Quantitative assessment of growth and function of the cardiac chambers in the normal human fetus: a prospective longitudinal echocardiographic study

Differential biventricular adaption to pulmonary vascular disease in patients with idiopathic/heritable and congenital heart disease: a prospective cardiac magnetic resonance and invasive study

AIMS

Despite shared pathophysiological mechanisms, patients with idiopathic/heritable pulmonary arterial hypertension (IPAH/HPAH) have a poorer prognosis than those with PAH after congenital heart defect repair. Ventricular adaption remains unclear and could provide a basis for explaining differences in clinical outcomes. The aim of this prospective study was to assess clinical status, haemodynamic profile, and biventricular adaptation to PAH in children with various forms of PAH.

METHODS AND RESULTS

Consecutive patients with IPAH/HPAH or post-operative PAH were prospectively recruited (n = 64). All patients underwent a comprehensive, protocolized assessment including functional assessment, measurement of brain natriuretic peptide (BNP) levels, invasive measurements, and a cardiac magnetic resonance (CMR) assessment. A cohort of age- and sex-matched healthy subjects served as controls. Patients with post-operative PAH had a better functional class (61.5 vs. 26.3% in Class I/II, P = 0.02) and a longer 6-min walk distance (320 ± 193 vs. 239 ± 156 m, P = 0.008) than IPAH/HPAH. While haemodynamic parameters were not significantly different between IPAH/HPAH and post-operative patients, post-operative patients with PAH presented with higher left ventricular volumes and better right ventricular function compared with patients with IPAH/HPAH (P < 0.05). On correlation analyses, left ventricular volumetric parameters were highly correlated with BNP and 6-min walk test distance in this population.

CONCLUSION

Despite comparable haemodynamic profiles, patients with post-operative PAH had less functional limitation than their IPAH/HPAH counterparts. This is potentially related to the differential biventricular adaptation pattern evident on CMR with better myocardial contractility and higher left ventricular volumes in post-operative patients with PAH, highlighting the importance of ventriculo-ventricular interaction in the setting of PAH.

Comparison of the left and right ventricular size and systolic function of low-risk fetuses in the third trimester: Which is more dominant?

Objective

To quantify fetal cardiovascular parameters utilizing fetal-specific 2D speckle tracking technique and to explore the differences in size and systolic function of the left and right ventricles in low-risk pregnancy.

Methods

A prospective cohort study was performed in 453 low-risk single fetuses (28+0–39+6 weeks) to evaluate ventricular size [i.e., end-diastolic length (EDL), end-systolic length (ESL), end-diastolic diameter (ED), end-systolic diameter (ES), end-diastolic area, end-systolic area, end-diastolic volume (EDV), and end-systolic volume (ESV)] and systolic function [i.e., ejection fraction (EF), stroke volume (SV), cardiac output (CO), cardiac output per kilogram (CO/KG), and stroke volume per kilogram (SV/KG)].

Results

This study showed that (1) the reproducibility of the interobserver and intraobserver measurements was good to excellent (ICC 0.626–0.936); (2) with advancing gestation, fetal ventricular size and systolic function increased, whereas right ventricular (RV) EF decreased and left ventricular (LV) EF was not significantly changed; (3) LV length was longer than RV length in diastole (2.24 vs. 1.96 cm, P &lt; 0.001) and systole (1.72 vs. 1.52 cm, P &lt; 0.001); (4) LV ED-S1 and ES-S1 were shorter than the RV ED-S1 and ES-S1 (12.87 vs. 13.43 mm, P &lt; 0.001; 5.09 vs. 5.61 mm, P &lt; 0.001); (5) there were no differences between the LV and RV in EDA or EDV; (6) the mean EDV ratio of right-to-left ventricle was 1.076 (95% CI, 1.038–1.114), and the mean ESV ratio was 1.628 (95% CI, 1.555–1.701); (7) the EF, CO and SV of the LV were greater than the RV (EF: 62.69% vs. 46.09%, P &lt; 0.001; CO: 167.85 vs. 128.69 ml, P &lt; 0.001; SV: 1.18 vs. 0.88 ml, P &lt; 0.001); (8) SV and CO increased with ED-S1 and EDL, but EF was not significantly changed.

