血管移植中不同段脐带静脉的生物力学特性研究

背景：临床施行血管重建术，内径小于6mm的人工合成血管替代人体小动脉或静脉一直未获得满意的效果，因而目前小动脉及静脉代用品的研制成为亟待解决的问题。目的：为脐带静脉作为小口径移植材料的临床应用提供理论依据。设计：非随机分组对照研究。地点和对象：实验在郧阳医学院解剖学教研室完成，对象为湖北省十堰市太和医院妇产科收集胎龄在37～40周自然分娩正常胎儿脐带静脉20例，产妇年龄在20～30岁。干预：取胎儿脐带静脉20例，依胎盘端为近端，胎儿端为远端分为近、中、远3段。在生物软组织力学试验机上测定近、中、远段脐带静脉的压力-直径关系，计算出弹性模量。横断取材，冷冻切片，苏木精-伊红法染色，用计算机图像分析系统测量其几何形态学指标。主要观察指标：脐带静脉的血管各相同性增量弹性模量(Einc)、血管压力-应变弹性模量(Ep)、血管容积弹性模量(Ev)、直径和壁厚。结果：近、中、远段脐带静脉的Einc和Ev均随压力的上升而增大，近段3种弹性模量(Einc：26．98&;#177;3．21，Ep：16．58．4&;#177;2．12，Ev8．31&;#177;2．35)均低于远段(Einc：33．20&;#177;4．21，Ep：119．452．87，Ev：9．71&;#177;1．32)(F=95．74∽126．52,P&;lt;0．05)。由近段到远段呈增大趋势。中膜厚度[(0．30&;#177;0．05)mm，(0．24&;#177;0．03)mm]及直径[(3．07&;#177;0．12)mm，(2．30&;#177;0．13)mm]值从近段到远段逐渐减小(F=12．76，P&;lt;0．01)。结论：脐带静脉作为小口径动脉移植的替代材料是可行的，在血管移植时。应注意选择不同段脐带静脉，使作为移植材料的脐带静脉与宿主血管材料间的生物力学特性尽量相近，以提高移植血管的远期通畅率。     

增龄变化对血管移植材料脐带静脉顺应性的影响

背景血管重建术中内径小于6 mm的人工合成血管替代人体小动脉或静脉一直未获得满意的效果,因而目前小动脉及静脉代用品成为亟待解决的问题.目的观察不同胎龄脐带静脉压力-容积关系,为血管移植材料脐带静脉的生物力学性质上提供实验数据.设计非随机对照实验.材料实验于2004-06在郧阳医学院医用生物力学实验室完成,湖北省十堰市太和医院妇产科收集胎龄在24～42周自然流产或分娩的正常胎儿脐带静脉50条(经产妇许可),产妇年龄20～30岁.其中胎龄24～27周8例,28～32周7例,33～36周8例,37周4例,38周5例,39周5例,40周5例,41周4例,42周4例.干预取胎儿脐带50条,测量一段脐带长度(2 cm)并标记两端点后,切下脐带置于生理盐水中.仔细地对脐带静脉进行机械剥离后,将试件两端标记点固定在软组织生物力学试验台上,测定其压力-容积关系,计算出顺应性.主要观察指标不同脐带静脉的压力、容积及顺应性.结果50条脐带全部进入结果分析.①37～40周脐带静脉压力-容积曲线比较接近,而28周,42周脐带静脉压力-容积曲线幅度明显下降,经二次回归分析可见38周胎龄压力-容积曲线回归系数绝对值最大.②脐带静脉顺应性随胎龄增加而增大[24～27周(2.22-±0.34)×10-4mL/(kP·cm),28～32周(3.65±0.46)×10-4 mL/(kPa·cm),33～36周(4.22±0.55)×10-4mL/(kPa·cm),37周(7.63±0.48)×10-4 mL/(kPa·cm),38周(8.32±0.76)×10-4mL/(kPa·cm)],但39周以后又降低[39周(7.61±0.46)×10-4 mL/(kPa·cm),40周(7.53±0.72)×10-4 mL/(kPa·cm),41周(4.13±0.35)×10-4 mL/(kPa·cm),42周(2.25±0.62)×10-4 mL/(kPa·cm)].37～40周脐带静脉的顺应性较相近,而42周及28周以下脐带静脉的顺应性与37～40周比较(F=65.84-86.52,P＜0.01).结论人脐带静脉是动脉移植物的良好替代材料,在移植时除了考虑脐带静脉与宿主动脉相匹配外,还应注意其顺应性与胎龄的关系,实验结果提示,胎龄在37～40周的脐带静脉作为临床应用的移植材料较为理想.     

