Preliminary investigations into a new method of functional assessment of the fetal heart using a novel application of 'real-time' cardiac magnetic resonance imaging

OBJECTIVES: Because of quantitative echocardiographic limitations of fetal ventricular volumes as well as poor windows, we sought to determine if real-time magnetic resonance imaging (MRI) could be used. METHODS: Real-time, functional, true fast imaging with steady-state precession, cardiac MRI was performed on 2 fetuses (one with hypoplastic left heart syndrome and one with ductal constriction). Fetal echocardiography was performed and cardiac index by Doppler was used to validate volume measures by MRI. RESULTS: This technique was able to visualize the beating heart and assess ventricular volumes. Cardiac index and assessment of right ventricular hypertrophy and dilation by echocardiography were consistent with the ventricular volumes and right ventricular hypertrophy obtained by cardiac MRI. CONCLUSION: Real-time, functional fetal cardiac MRI is possible and can be used to quantitatively assess ventricular volumes and cardiac index in utero.     

Fetal cardiac asymmetry: a marker for congenital heart disease

Objective: To determine the sensitivity of prenatally detected fetal cardiac asymmetry as a sonographic marker for congenital heart disease.Methods: The normal ratios of pulmonary artery to aorta diameters and of right ventricle to left ventricle diameters were derived from normal fetuses scanned at 17 weeks or more in a 65-month period. Cross-sectional diameters of cardiac ventricles and great arteries were measured at the level of the valves at the time of the scan. Fetuses with confirmed cardiac anomalies detected prenatally during the study were examined to identify how many had cardiac asymmetry, determined by abnormal ratios.Results: Linear regression analysis of the group of 881 normal fetuses showed the normal pulmonary artery to aorta diameter ratio remained constant throughout pregnancy and the normal right ventricle to left ventricle ratio increased slightly with progressing gestational age. The 90% confidence intervals were 0.79, 1.24 for the right ventricle to left ventricle ratio and 0.84, 1.41 for the pulmonary artery to aorta ratio. Of the 73 fetuses with abnormal hearts, 66% had either ventricular or great artery asymmetry (at least one of the two ratios was abnormal). However, if no asymmetry was present, the cardiac defect was more likely to be a minor one.Conclusion: Cardiac asymmetry was present in two-thirds of fetuses with cardiac anomalies diagnosed prenatally. If cardiac asymmetry is found, a more thorough examination of the fetal heart is indicated.     

Real-time 3-D echocardiographic evaluation of the fetal heart using instantaneous volume-rendered display

AIM: Using new real-time 3-D fetal echocardiography with instantaneous volume-rendered display, we evaluated the heart anatomy of a number of normal fetuses during pregnancy. METHODS: Eighteen normal fetuses in 17 pregnancies (16 singletons and one twin) at 18-38 weeks' gestation were studied using a transabdominal real-time 3-D ultrasound machine. This machine proved capable of providing continuous 3-D sonographic images every 0.05 and 0.035 s without the need for an external workstation or other additional, costly equipment. For each patient, the fetal heart was first monitored using conventional 2-D echocardiography and was monitored again within 10 min using real-time 3-D echocardiography. RESULTS: Consecutive real-time 3-D images showing a four-chamber view, long-axis view, short-axis view, and right ventricular outflow tract view were obtained in 100%, 66.6%, 38.8%, and 22.2% of fetuses in the study, respectively. Morphological changes to each atrium or ventricle could be observed clearly and in detail throughout the cardiac cycle. The opening and closing of each valve were clearly visible. Moreover, these observations could be made from any direction. CONCLUSIONS: Real-time 3-D echocardiography provides a novel means for evaluation of the fetal heart in 3-D in real time in the second and third trimester of pregnancy. Real-time 3-D echocardiography may be an important modality in future fetal cardiac research and in evaluation of congenital heart disease in the fetus.     

Right Fetal Cardiac Axis: Clinical Significance and Associated Findings

Objective: To ascertain the clinical significance of right fetal cardiac axis.Methods: Fetal cardiac axis was assessed prospectively in ultrasound examinations of 16,562 fetuses over a 6-year period.Results: Twenty-two fetuses had a right cardiac axis. When classified by ventricular and atrial configuration, six fetuses had mirror-image hearts with situs inversus, 12 had rotation of the heart axis alone, and four had inversion of the ventricles. Fourteen of the 22 had underlying structural cardiac defects, most of which were atrioventricular septal defects, double outlet right ventricles, or common atria. The chromosomes and/or phenotypes of all 22 were normal. All four fetuses with polysplenia and asplenia died. Major extracardiac defects were few (two) but lethal.Conclusion: Right cardiac axis in the fetus is associated with a high incidence of structural cardiac defects. In the absence of severe extracardiac defects, polysplenia, or asplenia, neonatal outcome was good.     

