Application of Doppler echocardiography in the assessment of fetal cardiac disease

Pulsed Doppler echocardiography was used in conjunction with real-time two-dimensional and M-mode ultrasound techniques in 19 fetuses between 28 and 40 weeks of gestation. Of these, nine also had echocardiographic examination performed neonatally. In one fetus with complete heart block, pulsed Doppler echocardiography showed tricuspid regurgitation. The ventricular and atrial rates were accurately determined by M-mode ultrasound; pericardial effusion was noted in the two-dimensional examination. The left ventricular stroke volume, as measured by the Doppler technique, was 13.5 ml, and the minute output was 486 ml/min. In another fetus, Doppler studies assisted two-dimensional echocardiography in detecting pulmonary aneurysm. Neonatal echocardiography confirmed this and also showed the presence of tetralogy of Fallot. In three fetuses with ventricular ectopy, 30% to 50% reduction in the right ventricular stroke volume was recorded by the Doppler technique. This study demonstrates the clinical potential of pulsed Doppler echocardiography in assessing fetal cardiac disorders and justifies further investigation to define its clinical utility.     

Fetal echocardiography. I: Methods, limitations and indications

The prenatal detection of congenital heart disease is rather seldom, compared with other fetal malformations. The paper considers the necessity of the development of fetal echocardiography and presents therefore an introduction for the prenatal sonographer. The fetal cardiac characteristics are first analysed, before considering the possibilities and frontiers of the investigation. The different available sonographic methods like the real-time, M-mode, pulsed Doppler and color Doppler are discussed and the importance of each one is emphasized. The indications for fetal echocardiography are further enumerated, as well as the possible consequences resulting from the diagnosis of a heart abnormality. Because of the sophisticated ultrasound devices needed for a precise diagnosis as well as the optimal postnatal care, suspected fetuses have to be referred to centers specialised in perinatal medicine.     

Fetal two-dimensional Doppler echocardiography (colour flow mapping) and its place in prenatal diagnosis

One hundred and fifty fetuses between 16 and 38 weeks of gestation were studied by fetal echocardiography using colour-coded two-dimensional Doppler echocardiography. Two-dimensional, M-mode, and Doppler spectral analyses were also performed. In 14 fetuses, structural and/or functional abnormalities were detected. Abnormalities were correctly ruled out in all the other fetuses. The advantages of two-dimensional Doppler echocardiography are (1) rapid screening for flow abnormalities in the fetal heart, and thus shortening of the Doppler examination time; (2) rapid diagnosis of valvular regurgitation, valvular stenosis, and abnormal shunting of blood across the interatrial and interventricular septa; and (3) facilitation of the diagnosis of complex congenital heart defects which in certain cases is possible only by using two-dimensional Doppler echocardiography.     

胎儿心律失常的超声心动图检测及其临床意义

目的 探讨超声心动图检测对胎儿心律失常的诊断价值及临床意义。方法 采用超声心动图对725例胎龄16-41周临床疑诊为心律失常或存在其他异常的胎儿进行检测。结果 共检出胎儿心律失常90例。其中,期前收缩72例(房性期前收缩65例,室性期前收缩7例),心动过缓9例,心动过速6例,2:1房室传导阻滞2例,心房扑动1例。4例心动过缓胎儿并发先天性心血管畸形患者,2例在随访过程中死于宫内(尸体解剖证实为单心室伴肺动脉瓣狭窄1例,心脏横纹肌瘤1例),2例终止妊娠(尸体解剖证实为二尖瓣闭锁1例,共同房室通道1例)。1例胎龄38周心房扑动胎儿经吸氧及严密监护24h后,心律失常无缓解,立即行剖宫产术,出生后应用西地兰后心律转为窦性。其余85例胎儿心律失常均为阵发性,不伴有胎儿心脏形态、结构畸形及胎儿水肿,均足月出生,出生后听诊均未闻及心脏杂音及心律失常。结论 胎儿超声心动图是产前检查胎儿心律失常的可靠的无创性影像技术,其应用有助于早期检出并指导心律失常胎儿的处理。     

Echocardiographic detection of fetal cardiac arrhythmias]

Using real-time directed M-mode and Doppler echocardiography we identified cardiac arrhythmias in 10 fetuses. One had signal tachycardia, one bradycardia, 5 supraventricular premature contractions, and 2 ventricular premature contractions (VPC), which were all self-limited. The diagnosis of VPC in one case was based on premature ending of foramen ovale flap's 2 nd wave on M-mode recording. All cases carried a favorable prognosis except the one with VPC who had a small ventricular septal defect overlooked prenatally. The 10 th case had II degrees atrioventricular block complicated by heart failure and died in utero. This study showed that most arrhythmias can be detected antenatally by analysing atrioventricular contraction sequences. It also proved that the characteristic M-mode pattern of foramen ovale flap is of value in evaluating the types of arrhythmias.     