脐带静脉组织结构的定量分析评估其替代小动脉移植材料的可行性

背景长期以来,因缺乏理想的血管移植材料而制约了血管疾病的治疗效果.组织工程技术已解决了大口径人工血管替代品,但小动脉人工血管替代品一直未获得理想的材料.目的观察不同胎龄、不同段脐带静脉的几何形态和显微结构成分,以探讨脐带静脉作为小动脉移植材料的可行性.设计分组对照观察.单位郧阳医学院医用生物力学实验室.对象实验于2001-09/2004-07在郧阳医学院医用生物力学实验室完成.选择十堰市太和医院妇产科收集胎龄在24～42周自然流产或分娩的胎儿脐带50例(经产妇许可),产妇年龄在20～30岁.方法①对脐带静脉进行机械剥离,制备成脐带静脉标本.根据胎龄分为5组24～27周组7例;28～32周组7例;33～36周组8例;37～40周组20例;41～42周组8例.其中取胎龄在37～40周的脐带20例,依胎盘端为近端,胎儿端为远端分为近、中、远3段.常规石蜡包埋、切片.用苏木精-伊红染色法、Weigert法、苯胺蓝法及桔黄G法分别染组织结构、弹性纤维、胶原纤维和平滑肌.②脐带静脉图像定量分析测量管径、壁厚、内膜、中膜和外膜厚度,采用德国产Leica-Q500IW彩色图像处理系统.提取中膜平滑肌细胞核,计算机自动计数测量框内细胞核的数目和面积,然后换算出单位面积内的细胞核的数目和面积,以此作为中膜平滑肌细胞核的数密度和面密度;分别测量血管壁中膜平滑肌、胶原纤维和弹性纤维各成分的绝对面积,计算不同着色面积与测试区域整体面积之比,从而求出平滑肌、胶原纤维和弹性纤维在各血管壁中的相对含量.主要观察指标①不同胎龄脐带静脉的几何形态变化.②不同胎龄脐带静脉的显微结构成分.③不同段脐带静脉的显微结构成分.结果①不同胎龄脐带静脉的几何形态变化随胎龄增加,脐带静脉中膜厚度和外径在各胎龄组间均有显著的增加(24～27周,28～32周,33～36周,37～40周,41～42周中膜厚分别为0.186,0.203,0.237,0.264,0.268 mm,F=133.35,P＜0.01;外径分别为1.861,1.962,2.303,2.464,2.465 mm,F=37.35,P＜0.01).②不同胎龄脐带静脉的显微结构成分从24～40周,随胎龄增加,脐带静脉中膜弹性纤维含量逐渐增多,胶原纤维的含量及胶原纤维/弹性纤维比值逐渐减少.③不同段脐带静脉的显微结构成分弹性纤维的含量近段比远段多(10.16,6.36Aa%,F=5.77～12.3,P＜0.05),由近段到远段胶原纤维/弹性纤维比值逐渐增大(F=7.63～13.4,P＜0.05).结论①脐带静脉具有与普通中等动脉相似的结构,37～40周脐带静脉管壁的胶原纤维、弹性纤维含量适中,既能承载一定的应力,又有较大的扩张能力,还富含平滑肌,具备收缩能力.②在血管移植时,以选用37～40周脐带静脉为佳,且近段顺应性优于远段,可适时选用,以利于脐带静脉移植于动脉后,能很快适应动脉的力学环境,提高移植后的远期通畅率.     

