速度向量成像技术评估胎儿心功能及其在复杂先天性心脏病的应用研究
摘要
背景
速度向量成像技术(velocity vector imaging, VVI)是一种定量评价心肌功能的新超声技术,能直观地显示心肌在纵向、径向和环向上的运动特征,能够无创、准确和快速评价心肌运动的协调性。国内外大量研究显示VVI能够提供整体与局部的心肌功能分析,显示心脏收缩、舒张、扭转运动及心肌运动三维定量等重要信息。VVI在成人心脏疾病中已得到广泛的研究。
近25年来,超声心动图的迅速发展也帮助我们更好地了解了胎儿心脏生理。我们通过主观评估心脏收缩舒张功能和观察胎儿水肿来衡量心功能。但是,对于胎儿发育过程中心脏力学和功能学仍然缺乏准确理解。早期对胎儿心肌的应变和应变率成像技术研究曾因胎儿心率过快和难以显示心动周期而无法进行。
1999年,Harada等人第一次发表了应用多普勒研究胎儿心肌组织的运动和速度可行性的报告。此后,一些初步的研究验证了这项技术,并且测量了正常状态下的心肌纵向速度。在最近的一项研究中,Di Salvo等人发现,应变和应变率也可用来评估胎儿心功能。但是这些以多普勒为基础的技术由于受到检查角度的限制,仅可测量超声波传播方向的速度参数。而新近开发的VVI技术可克服上述限制并提供独特的心肌动力学信息。2007年Younoszai等人将这一技术应用于胎儿超声心动图,探讨了VVI对于测量正常胎儿心肌功能的应用方法学及可行性[5]。最近Piers等人指出VVI的测量结果和DTI高度相关,先天性心脏病或者是功能性心脏病胎儿的整体长轴应变和应变率有降低的趋势[11]。其后国内国内也有学者应用VVI测量正常胎儿心肌运动参数,但是尚未系统的全方位的评价胎儿心功能。目前为止,国内外并没有学者将VVI在胎儿先天性心脏病的应用作分类研究,其临床应用的意义有待进一步发掘。
第一章超声速度向量成像技术对正常胎儿心肌运动的评价
[目的]
对于胎儿心脏生理机制的研究曾由于胎心率过快、胎位、胎动、检查角度等诸多因素的影响而难以进行,而新兴的VVI技术可克服上述限制,用于胎儿心脏功能定量的研究。本研究旨在采用VVI技术测量正常胎儿心肌整体和局部应变、应变率、速度、室壁运动延迟时间等参数,为进一步探索先天性心脏病胎儿心肌运动,并评价其心脏功能提供理论依据和参考。
[方法]
1.研究对象：2008年12月-2009年12月在深圳市妇幼保健院行中晚孕胎儿大体畸形筛查的正常孕妇。以上孕妇均有准确的停经史,或经早期超声检查证明胎龄与孕周相符,孕妇均身体健康,无吸烟、嗜酒史,无高血压、糖尿病、肝肾等慢性疾病,无心血管疾病、呼吸系统疾病以及呼吸急促史,无先天性心脏病生育史及家族史,胎儿均为单胎妊娠,经产科临床及产前产后超声检查无明显异常。
2.图像采集：使用Siemens Sequoia 512彩色超声诊断仪,探头型号6C2,频率为4-6MHz,由从事产前超声检查的专业人员采集胎儿动态标准四腔心切面图,心内膜边界显示清楚连贯,帧频维持在30 Hz以上,动态存储于MO盘。
3.VVI检测：用MO盘读盘后,脱机进入Syngo US Workplace VVI分析软件,导入胎儿动态标准四腔心切面图,并在该图像上选择应用VVI分析模式,设参照物于心尖部,在舒张末期顺时针方向根据内膜弯曲程度沿心内膜手动描迹8—10个点,系统将自动追踪心内膜缘。
4.记录结果：
4.1记录整体心肌的测量参数：应变(S)、应变率(SR)、速度(V)、室壁运动延迟时间(Opposing wall delay)；记录6个节段心肌(游离壁基底段、游离壁中间段、游离壁心尖段、室间隔基底段、室间隔中间段、室间隔心尖段)的应变、应变率、运动速度、室壁运动延迟时间的数据；获得整体心肌的速度向量图。
4.2获得心肌运动的应变(S)—时间、应变率(SR)—时间、运动速度(V)—时间曲线；分别获得左心室游离壁、右心室游离壁和室间隔房室瓣瓣环处的纵向收缩期速度峰值(Vs)和舒张期速度峰值(Vd)测值,以及左心室游离壁、右心室游离壁和室间隔中部的应变、应变率的测值。
[结果]
1.本研究获得147例正常胎儿心室整体和六个节段心肌应变、应变率、室壁运动延迟时间的测值。左心室的整体、室间隔基底部、室间隔中部、室间隔心尖部、游离壁心尖部、游离壁中部、游离壁基底部的应变分别为(-16.05±2.26%)、(-16.87±4.01%)、(-15.45±6.83%)、(-15.71±5.68%)、(-16.76±6.64%)、(-15.96±6.63%)、(-15.57±5.75%)；右心室的整体、室间隔基底部、室间隔中部、室间隔心尖部、游离壁心尖部、游离壁中部、游离壁基底部的应变分别为(-16.13±1.78%)、(-16.04±2.90%)、(-16.06±6.79%)、(-16.28±1.95%)、(-16.51±2.28%)、(-15.89±2.06%)、(-15.71±3.36%)；左心室的整体、室间隔基底部、室间隔中部、室间隔心尖部、游离壁心尖部、游离壁中部、游离壁基底部的应变率分别为(-2.14±0.70/s)、(-2.06±0.84/s)、(-2.10±0.64/s)、(-2.26±0.75/s)、(-2.16±0.55/s)、(-2.21±0.79/s)、(-2.08±0.65/s)；右心室的整体、室间隔基底部、室间隔中部、室间隔心尖部、游离壁心尖部、游离壁中部、游离壁基底部的应变率分别为(-2.06±0.98/s)、(-2.24±1.13/s)、(-2.08±0.76/s)、(-2.10±1.42/s)、(-2.03±0.75/s)、(-1.96±1.17/s)、(-1.93±0.79/s)；左心室应变、应变率、速度的室壁运动延迟时间分别为(94.30±3.93ms)、(93.68±3.17 ms)、(92.22±4.31 ms)；右心室应变、应变率、速度的室壁运动延迟时间分别为(93.23±51.81ms)、(96.92±47.60ms)、(91.19±52.93ms)；各组应变、应变率、室壁运动延迟时间的测值的比较均无统计学意义(P>0.05)。
2.本研究获得147例正常胎儿心室整体和局部心肌速度的测值。左心室的整体、室间隔基底部、室间隔中部、室间隔心尖部、游离壁心尖部、游离壁中部、游离壁基底部的速度分别为(1.41±0.29cm/s)、(2.35±0.99cm/s)、(1.73±0.92cm/s)、(0.81±0.37cm/s)、(0.58±0.30cm/s)、(1.19±0.60cm/s)、(1.80±0.87cm/s)；右心室的整体、室间隔基底部、室间隔中部、室间隔心尖部、游离壁心尖部、游离壁中部、游离壁基底部的速度分别为(1.53±0.33cm/s)、(2.40±1.18cm/s)、(1.81±0.89cm/s)、(1.06±0.60cm/s)、(0.78±0.41cm/s)、(1.27±0.51cm/s)、(1.84±0.79cm/s)；左心室整体和六个节段心肌速度各测值之间的比较有统计学差异(F=133.463,P=0.000),右心室整体和六个节段心肌速度各测值之间的比较有统计学差异(F=78.198,P=0.000)；左心室和右心室(整体、室间隔心尖部、游离壁心尖部)速度测值的比较有统计学意义(1.41cm/s VS 1.53cm/s, t=3.033, P=0.003;0.81cm/s VS 1.06cm/s, t=4.458,P=0.000; 0.58cm/s VS 0.78cm/s, t=4.721,P=0.000)；速度测值(室间隔基底部、室间隔中部、游离壁中部、游离壁基底部)在左心室和右心室之间比较的均无统计学意义(P>0.05)；左、右心室心肌的速度由基底部到心尖呈递减趋势。
3.本研究获得145例正常胎儿左心室(LV)游离壁、室间隔(Septal)和右心室(RV)游离壁测值应变、应变率、收缩期速度、舒张期速度的测值。左心室游离壁、室间隔、右心室游离壁房室瓣瓣环处纵向收缩期速度(Vs)的VVI测值分别为(1.11±0.72cm/s)、(1.24±0.50cm/s)、(1.23±0.59cm/s)；左心室游离壁、室间隔、右心室游离壁房室瓣瓣环处纵向舒张期速度(Vd)的VVI测值分别为(1.16±0.67cm/s)、(1.22±0.64cm/s)、(1.16±0.64cm/s)；左心室游离壁、室间隔、右心室游离壁中部纵向应变(S)的VVI测值分别为(-15.93±6.66%)、(-15.56±6.79%)、(-15.89±2.06%)；左心室游离壁、室间隔、右心室中部纵向应变率(SR)的VVI测值分别为(-2.17±0.55/s)、(-2.10±0.64/s)、(-2.08±0.76/s)；Vs、Vd、S、SR测值的各组间比较均无统计学意义(P>0.05)。
4.145例正常胎儿心室心肌整体和局部的运动速度与孕周均呈正相关(P<0.01),说明胎儿心肌运动速度和孕周密切相关,随着孕周的增加而增加。正常胎儿左、右心室的心肌整体和局部的应变率与胎心率均呈正相关(P<0.01),说明胎儿心肌应变率随着胎心率的增加而增加。
5.速度向量图：显示左心室速度的向量长度从基底段到心尖逐渐缩短,运动随着心室的收缩和舒张改变方向。应变—时间、应变率—时间、速度—时间曲线图：速度—时间曲线显示速度大小由室壁基底段向心尖段逐渐递减,应变、应变率曲线随节段的变化保持稳定。
[结论]
本研究测量了正常胎儿整体和局部心肌应变、应变率、运动速度、室壁运动延迟时间等参数,应变率随着胎心率的增加而增加,而应变在中晚孕期和正常胎心率范围内维持稳定,说明胎儿心肌形变能力在一定范围内具有代偿功能,以保证其心功能的稳定性。VVI技术作为测量分析心肌运动参数的工具,可克服检查角度的限制,从而评价心室整体和局部节段功能,为进一步探索先天性心脏病胎儿心肌运动,并为其心脏功能的定量评价提供理论依据和参考。
第二章超声速度向量成像技术对左心发育不良综合征心室纵向功能的研究
[目的]
左心发育不良综合征(Hypoplastic left heart syndrome, HLHS),是一种少见而危及生命的复杂先天性心脏畸形,约占先天性心血管畸形的14%,主要为左心流入和/或流出道发育不良引起的一组病变,包括左心室狭小、二尖瓣闭锁或狭窄、主动脉瓣闭锁、升主动脉发育不良等。本研究拟采用VVI技术对比测量分析正常胎儿和HLHS胎儿左、右心室的应变、应变率、速度及其室壁运动延迟时间等心肌运动参数来评价心肌运动,通过分析上述参数的变化探讨HLHS胎儿心肌功能的异常变化,为该病临床的产前遗传咨询、宫内治疗、出生后治疗、预后提供理论依据和参考。
[方法]
1.研究对象：2007年12月-2009年12月在深圳市妇幼保健院行中晚孕胎儿大体畸形筛查的56例孕妇,经产前超声检查诊断为HLHS;正常对照组孕妇的入选条件同第一章。病例组和对照组按孕周以1：1配对。
2.图像采集和VVI检测方法同第一章。
3.记录结果：获得整体心肌的速度向量图；记录左心室和右心室整体心肌的测量参数：应变、应变率、运动速度、室壁运动延迟时间；获得局部心肌运动的应变—时间、应变率—时间、速度—时间曲线。
4.产后随访和病理解剖追踪出生后手术及预后情况；要求在深圳市妇幼保健院引产者并签署胎儿尸体病理解剖同意书后行尸解。
[结果]
1. HLHS胎儿心肌测量参数的变化：正常胎儿和HLHS胎儿左心室整体心肌应变的平均差值为(4.08±6.71%)；应变率的平均差值为(0.53±0.86/s)；速度的平均差值为(-0.27±0.63cm/s)；正常胎儿和HLHS胎儿左心室应变、应变率、速度三个参数的室壁运动室壁运动延迟时间的平均差值分别为(801.75±335.26ms；923.08±477.22ms;850.80±391.45ms)。右心室整体应变的平均差值为(3.99±9.15%)；应变率的平均差值为(0.32±0.97/s)；速度的平均差值为(-0.76±0.70cm/s)；三个参数室壁运动延迟时间的平均差值分别为(95.07±74.98ms；75.40±77.41ms；89.27±82.00 ms)。正常胎儿和HLHS胎儿整体心肌应变、应变率、速度、室壁运动延迟时间的配对比较均有统计学意义(P<0.01)。