Conclusion

Low-risk fetal cardiovascular physiology is characterized by a larger RV volume (especially after 32 weeks) and greater LV outputs (EF, CO, SV, SV/KG and CO/KG).

Speckle Tracking Analysis to Evaluate the Size, Shape, and Function of the Atrial Chambers in Normal Fetuses at 20-40 Weeks of Gestation

OBJECTIVES

The purpose of this study was to use speckle tracking analysis to evaluate the size, shape, and function of the atrial chambers in normal fetuses and develop a z-score calculator that can be used in future studies in fetuses at risk for cardiovascular disease.

METHODS

The control group consisted of 200 normal fetuses examined between 20 and 40 weeks of gestation in which speckle tracking analysis of right (RA) and left (LA) atrial chambers was performed. The atrial end-diastolic and end-systolic endocardial borders for each chamber were identified from which measurements of atrial length, width, area, and volume were computed. Equations were derived using fractional polynomial regression analysis to compute z-score equations.

RESULTS

The LA end-diastolic volume, RA and LA end-diastolic area, length, base width, and mid-chamber widths increased with gestational age and fetal size. Left atrial emptying and ejection volumes increased with gestational age and fetal size. The fractional area change was significantly less for the RA than the LA. The LA base and mid-chamber fractional shortening were significantly greater than the RA. There was a significant difference between the RA and LA global contractile strain.

CONCLUSION

Mean and standard deviation equations for each of the measurements described in this study were computed to create a z-score calculator that can be utilized in the clinical environment when evaluating fetuses with suspected atrial pathology that could alter the size, shape, and function of the atrial chambers.

Lack of morphometric evidence for ventricular compaction in humans

The remodeling of the compact wall by incorporation of trabecular myocardium, referred to as compaction, receives much attention because it is thought that its failure causes left ventricular non-compaction cardiomyopathy (LVNC). Although the notion of compaction is broadly accepted, the nature and strength of the evidence supporting this process is underexposed. Here, we review the literature that quantitatively investigated the development of the ventricular wall to understand the extent of compaction in humans, mice, and chickens. We queried PubMed using several search terms, screened 1127 records, and selected 56 publications containing quantitative data on ventricular growth. For humans, only 34 studies quantified wall development. The key premise of compaction, namely a reduction of the trabecular layer, was never documented. Instead, the trabecular layer grows slower than the compact wall in later development and this changes wall architecture. There were no reports of a sudden enlargement of the compact layer (from incorporated trabeculae), be it in thickness, area, or volume. Therefore, no evidence for compaction was found. Only in chickens, a sudden increase in compact myocardial thickness layer was reported coinciding with a decrease in trabecular thickness. In mice, morphometric and lineage tracing investigations have yielded conflicting results that allow for limited compaction to occur. In conclusion, compaction in human development is not supported while rapid intrinsic growth of the compact wall is supported in all species. If compaction takes place, it likely plays a much smaller role in determining wall architecture than intrinsic growth of the compact wall.

A 24-segment fractional shortening of the fetal heart using FetalHQ

OBJECTIVES

To evaluate 24-segment fractional shortening (FS) of the fetal heart using FetalHQ by speckle-tracking regarding reproducibility and the change with advancing gestation.

METHODS

Eighty-one pregnant women at 18-21+6 and 28-31+6 weeks of gestation were studied using FetalHQ with the speckle-tracking technique to calculate 24-segment FS of left and right ventricles. Intra- and inter-class correlation coefficients and intra- and inter-observer agreements of measurements for FS were assessed in each segment.

