脐血管的彩色多普勒血流显像和脉冲多普勒研究

本文报告了98例胎儿脐血管彩色多普勒血流显像(CDFI)和脐动脉血流的脉冲多普勒(PW)收缩期最大速度与舒张期速度比值(VS/VD)结果,用回归方法进行了统计学处理和分析。正常69例,脐动脉血流VS/VD随孕周增大而逐渐减少(y= 4.286-0.052x),说明胎盘血流阻力随孕周增大而降低,血流量增加适应胎儿生长发育需要。脐带绕颈14例,其VS/VD随孕周增大较正常下降不显著(P<0.05)(y=3.704-0.028x),表示脐动脉血流阻力升高影响胎儿血供。 8例IUGR, VS/VD较正常组升高(P<0.001)且随孕周增大不明显(y=4.112-0.034x),提示胎盘血流阻力升高,血流量减低…     

产前超声对孕11-13周+6胎儿肢体畸形的诊断价值分析

目的:观察孕11-13+6周产前超声检查在诊断胎儿肢体畸形的意义。方法:以2015年1月1日-2017年12月31日入院行孕检的2013例孕妇为本次观察对象,所有孕妇给予行规范化超声检查,测胎儿NT厚度,观察胎儿肢体结构、形态等情况,对早期检查异常者并给予引产者行X线检查,对于继续妊娠者追踪妊娠结局,观察中期超声检查结果。结果:孕早期检出7例,误诊1例、漏诊3例,孕中期检出2例,孕11-13+6周检出率为66.6%,9例异常胎儿其中2例NT出现异常,所占比例为22.2%。结论:胎儿肢体畸形在孕11-13+6周行超声检查检出率较高。     

用指数模型探讨胎儿肾脏的生长速度

近年来,国内外一些学者通过超声测量,在对胎儿肾脏生长状况进行的研究中,多将超声测值直接进行线性回归分析,从而得出胎儿肾脏以恒定的速度随孕周增长的结论。本文探讨了用更符合胎儿生长状况的指数模型处理胎儿肾脏超声测值的方法,并由此获得了更全面的反映孕期胎肾生长状况的生长速度。本文的结果表明:胎儿肾脏各径线的生长速度是随着孕龄的增大逐渐减小。 本文将27、33、39周三个孕龄计56例正常胎肾测值在取得每个孕周的均值及标准差后,与其它作者的结果进行比较。经均数间的t检验,每个孕龄的胎肾各径线,在左肾之间及不同作者之间均无显…     

E15 超声多普勒测量脐动脉血流速度法预测胎儿健康的探讨

本文用双功超声多普勒检测胎儿肾动脉多普勒频谱,以了解产前宫内胎儿循环状态,提出了胎儿监护的新途径,有助于早期诊断胎儿宫内生长迟缓和羊水异常。 研究对象为31例单胎孕妇,年龄26～39岁,超声检查胎儿各径线值和羊水在正常范围,分为31～35孕周和36～40孕周二组。 使用东芝SSH-65A超声仪,频率2.5MHz,以二维图像显示胎儿肾脏的冠状切面,于肾门处获清晰肾动脉频谱后测量收缩期峰值速度和舒张期流速,并计算阻力指数。 结果表明,31～40孕周胎儿肾动脉检出率达90%,31～35孕周组收缩期峰值为36.5mm/s,舒张期流速为8.6mm/s,36～40孕周组分别为4…     

E17 胎儿先天畸形的超声诊断

妊高征是产科常见并发症,它是引起胎儿宫内发育迟缓及围产儿死亡的主要因素。很早就认识到子宫胎盘血流灌注障碍与妊高征关系密切,推测在孕早期滋养层对螺旋动脉侵蚀过程受限,子宫动脉外周血管阻力增加,表现为舒张末期血流速度降低。超声多普勒作为一种无创性检查方法,可较准确地估测子宫胎盘血流状况。我们对150例孕中期孕妇运用超声多普勒测量其子宫动脉血流速度波形,研究不同的胎盘位置对双侧子宫动脉血流速波的影响,同时前瞻性观察上述孕妇的妊高征发病情况,探讨孕中期双侧子宫动脉血流速波测量联合脐动脉测量对妊高症进行预测的可能性…     

