胎儿心脏主动脉弓反向血流的病理意义

Pathological significance of retrograde flow in fetal aortic arch

目的通过分析主动脉弓部出现反向血流的疾病类型和血流动力学特点，总结胎儿心脏主动脉弓反向血流信号的病理意义。方法研究对象为2013年1月至2016年10月胎儿心脏病母胎医学研究北京市重点实验室多中心数据库中，经超声发现主动脉弓部反向血流的心内、外异常胎儿。排除心脏结构正常，无心外异常的胎儿。筛选报告中描述的，或诊断中包括主动脉弓部反向血流信号的病例图像。对筛选出的病例图像进行回顾和再次确认。彩色多普勒图像中，主动脉弓血流方向与导管血流方向不一致，即为反向血流信号。发现主动脉弓反向血流信号后，用频谱多普勒对反向血流信号的时相进行确认和分类，明确收缩期和舒张期，并按反向血流信号出现的心动周期时相分期（收缩中-末期、收缩期、舒张期、收缩期＋舒张期）。同时，对这些病例按心脏结构异常和心外异常进行病因分类。并追踪这些病例的临床结局。对本研究的数据采用描述性统计方法进行分析。 结果（1）21 607例中，超声检查提示主动脉弓反向血流信号的病例共62例（0.29%）。这62例平均孕周为（29.5±4.6）周，孕妇平均年龄为（26.1±2.9）岁。（2）62例中，心脏结构和/或功能异常者58例（93.5%），其中左心流出系统异常44例，左心容量明显减低但左心功能正常14例。心外异常4例（6.5%），均为胎儿循环-外周循环阻力异常，包括胎盘功能异常致胎儿生长受限（3例）和大脑动静脉瘘（1例）。（3）62例中，包含主动脉瓣重度狭窄或闭锁的病例（32例，51.6%），以及主动脉瓣缺如致大量返流（1例，1.6%）和大脑动静脉瘘（1例，1.6%），均可见主动脉弓反向血流信号充盈全部的主动脉弓部。其他类型病变的主动脉弓部反向血流主要出现在弓部中段至远段峡部（28例，45.2%）。（4）左心容量明显减低，但左心功能正常的胎儿（24例，38.7%）主动脉弓部反向血流出现在收缩中-末期。主动脉瓣重度返流或粗大冠脉瘘，以及胎儿外周循环阻力异常等病例（6例，9.7%），主动脉弓反向血流出现在舒张期。以左心流出系统梗阻为主的病例，主动脉弓反向血流出现在收缩期＋舒张期（32例，51.6%）。（5）62例胎儿中的46例（74.2%）终止妊娠（其中26例进行病理检查，心脏病理解剖均与胎儿心脏超声诊断一致），1例（1.6%）宫内停止发育，15例（24.2%）继续妊娠至出生，其中13例为足月分娩，2例早产。这15例中，1例因合并其他心外异常，于在新生儿期死亡；其余14例（4例行手术矫治）随访至2017年3月，生长发育、心脏功能等情况均未见异常。 结论胎儿期主动脉弓部出现反向血流信号主要见于心脏结构和/或功能异常和心外异常。不同疾病的主动脉弓部反向血流信号的血流动力学特点不同。临床上对于弓部反向血流信号应注意分析其血流动力学特点，结合超声表现，以明确病因诊断，提高胎儿心脏超声检查质量。

ObjectiveTo summarize the pathological significance of retrograde flow in fetal aortic arch by analyzing the associated diseases and hemodynamic characteristics.MethodsA retrospective study on retrograde flow in fetal aortic arch was conducted on fetuses with intra- or extra-cardiac abnormality. All data were collected from the database of Fetal Heart Disease Maternal Fetal Medicine Research Important Laboratories in Beijing from January 2013 to October 2016. Fetuses with normal cardiac structure and without extra-cardiac abnormality in late pregnancy were excluded from this study. Ultrasound images with description of retrograde flow in fetal aortic arch in report or presenting retrograde flow signal during scanning were recruited. All selected cases were reviewed and the diagnosis was reconfirmed. The signal of retrograde flow in the aortic arch was that the direction of blood flow in the aortic arch was inconsistent with that of the ductus arteriosus. Spectral Doppler was used to define systolic or diastolic retrograde flow and all cases were divided into four groups accordingly： middle-late systole, systole, diastole, systole＋diastole for analysis. The etiology of retrograde flow in the aortic arch was analyzed based on cardiac structure abnormality and extra-cardiac abnormality. Clinical outcomes were followed up. Descriptive statistics was used to analyze all the data.Results（1） Among 21 607 cases reviewed, 62 （0.29%） were recruited with the mean gestational age of （29.5±4.6） weeks and and average age of （26.1±2.9） years, respectively. （2） Fifty-eight （93.5%） of the 62 cases were diagnosed with cardiac structure and/or cardiac function abnormality, including 44 of left ventricular outflow abnormality and 14 of significantly reduced left ventricular volume with normal left ventricular function. The other four cases （6.5%） with extra-cardiac abnormality were all complicated with abnormal peripheral circulation resistance in fetal systemic circulation, which included intrauterine growth restriction resulting from placental insufficiency （three cases） and cerebral arteriovenous fistula （one case）. （3） Retrograde flow filling the whole aortic arch was found in 32 cases （51.6%） with severe aortic stenosis or atresia, one （1.6%） with severe aortic regurgitation caused by absence of aortic valve and one （1.6%） with cerebral arteriovenous fistula. Retrograde flow with other causes mainly presented in the middle part and the distal isthmus of the aortic arch. （4） Retrograde flow presented in the middle and late systole was observed in 24 cases （38.7%） of significantly reduced left ventricular volume with normal left ventricular function, while those presented in the diastole were found in cases with severe aortic regurgitation, large coronary fistula, or abnormal peripheral circulation resistance （six cases, 9.7%）. Thirty-two fetuses （51.6%）, diagnosed with left ventricular outflow tract obstruction, showed retrograde flow in both systole and diastole. （5） Among the 62 pregnancies, 46 （74.2%） were terminated, one （1.6%） ended due to fetal intrauterine death, and the other 15 （24.2%） continued to delivery （13 of term pregnancy, and two of preterm pregnancy）. Autopsies were performed on 26 out of the 46 terminated fetuses, and the results were consistent with the fetal echocardiography. Of the 15 newborns, one died due to extra-cardiac abnormality, and the other 14 （four underwent operation） remained well in development and heart function during follow-up until March, 2017.ConclusionsThe retrograde flow signal in the aortic arch is commonly seen in fetal cardiac structural and/or functional abnormality. Hemodynamic characteristics of the retrograde flow may vary depending on the etiology. Therefore, clinicians should pay attention to analyze the hemodynamics in combination with ultrasound findings to identify the etiology and to improve the accuracy of fetal echocardiography.