RESULTS

With respect to intra-observer reproducibility, all FS values showed correlations between 0.575 and 0.862 for the left ventricle, with good intra-observer agreements except for left ventricular segments 14-24. Right ventricular FS values showed correlations between 0.334 and 0.685, with good intra-observer agreements. With respect to inter-observer reproducibility, all FS values showed correlations between 0.491 and 0.801 for the left ventricle, with good intra-observer agreements except for left ventricular segments 16-22. Right ventricular FS values showed correlations between 0.375 and 0.575, with good inter-observer agreements. There were significant differences in the mean FS values in the basal segment (segments 1-5) of the left ventricle between 18 and 21+6 and 28-31+6 weeks of gestation (p<0.05), whereas there were significant differences in all mean FS values in the right ventricle between both gestational ages (p<0.05).

CONCLUSIONS

These results suggest that the reproducibility of the 24-segment FS of the fetal heart using FetalHQ is fair. However, there may be significant differences in FS values with advancing gestational age, especially for the right ventricle.

Measurement of fetal automated fractional shortening using two-dimensional tracking in multiple centers

PURPOSE

To establish a normal reference range for automated fractional shortening (Auto FS) in normal singleton fetuses measured at multiple centers.

METHODS

This study was conducted from May 2017 to March 2019. It was undertaken on normal singleton fetuses. First, a four-chamber view of the fetal heart was recorded in the B-mode. Then, the region of interest was set on the edge of the ventricular septum and on the edge of the ventricular muscle at a point one-third away from the atrioventricular valve and toward the cardiac apex. Tracking was automatically performed. Values measured in the right ventricle were defined as R-Auto FS, and in the left ventricle as L-Auto FS. Furthermore, combined-Auto FS was defined as the measurement across both ventricles.

RESULTS

A total of 442 normal fetuses were assessed. R-Auto FS decreased significantly with gestational age, and L-Auto FS showed a similar tendency (Spearman's correlation analysis: r_s =  - 0.415 and r_s =  - 0.252, respectively). Combined-Auto FS showed a similar decline as the gestational age increased (r_s =  - 0.451).

CONCLUSION

In this study, we succeeded in defining a reference Auto FS value not only at one institution but also multiple centers. This study suggests that Auto FS can be used clinically and effectively.

Initial fetal to initial postnatal echocardiogram in uncomplicated atrioventricular septal defects: Do significant changes occur?

BACKGROUND

Yield of serial echocardiography in fetuses with atrioventricular septal defects (fAVSD) has not been well defined. The goal of this study was to document if any major changes occurred from initial fetal to initial postnatal echocardiogram in uncomplicated fAVSD.

METHODS

fAVSD were excluded if initial fetal scan documented complex CHD or any concerns. Changes in ventricular function, valvular regurgitation, or diagnosis between first fetal and first postnatal echocardiogram were recorded.

RESULTS

Fifty-seven fAVSD met criteria. Ninety-six fetal echocardiograms were done in 57 patients. Initial fetal scan was performed at 24.3 ± 3.7 weeks of estimated gestational age. All fAVSD had normal function, 38 had no atrioventricular valve regurgitation (AVVR), and 19 had mild AVVR. First postnatal echocardiogram was performed at 6.3 ± 15.3 days. Fifty-six patients had normal function, 1 patient had mild dysfunction, 16 patients had no AVVR, 36 had mild AVVR, and 5 had moderate AVVR. Three patients (5%) had an improvement in AVVR by one degree, 27 patients (47%) had no change in AVVR, 24 patients (42%) had an increase in AVVR by one degree, and 3 patients (5%) had an increase in AVVR by two degrees. There was no major missed anatomical diagnosis from first prenatal to first postnatal echocardiogram.

CONCLUSION

In fAVSD that had no concerns on their initial fetal echocardiogram, the majority of patients had no major changes noted between their initial fetal echocardiogram and their first postnatal echocardiogram. Repeat fetal echocardiograms may not necessarily be needed in this cohort of patients.

Assessment of ventricular contractility in fetuses with an estimated fetal weight less than the tenth centile

OBJECTIVE

To determine whether abnormal global, transverse, and longitudinal ventricular contractility of the heart in fetuses with an estimated fetal weight <10th centile is present, irrespective of Doppler studies of the umbilical artery and cerebroplacental ratio.