胎儿肾脏生长的超声学观察

本文对129例孕龄25周至产前正常孕妇进行胎儿肾脏的超声观察和分析,分别测定各孕龄期双肾三径(前后径、横径及长径),从中可以看出三径随孕龄增加而增长:左肾长径从25周平均3.06增至29周时4.40cm,横径2.5增至2.79cm,前后径1.52增至2.31cm;右肾长径3.18增至4.30cm。横径1.84增至2.59cm,前后径1.76增至2.37cm。和国外有关资料比较相近似,本文简单讨论了胎儿肾脏正常值测定的临床应用价值。胎儿肾脏生长的超声学观察@耿兰溪$中国人民解放军第97医院 @徐卫东$中国人民解放军第97医院 @刘牧$中国人民解放军第97医院…     

NT超声检查在早孕期胎儿筛查中的临床价值观察

目的:探究颈项透明层厚(NT)超声检查在早孕期胎儿筛查中的临床价值.方法:研究对象为2018年5月-2020年11月在本院500例孕11-13+6周孕妇,采用超声对胎儿颈项透明层厚进行评估测量,并将其测量结果同随访结果进行对比.结果:500例孕产妇中,仅NT≥2.5 mm者16例,其中14例正常胎儿,1例至中孕期胎死宫...     

胎儿颈项透明层厚度（NT）结合孕中期四维彩超筛查胎儿先天畸形的临床价值

目的:探析胎儿颈项透明层厚度(NT)结合孕中期四维彩超筛查胎儿先天畸形的临床价值。方法:选择2000例为研究对象,在其孕11-14周、22-28周分别行NT超声检测、四维彩超检测。结果:NT超声检测胎儿异常率(5.40%)与确诊率(6.25%)相比,无明显差异(P0.05)。四维彩超胎儿异常检出率(4.96%)和确诊率(5.47%)相比,无统计学差异(P0.05)。NT超声结合四维彩超胎儿异常检出率(10.25%)明显高于单独NT超声检测(5.40%)、四维彩超(4.96%),(P0.05)。结论:在胎儿先天性畸形筛查中NT超声、四维彩超的应用,前者可检出早发性胎儿异常,并能预测胎儿唐氏综合征发生风险,后者可检测出多数胎儿结构异常,两者联用可提高胎儿先天畸形筛查准确性。     

超声胎儿鼻骨测量对染色体异常的诊断分析

目的:总结分析超声胎儿鼻骨测量在染色体异常诊断中的应用价值。方法:以我院2015年1月-2016年12月收治并实施产前检查的20489例11-23+6周孕妇为研究对象,对于胎儿鼻骨测量存在异常的建议进行染色体核型分析,明确胎儿鼻骨超声测量对染色体异常的诊断价值,回顾性分析所有孕妇超声胎儿鼻骨测量的相关资料。结果:20489例孕妇胎儿超声检查中有449例存在胎儿鼻骨异常(449/20489),其中449例均通过了染色体核型分析,结果有46例存在染色体异常,染色体异常检出率为0.22%(46/20489)和10%(46/449);随着孕周的增加,胎儿鼻骨长度呈现出上升趋势,组间差异性对比具有统计学意义(P0.05)。结论:在胎儿染色体异常诊断中,使用超声实施胎儿鼻骨测量,能够依据鼻骨测量后鼻骨缺失或者短小等异常情况进一步对染色体异常作出评价,具有较高的诊断准确率,值得推广应用。     

探讨妊娠对心电图P-R间期的影响

目的:比较妊娠前后各阶段P-R间期的变化。方法:对我科2016年280例25-35岁健康女性常规心电图进行分析,按照未孕、早孕(≤12周)、中晚孕和产后6个月分为四组,每组70人,统计并分析各组P-R间期的变化。结果:早孕组与未孕组差异明显有统计学意义(P0.05);中晚孕组与未孕组和早孕组差异均有统计学意义(P0.05);产后组与未孕组差异无统计学意义。结论:妊娠期P-R间期较同龄健康未孕女性短,且随妊娠月龄的增加逐渐缩短,产后逐渐恢复到孕前水平。     