2.不同孕周对HLHS胎儿左心室(LV)和右心室(RV)整体运动速度、应变、应变率的影响：正常胎儿左心室和右心室的心肌整体运动速度均与孕周呈正相关(P<0.01), HLHS胎儿左心室和右心室的心肌整体运动速度与孕周无相关关系(P>0.05)；正常胎儿和HLHS胎儿左、右心室的心肌整体应变与孕周无相关关系(P>0.05)。以上说明正常胎儿心肌运动速度和孕周密切相关,随着孕周的增加而增加,而HLHS胎儿的各VVI参数和孕周无相关关系。
3.胎心率对HLHS胎儿左心室(LV)和右心室(RV)整体应变、应变率、运动速度的影响：正常胎儿左心室和右心室的心肌整体应变率测值与胎心率均呈正相关(P<0.01), HLHS胎儿左心室和右心室的心肌整体应变率值与胎心率无相关关系(P>0.05)；正常胎儿和HLHS胎儿左、右心室的心肌整体应变、运动速度与胎心率无相关关系(P>0.05)。以上说明正常胎儿心肌应变率和胎心率密切相关,随着胎心率的增加而增加,而HLHS胎儿的各VVI参数和胎心率无相关关系。
4.随访结果：本研究56例HLHS胎儿中,11例在深圳市妇幼保健院引产,其中有10例行病理解剖：34例在外院引产,均未行病理解剖；11例失访。行病理解剖的10例HLHS胎儿中,均有典型的心脏表现：左心变小(或无左心室,仅见一室间隔残端),主动脉瓣狭窄、发育不良或闭锁,升主动脉发育不良,二尖瓣狭窄、发育不良或闭锁,主动脉较主肺动脉内径变窄。其中Ⅰ型：主动脉瓣、二尖瓣均狭窄者7例；Ⅱ型：主动脉瓣、二尖瓣均闭锁者0例；Ⅲ型：主动脉瓣闭锁、二尖瓣狭窄者1例；Ⅳ型：主动脉瓣狭窄、二尖瓣闭锁者2例。
[结论]
HLHS胎儿左心发育不良,右心功能性代偿,左、右心室心肌应变、应变率、速度均降低,心室室壁运动延迟时间增加,心室运动的同步协调性降低。孕周对左、右心室肌速度无明显影响,胎心率对左、右心室肌应变率无明显影响,说明左心室肌发育不良,其心肌功能明显降低；而对于功能性右心室而言,可能是由于长期代偿下的心肌功能受损,或是我们没有将代偿期和失代偿期的心功能进行分类分析,这些尚待更深入的研究。综上述,应变、应变率、速度、室壁运动延迟时间是可以用来评估HLHS胎儿心肌功能的可靠参数,结合不同孕周和胎心率对这些参数的影响,可以更好的分析胎儿心肌所处的功能状态。
第三章超声速度向量成像技术对右心发育不良综合征心室纵向功能的研究
[目的]
右心发育不良综合征(Hypoplastic right heart, HRH),是一种少见的复杂先天性心脏畸形,它包括各种以右心室发育不良为共同特征的先天性心脏异常,主要为肺动脉瓣和/或三尖瓣的发育不良(闭锁或重度狭窄)。本研究拟采用VVI技术对比测量分析正常胎儿和HRH胎儿左心室和右心室的应变、应变率、速度及其室壁运动延迟时间等心肌运动参数来评价心肌运动,通过分析上述参数的变化探讨HRH胎儿心肌功能的异常变化,为该病临床的产前遗传咨询、宫内治疗、出生后治疗、预后提供理论依据和参考。
[方法]
1.研究对象：2007年12月-2009年12月在深圳市妇幼保健院行中晚孕胎儿大体畸形筛查的12例孕妇,经产前超声检查诊断为HRH；正常对照组孕妇的入选条件同第一章。病例组和对照组按孕周以1：3配对。
2.图像采集、VVI检测、记录结果、随访的方法同第二章。
[结果]
1.HRH胎儿心肌测量参数的变化：正常胎儿和HRH胎儿右心室整体心肌应变的平均差值为(4.02±1.63%)；应变率的平均差值为(0.70±0.15/s)；速度的平均差值为(-0.54±0.10cm/s)；应变、应变率、速度三个参数的室壁运动延迟时间的平均差值分别为(652.60±312.17ms；949.06±430.19ms；876.86±543.97 ms)；正常胎儿和HRH胎儿左心室整体心肌应变的平均差值为(1.28±1.18%)；应变率的平均差值为(0.24±0.16/s)；速度的平均差值为(-0.28±0.08/s)；应变、应变率、速度三个参数的室壁运动室壁运动延迟时间的平均差值分别为(78.58±13.62ms；89.12±18.45ms；128.57±14.06ms)。正常胎儿和HRH胎儿右心室整体应变、应变率、速度、室壁运动延迟时间的比较均有统计学意义(P<0.01)。正常胎儿和HRH胎儿左心室心肌应变、应变率、速度测值的比较均无统计学意义(P>0.05)；
2.不同孕周对HRH胎儿左心室(LV)和右心室(RV)整体运动速度、应变、应变率的影响：正常胎儿左心室和右心室的心肌整体运动速度与孕周呈正相关(P<0.01),HRH胎儿左心室和右心室的心肌整体运动速度与孕周无相关关系(P>0.05)；正常胎儿和HRH胎儿左、右心室的心肌整体应变、应变率与孕周无相关关系(P>0.05)。以上说明正常胎儿心肌运动速度和孕周密切相关,随着孕周的增加而增加,而HRH胎儿的各VVI参数和孕周无相关关系。
3.胎心率对HRH胎儿左心室(LV)和右心室(RV)整体应变、应变率、运动速度的影响：正常胎儿左心室和右心室的心肌整体应变率测值与胎心率呈正相关(P<0.01),HRH胎儿左、右心室的心肌整体应变率值与胎心率无相关关系(P>0.05)；正常胎儿和HRH胎儿左、右心室的心肌整体应变、速度与胎心率无相关关系(P>0.05)。以上说明正常胎儿心肌应变率和胎心率密切相关,随着胎心率的增加而增加,而HRH胎儿的各VVI参数和胎心率无相关关系。
4.随访结果：本研究12例HRH胎儿中,6例在深圳市妇幼保健院引产并行病理解剖：4例在外院引产,均未行病理解剖；2例失访。行病理解剖的6例HRH胎儿心脏均有典型的表现：右心室变小,三尖瓣狭窄、发育不良或闭锁,肺动脉瓣闭锁、狭窄或正常,主肺动脉内径较主动脉窄。其中,三尖瓣狭窄、肺动脉瓣闭锁者(Ⅰ型)2例；三尖瓣闭锁、肺动脉瓣狭窄(Ⅱ型)2例；三尖瓣狭窄而肺动脉瓣狭窄者(Ⅲ型)2例。
[结论]
HRH胎儿右心发育不良,左心功能性代偿,左、右心室心肌应变、应变率、速度均降低,心室室壁运动延迟时间增加,心室运动的同步协调性降低。孕周对左、右心室肌速度无明显影响,胎心率对左、右心室肌应变率无明显影响,说明右心室肌发育不良,其心肌功能明显降低；而对于功能性左心室而言,仍需将代偿期和失代偿期的心功能进行分类分析,这些尚待更深入的研究。综上述,应变、应变率、速度、室壁运动延迟时间是可以用来评估HRH胎儿心肌功能的可靠参数,结合不同孕周和胎心率对这些参数的影响,可以更好的分析胎儿心肌所处的功能状态。
第四章超声速度向量成像技术对心肌致密化不全心室纵向功能的研究
[目的]
心肌致密化不全(noncompaction of the ventricular myocardium, NVM)是由于胚胎初期正常心内膜和心肌发育停止所致的先天性心肌病,由于基因突变等因素使心肌的致密化过程失败,室壁肌层保留疏松状态。本研究旨在采用超声产前诊断NVM,结合VVI技术测量NVM产前心肌运动速度、应变、应变率、室壁运动延迟时间,通过测量研究上述参数来探讨NVM心肌功能的异常变化。
[方法]
1.研究对象：2007年12月-2009年12月在深圳市妇幼保健院行中晚孕胎儿大体畸形筛查的9例孕妇,经产前超声检查诊断为NVM,并由产后病理解剖证实的孕妇为病例组；正常对照组孕妇的入选条件同第一章。病例组和对照组按孕周以1：3配对。
2.图像采集、VVI检测、记录结果、随访的方法同第二章。
[结果]
1.NVM胎儿心肌整体测量参数和局部病变部位的变化：正常胎儿和NVM胎儿左心室整体应变的平均差值为(5.53±4.70%)；应变率的平均差值为(0.87±0.67/s)；速度的平均差值为(-0.44±0.09cm/s)；应变、应变率、速度三个参数室壁运动延迟时间的平均差值分别为(1713.70±272.68ms；1670.91±403.50ms;2051.44±336.05)。正常胎儿和NVM胎儿左心室局部病变部位应变的平均差值为(4.13±3.48%)；应变率的平均差值为(-1.08±0.66/s)；速度的平均差值为(-0.92±0.31cm/s)；应变、应变率、速度三个参数的室壁运动室壁运动延迟时间的平均差值分别为(1706.43±441.45ms；1874.00±396.74ms；2062.81±336.55)。正常胎儿和NVM胎儿心室整体应变、应变率、速度、室壁运动延迟时间的比较均有统计学意义(P<0.01)；正常胎儿和NVM胎儿心室局部应变、应变率、速度、室壁运动延迟时间的比较均有统计学意义(P<0.01)。
2.不同孕周对NVM胎儿心室整体运动速度、应变、应变率的影响：NVM胎儿心室整体心肌运动速度、应变、应变率均与孕周无明显相关关系(P>0.05)。
3.胎心率对NVM胎儿整体心肌应变率、应变、运动速度等参数的影响：本章的研究中,NVM胎儿心室整体心肌应变率、应变、运动速度与胎心率无相关关系(P>0.05),但是应变率有随胎心率的升高而增加的趋势。
4.随访结果：本研究9例HRH胎儿中,均在深圳市妇幼保健院引产并行病理解剖,均有典型的心脏表现：心室壁可见过多、粗大的肌小梁突入心室腔.其间可见深陷的小梁间隙,成网格状改变。
[结论]
NVM胎儿局部病变和整体心肌的应变、应变率、速度均降低,心室室壁运动延迟时间增加,心室运动的同步协调性降低。孕周对NVM胎儿心肌的速度无明显影响。NVM胎儿心肌的应变率随着胎心率的增高而增加,说明其心肌尚有一定的形变能力,以维持稳定的心输出量。本研究没有将代偿期和失代偿期的心功能进行分类分析,尚待更深入的研究。应变、应变率、速度、室壁运动延迟时间是可以用来评估HRH胎儿心肌功能的可靠参数,结合不同孕周和胎心率对这些参数的影响,可以更好的分析胎儿心肌所处的功能状态。
Background
Velocity vector imaging (VVI) is a newly developed offline analysis software package that allows evaluation of myocardial tissue motion and velocity without the limitations of Doppler echocardiography. It utilizes a combination of speckle tracking with complex geometric analysis to follow the myocardium through the cardiac cycle. It offers an intuitive analysis of myocardial mechanics.
During the past 25 years the rapid evolution of echocardiography has led to a greater understanding of fetal cardiac physiology. Traditionally fetal cardiac function has been measureed by subjective assessment of contractility and observation for hydrops fetalis. However, a precise understanding of fetal cardiac mechanics and function is lacking.
Myocardial tissue motion and velocities have now been investigated in the fetal heart with the first published report indicating its feasibility appearing in 1999 by Harada et al. Since that time a number of preliminary studies have been performed validating the technique and reporting normal longitudinal velocities. In a recent report, Di Salvo et al demonstrated that evaluation of strain and strain rate can also be measured in the fetus with limited variability. These Doppler-based techniques are subject to some technical limitations and are dependent on obtaining an optimal angle of interrogation. It offers an intuitive analysis of myocardial mechanics. However, VVI has not been well studied in normal fetus and there is few reports of its use in the fetal congenital heart disease.