脐血管解剖结构、血流参数与胎儿生长发育的关系

目的　探讨脐带血管的解剖结构和血流参数与胎儿生长发育的关系。方法　应用彩色多普勒超声测量脐带、脐动脉、脐静脉直径 ,计算横截面积。分别于脐带胎盘附着部、漂浮部、脐轮部测量血流参数 ,并进行比较。结果　孕 2 1～ 40周脐带直径 ( 1.2 5± 0 .2 1)～ ( 1.5 0± 0 .18)cm ,面积 ( 1.2 6± 0 .13 )～( 1.83± 0 .47)cm2 ;脐动脉直径 ( 0 .2 8± 0 .0 6)～ ( 0 .40± 0 .0 9)cm ,面积 ( 0 .0 6± 0 .0 3 )～ ( 0 .14± 0 .0 6)cm2 ;脐静脉直径 ( 0 .5 4± 0 .11)～ ( 0 .79± 0 .11)cm ,面积 ( 0 .2 5± 0 .0 2 )～ ( 0 .49± 0 .15 )cm2 。孕 2 5周前胎盘附着部脐动脉血流参数低于漂浮部和脐轮部 (P <0 .0 5 ) ,孕 3 6周后胎盘附着部脐动脉血流参数高于漂浮部和脐轮部 ( P <0 .0 5 ) ,2 6～ 3 5周之间 3组差别无显著性意义 ( P >0 .0 5 )。结论　正常妊娠期脐带、脐动脉、脐静脉直径和面积随孕龄、胎儿双顶径、枕额径、头围持续增长 ,脐动脉血流参数值则持续下降。随意测量脐动脉所获得的血流参数值不能精确反映胎儿宫内情况 ,胎盘附着部脐动脉血流参数值可反映胎儿生长发育状况。     

脐带静脉组织结构的定量分析：评估其替代小动脉移植材料的可行性

碟子背景：长期以来，因缺乏理想的血管移植材料而制约了血管疾病的治疗效果。组织工程技术已解决了大口径人工血管替代品，但小动脉人工血管替代品一直未获得理想的材料。目的：观察不同胎龄、不同段脐带静脉的几何形态和显微结构成分，以探讨脐带静脉作为小动脉移植材料的可行性。设计：分组对照观察。单位：郧阳医学院医用生物力学实验室。对象：实验于2001—09／2004—07在郧阳医学院医用生物力学实验室完成。选择十堰市太和医院妇产科收集胎龄在24～42周自然流产或分娩的胎儿脐带50例（经产妇许可），产妇年龄在20-30岁。方法：①对脐带静脉进行机械剥离，制备成脐带静脉标本。根据胎龄分为5组：24～27周组7例；28～32周组7例；33-36周组8例；37～40周组20例；41～42周组8例。其中取胎龄在37—40周的脐带20例，依胎盘端为近端，胎儿端为远端分为近、中．远3段。常规石蜡包埋、切片。用苏木精-伊红染色法．Weigert法．苯胺蓝法及桔黄G法分别染组织结构、弹性纤维、胶原纤维和平滑肌。②脐带静脉图像定量分析：测量管径，壁厚．内膜．中膜和外膜厚度，采用德国产Leica—Q500IW彩色图像处理系统。提取中膜平滑肌细胞核，计算机自动计数测量框内细胞核的数目和面积，然后换算出单位面积内的细胞核的数目和面积，以此作为中膜平滑肌细胞核的数密度和面密度；分别测量血管壁中膜平滑肌．胶原纤维和弹性纤维各成分的绝对面积，计算不同着色面积与测试区域整体面积之比，从而求出平滑肌．胶原纤维和弹性纤维在各血管壁中的相对含量。主要观察指标：①不同胎龄脐带静脉的几何形态变化。②不同胎龄脐带静脉的显微结构成分。③不同段脐带静脉的显微结构成分。结果：①不同胎龄脐带静脉的几何形态变化：随胎龄增加，脐带静脉中膜厚度和外径在各胎龄组间均有显著的增加（24～27周，28～32周，33～36周，37～40周，41～42周中膜厚分别为0.186，0．203，0．237，0，264，0．268mm，F=133.35，P〈0.01；外径分别为1．861，1．962，2．303，2．464，2．465mm，F=37．35，P〈0．01）。②不同胎龄脐带静脉的显微结构成分：从24-40周，随胎龄增加，脐带静脉中膜弹性纤维含量逐渐增多，胶原纤维的含量及胶原纤维／弹性纤维比值逐渐减少。③不同段脐带静脉的显微结构成分：弹性纤维的含量近段比远段多（10，16，6．36Aa％，F=5.77～12．3，P〈0．05），由近段到远段胶原纤维／弹性纤维比值逐渐增大（F=7．63～13．4,P〈0.05）。结论：①脐带静脉具有与普通中等动脉相似的结构，37～40周脐带静脉管壁的胶原纤维、弹性纤维含量适中，既能承载一定的应力，又有较大的扩张能力，还富含平滑肌，具备收缩能力。②在血管移植时，以选用37-40周脐带静脉为佳，且近段顺应性优于远段，可适时选用，以利于脐带静脉移植于动脉后，能很快适应动脉的力学环境，提高移植后的远期通畅率。     