Intracardiac echogenic focus and its location: association with congenital heart defects

Purpose: Significance of intracardiac echogenic focus (ICEF) in the fetal heart remains controversial. We aimed to investigate whether the location of ICEF is associated with fetal cardiac structure defects (CSDs) in low-risk pregnant women.

Materials and Methods: A retrospective cohort study was conducted. Singleton pregnancies with normal values of triple fetal serum markers were included. 758 of 9782 fetuses with ICEF were reviewed for involvement of three ICEF locations (left, right, and bilateral ventricles (BVs)) in CSDs. χ² or Fisher’s exact test was performed for statistical analysis.

Results: ICEF prevalence was 7.7% and its location was most frequently in the left ventricle (LV) (84.8%), followed by the BV (11.6%) and the right ventricle (RV) (3.6%). No statistically significant difference was found between the ICEF location and maternal age (χ²?=?3.92, p-value?=?.1409). There were cardiac defects with an isolated echogenic focus in 24 of 758 fetuses (3.2%). Significant difference for CSDs was observed among groups of RV, LV, and BV (p-fisher?=?.0146).

Conclusions: Significantly more CSDs cases were identified in fetuses with ICEF in RV. Further investigation is warranted to examine the histological characteristics of fetal echogenic focus in the RV.     

Fetal cardiac function assessed by spatio-temporal image correlation

Background  

Three-dimensional (3D) and four-dimensional (4D) ultrasound have been proposed to be valuable tools for the examination of fetal heart. Spatio-temporal image correlation (STIC) is a technique that adds a time component to 3D ultrasound imaging of the fetal heart, so we can evaluate cardiac structures as a 4D cine sequence containing information of one full cardiac cycle. STIC gives the investigator the opportunity to freeze the displayed cardiac loop in end-diastolic and end-systolic phases. By STIC, 3D measurements of both the left and right ventricle can be used to calculate fetal heart stroke volume, cardiac output and ejection fraction, and expressions of cardiac function. The ultimate goal of STIC technique is to improve fetal cardiac function analysis by decreasing the dependency on operator skills required by two-dimensional ultrasound.     

Evidence of redistribution of cardiac output in asymmetrical growth retardation

Thirty-one fetuses with growth retardation were studied by Doppler estimation of the cardiac output from each side of the fetal heart. Asymmetrical growth retardation was diagnosed in 16 fetuses by a head to abdominal circumference ratio above the 95th centile. In the 15 fetuses with symmetrical growth retardation, the distribution of cardiac output was normal. The mean and maximum velocity of blood flow in the pulmonary artery and aorta were similar to values in normal fetuses, and there was a greater calculated output from the right heart than from the left. The right heart flow expressed as a percentage of the combined cardiac output was not statistically significantly different from that in normal fetuses. In contrast, all 16 fetuses with asymmetrical growth retardation had a higher mean and maximum velocity in the aorta than in the pulmonary artery. The calculated volume flow from each side of the heart showed a greater output from the left than the right heart in 15. The right heart flow expressed as a percentage of the combined cardiac output was statistically different from the value in normal fetuses. These findings are consistent with theories of the redistribution of fetal blood flow, where cerebral blood flow is preferentially 'spared'.     

Evidence of redistribution of cardiac output in asymmetrical growth retardation

Summary. Thirty-one fetuses with growth retardation were studied by Doppler estimation of the cardiac output from each side of the fetal heart. Asymmetrical growth retardation was diagnosed in 16 fetuses by a head to abdominal circumference ratio above the 95th centile. In the 15 fetuses with symmetrical growth retardation, the distribution of cardiac output was normal. The mean and maximum velocity of blood flow in the pulmonary artery and aorta were similar to values in normal fetuses, and there was a greater calculated output from the right heart than from the left. The right heart flow expressed as a percentage of the combined cardiac output was not statistically significantly different from that in normal fetuses. In contrast, all 16 fetuses with asymmetrical growth retardation had a higher mean and maximum velocity in the aorta than in the pulmonary artery. The calculated volume flow from each side of the heart showed a greater output from the left than the right heart in 15. The right heart flow expressed as a percentage of the combined cardiac output was statistically different from the value in normal fetuses. These findings are consistent with theories of the redistribution of fetal blood flow, where cerebral blood flow is preferentially 'spared'.     