Effect of ultrafiltration on placental‐fetal blood flow in pregnancy of woman undergoing chronic hemodialysis

Introduction: Patient who was undergoing hemodialysis (HD) thrice weekly usually gain 1 to 4 kg of weight in interdialytic period, mainly due to fluid accumulation by ingestion of water. Ultrafiltration (UF) during HD will be need to remove fluid excess to avoid severe medical complications secondary to fluid overload. However, in pregnant woman UF can increase the episodes of intradialytic hypotension which may lead to placental ischemic injury and predispose to fetal distress. There is little information about safe fluid amount withdrawn by UF during pregnancy. Methods: We prospectively study by obstetric Doppler ultrasonography the fluxometric parameters: pulsatility index (PI) and resistance index (RI) of fetal middle cerebral, uterine, and umbilical artery obtained at the beginning and the end of HD session, the acute and chronic effect of UF on placenta and fetus blood flow, as well as the fetal outcome in 1 pregnant woman on chronic HD. Findings: We did not observe any acute harmful effect on fetal middle cerebral, placental and umbilical artery blood flow when UF rate of 2.1 ± 0.04 L (6 < 8 mL/h/kg) during HD session, no significant statistical difference was observed when compared PI and RI before and after UF and also when we compared these data with reference value on normal pregnancy to the same gestational age. Discussion: UF rate of 6 < 8 mL/h/kg during HD did not bring any acute harmful effect on fetal middle cerebral, placental, and umbilical blood flow and the UF rate of 1.4 6 0.4 L (< 6 mL/h/kg) / HD session that was done in all others HD during pregnancy was safe, without any chronic fetal deleterious effect. Obstetric Doppler ultrasonography is a simple and noninvasive method to fetal follow‐up and can aid to determine safe UF rate in pregnant women during gestation.     

Synergy between shear-induced migration and secondary flows on red blood cells transport in arteries: considerations on oxygen transport

Shear-induced migration of red blood cells (RBCs) is a well-known phenomenon characterizing blood flow in the small vessels (micrometre to millimetre size) of the cardiovascular system. In large vessels, like the abdominal aorta and the carotid artery (millimetre to centimetre size), the extent of this migration and its interaction with secondary flows has not been fully elucidated. RBC migration exerts its influence primarily on platelet concentration, oxygen transport and oxygen availability at the luminal surface, which could influence vessel wall disease processes in and adjacent to the intima. Phillips'' shear-induced particle migration model, coupled to the Quemada viscosity model, was employed to simulate the macroscopic behaviour of RBCs in four patient-specific geometries: a normal abdominal aorta, an abdominal aortic aneurysm (AAA), a normal carotid bifurcation and a stenotic carotid bifurcation. Simulations show a migration of RBCs from the near-wall region with a lowering of wall haematocrit (volume fraction of RBCs) on the posterior side of the normal aorta and on the lateral-external side of the iliac arteries. A marked migration is observed on the outer wall of the carotid sinus, along the common carotid artery and in the carotid stenosis. No significant migration is observed in the AAA. The spatial and temporal patterns of wall haematocrit are correlated with the near-wall shear layer and with the secondary flows induced by the vessel curvature. In particular, secondary flows accentuate the initial lowering in RBC near-wall concentration by convecting RBCs from the inner curvature side to the outer curvature side. The results reinforce data in literature showing a decrease in oxygen partial pressure on the inner curvature wall of the carotid sinus induced by the presence of secondary flows. The lowering of wall haematocrit is postulated to induce a decrease in oxygen availability at the luminal surface through a diminished concentration of oxyhaemoglobin, hence contributing, with the reported lowered oxygen partial pressure, to local hypoxia.     