腓肠神经营养血管远端蒂皮瓣的解剖学研究

背景有关腓肠神经营养血管远端蒂皮瓣的血管分布特点缺少具体可操作性的研究.目的探讨腓肠神经营养血管皮瓣远端蒂的血管分布规律,为临床足部损伤修复的术式设计提供解剖学依据.设计单一样本研究.单位解放军南京军区福州总医院军区临床解剖学研究中心,解放军第九十七医院骨科.对象32侧经动脉灌注红色乳胶成人下肢标本(由解放军南京军区临床解剖学研究中心提供).方法解剖观测远端蒂部的血管来源和小隐静脉深交通支.主要观察指标①远端蒂腓肠神经的营养血管.②远端蒂小隐静脉的营养血管.③远端蒂小隐静脉的浅深交通支.结果远端蒂部的营养血管有2～5支来自跟外侧动脉穿支、腓动脉终末穿支外径分别为(0.6±0.2),(0.8±0.2)mm,距外踝尖上分别为(1.0±1.3),(2.8±1.0)cm;腓动脉肌间隔穿支0～3支,出现率依次为96.7%,66.7%和20.0%,外径分别为(0.9±0.3),(1.0±0.2)和(0.8±0.4)mm,距外踝尖上分别为(5.3±2.1),(6.8±2.8)和(7.0±4.0)cm.远端蒂中的小隐静脉营养血管来源有两种类型,①神经-静脉营养血管;②静脉-神经营养血管.小隐静脉浅深交通支距外踝尖上(3.4±0.9)cm,外径(1.7±0.5)mm,汇入腓静脉.结论跟外侧动脉穿支、腓动脉终末穿支及腓动脉肌间隔穿支发出深筋膜支、皮支、神经及静脉营养支,形成腓肠神经小隐静脉血管链,深、浅筋膜血管网.小隐静脉浅深交通支汇入腓静脉.     

正常人内听道段神经、血管MRI表现

目的探讨内听道段神经、血管的正常MRI表现及对神经形态予以量化研究。方法健康成人志愿者60耳行内耳MRI FIESTA序列检查。观察并测量内听道段神经、血管,比较不同断面对神经、血管的显示情况。结果薄层厚采集图像可清晰显示微小神经结构及其走行。内听道底部面神经直径为(1.00±0.03)mm;前庭上神经直径为(0.98±0.04)mm;前庭下神经直径为(0.71±0.03)mm;蜗神经直径为(1.03±0.04)mm;后壶腹神经直径为(0.47±0.02)mm。结论MRI能够准确清晰显示内听道段神经及血管的正常形态,并可对神经进行量化测量,为临床和影像学检查提供诊断依据。     