Chapter 1 Evaluation of normal fetal cardiac function by velocity vector imaging
[Objectives] To investigate the application and the influencing factors of velocity vector imaging for evaluation of myocardial mechanics in the normal fetal ventricles.
[Methods] Selected were normal fetuses who underwent systemic ultrasonic examination in Shenzhen maternity and child healthcare hospital from December 2007 to December 2009.Two-dimensional 4-chamber images of the heart were interrogated offline using Syngo US Workplace VVI software. Measurements of global and segmental longitudinal velocity, strain, strain rate and opposing wall delay were performed on the left and right ventricle. Comparison was made between each segmental and global, and left and right ventricular measurement respectively. Learning curves of velocity, strain, and strain rate and velocity vector images were performed. Longitudinal strain, strain rate, and diastolic and systolic velocity were measured in the left ventricular free wall, ventricular septum, and right ventricular free wall. The correlation of above measurements with gestational weeks and fetal heart rate was analyzed.
[Results]
1. The measurements of global and segmental strain, strain rate, and opposing wall delay in left and right ventricles were obtained (n=147). There was no significant differences among groups (P>0.05). The strain of left ventricular global, base septal, mid septal, apical septal, apical free wall, mid free wall, base free wall were (-16.05±2.26%)、(-16.87±4.01%)、(-15.45±6.83%)、(-15.71±5.68%)、(-16.76±6.64%)、(-15.96±6.63%)、(-15.57±5.75%), respectively. The strain of right ventricular global, base septal, mid septal, apical septal, apical free wall, mid free wall, base free wall were (-16.13±1.78%)、(-16.04±2.90%)、(-16.06±6.79%)、(-16.28±1.95%)、(-16.51±2.28%)、(-15.89±2.06%)、(-15.71±3.36%), respectively. The strain rate of left ventricular global, base septal, mid septal, apical septal, apical free wall, mid free wall, base free wall were (-2.14±0.70/s)、(-2.06±0.84/s)、(-2.10±0.64/s)、(-2.26±0.75/s)、(-2.16±0.55/s)、(-2.21±0.79/s)、(-2.08±0.65/s), respectively. The strain rate of right ventricular global, base septal, mid septal, apical septal, apical free wall, mid free wall, base free wall were (-2.06±0.98/s)、(-2.24±1.13/s)、(-2.08±0.76/s)、(-2.10±1.42/s)、(-2.03±0.75/s)、(-1.96±1.17/s)、(-1.93±0.79/s).The time of opposing wall delay of left ventricular strain, strain rate and velocity were (94.30±3.93ms)、(93.68±3.17ms)、(92.22±4.31 ms).The time of opposing wall delay of right ventricular strain, strain rate and velocity were (93.23±51.81ms)、(96.92±47.60ms)、(91.19±52.93ms). There was no significant differences among groups (P>0.05).
2. The measurements of global and segmental velocity in left and right ventricles were obtained (n=147). The velocity of left ventricular global, base septal, mid septal, apical septal, apical free wall, mid free wall, base free wall were (1.41±0.29cm/s)、(2.35±0.99cm/s)、(1.73±0.92cm/s)、(0.81±0.37cm/s)、(0.58±0.30cm/s)、(1.19±0.60cm/s)、(1.80±0.87cm/s),respectively. The velocity of right ventricular global, base septal, mid septal, apical septal, apical free wall, mid free wall, base free wall were (1.53±0.33cm/s)、(2.40±1.18cm/s)、(1.81±0.89cm/s)、(1.06±0.60cm/s)、(0.78±0.41cm/s)、(1.27±0.51cm/s)、(1.84±0.79cm/s). There was significant differences among global and six segmental group in left ventricle (F=133.463, P=0.000) and in right ventricle (F=78.198, P=0.000). The comparison between left and right ventricular velocity (global, apical septal, apical free wall) showed significant differences (1.41cm/s VS 1.53cm/s, t=3.033, P=0.003; 0.81cm/s VS 1.06cm/s, t=4.458, P=0.000; 0.58cm/s VS 0.78cm/s, t=4.721, P=0.000). The comparison between left and right ventricular velocity (base septal, mid septal, mid free wall, base free wall) showed no significant differences (P>0.05).The velocity decreased from the base to apical ventricles.
3. The measurements of strain, strain rate, diastolic and systolic velocity, and opposing wall delay in the left ventricular free wall, ventricular septum, and right ventricular free wall were obtained (n=145). The systolic and diastolic velocity in the left ventricular free wall, ventricular septum, and right ventricular free wall were (1.11±0.72cm/s), (1.24±0.50cm/s), (1.23±0.59cm/s), (1.16±0.67cm/s), (1.22±0.64cm/s), (1.16±0.64cm/s), and the strain were (-15.93±6.66%), (-15.56±6.79%), (-15.89±2.06%), and strain rate were (-2.17±0.55/s), (-2.10±0.64/s), (-2.08±0.76/s). The paired comparison between groups showed no significant differences (P<0.01).
4. The gestational age had significant positive correlation with the velocity in normal fetus (n=145, P<0.01).The fetal heart rate had significant positive correlation with the strain in normal fetus (P<0.01).