Early prenatal diagnosis of major cardiac anomalies in a high-risk population

OBJECTIVE: To examine the accuracy of early fetal echocardiography performed in a high-risk population combining transvaginal and transabdominal routes. METHODS: A series of 330 high-risk pregnancies were screened by transvaginal and transabdominal scan at 12-17 weeks' gestation in a prospective multicentre trial in Spain between September 1999 and May 2001. A total of 334 fetal heart examinations were performed, including four twin pregnancies. Maternal age ranged from 17 to 46 years (mean 33 years with 36% of women over 34 years). The median gestational age at scan was 14.2 weeks (range 12-17 weeks). For each fetus, visualization of the four-chamber view, the origin of the great arteries, aortic and ductal arches and systemic venous return was attempted in a segmental approach. B-mode and colour/pulsed Doppler flow imaging were used in all cases. The duration of complete heart examination was less than 30 minutes. The examinations were performed by three experienced operators. Reliability was assessed by conventional transabdominal echocardiography at 20-22 weeks, by postnatal follow-up in the first three months of life, and/or by autopsy in cases of termination of pregnancy. RESULTS: The rate of successful visualization of the fetal heart was 94.6% (316/334). In 48 out of 334 (14.4%) fetuses the final diagnosis was abnormal. In 38 out of 48 (79.2%) cases with heart defects the diagnosis was suspected at early echocardiography. In the group with congenital heart defects, 27 cases had an abnormal karyotype (56.3%) and 31 cases showed extracardiac anomalies (64.6%). There were 10 false-negative cases at early scan. There were no false-positive diagnoses. CONCLUSIONS: This experience stresses the usefulness of early fetal echocardiography when performed by expert operators on fetuses specifically at risk for cardiac disease. The high rate of successful visualization of the fetal heart provides a reliable diagnosis of major cardiac defects at this early stage of pregnancy.     

Color Doppler of the splenic artery in the prenatal diagnosis of heterotaxic syndromes

The objective of this paper is to determine whether color and pulsed Doppler of the splenic artery is helpful in the prenatal diagnosis of polysplenia or asplenia in heterotaxic syndromes. Over a 3-year period, localization of the splenic artery by color and pulsed Doppler was attempted on all fetuses with the diagnosis of heterotaxic syndromes. Postnatal follow-up was obtained on all neonates. The diagnosis of heterotaxic syndromes was performed on eight fetuses during the study period. Mean gestational age at diagnosis was 20.1 weeks. All fetuses had situs ambiguous and complex cardiac abnormalities. All pregnancies were managed expectantly and none were terminated. The splenic artery was imaged by color and pulsed Doppler in 6 of 8 fetuses, all with one or multiple spleens confirmed postnatally. The splenic artery could not be imaged in two fetuses, both with asplenia confirmed postnatally. The perinatal mortality rate was 88% (7 of 8) and the one surviving infant is currently alive and well at 3 years of age. Color and pulsed Doppler of the splenic artery can aid in the prenatal diagnosis of heterotaxic syndromes. This information is of value and should result in improved prenatal counseling and management of affected pregnancies.     

Validation of noninvasive fetal renal artery flow measurement by pulsed Doppler in the lamb.

OBJECTIVE: Our objective was to evaluate the accuracy of quantitative measurement of blood flow of the left renal artery in the fetal lamb by means of range-gated, two-dimensional pulsed Doppler ultrasonography. STUDY DESIGN: Doppler measurements were compared with invasive measurements obtained with a perivascular flow probe (Transonic) placed on the fetal renal artery. Renal blood flow was manipulated acutely either by volume expansion or depletion or by means of pharmacologic agents. With each manipulation values of the left fetal renal artery blood flow were obtained with both methods. The size of the fetal renal artery was determined by postmortem examination. RESULTS: A total of 36 paired flow measurements were obtained on five fetuses. One fetus had only Transonic determination of renal blood flow. Pulsed Doppler ultrasonography blood flow and transit-time ultrasonography blood flow estimations were correlated (F = 82.4, R2 = 0.73, p < 0.001). CONCLUSION: This study suggests that two-dimensional pulsed Doppler can reliably estimate renal blood flow in the fetal lamb.     

