室间隔夹层瘤的超声诊断(附4例报告)

目的 总结室间隔夹层瘤的超声心动图诊断及临床应用价值。方法1985～2005年超声诊断罕见的室间隔夹层瘤4例。超声主要取左室长轴、四腔心、五腔心、大动脉短轴及非标准切面，观察主动脉窦的形态及结构：如扩张窦瘤的大小、窦壁厚度、窦瘤破口的部位、窦瘤破口与室间隔之间的关系，主动脉窦瘤与室间隔夹层瘤之间交通口的大小，测量形成室间隔夹层瘤的大小及夹层瘤左、右室面的厚度，结合彩色多普勒观察心动周期夹层瘤与主动脉窦瘤血流动态变化，频谱多普勒测量窦瘤与室间隔夹层瘤之间的血流速度。结果4例室间隔夹层瘤均为主动脉右窦破人室间隔基底段，且均行手术治疗证实超声诊断。结论超声心动图对室间隔夹层瘤可直接做出诊断，超声诊断价值在于早发现、早诊断、及早治疗，并可为外科选择手术方式提供重要的有价值的依据。     

Removing the effect of SVD algorithmic artifacts present in quantitative MR perfusion studies.

Quantitative cerebral blood flow (CBF) values can be obtained from dynamic susceptibility contrast (DSC) MR perfusion studies using the standard singular value decomposition (sSVD) deconvolution algorithm. Reports in the literature from simulation and in vivo studies suggest that CBF estimates obtained using sSVD deconvolution depend on the arterial-tissue delay (ATD). By contrast, Fourier transform (FT) deconvolution produces CBF estimates that are independent of ATD. The diagnostic reliability of quantitative CBF measurements to define areas of normal tissue flow and tissue at risk is brought into doubt by such gross sensitivity to the specifics of the deconvolution approach. This variation of CBF values with ATD is shown to be an artifact associated with the current implementation of the sSVD deconvolution algorithm. A reformulated version of the SVD deconvolution algorithm (rSVD) is presented and compared to the standard SVD algorithm through simulation and patient case studies.     

Pulmonary blood volume and interventricular circulation time in physically trained and untrained subjects

Summary Resting pulmonary plasma and blood volumes (PPV and PBV), interventricular circulation time (IVCT), cardiac and stroke index (CI and SI), heart rate (HR), total plasma and blood volumes (PV and BV) were determined in athletes (two male groups representing different types of sport activities, and one female group) and compared with those of non-athletes (one male and one female group).In addition to high maximal aerobic power, the athletes were characterized by greater SI, BV and PV and lower resting HR than non-athletes. PPV and PBV were significantly larger and IVCT significantly longer in the trained than in the untrained groups, probably reflecting an improved capacity of the pulmonary circulation. PPV as per cent of PV was almost equal in all the groups, indicating the same distribution of plasma between the pulmonary and systemic circulation. The data also indicate that total blood volume is an important determinant of the magnitude of the pulmonary vascular bed. The increased volume of flowing blood and increased stroke volume in athletes probably allows for a reduction in flow velocity and thereby a reduction in kinetic energy.     

Stabilization of positive coupled differential‐difference equations with unbounded time‐varying delays

This paper researches the static output‐feedback stabilization of single‐input single‐output (SISO) positive coupled differential‐difference equations (CDDEs) with unbounded time‐varying delays. First, a necessary and sufficient condition is provided for the positivity and asymptotical stability of CDDEs with unbounded time‐varying delays. For this type of system, based on the constructed estimates of its solution, a necessary and sufficient condition on asymptotical stability is provided. Then, based on this criterion, for CDDEs with unbounded time‐varying delays, a kind of static output‐feedback controller is designed to ensure the positivity and asymptotical stability of the corresponding closed‐loop systems. It is also worth pointing out that the controller is designed by the linear programming method without parameterization technique. This design approach can also be applied to the static state feedback stabilization problem of CDDEs with unbounded time‐varying delays. Finally, two illustrative examples are given to show the effectiveness of our results.     

健康人动脉结构及功能改变与室间隔厚度的相关性研究

目的 研究健康人中动脉结构和功能改变与心室间隔厚度的关系.方法 以颈动脉内膜中层厚度( IMT)和肱动脉血流介导的血管舒张反应(FMD)二指标反应动脉结构和功能改变.采用超声多普勒测定68例健康人(男16人,女52人)的IMT、FMD和室间隔厚度( IVST).结果 健康人中IVST与IMT呈正相关(r=0.394,P=-0.001),与FMD呈负相关(r=0.337,P＜ 0.01),IVST也与年龄和收缩压呈正相关.以IVST为因变量的多因素回归分析显示,IMT和FMD是其独立影响因素.结论 健康人中IMT、FMD和IVST相关,动脉结构和功能改变影响心室间隔厚度.