5. Velocity vector images and learning curves of longitudinal velocity, strain, and strain rate were obtained. The learning curve showed that the velocity decreased from the base to the apex and that the strain and strain rate remained stable.
[Conclusions] Measurement of cardiac strain and strain rate using VVI can be applied to evaluate global and segmental ventricular motion and function.
Chapter 2 Evaluation of hypoplastic left heart syndrome in fetus by velocity vector imaging
[Objectives] To investigate the application of velocity vector imaging for evaluation of myocardial mechanics in hypoplastic left heart syndrome.
[Methods] Selected were fifty-six fetus who underwent systemic ultrasonic examination and had been diagnosed as hypoplastic left heart syndrome in Shenzhen maternity and child healthcare hospital from December 2007 to December 2009. The control was healthy pregnant women without contributable history. The case and control group were 1:1 paired. Two-dimensional 4-chamber images of the heart were interrogated offline using Syngo US Workplace VVI software. Measurements of global and segmental longitudinal velocity, strain, strain rate and opposing opposing wall delay were performed on the right and left ventricle. Comparison was made between each segmental and global, and left and right ventricular measurement respectively. Learning curves of velocity, strain, and strain rate and velocity vector images were performed. The correlation of above measurements with gestational weeks and fetal heart rate was analyzed.
[Results]
1. The comparison of global strain, strain rate, velocity, and opposing opposing wall delay between HLHS and control group showed significant differences (P<0.01). The mean differences of left ventricular strain, strain rate, and velocity between normal and HLHS fetus were (4.08±6.71%), (0.53±0.86/s), (-0.27±0.63cm/s). The mean differences of left ventricular opposing wall delay in strain, strain rate, and velocity between normal and HLHS fetus were (801.75±335.26ms,923.08±477.22ms, 850.80±391.45ms). The mean differences of right ventricular strain, strain rate, and velocity between normal and HLHS fetus were (3.99±9.15%), (0.32±0.97/s), (-0.76±0.70cm/s). The mean differences of right ventricular opposing wall delay in strain, strain rate, and velocity between normal and HLHS fetus were (95.07±74.98ms,75.40±77.41ms,89.27±82.00 ms).
2. The gestational age had no significant correlation with the velocity in HLHS fetuses (P>0.05).The fetal heart rate had no significant correlation with the strain rate in normal fetus (P>0.05).
[Conclusions] Measurement of VVI indices can be applied to evaluate global and segmental ventricular motion and function in the HLHS fetus.
Chapter 3 Evaluation of hypoplastic right heart syndrome in fetus by velocity vector imaging
[Objectives] To investigate the application of velocity vector imaging for evaluation of myocardial mechanics in hypoplastic right heart syndrome.
[Methods] Selected were twelve fetus who underwent systemic ultrasonic examination and had been diagnosed as hypoplastic right heart syndrome in Shenzhen maternity and child healthcare hospital from December 2007 to December 2009. The control was healthy pregnant women without contributable history. The case and control group were 1:3 paired. Two-dimensional 4-chamber images of the heart were interrogated offline using Syngo US Workplace VVI software. Measurements of global and segmental longitudinal velocity, strain, strain rate and opposing opposing wall delay were performed on the right and left ventricle. Comparison was made between each segmental and global, and left and right ventricular measurement respectively. Learning curves of velocity, strain, and strain rate and velocity vector images were performed. The correlation of above measurements with gestational weeks and fetal heart rate was analyzed.
[Results]
1. The comparison of global strain, strain rate, velocity, and opposing wall delay between HRH and control group in right ventricle showed significant differences (P <0.01). The mean differences of right ventricular strain, strain rate, and velocity between normal and HRH fetus were (4.02±1.63%), (0.70±0.15/s), (-0.54±0.10cm/s). The mean differences of right ventricular opposing wall delay in strain, strain rate, and velocity between normal and HRH fetus were (652.60±312.17ms,949.06±430.19ms,876.86±543.97 ms). The comparison of global strain, strain rate, velocity, and opposing wall delay between HRH and control group in left ventricle showed no significant differences (P>0.05).The mean differences of left ventricular strain, strain rate, and velocity between normal and HRH fetus were(1.28±1.18%),(0.24±0.16/s),(-0.28±0.08/s). The mean differences of left ventricular opposing wall delay in strain, strain rate, and velocity between normal and HRH fetus were (78.58±13.62ms,89.12±18.45ms,128.57±14.06ms).
2. The gestational age had no significant correlation with the velocity in HLHS fetuses (P>0.05).The fetal heart rate had no significant correlation with the strain rate in normal fetus (P>0.05).
[Conclusions] Measurement of VVI indices can be applied to evaluate global and segmental ventricular motion and function in the HRH fetus.
Chapter 4 Evaluation of noncompaction of the ventricular myocardium in fetus by velocity vector imaging
[Objectives]To investigate the application of velocity vector imaging for evaluation of myocardial mechanics in noncompaction of the ventricular myocardium.