增龄变化对血管移植材料脐带静脉顺应性的影响

背景：血管重建术中内径小于6mm的人工合成血管替代人体小动脉或静脉一直未获得满意的效果，因而目前小动脉及静脉代用品成为亟待解决的问题，目的：观察不同胎龄脐带静脉压力-容积关系，为血管移植材料脐带静脉的生物力学性质上提供实验数据：设计；非随机对照实验。材料：实验于2004—06在郧阳医学院医用生物力学实验室完成，湖北省十堰市太和医院妇产科收集胎龄在24～42周自然流产或分娩的正常胎儿脐带静脉50条（经产妇许可），产妇年龄20～30岁。其中胎龄24～27周8例，28～32周7例，33～36周8例，37周4例，38周5例，39周5例，40周5例，41周4例，42周4例。干预：取胎儿脐带50条．测量一段脐带长度（2cm）并标记两端点后，切下脐带置于生理盐水中。仔细地对脐带静脉进行机械剥离后，将试件两端标记点固定在软组织生物力学试验台上，测定其压力-容积关系，计算出顺应性：主要观察指标：不同脐带静脉的压力、容积及顺应性。结果：50条脐带全部进入结果分析，①37～40周脐带静脉压力-容积曲线比较接近，而28周，42周脐带静脉压力-容积曲线幅度明显下降，经二次回归分析可见38周胎龄压力-容积曲线回归系数绝对值最大。②脐带静脉顺应性随胎龄增加而增大[24～27周（2．22&;#177;0．34）&;#215;10^-4mL／（kPa、cm），28～32周（3．65&;#177;0．461&;#215;10^-4mL／（kPa、cm）,33～36周（4．22&;#177;0．55）&;#215;10^-4mL／（kPa&;#183;cm），37周（7．63&;#177;0．48）&;#215;10^-4mL／（kPa&;#183;cm），38周（8．32&;#177;0．76）&;#215;10^-4mL／（kPa、cm）]，但39周以后又降低[39周（7．61&;#177;0．46）&;#215;10^-4mL／（kPa&;#183;cm），40周（7．53&;#177;0．72）x10^-4ml／（kPa、cm），41周（4．13&;#177;0．35）&;#215;10^-4mL／（kPa、cm），42周（2．25&;#177;0．62）&;#215;10^-4mL／（kPa&;#183;cm）]。37～40周脐带静脉的顺应性较相近，而42周及28周以下脐带静脉的顺应性与37～40周比较（F=65．84—86．52，P〈0．01）。结论：人脐带静脉是动脉移植物的良好替代材料，在移植时除了考虑脐带静脉与宿主动脉相匹配外，还应注意其顺应性与胎龄的关系，实验结果提示，胎龄在37—40周的脐带静脉作为临床应用的移植材料较为理想．     

组织工程化血管构建中的支架材料

目前人工血管在代用大动脉方面已取得满意的效果,然而在中小动脉、静脉,尤其是在直径<6mm小口径血管的移植中,还没有一种人工材料能够完全满足当前小血管系统     

肝硬化患者门静脉系压力与其B超下宽度对比观察及临床意义

本文对38例门脉性肝硬化患者门脉系统血管直径进行了超声探测,肝硬化手术组18例,术前门静脉直径16.11±0.96mm((?)±SD),脾静脉11.02±2.04mm,肠系膜上静脉10.30±1.47mm,行脾切除手术时测肠系膜上静脉压力均值为35.52±3.99cmH_2O,肠系膜上静脉压力与其管径宽度的关系分析,两者呈直线线形正相关(r=0.8073,P<0.01),术后测量门静脉宽度降低。本资料提示脾切除可降低门静脉压力。     

胎儿脐静脉移植材料的应力松弛特性

背景：人脐静脉是动脉移植物的良好替代材料,在移植时除了考虑脐静脉与宿主动脉相匹配外,还应注意其顺应性. 目的：检测胎儿脐静脉近胎盘段和远胎盘段试样的应力松弛特性. 方法：取22-28岁、胎龄38-40周、自然分娩产妇的正常胎儿脐静脉近胎盘段和远胎盘段各10个试样,在电子万能实验机上进行应力松弛实验,在（36.5±0.5）℃的温度场下,以0.1%/s 的应变增加速度对试样施加应变,设定时间为7200 s.采集100个数据,采用归一化分析的方法计算两组试样的归一化应力松弛方程. 结果与结论：脐静脉近胎盘段组7200 s应力下降了0.275 MPa,脐静脉远胎盘段组7200 s应力下降了0.203 MPa,两组7200 s应力下降量差异有显著性意义（P〈0.05）.两组试样应力松弛曲线是以对数关系变化的,并且胎儿脐静脉近胎盘段和远胎盘段具有不同的应力松弛特性.     