Prenatal diagnosis of six major cardiac malformations in Europe--a population based study

AIM: To present data on prenatal diagnosis of six major cardiac malformations in low-risk European populations. METHODS: Data from 12 Eurocat registries on congenital malformations. All registries have multiple sources of information and use the same methods of data collection and coding. The six cardiac malformations included were hypoplastic left heart, tricuspid atresia, single ventricle, Tetralogy of Fallot, transposition of great arteries and common A-V-canal. RESULTS: There were significant differences in the proportion of cases diagnosed prenatally, with the highest detection rate in France (91% for single ventricle in Paris) and the lowest detection rate in countries without prenatal ultrasound screening (no cases diagnosed prenatally in the Danish registry area). Prenatal detection rate was significantly higher for the three malformations affecting the size of the ventricles (hypoplastic left heart, tricuspid atresia, single ventricle) compared to the other three malformations (46% versus 24%, p<0.001). Time of diagnosis was late, with only one third diagnosed before 24 weeks of gestation. The risk of fetal death seems to be low. CONCLUSION: There are significant regional differences in prenatal detection rate of major cardiac malformations in Europe.     

Increased expression of vascular endothelial growth factor in cardiac structures of fetus with hydrops as compared to nonhydropic controls

OBJECTIVE: The hypothesis that severe fetal hydrops is caused by an excess of vascular endothelial growth factor (VEGF), mainly produced in the fetal heart, is tested. METHODS: Immunohistochemical VEGF-stained postmortem biopsies from the right ventricle and right atrium of 8 hydropic fetuses were compared to those of 8 nonhydropic fetuses. The endocardium, myocardium, epicardium, endothelium, and vascular smooth muscle cells were scored on intensity of VEGF-staining. The Mann-Witney test was used to test for significancy (p < 0.05) of the differences in staining. Increased vascularization as a result of VEGF was measured in both groups by standard randomization count. RESULTS: The endocardium, epicardium and endothelium of the coronary vessels showed significantly (p < 0.05) more intense VEGF-staining in the hydrops group than in the control group. The atria showed more intense staining than the ventricles in both groups. The hydropic fetuses showed a significantly increased number of coronary vessels in the myocardium. These vessels contained more blood cells than the coronary vessels in nonhydropic fetuses. CONCLUSION: The fetal heart appears to be a major source of excess VEGF in fetal hydrops.     

Diagnosis and prognosis in double-outlet right ventricle

The aim of this study was to examine prenatal diagnosis of double-outlet right ventricle (DORV)-associated anomalies and prognosis of each case. Medical records were reviewed of fetuses with DORV who had fetal echocardiography at our institution from 2002 to 2006. Pre- and postnatal diagnosis and outcome were compared and evaluated. Twenty-one fetuses were diagnosed with DORV. The pregnancy was terminated in seven cases. Three cases had chromosomal abnormalities; three cases, hypoplastic left ventricle; and one case, encephalocele. Accurate prenatal diagnosis of the ventricular septal defect, outflow obstruction, and great artery relationship was achieved in 14 of 16 cases (87.5%). Only 2 of 13 live-born cases survived beyond 6 months. The overall prognosis for fetuses with DORV is poor. DORV is found in fetuses with a huge spectrum of associated cardiac and extracardiac anomalies. Careful assessment by fetal echocardiography can determine important anatomic details with adequate correctness for precise counseling.     

3D real-time imaging of the fetal heart

OBJECTIVE: The aim of this study was to evaluate the clinical utility of a novel 3D scanner system for real-time 3D fetal echocardiography. METHOD: In a prospective study, 13 single, healthy 20- to 24-week-old fetuses were examined with conventional 2D and real-time 3D echocardiography. The visualization rates and imaging quality of standard cardiac views were compared between both methods. RESULTS: The visualization rates of standard cardiac planes were found to be slightly increased and more easily obtainable in 3D imaging whereas the image quality showed better results with conventional 2D echocardiography. CONCLUSION: Our data show that real-time 3D fetal echocardiography can be considered a useful tool in the evaluation of the fetal heart with the necessity for further refinement of the resolution quality Copyright 2000 S. Karger AG, Basel.     

Interventional fetal balloon valvuloplasty for congenital heart disease—current shortcomings and possible perspectives

Fetal cardiac interventions are new and relatively unknown investigational options for modifying congenital heart disease in utero. Techniques for safer access to the fetus must be improved, and selection criteria for patients for whom these procedures are potentially beneficial must be developed. Currently, antenatal cardiac intervention attempts are being made to either prevent or reverse hydrops in fetuses with cardiac valve disease or outflow tract obstruction or to recruit hypoplastic ventricles. Most important are early detection and referral of these fetuses, thereby enabling timely procedures with improved outcomes. However, performing successful fetal cardiac interventions requires multidisciplinary collaboration between obstetricians, pediatric cardiologists, pediatric cardiac surgeons, and anesthesiologists, as each discipline provides specific skills for these critically ill babies.     