[Methods] Selected were nine fetus who underwent systemic ultrasonic examination and had been diagnosed as noncompaction of the ventricular myocardium in Shenzhen maternity and child healthcare hospital from December 2007 to December 2009. The control was healthy pregnant women without contributable history. The case and control group were 1:3 paired. Two-dimensional 4-chamber images of the heart were interrogated offline using Syngo US Workplace VVI software. Measurements of global and segmental longitudinal velocity, strain, strain rate and opposing wall delay were performed on the right and left ventricle. Comparison was made between each segmental and global, and left and right ventricular measurement respectively. Learning curves of velocity, strain, and strain rate and velocity vector images were performed. The correlation of above measurements with gestational weeks and fetal heart rate was analyzed.
[Results]
1. The comparison of global and segmental strain, strain rate, velocity, and opposing wall delay between NVM and control group showed significant differences (P< 0.01).
2. The gestational age had no significant correlation with the velocity in HLHS fetuses (P>0.05).The fetal heart rate had no significant correlation with the strain rate in normal fetus (P>0.05).
[Conclusions] Measurement of VVI indices can be applied to evaluate global and segmental ventricular motion and function in the noncompaction of the ventricular myocardium fetus
速度向量成像技术(velocity vector imaging, VVI)是一种定量评价心肌功能的新超声技术,能直观地显示心肌在纵向、径向和环向上的运动特征,能够无创、准确和快速评价心肌运动的协调性。国内外大量研究显示VVI能够提供整体与局部的心肌功能分析,显示心脏收缩、舒张、扭转运动及心肌运动三维定量等重要信息。VVI在成人心脏疾病中已得到广泛的研究。
近25年来,超声心动图的迅速发展也帮助我们更好地了解了胎儿心脏生理。我们通过主观评估心脏收缩舒张功能和观察胎儿水肿来衡量心功能。但是,对于胎儿发育过程中心脏力学和功能学仍然缺乏准确理解。早期对胎儿心肌的应变和应变率成像技术研究曾因胎儿心率过快和难以显示心动周期而无法进行。
1999年,Harada等人第一次发表了应用多普勒研究胎儿心肌组织的运动和速度可行性的报告。此后,一些初步的研究验证了这项技术,并且测量了正常状态下的心肌纵向速度。在最近的一项研究中,Di Salvo等人发现,应变和应变率也可用来评估胎儿心功能。但是这些以多普勒为基础的技术由于受到检查角度的限制,仅可测量超声波传播方向的速度参数。而新近开发的VVI技术可克服上述限制并提供独特的心肌动力学信息。2007年Younoszai等人将这一技术应用于胎儿超声心动图,探讨了VVI对于测量正常胎儿心肌功能的应用方法学及可行性[5]。最近Piers等人指出VVI的测量结果和DTI高度相关,先天性心脏病或者是功能性心脏病胎儿的整体长轴应变和应变率有降低的趋势[11]。其后国内国内也有学者应用VVI测量正常胎儿心肌运动参数,但是尚未系统的全方位的评价胎儿心功能。目前为止,国内外并没有学者将VVI在胎儿先天性心脏病的应用作分类研究,其临床应用的意义有待进一步发掘。
第一章超声速度向量成像技术对正常胎儿心肌运动的评价
[目的]
对于胎儿心脏生理机制的研究曾由于胎心率过快、胎位、胎动、检查角度等诸多因素的影响而难以进行,而新兴的VVI技术可克服上述限制,用于胎儿心脏功能定量的研究。本研究旨在采用VVI技术测量正常胎儿心肌整体和局部应变、应变率、速度、室壁运动延迟时间等参数,为进一步探索先天性心脏病胎儿心肌运动,并评价其心脏功能提供理论依据和参考。
[方法]
1.研究对象：2008年12月-2009年12月在深圳市妇幼保健院行中晚孕胎儿大体畸形筛查的正常孕妇。以上孕妇均有准确的停经史,或经早期超声检查证明胎龄与孕周相符,孕妇均身体健康,无吸烟、嗜酒史,无高血压、糖尿病、肝肾等慢性疾病,无心血管疾病、呼吸系统疾病以及呼吸急促史,无先天性心脏病生育史及家族史,胎儿均为单胎妊娠,经产科临床及产前产后超声检查无明显异常。
2.图像采集：使用Siemens Sequoia 512彩色超声诊断仪,探头型号6C2,频率为4-6MHz,由从事产前超声检查的专业人员采集胎儿动态标准四腔心切面图,心内膜边界显示清楚连贯,帧频维持在30 Hz以上,动态存储于MO盘。
3.VVI检测：用MO盘读盘后,脱机进入Syngo US Workplace VVI分析软件,导入胎儿动态标准四腔心切面图,并在该图像上选择应用VVI分析模式,设参照物于心尖部,在舒张末期顺时针方向根据内膜弯曲程度沿心内膜手动描迹8—10个点,系统将自动追踪心内膜缘。
4.记录结果：
4.1记录整体心肌的测量参数：应变(S)、应变率(SR)、速度(V)、室壁运动延迟时间(Opposing wall delay)；记录6个节段心肌(游离壁基底段、游离壁中间段、游离壁心尖段、室间隔基底段、室间隔中间段、室间隔心尖段)的应变、应变率、运动速度、室壁运动延迟时间的数据；获得整体心肌的速度向量图。
4.2获得心肌运动的应变(S)—时间、应变率(SR)—时间、运动速度(V)—时间曲线；分别获得左心室游离壁、右心室游离壁和室间隔房室瓣瓣环处的纵向收缩期速度峰值(Vs)和舒张期速度峰值(Vd)测值,以及左心室游离壁、右心室游离壁和室间隔中部的应变、应变率的测值。
[结果]
1.本研究获得147例正常胎儿心室整体和六个节段心肌应变、应变率、室壁运动延迟时间的测值。左心室的整体、室间隔基底部、室间隔中部、室间隔心尖部、游离壁心尖部、游离壁中部、游离壁基底部的应变分别为(-16.05±2.26%)、(-16.87±4.01%)、(-15.45±6.83%)、(-15.71±5.68%)、(-16.76±6.64%)、(-15.96±6.63%)、(-15.57±5.75%)；右心室的整体、室间隔基底部、室间隔中部、室间隔心尖部、游离壁心尖部、游离壁中部、游离壁基底部的应变分别为(-16.13±1.78%)、(-16.04±2.90%)、(-16.06±6.79%)、(-16.28±1.95%)、(-16.51±2.28%)、(-15.89±2.06%)、(-15.71±3.36%)；左心室的整体、室间隔基底部、室间隔中部、室间隔心尖部、游离壁心尖部、游离壁中部、游离壁基底部的应变率分别为(-2.14±0.70/s)、(-2.06±0.84/s)、(-2.10±0.64/s)、(-2.26±0.75/s)、(-2.16±0.55/s)、(-2.21±0.79/s)、(-2.08±0.65/s)；右心室的整体、室间隔基底部、室间隔中部、室间隔心尖部、游离壁心尖部、游离壁中部、游离壁基底部的应变率分别为(-2.06±0.98/s)、(-2.24±1.13/s)、(-2.08±0.76/s)、(-2.10±1.42/s)、(-2.03±0.75/s)、(-1.96±1.17/s)、(-1.93±0.79/s)；左心室应变、应变率、速度的室壁运动延迟时间分别为(94.30±3.93ms)、(93.68±3.17 ms)、(92.22±4.31 ms)；右心室应变、应变率、速度的室壁运动延迟时间分别为(93.23±51.81ms)、(96.92±47.60ms)、(91.19±52.93ms)；各组应变、应变率、室壁运动延迟时间的测值的比较均无统计学意义(P>0.05)。
2.本研究获得147例正常胎儿心室整体和局部心肌速度的测值。左心室的整体、室间隔基底部、室间隔中部、室间隔心尖部、游离壁心尖部、游离壁中部、游离壁基底部的速度分别为(1.41±0.29cm/s)、(2.35±0.99cm/s)、(1.73±0.92cm/s)、(0.81±0.37cm/s)、(0.58±0.30cm/s)、(1.19±0.60cm/s)、(1.80±0.87cm/s)；右心室的整体、室间隔基底部、室间隔中部、室间隔心尖部、游离壁心尖部、游离壁中部、游离壁基底部的速度分别为(1.53±0.33cm/s)、(2.40±1.18cm/s)、(1.81±0.89cm/s)、(1.06±0.60cm/s)、(0.78±0.41cm/s)、(1.27±0.51cm/s)、(1.84±0.79cm/s)；左心室整体和六个节段心肌速度各测值之间的比较有统计学差异(F=133.463,P=0.000),右心室整体和六个节段心肌速度各测值之间的比较有统计学差异(F=78.198,P=0.000)；左心室和右心室(整体、室间隔心尖部、游离壁心尖部)速度测值的比较有统计学意义(1.41cm/s VS 1.53cm/s, t=3.033, P=0.003;0.81cm/s VS 1.06cm/s, t=4.458,P=0.000; 0.58cm/s VS 0.78cm/s, t=4.721,P=0.000)；速度测值(室间隔基底部、室间隔中部、游离壁中部、游离壁基底部)在左心室和右心室之间比较的均无统计学意义(P>0.05)；左、右心室心肌的速度由基底部到心尖呈递减趋势。
3.本研究获得145例正常胎儿左心室(LV)游离壁、室间隔(Septal)和右心室(RV)游离壁测值应变、应变率、收缩期速度、舒张期速度的测值。左心室游离壁、室间隔、右心室游离壁房室瓣瓣环处纵向收缩期速度(Vs)的VVI测值分别为(1.11±0.72cm/s)、(1.24±0.50cm/s)、(1.23±0.59cm/s)；左心室游离壁、室间隔、右心室游离壁房室瓣瓣环处纵向舒张期速度(Vd)的VVI测值分别为(1.16±0.67cm/s)、(1.22±0.64cm/s)、(1.16±0.64cm/s)；左心室游离壁、室间隔、右心室游离壁中部纵向应变(S)的VVI测值分别为(-15.93±6.66%)、(-15.56±6.79%)、(-15.89±2.06%)；左心室游离壁、室间隔、右心室中部纵向应变率(SR)的VVI测值分别为(-2.17±0.55/s)、(-2.10±0.64/s)、(-2.08±0.76/s)；Vs、Vd、S、SR测值的各组间比较均无统计学意义(P>0.05)。
4.145例正常胎儿心室心肌整体和局部的运动速度与孕周均呈正相关(P<0.01),说明胎儿心肌运动速度和孕周密切相关,随着孕周的增加而增加。正常胎儿左、右心室的心肌整体和局部的应变率与胎心率均呈正相关(P<0.01),说明胎儿心肌应变率随着胎心率的增加而增加。
5.速度向量图：显示左心室速度的向量长度从基底段到心尖逐渐缩短,运动随着心室的收缩和舒张改变方向。应变—时间、应变率—时间、速度—时间曲线图：速度—时间曲线显示速度大小由室壁基底段向心尖段逐渐递减,应变、应变率曲线随节段的变化保持稳定。
[结论]
本研究测量了正常胎儿整体和局部心肌应变、应变率、运动速度、室壁运动延迟时间等参数,应变率随着胎心率的增加而增加,而应变在中晚孕期和正常胎心率范围内维持稳定,说明胎儿心肌形变能力在一定范围内具有代偿功能,以保证其心功能的稳定性。VVI技术作为测量分析心肌运动参数的工具,可克服检查角度的限制,从而评价心室整体和局部节段功能,为进一步探索先天性心脏病胎儿心肌运动,并为其心脏功能的定量评价提供理论依据和参考。