超声回声跟踪技术评价不伴危险因素的糖耐量减低患者颈动脉僵硬度改变

目的 使用超声回声跟踪技术评估不伴有危险因素的糖耐量减低(IGT)患者的颈动脉僵硬度.方法 选择明确诊断为IGT的患者50例(IGT组),另选年龄、性别等相匹配的50名健康志愿者作为对照组,采用超声回声跟踪技术测定两组颈动脉僵硬度.结果 IGT组的颈动脉硬化度、弹性系数、顺应性、脉搏波传导速度均较对照组增高[硬化度:9.93±3.35 vs 8.40±2.58;弹性系数:135.63±51.85 vs 110.19±35.68;顺应性:(0.86±0.31)mm2/kPa vs (0.71±0.24)mm2/kPa;脉搏波传导速度:(7.32±1.93)m/s vs (6.37±1.37)m/s],而两组膨大系数差异无统计学意义[(4.46±8.22)％ vs (3.81±12.24)％].结论 应用超声回声跟踪技术能准确测量糖耐量减低患者颈总动脉的僵硬度参数,无创地早期评价其血管病变程度,为临床治疗提供客观依据.     

急性冠状动脉综合征参考段血管病变对血管内超声评估冠状动脉重构的影响

目的 探讨急性冠状动脉综合征(ACS)患者参考段血管病变对血管内超声(IVUS)评估冠状动脉重构的影响.方法 对103例ACS患者行常规冠状动脉造影,IVUS检测103个靶病变和参考段血管处动脉粥样斑块形态学参数.重构指数(RI)为病变部位外弹力膜(EEM)面积与近端参考段EEM面积之比,RI>1为正重构(67例),RI≤1为负重构(36例).分析重构分组之间的斑块形态学特点,比较各参数在远端与近端参考段血管之间的差异和相关性.结果 仅1例患者未见参考段血管的病变.正性与负性重构组103处靶病变以及102处参考段血管位点问斑块负荷、管腔面积和EEM面积差异无统计学意义;与远端参考段血管比较,斑块负荷在近端参考段显著增加[(39.76±12.54)%对(32.38±3.97)%,P<0.001],斑块面积也明显增大[(6.14±3.20)mm2对(4.75±3.07)mm2,P=0.001].EEM面积在远端参考段扩增明显高于近端参考段[(14.99±4.12)mm2对(28.37±4.48)mm2,P<0.001].斑块负荷、斑块面积和管腔面积在近端与远端参考段之间均有显著正相关性(均为P<0.05).结论 ACS患者参考段血管弥漫性病变可能影响IVUS冠脉重构的评估;重构是一个动态过程,静态与系列方法结合评估冠脉重构可能更为准确.

Abstract：

Objective To investigate the influence of atherosclerotic reference segments on coronary remodeling by intravascular ultrasound(IVUS) in patients with acute coronary syndrome(ACS). Methods One hundred and three consecutively enrolled patients [male 68 cases,female 35 cases,average age (60 ±11) years] with ACS were undergone by coronary artery angiography and IVUS with time selecting operation. The remodeling index(RI) was defined as lesion external elastic membrane cross section aere (EEM CSA) divided by the mean reference EEM CSA at the culprit vessel. Positive remodeling was RI≥ (67 cases), negative remodeling was RI <1(36 cases). The parameters of plaque were analysed between two remodeling groups, as well as compared between distal and proximal references. Results Only one patients do not have plaque at reference sites. In the analysis of 103 lesions and 102 reference sites, there were not significant different in plaque burden,plaque CSA,lumen CSA and lesion EEM CSA between two groups. Distal plaque burden[(39. 76 ±12. 54)% vs (32.38 ± 13.97)%, P <0.001] and plaque CSA [(6.14 ± 3.20)mm2 vs (4. 75 ± 3. 07) mm2, P = 0. 001] were larger than those at proximal reference. EEM CSA at distal reference was smaller than proximal one[(14. 99 ± 4. 12)mm2 vs (28. 37 ± 4. 48)mm2 , P <0. 001]. Plaque burden, plaque CSA and lumen CSA persented positive corelation between distal and proximal reference sites. Conclusions The reference segments lay a severe diffuse atherosclerosis in the group of ACS, which may influence assessment of coronary remodeling. Coronary remodeling as a process, a accurate evaluation could be result from the combination of static and serial approach by IVUS.     