STUDY DESIGN

This was a retrospective study of 50 fetuses with an estimated fetal weight <10th centile that were classified based on Doppler results from the pulsatility indices of the umbilical artery and middle cerebral artery, and the calculated cerebroplacental ratio (pulsatility indices of the umbilical artery/middle cerebral artery). Right and left ventricular measurements were categorized into 3 groups: (1) global ventricular contractility (fractional area change), (2) transverse ventricular contractility (24-segment transverse fractional shortening), and (3) basal-apical longitudinal contractility (longitudinal strain, longitudinal displacement fractional shortening, and basal lateral and septal wall annular plane systolic excursion). Z scores for the above measurements were computed for fetuses with an estimated fetal weight <10th centile using the mean and standard deviation derived from normal controls. Ventricular contractility measurements were considered abnormal if their Z score values were <5th centile (z score <-1.65) or >95th centile (Z score >1.65), depending on the specific ventricular measurement.

RESULTS

The average gestational age at the time of the examination was 32 weeks 4 days (standard deviation 3 weeks 4 days). None of the 50 study fetuses demonstrated absent or reverse flow of the umbilical artery Doppler waveform. Eighty-eight percent (44/50) of fetuses had one or more abnormal measurements of cardiac contractility of 1 or both ventricles. Analysis of right ventricular contractility demonstrated 78% (39/50) to have 1 or more abnormal measurements, which were grouped as follows: global contractility 38% (19/50), transverse contractility 66% (33/50); and longitudinal contractility 48% (24/50). Analysis of left ventricular contractility demonstrated 1 or more abnormal measurements in 58% (29/50) that were grouped as follows: global contractility 38% (19/50); transverse contractility 40% (20/50); and longitudinal contractility 40% (20/50). Of the 50 study fetuses, 25 had normal pulsatility index of the umbilical artery and cerebroplacental ratios, 80% of whom had 1 or more abnormalities of right ventricular contractility and 56% of whom had 1 or more abnormalities of left ventricular contractility. Abnormal ventricular contractility for these fetuses was present in all 3 groups of measurements; global, transverse, and longitudinal. Those with an isolated abnormal pulsatility index of the umbilical artery (n=11) had abnormalities of transverse contractility of the right ventricular and global contractility in the left ventricle. When an isolated cerebroplacental ratio abnormality was present, the right ventricle demonstrated abnormal global, transverse, and longitudinal contractility, with the left ventricle only demonstrating abnormalities in transverse contractility. When both the pulsatility index of the umbilical artery and cerebroplacental ratio were abnormal (3/50), transverse and longitudinal contractility measurements were abnormal for both ventricles, as well as abnormal global contractility of the left ventricle.

CONCLUSIONS

High rates of abnormal ventricular contractility were present in fetuses with an estimated fetal weight <10th centile, irrespective of the Doppler findings of the pulsatility index of the umbilical artery, and/or cerebroplacental ratio. Abnormalities of ventricular contractility were more prevalent in transverse measurements than global or longitudinal measurements. Abnormal transverse contractility was more common in the right than the left ventricle. Fetuses with estimated fetal weight less than the 10th centile may be considered to undergo assessment of ventricular contractility, even when Doppler measurements of the pulsatility index of the umbilical artery, and cerebroplacental ratio are normal.

Assessment of fetal cardiac function with echocardiography

The circulatory physiology of fetuses differs from that of neonates. The concept of biventricular combined cardiac output is necessary to understand and assess the fetal cardiac function. Fetal cardiac function has been estimated using echocardiographic methods such as M-mode, B-mode and pulsed wave Doppler. In addition, recent studies have reported the utility of tissue Doppler imaging in fetal echocardiography. However, parameters for fetal cardiac function remain to be established. Recently, we developed two novel techniques for assessing fetal cardiac function: an automatic fractional shortening method and E/e' determination using the dual-gate Doppler method. These two techniques are expected to be reliable and useful for assessing the fetal status in various pathological conditions.