第二章超声速度向量成像技术对左心发育不良综合征心室纵向功能的研究
[目的]
左心发育不良综合征(Hypoplastic left heart syndrome, HLHS),是一种少见而危及生命的复杂先天性心脏畸形,约占先天性心血管畸形的14%,主要为左心流入和/或流出道发育不良引起的一组病变,包括左心室狭小、二尖瓣闭锁或狭窄、主动脉瓣闭锁、升主动脉发育不良等。本研究拟采用VVI技术对比测量分析正常胎儿和HLHS胎儿左、右心室的应变、应变率、速度及其室壁运动延迟时间等心肌运动参数来评价心肌运动,通过分析上述参数的变化探讨HLHS胎儿心肌功能的异常变化,为该病临床的产前遗传咨询、宫内治疗、出生后治疗、预后提供理论依据和参考。
[方法]
1.研究对象：2007年12月-2009年12月在深圳市妇幼保健院行中晚孕胎儿大体畸形筛查的56例孕妇,经产前超声检查诊断为HLHS;正常对照组孕妇的入选条件同第一章。病例组和对照组按孕周以1：1配对。
2.图像采集和VVI检测方法同第一章。
3.记录结果：获得整体心肌的速度向量图；记录左心室和右心室整体心肌的测量参数：应变、应变率、运动速度、室壁运动延迟时间；获得局部心肌运动的应变—时间、应变率—时间、速度—时间曲线。
4.产后随访和病理解剖追踪出生后手术及预后情况；要求在深圳市妇幼保健院引产者并签署胎儿尸体病理解剖同意书后行尸解。
[结果]
1. HLHS胎儿心肌测量参数的变化：正常胎儿和HLHS胎儿左心室整体心肌应变的平均差值为(4.08±6.71%)；应变率的平均差值为(0.53±0.86/s)；速度的平均差值为(-0.27±0.63cm/s)；正常胎儿和HLHS胎儿左心室应变、应变率、速度三个参数的室壁运动室壁运动延迟时间的平均差值分别为(801.75±335.26ms；923.08±477.22ms;850.80±391.45ms)。右心室整体应变的平均差值为(3.99±9.15%)；应变率的平均差值为(0.32±0.97/s)；速度的平均差值为(-0.76±0.70cm/s)；三个参数室壁运动延迟时间的平均差值分别为(95.07±74.98ms；75.40±77.41ms；89.27±82.00 ms)。正常胎儿和HLHS胎儿整体心肌应变、应变率、速度、室壁运动延迟时间的配对比较均有统计学意义(P<0.01)。
2.不同孕周对HLHS胎儿左心室(LV)和右心室(RV)整体运动速度、应变、应变率的影响：正常胎儿左心室和右心室的心肌整体运动速度均与孕周呈正相关(P<0.01), HLHS胎儿左心室和右心室的心肌整体运动速度与孕周无相关关系(P>0.05)；正常胎儿和HLHS胎儿左、右心室的心肌整体应变与孕周无相关关系(P>0.05)。以上说明正常胎儿心肌运动速度和孕周密切相关,随着孕周的增加而增加,而HLHS胎儿的各VVI参数和孕周无相关关系。
3.胎心率对HLHS胎儿左心室(LV)和右心室(RV)整体应变、应变率、运动速度的影响：正常胎儿左心室和右心室的心肌整体应变率测值与胎心率均呈正相关(P<0.01), HLHS胎儿左心室和右心室的心肌整体应变率值与胎心率无相关关系(P>0.05)；正常胎儿和HLHS胎儿左、右心室的心肌整体应变、运动速度与胎心率无相关关系(P>0.05)。以上说明正常胎儿心肌应变率和胎心率密切相关,随着胎心率的增加而增加,而HLHS胎儿的各VVI参数和胎心率无相关关系。
4.随访结果：本研究56例HLHS胎儿中,11例在深圳市妇幼保健院引产,其中有10例行病理解剖：34例在外院引产,均未行病理解剖；11例失访。行病理解剖的10例HLHS胎儿中,均有典型的心脏表现：左心变小(或无左心室,仅见一室间隔残端),主动脉瓣狭窄、发育不良或闭锁,升主动脉发育不良,二尖瓣狭窄、发育不良或闭锁,主动脉较主肺动脉内径变窄。其中Ⅰ型：主动脉瓣、二尖瓣均狭窄者7例；Ⅱ型：主动脉瓣、二尖瓣均闭锁者0例；Ⅲ型：主动脉瓣闭锁、二尖瓣狭窄者1例；Ⅳ型：主动脉瓣狭窄、二尖瓣闭锁者2例。
[结论]
HLHS胎儿左心发育不良,右心功能性代偿,左、右心室心肌应变、应变率、速度均降低,心室室壁运动延迟时间增加,心室运动的同步协调性降低。孕周对左、右心室肌速度无明显影响,胎心率对左、右心室肌应变率无明显影响,说明左心室肌发育不良,其心肌功能明显降低；而对于功能性右心室而言,可能是由于长期代偿下的心肌功能受损,或是我们没有将代偿期和失代偿期的心功能进行分类分析,这些尚待更深入的研究。综上述,应变、应变率、速度、室壁运动延迟时间是可以用来评估HLHS胎儿心肌功能的可靠参数,结合不同孕周和胎心率对这些参数的影响,可以更好的分析胎儿心肌所处的功能状态。
第三章超声速度向量成像技术对右心发育不良综合征心室纵向功能的研究
[目的]
右心发育不良综合征(Hypoplastic right heart, HRH),是一种少见的复杂先天性心脏畸形,它包括各种以右心室发育不良为共同特征的先天性心脏异常,主要为肺动脉瓣和/或三尖瓣的发育不良(闭锁或重度狭窄)。本研究拟采用VVI技术对比测量分析正常胎儿和HRH胎儿左心室和右心室的应变、应变率、速度及其室壁运动延迟时间等心肌运动参数来评价心肌运动,通过分析上述参数的变化探讨HRH胎儿心肌功能的异常变化,为该病临床的产前遗传咨询、宫内治疗、出生后治疗、预后提供理论依据和参考。
[方法]
1.研究对象：2007年12月-2009年12月在深圳市妇幼保健院行中晚孕胎儿大体畸形筛查的12例孕妇,经产前超声检查诊断为HRH；正常对照组孕妇的入选条件同第一章。病例组和对照组按孕周以1：3配对。
2.图像采集、VVI检测、记录结果、随访的方法同第二章。
[结果]
1.HRH胎儿心肌测量参数的变化：正常胎儿和HRH胎儿右心室整体心肌应变的平均差值为(4.02±1.63%)；应变率的平均差值为(0.70±0.15/s)；速度的平均差值为(-0.54±0.10cm/s)；应变、应变率、速度三个参数的室壁运动延迟时间的平均差值分别为(652.60±312.17ms；949.06±430.19ms；876.86±543.97 ms)；正常胎儿和HRH胎儿左心室整体心肌应变的平均差值为(1.28±1.18%)；应变率的平均差值为(0.24±0.16/s)；速度的平均差值为(-0.28±0.08/s)；应变、应变率、速度三个参数的室壁运动室壁运动延迟时间的平均差值分别为(78.58±13.62ms；89.12±18.45ms；128.57±14.06ms)。正常胎儿和HRH胎儿右心室整体应变、应变率、速度、室壁运动延迟时间的比较均有统计学意义(P<0.01)。正常胎儿和HRH胎儿左心室心肌应变、应变率、速度测值的比较均无统计学意义(P>0.05)；
2.不同孕周对HRH胎儿左心室(LV)和右心室(RV)整体运动速度、应变、应变率的影响：正常胎儿左心室和右心室的心肌整体运动速度与孕周呈正相关(P<0.01),HRH胎儿左心室和右心室的心肌整体运动速度与孕周无相关关系(P>0.05)；正常胎儿和HRH胎儿左、右心室的心肌整体应变、应变率与孕周无相关关系(P>0.05)。以上说明正常胎儿心肌运动速度和孕周密切相关,随着孕周的增加而增加,而HRH胎儿的各VVI参数和孕周无相关关系。
3.胎心率对HRH胎儿左心室(LV)和右心室(RV)整体应变、应变率、运动速度的影响：正常胎儿左心室和右心室的心肌整体应变率测值与胎心率呈正相关(P<0.01),HRH胎儿左、右心室的心肌整体应变率值与胎心率无相关关系(P>0.05)；正常胎儿和HRH胎儿左、右心室的心肌整体应变、速度与胎心率无相关关系(P>0.05)。以上说明正常胎儿心肌应变率和胎心率密切相关,随着胎心率的增加而增加,而HRH胎儿的各VVI参数和胎心率无相关关系。
4.随访结果：本研究12例HRH胎儿中,6例在深圳市妇幼保健院引产并行病理解剖：4例在外院引产,均未行病理解剖；2例失访。行病理解剖的6例HRH胎儿心脏均有典型的表现：右心室变小,三尖瓣狭窄、发育不良或闭锁,肺动脉瓣闭锁、狭窄或正常,主肺动脉内径较主动脉窄。其中,三尖瓣狭窄、肺动脉瓣闭锁者(Ⅰ型)2例；三尖瓣闭锁、肺动脉瓣狭窄(Ⅱ型)2例；三尖瓣狭窄而肺动脉瓣狭窄者(Ⅲ型)2例。
[结论]
HRH胎儿右心发育不良,左心功能性代偿,左、右心室心肌应变、应变率、速度均降低,心室室壁运动延迟时间增加,心室运动的同步协调性降低。孕周对左、右心室肌速度无明显影响,胎心率对左、右心室肌应变率无明显影响,说明右心室肌发育不良,其心肌功能明显降低；而对于功能性左心室而言,仍需将代偿期和失代偿期的心功能进行分类分析,这些尚待更深入的研究。综上述,应变、应变率、速度、室壁运动延迟时间是可以用来评估HRH胎儿心肌功能的可靠参数,结合不同孕周和胎心率对这些参数的影响,可以更好的分析胎儿心肌所处的功能状态。
第四章超声速度向量成像技术对心肌致密化不全心室纵向功能的研究
[目的]
心肌致密化不全(noncompaction of the ventricular myocardium, NVM)是由于胚胎初期正常心内膜和心肌发育停止所致的先天性心肌病,由于基因突变等因素使心肌的致密化过程失败,室壁肌层保留疏松状态。本研究旨在采用超声产前诊断NVM,结合VVI技术测量NVM产前心肌运动速度、应变、应变率、室壁运动延迟时间,通过测量研究上述参数来探讨NVM心肌功能的异常变化。
[方法]
1.研究对象：2007年12月-2009年12月在深圳市妇幼保健院行中晚孕胎儿大体畸形筛查的9例孕妇,经产前超声检查诊断为NVM,并由产后病理解剖证实的孕妇为病例组；正常对照组孕妇的入选条件同第一章。病例组和对照组按孕周以1：3配对。
2.图像采集、VVI检测、记录结果、随访的方法同第二章。
[结果]
1.NVM胎儿心肌整体测量参数和局部病变部位的变化：正常胎儿和NVM胎儿左心室整体应变的平均差值为(5.53±4.70%)；应变率的平均差值为(0.87±0.67/s)；速度的平均差值为(-0.44±0.09cm/s)；应变、应变率、速度三个参数室壁运动延迟时间的平均差值分别为(1713.70±272.68ms；1670.91±403.50ms;2051.44±336.05)。正常胎儿和NVM胎儿左心室局部病变部位应变的平均差值为(4.13±3.48%)；应变率的平均差值为(-1.08±0.66/s)；速度的平均差值为(-0.92±0.31cm/s)；应变、应变率、速度三个参数的室壁运动室壁运动延迟时间的平均差值分别为(1706.43±441.45ms；1874.00±396.74ms；2062.81±336.55)。正常胎儿和NVM胎儿心室整体应变、应变率、速度、室壁运动延迟时间的比较均有统计学意义(P<0.01)；正常胎儿和NVM胎儿心室局部应变、应变率、速度、室壁运动延迟时间的比较均有统计学意义(P<0.01)。
2.不同孕周对NVM胎儿心室整体运动速度、应变、应变率的影响：NVM胎儿心室整体心肌运动速度、应变、应变率均与孕周无明显相关关系(P>0.05)。
3.胎心率对NVM胎儿整体心肌应变率、应变、运动速度等参数的影响：本章的研究中,NVM胎儿心室整体心肌应变率、应变、运动速度与胎心率无相关关系(P>0.05),但是应变率有随胎心率的升高而增加的趋势。
4.随访结果：本研究9例HRH胎儿中,均在深圳市妇幼保健院引产并行病理解剖,均有典型的心脏表现：心室壁可见过多、粗大的肌小梁突入心室腔.其间可见深陷的小梁间隙,成网格状改变。
[结论]
NVM胎儿局部病变和整体心肌的应变、应变率、速度均降低,心室室壁运动延迟时间增加,心室运动的同步协调性降低。孕周对NVM胎儿心肌的速度无明显影响。NVM胎儿心肌的应变率随着胎心率的增高而增加,说明其心肌尚有一定的形变能力,以维持稳定的心输出量。本研究没有将代偿期和失代偿期的心功能进行分类分析,尚待更深入的研究。应变、应变率、速度、室壁运动延迟时间是可以用来评估HRH胎儿心肌功能的可靠参数,结合不同孕周和胎心率对这些参数的影响,可以更好的分析胎儿心肌所处的功能状态。
Background
Velocity vector imaging (VVI) is a newly developed offline analysis software package that allows evaluation of myocardial tissue motion and velocity without the limitations of Doppler echocardiography. It utilizes a combination of speckle tracking with complex geometric analysis to follow the myocardium through the cardiac cycle. It offers an intuitive analysis of myocardial mechanics.