The antenatal diagnosis of congenital heart disease using fetal echocardiography: is color flow mapping necessary?

Doppler color flow mapping is widely used in fetal echocardiography. We studied the impact of color flow mapping on fetal cardiac diagnosess. Between January 1, 1989 and June 30, 1990, we performed 854 fetal echocardiograms on 776 fetuses. Color flow mapping was used in 45 of 48 fetuses diagnosed as having cardiac abnormalities. Scans were reviewed to assess how color flow mapping influenced the ultimate diagnoses. Color flow mapping was essential to the correct anatomical diagnoses in 13 fetuses (29%), helpful but not essential in 21 (47%), and added little to two-dimensional examination alone in 11 (24%). It was essential in determining the course and flow direction in the great vessels when outflow obstruction was present or with transposition, and it was helpful but not essential in locating small jets of atrioventricular valve regurgitation. It was not helpful when the anatomical abnormalities were clearly identified from two-dimensional examination alone. We conclude that color flow mapping is helpful in the delineation of anatomical diagnoses in three-quarters of cases of fetal heart disease, particularly when the great vessels are abnormal. It may speed examinations by directing pulsed Doppler sampling. We did not find it essential to the proper recognition of anatomically abnormal hearts.     

Right ventricular dysfunction in human fetal compromise

Fetal M-mode echocardiography was performed in 13 pregnancies complicated by intrauterine distress. Absent end-diastolic blood velocity in the fetal descending aorta was documented by pulsed Doppler examinations. The right ventricular fractional shortening of these fetuses was decreased and the ratio of the right/left ventricular end-diastolic diameters was increased. The left ventricular size and myocardial contractility did not differ from normal pregnancy. These findings reveal that relative right ventricular heart dysfunction is associated with severe intrauterine distress.     

Prenatal diagnosis of congenital fetal arrhythmias by simultaneous pulsed Doppler velocimetry of the fetal abdominal aorta and inferior vena cava

Various methods have been used for the diagnosis of congenital fetal arrhythmias. Currently, M-mode echocardiography is the most widely used method. However, good tracings are often difficult to obtain because of unfavorable fetal positions, resulting in long durations of examination. In early gestation, the fetal heart is often too small for clear M-mode echocardiography. Doppler velocity waveforms of the fetal inferior vena cava represent the right atrial activity, whereas those of the aorta reflect ventricular contraction. Because of the proximity of the vessels, it is easy to obtain simultaneous recording in opposite channels of Doppler waveforms from both vessels. A visual relationship between the atrial and ventricular contractions may be clearly established and a diagnosis may be made. The findings of simultaneous pulsed Doppler velocimetry of the fetal aorta and inferior vena cava were assessed in different types of congenital fetal arrhythmia: congenital heart block, premature atrial ectopic contractions, premature ventricular ectopic contractions, and supraventricular tachycardia. The correct diagnosis was made as early as 13 weeks' gestation, showing the application of this method in early pregnancy.     

Congenital heart disease and fetal thoracoabdominal anomalies: associations in utero and the importance of cytogenetic analysis.

We examined the frequency with which congenital heart disease (CHD) and cytogenetic abnormalities were found associated with omphalocele, gastroschisis, duodenal atresia and posterior diaphragmatic hernias. We performed fetal echocardiograms on 80 patients with these diagnoses and found congenital heart disease in 13 of 37 with omphalocele (35%), 2 of 17 with gastroschisis (12%), 4 of 15 with duodenal atresia (27%), and 2 of 11 with posterior diaphragmatic hernia (18%). Karyotypes were obtained in 74 and were abnormal in 24 (32%). Although most fetuses with these extracardiac malformations and abnormal karyotypes had associated CHD, many did not. Normal karyotypes were found in 69% of fetuses with CHD and omphalocele, and 50% of fetuses with CHD and duodenal atresia. We conclude that CHD may be present in fetuses with extracardiac malformations whether or not the karyotype is normal and that the prenatal evaluation of fetuses with these lesions should include both karyotype and fetal echocardiography. Although karyotypes play an important role in prenatal diagnosis, they are not predictive of normal cardiac structure when normal in the abnormalities studied. Even when the karyotype is normal in the presence of these abnormalities, fetal echocardiography is indicated.     

Pulmonary arterial Doppler velocimetry in fetuses with lung hypoplasia.