Increased erythropoiesis and elevated erythropoietin in infants born to diabetic mothers and in hyperinsulinemic rhesus fetuses.

The pathogenesis of the increased erythrocytosis and extramedullary erythropoiesis observed in infants of diabetic mothers (IDM) has been obscure. In the present studies, IDM were found to have elevated umbilical plasma erythropoietin (Ep) concentrations by radioimmunoassay. 22 of 61 IDM (36%) had levels above the range of 28 nonasphyxiated, appropriately grown normal infants. In 16 controls and 20 IDM, plasma Ep correlated directly with plasma insulin (P less than 0.001, r = 0.73). To investigate this relationship further, a chronic rhesus model was studied with continuous fetal hyperinsulinemia for 21 d in utero in the last third of pregnancy. In five experimental fetuses, plasma insulin levels averaged 4,210 microU/ml at delivery, whereas plasma Ep was above the range of six controls. In addition, the experimental fetuses had elevated reticulocyte counts in umbilical cord blood. The mechanism for the increased plasma Ep associated with hyperinsulinemia in the fetus is unexplained but may be mediated by fetal hypoxia.     

Umbilical vein blood flow in fetuses with normal and lean umbilical cord.

OBJECTIVE: To evaluate whether umbilical vascular coiling is correlated with the umbilical vein blood flow profile and to investigate if this is different between fetuses with a lean and those with a normal umbilical cord. METHODS: Consecutive women with a singleton gestation who delivered at term and who underwent an ultrasound examination within 24 h from delivery were studied. Umbilical cord and vessel areas were calculated. Umbilical vein blood flow parameters were obtained by digital color Doppler velocity profile integration. After delivery, the umbilical coiling index was calculated. RESULTS: One hundred and sixteen women were studied. Twelve (10.3%) had a lean umbilical cord (area < 10th centile). A significant correlation was found between the umbilical coiling index and the umbilical vein blood flow (r = 0.67, P < 0.001). A significant difference between fetuses with and without a lean cord was found in terms of: umbilical coiling index (0.18 +/- 0.08 vs. 0.29 +/- 0.09, P < 0.005), cord area (87.6 +/- 5.1 mm2 vs. 200.6 +/- 34.6 mm2, P < 0.001), Wharton's jelly amount (25.7 +/- 10.3 mm2 vs. 122.1 +/- 33.4 mm2, P < 0.001), umbilical vein blood flow (93.7 +/- 17.8 ml/kg per min vs. 126.0 +/- 23.4 ml/kg per min, P < 0.001), and umbilical vein blood flow mean velocity (6.6 +/- 2.7 cm/s vs. 9.0 +/- 3.6 cm/s, P < 0.05). The proportion of fetuses with an umbilical vein blood flow < 80 ml/kg per min was higher when the cord was lean than when it was normal (25% vs. 1.9%, P < 0.01). CONCLUSIONS: Lean umbilical cords differ from normal cords not only from a structural point of view but also in the umbilical vein blood flow characteristics. This could explain the increased incidence of intrapartum complications and fetal growth restriction among fetuses with a lean and/or hypocoiled cord.     

Ductus venosus blood flow velocity characteristics of fetuses with single umbilical artery.