During the past 25 years the rapid evolution of echocardiography has led to a greater understanding of fetal cardiac physiology. Traditionally fetal cardiac function has been measureed by subjective assessment of contractility and observation for hydrops fetalis. However, a precise understanding of fetal cardiac mechanics and function is lacking.
Myocardial tissue motion and velocities have now been investigated in the fetal heart with the first published report indicating its feasibility appearing in 1999 by Harada et al. Since that time a number of preliminary studies have been performed validating the technique and reporting normal longitudinal velocities. In a recent report, Di Salvo et al demonstrated that evaluation of strain and strain rate can also be measured in the fetus with limited variability. These Doppler-based techniques are subject to some technical limitations and are dependent on obtaining an optimal angle of interrogation. It offers an intuitive analysis of myocardial mechanics. However, VVI has not been well studied in normal fetus and there is few reports of its use in the fetal congenital heart disease.
Chapter 1 Evaluation of normal fetal cardiac function by velocity vector imaging
[Objectives] To investigate the application and the influencing factors of velocity vector imaging for evaluation of myocardial mechanics in the normal fetal ventricles.
[Methods] Selected were normal fetuses who underwent systemic ultrasonic examination in Shenzhen maternity and child healthcare hospital from December 2007 to December 2009.Two-dimensional 4-chamber images of the heart were interrogated offline using Syngo US Workplace VVI software. Measurements of global and segmental longitudinal velocity, strain, strain rate and opposing wall delay were performed on the left and right ventricle. Comparison was made between each segmental and global, and left and right ventricular measurement respectively. Learning curves of velocity, strain, and strain rate and velocity vector images were performed. Longitudinal strain, strain rate, and diastolic and systolic velocity were measured in the left ventricular free wall, ventricular septum, and right ventricular free wall. The correlation of above measurements with gestational weeks and fetal heart rate was analyzed.
[Results]
1. The measurements of global and segmental strain, strain rate, and opposing wall delay in left and right ventricles were obtained (n=147). There was no significant differences among groups (P>0.05). The strain of left ventricular global, base septal, mid septal, apical septal, apical free wall, mid free wall, base free wall were (-16.05±2.26%)、(-16.87±4.01%)、(-15.45±6.83%)、(-15.71±5.68%)、(-16.76±6.64%)、(-15.96±6.63%)、(-15.57±5.75%), respectively. The strain of right ventricular global, base septal, mid septal, apical septal, apical free wall, mid free wall, base free wall were (-16.13±1.78%)、(-16.04±2.90%)、(-16.06±6.79%)、(-16.28±1.95%)、(-16.51±2.28%)、(-15.89±2.06%)、(-15.71±3.36%), respectively. The strain rate of left ventricular global, base septal, mid septal, apical septal, apical free wall, mid free wall, base free wall were (-2.14±0.70/s)、(-2.06±0.84/s)、(-2.10±0.64/s)、(-2.26±0.75/s)、(-2.16±0.55/s)、(-2.21±0.79/s)、(-2.08±0.65/s), respectively. The strain rate of right ventricular global, base septal, mid septal, apical septal, apical free wall, mid free wall, base free wall were (-2.06±0.98/s)、(-2.24±1.13/s)、(-2.08±0.76/s)、(-2.10±1.42/s)、(-2.03±0.75/s)、(-1.96±1.17/s)、(-1.93±0.79/s).The time of opposing wall delay of left ventricular strain, strain rate and velocity were (94.30±3.93ms)、(93.68±3.17ms)、(92.22±4.31 ms).The time of opposing wall delay of right ventricular strain, strain rate and velocity were (93.23±51.81ms)、(96.92±47.60ms)、(91.19±52.93ms). There was no significant differences among groups (P>0.05).
2. The measurements of global and segmental velocity in left and right ventricles were obtained (n=147). The velocity of left ventricular global, base septal, mid septal, apical septal, apical free wall, mid free wall, base free wall were (1.41±0.29cm/s)、(2.35±0.99cm/s)、(1.73±0.92cm/s)、(0.81±0.37cm/s)、(0.58±0.30cm/s)、(1.19±0.60cm/s)、(1.80±0.87cm/s),respectively. The velocity of right ventricular global, base septal, mid septal, apical septal, apical free wall, mid free wall, base free wall were (1.53±0.33cm/s)、(2.40±1.18cm/s)、(1.81±0.89cm/s)、(1.06±0.60cm/s)、(0.78±0.41cm/s)、(1.27±0.51cm/s)、(1.84±0.79cm/s). There was significant differences among global and six segmental group in left ventricle (F=133.463, P=0.000) and in right ventricle (F=78.198, P=0.000). The comparison between left and right ventricular velocity (global, apical septal, apical free wall) showed significant differences (1.41cm/s VS 1.53cm/s, t=3.033, P=0.003; 0.81cm/s VS 1.06cm/s, t=4.458, P=0.000; 0.58cm/s VS 0.78cm/s, t=4.721, P=0.000). The comparison between left and right ventricular velocity (base septal, mid septal, mid free wall, base free wall) showed no significant differences (P>0.05).The velocity decreased from the base to apical ventricles.
3. The measurements of strain, strain rate, diastolic and systolic velocity, and opposing wall delay in the left ventricular free wall, ventricular septum, and right ventricular free wall were obtained (n=145). The systolic and diastolic velocity in the left ventricular free wall, ventricular septum, and right ventricular free wall were (1.11±0.72cm/s), (1.24±0.50cm/s), (1.23±0.59cm/s), (1.16±0.67cm/s), (1.22±0.64cm/s), (1.16±0.64cm/s), and the strain were (-15.93±6.66%), (-15.56±6.79%), (-15.89±2.06%), and strain rate were (-2.17±0.55/s), (-2.10±0.64/s), (-2.08±0.76/s). The paired comparison between groups showed no significant differences (P<0.01).
4. The gestational age had significant positive correlation with the velocity in normal fetus (n=145, P<0.01).The fetal heart rate had significant positive correlation with the strain in normal fetus (P<0.01).
5. Velocity vector images and learning curves of longitudinal velocity, strain, and strain rate were obtained. The learning curve showed that the velocity decreased from the base to the apex and that the strain and strain rate remained stable.
[Conclusions] Measurement of cardiac strain and strain rate using VVI can be applied to evaluate global and segmental ventricular motion and function.
Chapter 2 Evaluation of hypoplastic left heart syndrome in fetus by velocity vector imaging
[Objectives] To investigate the application of velocity vector imaging for evaluation of myocardial mechanics in hypoplastic left heart syndrome.
[Methods] Selected were fifty-six fetus who underwent systemic ultrasonic examination and had been diagnosed as hypoplastic left heart syndrome in Shenzhen maternity and child healthcare hospital from December 2007 to December 2009. The control was healthy pregnant women without contributable history. The case and control group were 1:1 paired. Two-dimensional 4-chamber images of the heart were interrogated offline using Syngo US Workplace VVI software. Measurements of global and segmental longitudinal velocity, strain, strain rate and opposing opposing wall delay were performed on the right and left ventricle. Comparison was made between each segmental and global, and left and right ventricular measurement respectively. Learning curves of velocity, strain, and strain rate and velocity vector images were performed. The correlation of above measurements with gestational weeks and fetal heart rate was analyzed.
[Results]
1. The comparison of global strain, strain rate, velocity, and opposing opposing wall delay between HLHS and control group showed significant differences (P<0.01). The mean differences of left ventricular strain, strain rate, and velocity between normal and HLHS fetus were (4.08±6.71%), (0.53±0.86/s), (-0.27±0.63cm/s). The mean differences of left ventricular opposing wall delay in strain, strain rate, and velocity between normal and HLHS fetus were (801.75±335.26ms,923.08±477.22ms, 850.80±391.45ms). The mean differences of right ventricular strain, strain rate, and velocity between normal and HLHS fetus were (3.99±9.15%), (0.32±0.97/s), (-0.76±0.70cm/s). The mean differences of right ventricular opposing wall delay in strain, strain rate, and velocity between normal and HLHS fetus were (95.07±74.98ms,75.40±77.41ms,89.27±82.00 ms).
2. The gestational age had no significant correlation with the velocity in HLHS fetuses (P>0.05).The fetal heart rate had no significant correlation with the strain rate in normal fetus (P>0.05).
[Conclusions] Measurement of VVI indices can be applied to evaluate global and segmental ventricular motion and function in the HLHS fetus.
Chapter 3 Evaluation of hypoplastic right heart syndrome in fetus by velocity vector imaging
[Objectives] To investigate the application of velocity vector imaging for evaluation of myocardial mechanics in hypoplastic right heart syndrome.
[Methods] Selected were twelve fetus who underwent systemic ultrasonic examination and had been diagnosed as hypoplastic right heart syndrome in Shenzhen maternity and child healthcare hospital from December 2007 to December 2009. The control was healthy pregnant women without contributable history. The case and control group were 1:3 paired. Two-dimensional 4-chamber images of the heart were interrogated offline using Syngo US Workplace VVI software. Measurements of global and segmental longitudinal velocity, strain, strain rate and opposing opposing wall delay were performed on the right and left ventricle. Comparison was made between each segmental and global, and left and right ventricular measurement respectively. Learning curves of velocity, strain, and strain rate and velocity vector images were performed. The correlation of above measurements with gestational weeks and fetal heart rate was analyzed.
[Results]
1. The comparison of global strain, strain rate, velocity, and opposing wall delay between HRH and control group in right ventricle showed significant differences (P <0.01). The mean differences of right ventricular strain, strain rate, and velocity between normal and HRH fetus were (4.02±1.63%), (0.70±0.15/s), (-0.54±0.10cm/s). The mean differences of right ventricular opposing wall delay in strain, strain rate, and velocity between normal and HRH fetus were (652.60±312.17ms,949.06±430.19ms,876.86±543.97 ms). The comparison of global strain, strain rate, velocity, and opposing wall delay between HRH and control group in left ventricle showed no significant differences (P>0.05).The mean differences of left ventricular strain, strain rate, and velocity between normal and HRH fetus were(1.28±1.18%),(0.24±0.16/s),(-0.28±0.08/s). The mean differences of left ventricular opposing wall delay in strain, strain rate, and velocity between normal and HRH fetus were (78.58±13.62ms,89.12±18.45ms,128.57±14.06ms).