下肢截肢患者心血管系统集中参数模型的血流动力学数值研究

下肢截肢虽已发现是心血管疾病的可能危险因素,但潜在的生物力学机制仍未得到充分了解。该研究的目的是了解术后不同时期和生活状态下肢截肢患者的心血管血流动力学状况,以评估异常血流动力学对心血管系统的影响。该文建立了含下肢动脉的心血管系统集中参数模型,模拟了截肢术后、术后成熟期和术后长期久坐三种常见的截肢患者状态。该文以7名下肢截肢患者超声实测下肢动脉直径为模型的参数设置参考。通过将正常人模型和下肢截肢模型的血压和血流量波形对比分析,发现截肢术后血管收缩压和舒张压幅值上升,腹主动脉及以下的动脉流量峰值明显下降;术后成熟期和长期久坐血压在舒张期早期峰值上升。这种异常的血流动力学变化可能是下肢截肢患者患高血压与心室肥大等心血管疾病的危险因素。该文建立的集中参数模型提供了截肢后血流动力学的变化规律,可为未来截肢患者康复治疗和心血管疾病预防提供理论指导。     

Mie and Rayleigh modeling of visible-light scattering in neonatal skin

Reduced-scattering coefficients of neonatal skin were deduced in the 450-750-nm range from integrating-sphere measurements of the total reflection and total transmission of 22 skin samples. The reduced-scattering coefficients increased linearly at each wavelength with gestational maturity. The distribution of diameters d and concentration ρ(A) of the skin-sample collagen fibers were measured in histological sections of nine neonatal skin samples of varying gestational ages. An algorithm that calculates Mie scattering by cylinders was used to model the scattering by the collagen fibers in the skin. The fraction of the reduced-scattering coefficient μ(s)' that was attributable to Mie scattering by collagen fibers, as deduced from wavelength-dependent analysis, increased with gestational age and approached that found for adult skin. An assignment of 1.017 for n(rel), the refractive index of the collagen fibers relative to that of the surrounding medium, allowed the values for Mie scattering by collagen fibers, as predicted by the model for each of the nine neonatal skin samples to match the values for Mie scattering by collagen fibers as expected from the measurements of μ(s)'. The Mie-scattering model predicted an increase in scattering with gestational age on the basis of changes in the collagen-fiber diameters, and this increase was proportional to that measured with the integrating-sphere method.     

胎儿心脏外翻畸形产前超声诊断及临床价值

目的:探讨胎儿心脏外翻畸形产前超声诊断及临床价值.方法:回顾性分析我院2015年1月-2020年2月产前超声检查发现3例胎儿心脏外翻畸形声像图及临床资料,并结合文献复习胎儿心脏外翻的超声诊断及预后.结果:2例晚孕期胎儿表现为心脏完全裸露胸腔外,其中1例合并右心发育不良、肺动脉瓣狭窄及胎儿唇裂畸形;1例合并单心室、近似单...     

Both pelvic radiography and lateral abdominal radiography correlate well with coronary artery calcification measured by computed tomography in hemodialysis patients: A cross‐sectional study

Introduction Lateral abdominal radiograph is suggested as an alternative to coronary artery computed tomography (CT) in evaluating vascular calcification. Simple scoring systems including pelvic radiograph scoring and abdominal scoring system were utilized to study their correlation with coronary artery calcification. Methods In 106 MHD patients, coronary artery CT, lateral abdominal, and pelvic radiograph were taken. The Agatston scoring system was applied to evaluate the degree of coronary artery calcification which was categorized according to Agatston coronary artery calcification score (CACS) ≥ 30, ≥100, ≥400, and ≥1000. Abdominal aortic calcification was scored by 4‐scored and 24‐scored systems. Pelvic artery calcification was scored by a 4‐scored system. Sensitivities and specificities of abdominal aortic calcification scores and pelvic artery calcification scores to predict different categories of coronary artery calcification were analyzed. We studied the diagnostic capability of abdominal aorta calcification and pelvic artery calcification to predict different CACS categories by calculating likelihood ratios. Receiver operator characteristic curves were used to determine the area under the curve for each of these testing procedures. Findings The prevalence was 48(45.3%), 15 (14.2%), 11 (10.4%), 11 (10.4%), and 11 (10.4%) for CACs > 0, ≥30, ≥100, ≥400, and ≥1000, respectively. The degree of CACs was positively correlated with patient age, prevalence of diabetes, abdominal aorta scores, and pelvic calcification scores. The areas under the curves for different CACS by all X‐ray scoring systems were above 0.70 except pelvic 4‐scored system for diagnosing CACS ≥30, without significant difference (P > 0.05). Discussion Both lateral abdominal and pelvic plain radiographs were demonstrated as acceptable alternatives to CT in evaluating vascular calcification.     