OBJECTIVES: Sonographic Doppler evaluation of the fetal ductus venosus has been proved to be useful in the evaluation of fetal cardiac function. The aim of this study was to investigate the ductus venosus blood flow profile in fetuses with single umbilical artery and to correlate it with the umbilical cord morphology. METHODS: Fetuses at >20 weeks' gestation with single umbilical artery who were otherwise healthy were consecutively enrolled into the study. The sonographic examination included evaluation of the following Doppler parameters: umbilical artery resistance index, maximum blood flow velocity of the ductus venosus during ventricular systole (S-peak) and atrial contraction (A-wave), ductus venosus time-averaged maximum velocity (TAMXV), and pulsatility index for veins (PIV). The cross-sectional area of the umbilical cord and its vessels were measured in all cases. The Doppler and morphometric values obtained were plotted on reference ranges. RESULTS: A total of 88 fetuses with single umbilical artery were scanned during the study period. Of these 52 met the inclusion criteria. The S-peak velocity, A-wave velocity, and TAMXV were below the 5th centile for gestational age in 57.7%, 59.6%, and 57.7% of cases, respectively. The PIV was within the normal range in 80.1% of cases. The umbilical vein cross-sectional area of fetuses with single umbilical artery was above the 95th centile for gestational age in 34.6% cases. CONCLUSIONS: The ductus venosus blood flow pattern is different in fetuses with single umbilical artery from that in those with a three-vessel cord. This difference may be caused in part by the particular morphology of umbilical cords with a single artery.     

Fetal aneuploidy and umbilical cord thickness measured between 14 and 23 weeks' gestational age.

OBJECTIVE: To evaluate and compare umbilical cord thickness of aneuploid fetuses with umbilical cord diameter nomograms generated from euploid fetuses between 14 and 23 weeks' gestational age. METHODS: A retrospective study was conducted in which 56 fetuses and neonates had diagnoses of abnormal karyotypes, of which 46 fetuses had numerical chromosomal abnormalities. Among these cases, 26 subjects with adequate umbilical cord sonographic images were included in the study. The umbilical cord thickness was measured and plotted against the umbilical cord diameter nomogram that was generated from previously published data. RESULTS: From 26 evaluated fetuses and neonates, in 14 subjects (53.8%), the umbilical cord thickness was greater than the 95th percentile for gestational age. A thick umbilical cord was observed in 57.8% of fetuses with trisomy 21 and 50% of subjects with trisomy 18 and monosomy 45,XO. One fetus with trisomy 2 had umbilical cord thickness within the normal range. The largest number of aneuploid fetuses with thick umbilical cords (87.5%) was observed between 16 and 17 gestational weeks. CONCLUSION: Aneuploid fetuses have thicker umbilical cords than euploid fetuses. The umbilical cord thickness can be related to an increased amount of Wharton jelly. Because of the smaller number of thick umbilical cords in aneuploid subjects at later gestational ages, we speculate that abnormal cord thickness has a natural tendency toward its own resolution with the advancement of gestational age.     

Umbilical cord morphologic characteristics and umbilical artery Doppler parameters in intrauterine growth-restricted fetuses.

OBJECTIVE: To compare prenatal morphometric changes of umbilical cord components in intrauterine growth-restricted fetuses with and without abnormal umbilical artery Doppler parameters. METHODS: Consecutive singleton intrauterine growth-restricted fetuses at a gestational age of older than 20 weeks were compared with matched appropriate-for-gestational-age fetuses. Intrauterine growth restriction was defined in the presence of a sonographic abdominal circumference below the 5th percentile for gestational age at the time of sonography and a birth weight below the 10th percentile. The sonographic examination included pulsed Doppler measurements of the umbilical artery resistance index and measurements of the umbilical cord cross-sectional area and the umbilical cord vessel area. RESULTS: A total of 84 intrauterine growth-restricted fetuses and 168 appropriate-for-gestational-age fetuses were included in the study. All umbilical cord components (umbilical cord cross-sectional area, vein area, artery area, and Wharton jelly area) were smaller in the intrauterine growth-restricted fetuses. The prevalence of lean umbilical cords (cross-sectional area < 10th percentile for gestational age) was significantly higher in intrauterine growth-restricted fetuses compared with appropriate-for-gestational-age fetuses (73.8% versus 11.3%; P < .0001). A significant and progressive reduction of the umbilical vein area corresponding to the degree of umbilical artery Doppler parameter abnormality was found. The umbilical artery area was not related to the hemodynamic changes of the blood flow in the umbilical arteries. CONCLUSIONS: The proportion of lean umbilical cords was higher in intrauterine growth-restricted fetuses than in appropriate-for-gestational-age fetuses. Umbilical vein caliber decreases significantly with worsening of umbilical artery Doppler parameters.