OBJECTIVE: The aim of the study was to examine Doppler flow velocity waveforms in the main stems of the pulmonary arteries in fetuses with autopsy-proven lung hypoplasia and to find out whether in these conditions typical patterns can be found. STUDY DESIGN: Doppler spectra were derived from the main stem of the right or left pulmonary artery in fetuses at high-risk for lung-hypoplasia. The following Doppler parameters were analyzed and compared to reference ranges: peak systolic velocity, acceleration time, time velocity integral, end-systolic reverse flow, pulsatility index (PI). Pulmonary hypoplasia was found in nine cases at autopsy after termination of pregnancy (19-23 weeks). According to etiology, three groups were considered: (A) bilateral renal malformations (n=4), (B) congenital diaphragmatic hernia (n=2), and (C) miscellaneous malformations including heart defects (n=3). RESULTS: The following Doppler parameters were found: normal values in end-systolic reversal flow in all cases, decreased peak systolic velocity and acceleration time in 3/9, decreased time velocity integral in 4/9 and increased pulsatility index in 6/9. Considering the etiology of pulmonary hypoplasia the pulsatility index was found to be the most sensitive, since all fetuses in groups A and B had an abnormal PI. CONCLUSIONS: Human fetuses with renal malformations and diaphragmatic hernia associated with lung hypoplasia show as early as 19-23 weeks of gestation an abnormal Doppler spectrum in the main stems of the pulmonary arteries. Increased PI is the best parameter to detect flow abnormality in this condition. Since the Doppler spectrum depends on cardiac anatomy and function, PI in lung hypoplasia seems to be reliable only when cardiac defects are absent.     

Prenatal diagnosis and management of congenital heart disease

Thirty-two fetuses were diagnosed as having congenital heart disease (CHD). The major indications for level II echocardiography other than suspected cardiac abnormalities were fetal malformations, nonimmune hydrops and cardiac arrhythmia. Only three patients had a previous history of fetal CHD. No false-abnormal diagnosis of severe CHD was made. Aortic arch anomalies represented the major diagnostic problem among the six correct but incomplete diagnoses. Sixty-one percent of the fetuses were growth retarded, thus confirming the severity of their CHD. Chromosomal anomalies and extracardiac malformations were associated in 19% and 44% of the fetuses, respectively. Obstetric management and fetal prognosis in cases of extracardiac malformations were greatly influenced by the diagnosis of CHD. The poorest perinatal outcome was associated with heart failure. The only intrauterine deaths occurred in that group, and only one neonate survived. The outcome was more favorable in neonates without other malformations or heart failure. Four of ten (40%) of those neonates survived, while the overall perinatal survival rate was 24%.     

Hemodynamic changes in the fetal arteries during the second half of pregnancy assessed by Doppler velocimetry

The applicability of Doppler velocimetry has been well established regarding intrauterine growth restriction and fetal hypoxia. This method can also be used to determine fetal anemia and cardiac malformations. The main fetal arteries evaluated by Doppler velocimetry are the middle cerebral artery and the umbilical artery. However, the fetal aorta is responsible for the distribution of blood flow to the upper and lower extremities of the human body and should also be properly valued. In order to characterize abnormalities in the arteries of high-risk fetuses, it is necessary to know the hemodynamic modifications of normal fetuses. On this basis, the authors performed a review of fetal hemodynamics evaluated by Doppler velocimetry in the fetal aorta and middle cerebral and umbilical arteries during the second half of pregnancy. The study of fetal vessels by Doppler velocimetry indirectly evaluates the hemodynamic changes occurring in fetuses at risk. In this respect, we emphasize the changes in Doppler velocimetry occurring in fetal anemia, in restricted intrauterine growth, and in normal fetuses.     

Fetal and neonatal cardiac assessment with Doppler

During recent years, Doppler ultrasound has become an instrument with which the fetal and neonatal cardiovascular system can be examined noninvasively. In fetuses with suspected cardiac anomalies, Doppler examinations can be used to complement two-dimensional and M-mode studies. Information derived from human fetal intracardiac studies has established that the human fetal heart is right-heart dominant, less compliant than the adult heart, and changes with advancing gestation. Much work remains to be performed to use this information to better manage ongoing pregnancies, and to optimize transition to neonatal life.     

Fetal echocardiography: accuracy and limitations in a population at high and low risk for heart defects.