2. The gestational age had no significant correlation with the velocity in HLHS fetuses (P>0.05).The fetal heart rate had no significant correlation with the strain rate in normal fetus (P>0.05).
[Conclusions] Measurement of VVI indices can be applied to evaluate global and segmental ventricular motion and function in the HRH fetus.
Chapter 4 Evaluation of noncompaction of the ventricular myocardium in fetus by velocity vector imaging
[Objectives]To investigate the application of velocity vector imaging for evaluation of myocardial mechanics in noncompaction of the ventricular myocardium.
[Methods] Selected were nine fetus who underwent systemic ultrasonic examination and had been diagnosed as noncompaction of the ventricular myocardium in Shenzhen maternity and child healthcare hospital from December 2007 to December 2009. The control was healthy pregnant women without contributable history. The case and control group were 1:3 paired. Two-dimensional 4-chamber images of the heart were interrogated offline using Syngo US Workplace VVI software. Measurements of global and segmental longitudinal velocity, strain, strain rate and opposing wall delay were performed on the right and left ventricle. Comparison was made between each segmental and global, and left and right ventricular measurement respectively. Learning curves of velocity, strain, and strain rate and velocity vector images were performed. The correlation of above measurements with gestational weeks and fetal heart rate was analyzed.
[Results]
1. The comparison of global and segmental strain, strain rate, velocity, and opposing wall delay between NVM and control group showed significant differences (P< 0.01).
2. The gestational age had no significant correlation with the velocity in HLHS fetuses (P>0.05).The fetal heart rate had no significant correlation with the strain rate in normal fetus (P>0.05).
[Conclusions] Measurement of VVI indices can be applied to evaluate global and segmental ventricular motion and function in the noncompaction of the ventricular myocardium fetus
引文
[1]Vannan MA, Pedrizzetti G, LiP, et al. Effect of cardiac resynchronization therapy on longitudinal and circumferential left ventricular mechanics by velocity vector imaging:description and initial clinical application of a novel method using high—frame rate B—mode echocardiographic images. Echocardiography,2005,22 (10):826-830.
[2]Bohs LN, Geiman BJ, Anderson ME, et al.Speckle tracking for multi— imensional flow estimation. Ultrasonics,2000,38 (128):369-375.
[3]Steel R, Ramnarine KV, Davidson F, et al. Angle—independent estimation of maximum velocity th rough stenosis using vector Doppler ultrasound. Ultrasound Med Bio 1,2003,29 (4):575-584.
[4]Steel R, Fish PJ, Ramnarine KV, et al. Velocity fluctuation reduction in vector Doppler ultrasound using a hybrid single/dual beam algorithm. IEEE Trans Ultrason Ferroelectr Freq Control,2003,50 (1):89-93.
[5]Younoszai AK, Saudek DE, Emery SP, Thomas JD Evaluation of myocardial mechanics in the fetus by velocity vector imaging. J Am Soc Echocardiogr 2008;21:470-474.
[6]Harada K, Tsuda A, Orino T, Tanaka T, Takada G. Tissue Doppler imaging in the normal fetus. Int J Cardiol 1999; 71:227-34.
[7]Chan LY, Fok WY, Wong JT, Yu CM, Leung TN, Lau TK. Reference charts of gestation—specific tissue Doppler imaging indices of systolic and diastolic functions in the normal fetal heart. Am Heart J 2005; 150:750-5.
[8]Huhta JC, Kales E, Casbohm A. Fetal tissue Doppler-a new technique for perinatal cardiology. Curr Opin Pediatr 2003,15:472-4.
[9]Paladini D, Lamberti A, Teodoro A, Arienzo M, Tartaglione A, Martinelli P. Tissue Doppler imaging of the fetal heart. Ultrasound Obstet Gynecol 2000, 16:530-5.
[10]Tutschek B, Zimmermann T, Buck T, Bender HG. Fetal tissue Doppler echocardiography:detection rates of cardiac structures and quantitative assessment of the fetal heart. Ultrasound Obstet Gynecol 2003; 21:26-32.
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[16]Tutschek B, Zimmermann T, Buck T, et al. Fetal tissue Doppler echocardiography:detection rates of cardiac structures and quantitative assessment of the fetal heart. Ultrasound Obstet Gynecol,2003,21:26-32.
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[1]Vannan MA, Pedrizzetti G, LiP, et al. Effect of cardiac resynchronization therapy on longitudinal and circumferential left ventricular mechanics by velocity vector imaging:description and initial clinical application of a novel method using high-frame rate B-mode echocardiographic images. Echocardiography,2005,22 (10): 826-830.
[2]Bohs LN, Geiman BJ, Anderson ME, et al. Speckle tracking for multi-dimensional flow estimation. Ultrasonics,2000,38 (128):369-375.
[3]Steel R, Ramnarine KV, Davidson F, et al. Angle-independent estimation of maximum velocity th rough stenosis using vector Doppler ultrasound. Ultrasound Med Biol,2003,29 (4):575-584.
[4]Steel R, Fish PJ, Ramnarine KV, et al. Velocity fluctuation reduction in vector Doppler ultrasound using a hybrid single/dual beam algorithm. IEEE Trans Ultrason Ferroelectr Freq Control,2003,50 (1):89-93.
[5]Friedman WF. The intrinsic physiologic properties of the developing heart. Prog Cardiovasc Dis 1972; 15:87-111.
[6]Younoszai AK, Saudek DE, Emery SP, Thomas JD:Evaluation of myocardial mechanics in the fetus by velocity vector imaging. J Am Soc Echocardiogr 2008;21:470-474.
[7]Harada K, Tsuda A, Orino T, Tanaka T, Takada G. Tissue Doppler imaging in the normal fetus. Int J Cardiol 1999; 71:227-34.
[8]Chan LY, Fok WY, Wong JT, Yu CM, Leung TN, Lau TK. Reference charts of gestation-specific tissue Doppler imaging indices of systolic and diastolic functions in the normal fetal heart. Am Heart J 2005; 150:750-5.
[9]Huhta JC, Kales E, Casbohm A. Fetal tissue Doppler-a new technique for perinatal cardiology. Curr Opin Pediatr 2003; 15:472-4.
[10]Paladini D, Lamberti A, Teodoro A, Arienzo M, Tartaglione A, Martinelli P. Tissue Doppler imaging of the fetal heart. Ultrasound Obstet Gynecol 2000;16:530-5.
[11]Tutschek B, Zimmermann T, Buck T, Bender HG. Fetal tissue Doppler echocardiography:detection rates of cardiac structures and quantitative assessment of the fetal heart. Ultrasound Obstet Gynecol 2003; 21:26-32.
[12]Di Salvo G, Russo MG, Paladini D, et al. Quantification of regional left and right ventricular longitudinal function in 75 normal fetuses using ultrasound-based strain rate and strain imaging. Ultrasound Med Biol 2005; 31:1159-62.
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[1]Vannan MA, Pedrizzetti G, LiP, et al. Effect of cardiac resynchronization therapy on longitudinal and circumferential left ventricular mechanics by velocity vector imaging:description and initial clinical application of a novel method using high-frame rate B-mode echocardiographic images. Echocardiography,2005,22 (10): 826-830.
[2]Bohs LN, Geiman BJ, Anderson ME, et al. Speckle tracking for multi-dimensional flow estimation. Ultrasonics,2000,38 (128):369-375.
[3]Steel R, Ramnarine KV, Davidson F, et al. Angle-independent estimation of maximum velocity th rough stenosis using vector Doppler ultrasound. Ultrasound Med Biol,2003,29 (4):575-584.
[4]Steel R, Fish PJ, Ramnarine KV, et al. Velocity fluctuation reduction in vector Doppler ultrasound using a hybrid single/dual beam algorithm. IEEE Trans Ultrason Ferroelectr Freq Control,2003,50 (1):89-93.
[5]Friedman WF. The intrinsic physiologic properties of the developing heart. Prog Cardiovasc Dis 1972; 15:87-111.
[6]Younoszai AK, Saudek DE, Emery SP, Thomas JD:Evaluation of myocardial mechanics in the fetus by velocity vector imaging. J Am Soc Echocardiogr 2008;21:470-474.
[7]Harada K, Tsuda A, Orino T, Tanaka T, Takada G. Tissue Doppler imaging in the normal fetus. Int J Cardiol 1999; 71:227-34.
[8]Chan LY, Fok WY, Wong JT, Yu CM, Leung TN, Lau TK. Reference charts of gestation-specific tissue Doppler imaging indices of systolic and diastolic functions in the normal fetal heart. Am Heart J 2005; 150:750-5.
[9]Huhta JC, Kales E, Casbohm A. Fetal tissue Doppler-a new technique for perinatal cardiology. Curr Opin Pediatr 2003; 15:472-4.
[10]Paladini D, Lamberti A, Teodoro A, Arienzo M, Tartaglione A, Martinelli P. Tissue Doppler imaging of the fetal heart. Ultrasound Obstet Gynecol 2000;16:530-5.
[11]Tutschek B, Zimmermann T, Buck T, Bender HG. Fetal tissue Doppler echocardiography:detection rates of cardiac structures and quantitative assessment of the fetal heart. Ultrasound Obstet Gynecol 2003; 21:26-32.
[12]Di Salvo G, Russo MG, Paladini D, et al. Quantification of regional left and right ventricular longitudinal function in 75 normal fetuses using ultrasound-based strain rate and strain imaging. Ultrasound Med Biol 2005; 31:1159-62.
[13]Piers CA Barker, Helene Houle, Jennifer S. Li, Stephen Miller, James Rene Herlong, Michael G.W. Camitta, et al. Global longitudinal cardiac strain and strain rate for assessment of fetal cardiac function:novel experience with Velocity Vector Imaging. Echocardiography 2009; 26:28-36.