彩色多普勒超声心动图检测胎儿先天性心脏病

目的　探讨彩色多普勒超声心动图检测胎儿先天性心脏病 (先心病 )的可行性。　方法　 2 96例胎儿分为两组 :14 2例有高危因素的胎儿 ,15 4例正常妊娠胎儿。应用多普勒测定胎儿心脏各切面 ,并在生后作超声心动随访。　结果　在 14 2例有高危因素的胎儿中 ,发现胎儿先心病 5例 ,其中右心发育不良综合征 1例、法洛四联症 2例、单纯性室间隔缺损 (室缺 ) 2例。漏诊 2例 ,为单纯性室缺1例及房间隔缺损 1例。 15 4例正常妊娠胎儿中未发现先心病。生后超声心动随访或引产尸检结果与产前诊断相符。　结论　彩色多普勒超声心动图在诊断胎儿先心病方面是比较准确和安全的 ,对高危孕妇需加强胎儿先心病的检测     

Prenatal ultrasound diagnosis of congenital heart disease associated with intrauterine growth retardation. A report of 2 cases

Two fetuses with extreme growth retardation (IUGR) of 31 and 34 weeks gestation were studied using a combination of two dimensional echocardiography (2DE), pulse wave Doppler (PWD) and differential measurement of the instantaneous vessel diameter techniques. The first fetus was diagnosed as having univentricular heart or possible double outlet right ventricle (DORV). Descending aorta blood flow was reduced as was indexing for weight. The second fetus was diagnosed as having univentricular heart with periodic bigeminal and trigeminal rhythm. Descending aorta blood flow was measured on two occasions and was reduced both times. Indexing for weight was within normal limits the first time and showed gross reduction on the second occasion prior to fetal demise. Fetal death occurred in both cases at 34 weeks gestation. Cardiovascular evaluation in fetuses with IUGR is useful as the detection of severe congenital cardiac abnormalities may substantially alter the management of these pregnancies, in particular caesarean section may be avoided when the prognosis for the fetus is considered hopeless.     

Modulation of echocardiographic parameters by fetal behaviour

In order to verify if fetal behavioural states could affect cardiac parameters, thirty-one healthy fetuses were studied near term. We evaluated systolic time intervals (pre-ejection period and ventricular ejection time), M-mode parameters (fractional shortening and mean circumferential shortening) and Doppler flow velocities (mean peak velocity of aortic and pulmonary arteries) of left and right ventricles. Both fetal breathing movements and fetal heart rate patterns seem to modify these parameters with an increase of cardiac contractility during active phases of fetal behaviour.     

Fetal myocardial peak systolic strain before and after intrauterine red blood cell transfusion - a tissue Doppler imaging study

Abstract Objectives: The purpose of this study is to evaluate the cardiac function in anemic fetuses by tissue Doppler imaging (TDI) measuring the myocardial peak systolic strain (PS) in fetuses before and after intrauterine transfusion (IUT) of red blood cells. Methods: In our prospective clinical study in anemic fetuses, high-frame-rate TDI data files from a four-chamber view of fetal hearts pre- and post-IUT were analyzed. The biventricular PS parameters of the mid-segment of the ventricular walls [region of interest (ROI) 1 right ventricle, ROI 2 left ventricle] and the basal segment of the ventricular walls (ROI 3 tricuspid annulus, ROI 4 mitral annulus) were compared with the PS data of the normal controls. Results: We analyzed the pre-/post-data sets from the 15 hearts of anemic fetuses and from the 17 controls. The threshold of statistical significance was set to P≤0.05. Compared with the controls, in anemic fetuses the left ventricular longitudinal myocardial PS (ROI 2, P=0.001) and PS in the basal segment of the right ventricle (ROI 3 P=0.009) was significantly increased (absolute amount). Compared with pre-IUT, post-IUT PS decreased significantly in both ventricles (ROI 1 P=0.025, ROI 2 P=0.02). Compared with the controls, post-IUT left ventricular PS was still higher (absolute amount) (ROI 2, P=0.026; ROI 4, P=0.009). Conclusions: The increase in myocardial PS due to severe fetal anemia is partially normalized by IUT. In anemic fetuses, assessment of TDI fetal myocardial PS is feasible.     