OBJECTIVE: Our objective was to assess the accuracy of prenatal echocardiography in detecting congenital heart defects in patients at high and low risk for structural cardiac anomalies. STUDY DESIGN: Sixty-nine consecutive fetuses with congenital heart defects who had had prenatal ultrasonography at greater than or equal to 18 weeks' gestation were evaluated to determine the accuracy of prenatal ultrasonography in identifying structural cardiac defects. Thirty-nine patients were at high risk and 30 patients were at low risk for cardiac anomalies. All fetuses were scanned with standard four-chamber and outflow tract views. Data concerning extracardiac anomalies and karyotypic abnormalities were tabulated. The accuracy of the four-chamber view alone in identifying congenital heart defects was evaluated. RESULTS: Fifty-seven of 69 fetuses (83%) were prenatally identified ultrasonographically as having a heart defect. There was no difference in the sensitivity of detecting cardiac anomalies between high-risk and low-risk groups. When the four-chamber view was used, only 63% of fetuses were recognized as having an abnormal heart. Extracardiac anomalies were noted in 36% and karyotypic abnormalities in 17% of patients. CONCLUSION: The four-chamber and outflow tract views done routinely in an ultrasonography laboratory seeing a mixed population of patients was successful in detecting 83% of fetuses with structural cardiac malformations. Because 43% of the fetuses with heart defects were referred for low-risk indications, systematic ultrasonographic examination of the fetal heart should not be reserved only for those at high risk.     

Role of fetal echocardiography in the management of isolated fetal heart block with ventricular rate <55 bpm.

Persistent bradycardia is an uncommon cardiac problem in fetuses but carries a high mortality in those with a ventricular rate <55 bpm. Fetal heart block is one of the most common causes of persistent fetal bradycardia (PFB). An optimal method for assessing and monitoring cardiovascular compensation in the setting of PFB due to heart block has not been fully established. We report the application of two-dimensional and Doppler echocardiography in close monitoring of cardiac function and hemodynamics in a third-trimester fetus with a ventricular rate <55 bpm due to heart block, which assisted in successful management of the pregnancy to term. Hemodynamic and cardiac adaptive changes in compromised fetuses, particularly due to heart block, are discussed.     

心脏轴测定在胎儿先天性心脏病产前超声诊断中的临床意义

目的探讨超声心动图测定心脏轴变化在胎儿先天性心脏病（先心病）产前诊断中的临床意义。方法应用Ａｃｕｓｏｎ１２８×Ｐ／１０彩色多普勒超声诊断仪检查５１８例胎龄１８～４０周的先心病高危胎儿和９０例正常胎儿,在心脏超声四腔观基础上测定胎儿心脏轴,并从多切面观察胎儿心内结构,以确定胎儿有无先心病。结果正常胎儿心脏轴为（４４．８±１０．３）度,先心病胎儿心脏轴为（５８．１±１５．７）度,两者比较,差异有显著性（Ｐ＜０．０１）。单纯四腔观检测胎儿先心病的敏感性为６８．５％,应用心脏超声四腔观加心脏轴测定检测胎儿先心病的敏感性为９１．４％,两者比较,差异有显著性（Ｐ＜０．０５）;５１８例先心病高危胎儿中,产前超声正确诊断先心病３４例,假阳性１例,假阴性１例。结论正常胎儿心脏轴范围２０～７５度,如心脏轴＞７５度,应高度怀疑胎儿先心病;心脏轴测定在胎儿先心病筛查中具有重要作用,可作为一种常规测量指标。     

Screening performance of first trimester nuchal translucency, ductus venosus blood flow and tricuspid regurgitation for cardiac defects

The present article summarises current knowledge on the risk of fetal cardiac malformations in fetuses with increased nuchal translucency (NT), abnormal ductus venosus blood flow pattern and tricuspid regurgitation. The risk of congenital heart disease (CHD) increases with increasing NT. However, nuchal translucency screening is only modestly efficient in the detection of congenital heart disease in low-risk pregnancies. If the nuchal translucency is normal, abnormal ductus venosus blood flow and tricuspid regurgitation show low sensitivities as single screening parameters. The combination of all 3 markers might increase the detection rates. Fetal echocardiography at 20 weeks of gestation is recommended in foetuses with an NT ≥95th percentile, as the incidence of CHD increases 2.5-fold. When the NT measurement is ≥99th percentile, the risk of CHD increases 10-fold. In this high-risk group and in fetuses with tricuspid regurgitation and/or an abnormal DV flow pattern along with an increased NT, first or early second trimester echocardiography performed by experts is warranted. The early examination of the fetal heart should be completed by a detailed echocardiogram at around 20 weeks of gestation.