Morphology and modulus of vapor grown carbon nano fibers

Two types of morphologies have been observed in vapor grown carbon nano fibers (CNFs) using transmission electron microscopy (TEM). In one case, a truncated cone microstructure was observed, with outer and inner diameters of 60 and 25 nm, respectively. In this type of CNF, graphite sheets were oriented at about 15° to the fiber axis. The second type of fiber was a double-layer CNF with outer and inner diameters of 83 and 20 nm, respectively. A truncated cone structure was also observed in the double-layer CNF. Graphite sheets in the outer layer of the double-layer fibers were oriented along the nano fiber axis. Tensile modulus for the first type of nano fiber along its axis was calculated to be 50 GPa, and for the second type of fiber the calculated modulus value was in the 100–775 GPa range, depending on the outer layer orientation. Modulus calculations based on these two morphologies explain the wide ranging experimental CNF modulus values reported in the literature.     

Integration of clinical and imaging data to predict death in hemodialysis patients

In a prior publication, we demonstrated that a model integrating clinical and simple imaging data predicted the presence and severity of coronary artery calcification in prevalent hemodialysis patients. Herein we report the ability of the same model to predict all‐cause death. We assessed all‐cause mortality in 141 consecutive maintenance hemodialysis patients from two dialysis centers followed for a median of 79 months from enrollment. Patients were risk stratified according to a simple cardiovascular calcification index (CCI) that included patient's age, dialysis vintage, calcification of the cardiac valves, and abdominal aorta. The mean patients’ age was 55 ± 14 years. Abdominal aorta calcification was present in 57% of the patients, and 44% and 38% had aortic and mitral valve calcification, respectively. During follow‐up, 75 deaths (93 deaths per 1000 person‐years) were recorded. The CCI was linearly associated with risk of death, such that the unadjusted hazard risk (HR) increased by 12% for each point increase in CCI (P < 0.001). Further adjustments for age, sex, study center, diabetes mellitus, history of cardiovascular disease, hypertension, congestive heart failure, left ventricular hypertrophy, systolic, and diastolic blood pressure did not substantially change the strength of this association (HR 1.10; 95%CI: 1.00–1.21; P = 0.03). The CCI is a simple clinical model that can be used to risk stratify maintenance hemodialysis patients.     

Analysis of the accuracy on computing nominal stress in a biaxial test for arteries

Biaxial tests are commonly used to investigate the mechanical behaviour of anisotropic soft biological tissues such as cardiovascular tissues. However, there is still no clear understanding of the influence that the biaxial test set-up conditions may have on the computing material stress of the experimental results. The aim of the present study is to further investigate the accuracy of calculated material stress from measured force during biaxial tests using finite element methods (FEM). The biaxial mechanical response of ascending aorta and pulmonary artery tissue samples was obtained by FEM simulation under two different gripping methods: (a) a system with noodle clamps and (b) a clamped system with needles which leave the specimen's edges free to expand laterally. The results show that the clamped method whose joints allow free movement in the lateral direction produces stresses closer to the universally accepted formulation of biaxial material stress in the central region. However, the system with noodle clamps, commonly used to grip the sample, produces an alteration of the measurement stresses. Our simulations show results giving an inaccurate estimation of the stress at the centre of the sample. In some cases, the stresses are overestimated and in others underestimated depending on the anisotropy of the sample. We can conclude that the clamped system with needles which leave the specimen's edges free to expand laterally should be used as an efficient methodology to other commonly used gripping methods for biological tissues with anisotropic materials.