Analysis of etiology,chromosome and prognosis for small left heart system development in 69 fetuses

Objective: To provide a basis for evaluating the prognosis of small left heart system development in fetuses, we analyzed its related factors.

Methods: The fetal echocardiogram was performed in 3859 pregnant women, and then small left heart system development was identified in 69 fetuses. The data of prenatal and postnatal echocardiograms, postnatal cardiac surgical treatment, chromosome and autopsy after induced labor were analyzed in the 69 fetuses.

Results: Except 1320 cases losing follow-up, 2539 cases had complete data. Among the 2539 cases, small left heart system development was identified in 69 fetuses. Of the 69 fetuses, 12 had hypoplastic left heart syndrome, 20 premature closure of foramen ovale, 13 total anomalous pulmonary venous drainage, 2 common pulmonary vein lumen atresia, 21 aortic coarctation or interruption and 1 right pulmonary hypoplasia. Among the 69 fetuses, chromosome abnormality was found in 7.

Conclusion: There are many etiological factors causing small left heart system development. The prognosis is poor in the fetuses with hypoplastic left heart syndrome, common pulmonary vein lumen atresia, pulmonary hypoplasia, other malformations or/and chromosome abnormality. Fetal echocardiography combined with chromosome examination can provide important bases for making diagnosis and evaluating the prognosis regarding small left heart system development.     

Biometry of the fetal heart between 10 and 17 weeks of gestation

OBJECTIVES: Assessment of the dimensions of the cardiac chambers and the great arteries in the human fetus may be helpful in the prenatal diagnosis of congenital heart disease. The purpose of this prospective cross-sectional study was to compile normative data in fetal cardiac measurements in early pregnancy. The structure of the fetal heart was examined in 136 normal singleton fetuses between 10 and 17 weeks of gestation. METHODS: The transversal heart diameter, both ventricular dimensions, interventricular septal thickness, heart area, heart circumference, thoracic diameter, thoracic circumference and thoracic area were measured in the four-chamber view during diastole. Diameters of the pulmonary trunk and ascending aorta were obtained in the short axis and long axis view during systole. Ultrasound examinations were performed with a 5.0-MHz transvaginal and/or transabdominal phased-array sector scanner. RESULTS: The four-chamber view and the cross-over of the pulmonary artery and the aorta were adequately visualized in 44% of the fetuses at 10 weeks of gestation, in 75% at 11 weeks of gestation, in 93% at 12 weeks of gestation and in 100% of the fetuses at 13-17 weeks of gestation. Before 14 weeks of gestation transvaginal sonography was superior to the transabdominal sonography in visualization of the fetal heart and great arteries. After 14 weeks of gestation transabdominal sonography accurately demonstrated the structure of the fetal heart. The ratio of right and left ventricle (RV/LV) and the ratio of the pulmonary trunk and aorta (PT/AO) were constant during this period of gestation (approximately 1.00 and 1. 10, respectively). The ratio of the cardiac and thoracic area showed only a slight increase with advancing gestational age, but with significant correlation. The fetal heart rate showed a slow decrease from 167 to 150 bpm in this period of gestation. The transversal heart diameter, both ventricular dimensions, interventricular septal thickness, heart area, cardiothoracic diameter ratio, aortic diameter and the pulmonary trunk diameter showed a highly significant linear correlation to the gestational age and the biparietal diameter. CONCLUSION: The advancing quality of ultrasound images allows fetal echocardiography in the first and early second trimester. Our normative data could be the basis of studying the development of cardiac structures in congenital heart disease and it might be helpful in the detection of some congenital heart defects in early pregnancy.     

Extrakardiale Doppler-Untersuchungen bei fetalen Herzfehlern

There have been few studies using Doppler measurements (umbilical artery, middle cerebral artery, ductus venosus) in fetuses with isolated heart disease. As a consequence of their hemodynamics, some specific cardiac lesions show significant alterations in fetal blood flow compared to controls. An increased pulsatility of the umbilical artery has occasionally been observed in those fetuses with the most severe obstructive lesions and reverse perfusion via the ductus arteriosus. In contrast to fetuses with intrauterine growth restriction and brain sparing following general redistribution, those with hypoplastic left heart or complete transposition of the great arteries may have isolated cerebral vasodilatation with decreased pulsatility of the middle cerebral artery as an adaptive local response to moderate hypoxia. An increased pulsatility of the ductus venosus has been described, especially in right heart lesions with increased right-atrial pressure, usually without being associated with cardiac compromise.