge. Thus, the presence of turbulent flow may significantly affect risk of rupture.     

Left ventricular midwall mechanics in healthy children and adolescents.

The assessment of left ventricular function in pediatric age generally has been made by measuring the extent and velocity of fiber shortening at the endocardium and relating these parameters to systolic wall stress. It has been suggested from animal and human studies that this "endocardial method" can result in an overestimation of myocardial function when healthy hearts and those with hypertrophy are compared. Thus an assessment of left ventricular pump function and contractility that takes into account the epicardial migration of the midwall circumferential fibers during systole (midwall analysis) is warranted. Although the normal range for midwall indexes of left ventricular mechanics has been established in adult subjects, up to now it has not been studied in pediatric subjects. To establish normal values for left ventricular midwall mechanics, 70 healthy children ranging in age from 3 days to 18 years were evaluated with 2-dimensional and M-mode echocardiography. Midwall fractional shortening (FSmw), rate-corrected mean velocity of circumferential fiber shortening (VCFcmw), and the relation between these indexes and left ventricular end-systolic wall stress (ESS) were calculated separately for the children younger than 2 (group 1, 20 subjects) and older than 2 (group 2, 50 subjects) years of age. Group 1 had significantly higher FSmw and VCFcmw compared with group 2. An inverse linear relation between FSmw and ESS and between VCFcmw and ESS was found in both age groups. The y-intercept was higher in group 1, and the slope of the mean regression line was steeper than in group 2 for both the relationships, suggesting an age-dependent midwall left ventricular pump function and contractility. These normative data can be used to assess the left ventricular midwall mechanics in pediatric patients with pressure or volume overload.     

速度向量成像评价冠心病患者颈动脉粥样斑块力学特性的临床研究

目的 探讨颈动脉正常和斑块部佗、硬斑块和软斑块及斑块的肩部和纤维帽顶部速度、应变及应变率变化规律.方法对86例冠心病伴颈动脉粥样斑块患者和50例正常人双侧颈动脉进行高频超声检查,检测颈动脉内膜-中层厚度(IMT);应用速度向量成像(VVI)斑点追踪技术检测颈动脉的运动速度、应变、应变率,并分组进行分析.结果冠心病组颈动脉IMT高于正常组,差异有统计学意义(P＜0.05);正常对照组颈动脉收缩期径向最大运动速度高于冠心病颈动脉无斑块部位的测值,差异有统计学意义(P＜0.05);软斑块收缩期最大运动速度、最大应变率高于硬斑块组,差异有统计学意义(P＜0.001或P＜0.05);颈动脉斑块肩部收缩期最大运动速度、应变率高于斑块纤维帽顶部.差异有统计学意义(P＜0.05或P＜0.001).结论 VVI技术可早期检测血管壁的弹性度,早期检测颈动脉荆样硬化及颈动脉粥样硬化斑块部位内膜运动的机械不一致性和不同部位的力学指标差别,有可能作为动脉粥样硬化不稳定斑块的初查和量化评价指标.     

The effect of peripheral vascular disease on structure and function of resistance arteries isolated from human skeletal muscle

Peripheral vascular disease (PVD) is associated with numerous pathophysiological adaptations of the microvasculature. Considering this, active and passive pressure‐dependent and pressure‐independent mechanisms of vascular control were studied in small resistance arteries isolated from patients with PVD. Using pressure myography and confocal microscopy, human skeletal muscle arteriolar structure and function were compared between paired arteries; one isolated from the healthy non‐diseased proximal skeletal muscle vascular bed (PSM, internal control) and the other from the diseased ischaemic part of the leg [distal skeletal muscle (DSM)]. Structurally, arteries isolated from the diseased part of the leg displayed significant atrophy compared with the non‐diseased arteries. Functionally, no differences were observed in the fundamental ability small resistance arteries to contract or relax. However, active pressure‐dependent myogenic contraction was significantly reduced in DSM arteries compared with PSM arteries. DSM versus PSM; 3 ± 1% versus 22 ± 4% and 3·4% ± 1·1% versus 25 ± 4% at 80 and 120 mmHg, respectively. Furthermore, structural remodelling in DSM arteries could also be correlated with significant changes in vascular wall mechanics. DSM arteries displayed significantly greater incremental dispensability, wall stress and wall strain compared with PSM arteries as a product of pressure‐dependent distension. These alterations in pressure‐dependent active myogenic tone and passive mechanical properties goes some way to explain uncontrolled orthostatic‐dependent changes in leg fluid volume and oedema formation experienced by these patients.     

多普勒血管超声检测高血压病患者内皮细胞功能的研究

目的 多普勒超声检测高血压病（CH）患者的肱动脉内皮细胞的功能,方法 采用超声显像法对44例 EH患者和22例正常组肱动脉测定,静息状态下血管内径,血流速度,反应性充血时的内径及血流速度,和舌下含服0．3mg硝酸甘油后5min测血管内径和血流速度。结果 EH组反应性充血诱发的肱动脉内径变化百分率明显低于对照组（P＜0．001）,反应性充血时的肱动脉血流速度EH组也明显低于正常对照组（P＜0．05）,服药后诱发血管扩张内径百分变化率EH组也低于对照组（P＜0．05）,结论 EH组血管内皮功能受损,硝酸甘油诱发的扩血管反应也有所下降。     

Effects of chronic atenolol therapy on cardiovascular response to isometric exercise in essential hypertension

Cardiovascular response to 2 min of isometric handgrip exercise at 50% of maximum voluntary contraction was studied echocardiographically in 10 essential hypertensives, before and during treatment with atenolol for a mean of 2 months. The patients responded with increases in heart rate, systolic and diastolic blood pressures, cardiac output and calculated triple product, no changes in stroke volume and total peripheral resistance, and decreases in ejection fraction, mean velocity of circumferential shortening and mean diastolic posterior wall velocity of the left ventricle before treatment. Chronic atenolol therapy attenuated the increases in heart rate, blood pressure and triple product, and the decreases in ejection fraction, mean velocity of circumferential shortening and mean diastolic posterior wall velocity of the left ventricle but resulted in a marked increase in total peripheral resistance. The pressure response and triple product rise in response to isometric handgrip exercise were also decreased. This suggests an obvious advantage to hypertensive patients who may, therefore, be protected from the risk of cardiovascular complications following isometric exercise.