A magnetics-based approach for fine-tuning afterload in engineered heart tissues

Afterload plays important roles during heart development and disease progression, however, studying these effects in a laboratory setting is challenging. Current techniques lack the ability to precisely and reversibly alter afterload over time. Here, we describe a magnetics-based approach for achieving this control and present results from experiments in which this device was employed to sequentially increase afterload applied to rat engineered heart tissues (rEHTs) over a 7-day period. The contractile properties of rEHTs grown on control posts marginally increased over the observation period. The average post deflection, fractional shortening, and twitch velocities measured for afterload-affected tissues initially followed this same trend, but fell below control tissue values at high magnitudes of afterload. However, the average force, force production rate, and force relaxation rate for these rEHTs were consistently up to 3-fold higher than in control tissues. Transcript levels of hypertrophic or fibrotic markers and cell size remained unaffected by afterload, suggesting that the increased force output was not accompanied by pathological remodeling. Accordingly, the increased force output was fully reversed to control levels during a stepwise decrease in afterload over 4 hours. Afterload application did not affect systolic or diastolic tissue lengths, indicating that the afterload system was likely not a source of changes in preload strain. In summary, the afterload system developed herein is capable of fine-tuning EHT afterload while simultaneously allowing optical force measurements. Using this system, we found that small daily alterations in afterload can enhance the contractile properties of rEHTs, while larger increases can have temporary undesirable effects. Overall, these findings demonstrate the significant role that afterload plays in cardiac force regulation. Future studies with this system may allow for novel insights into the mechanisms that underlie afterload-induced adaptations in cardiac force development.

Myocardial deformation in fetuses with coarctation of the aorta: a case-control study

OBJECTIVE

To study myocardial deformation by speckle tracking echocardiography in fetuses with coarctation of the aorta (CoA) compared with gestational age-matched normal controls.

METHODS

This was a retrospective study of 12 fetuses with postnatally confirmed CoA and 12 gestational age-matched controls seen at a tertiary fetal cardiology unit between January 2013 and July 2014. Two-dimensional speckle tracking in standard grayscale four-chamber view of the fetal heart was performed to assess left and right myocardial deformation. Global longitudinal strain, strain rate and velocities, and regional longitudinal strain were analyzed and compared with controls.

RESULTS

Median gestational age at echocardiography was 25 + 4 weeks. Fetuses with CoA presented with a narrower, but not shorter, left ventricle when compared with controls (mitral valve diastolic diameter, 5.90 vs 8.50 mm; P = 0.002; left ventricular diastolic length, 16.50 vs 18.50 mm; P = 0.05). Global longitudinal systolic strain (P = 0.004), systolic strain rate (P = 0.01) and diastolic strain rate (P = 0.004) of the left ventricle were significantly lower in fetuses with CoA compared with controls. Similar findings were observed for longitudinal systolic (P = 0.03) and diastolic (P = 0.01) velocities of the left ventricle. Right ventricular parameters were not different between groups.

CONCLUSIONS

Fetuses with CoA have lower left ventricular longitudinal systolic strain, systolic strain rate and diastolic strain rate when compared with gestational age-matched control fetuses. These differences in deformation might explain, at least in part, the cardiac asymmetry observed in fetuses with CoA. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Fetal echocardiography: reference values for the Chinese population

OBJECTIVE

Global racial variability in human development can lead to differences in size of fetal cardiac structures during gestation. Our objective is to establish normal reference ranges of fetal cardiac dimensions between 20 and 34 weeks from fetal echocardiograms recorded at a single center in China.

METHODS

A prospective cross-sectional study was undertaken on single pregnancies with normal fetuses of varying gestational ages (GAs). A total of 4396 normal fetuses were divided into 15 groups from 20 to 34 weeks according to the GA. Measurements included the inner diameter of the fetal cardiac chambers and arteries, the aortic arch isthmus (AI), the descending aorta (DAO), the ductus arteriosus (DA), and the foramen ovale (FO). Measurements were statistically analyzed and regression analysis was applied to assess for correlation with GA.

RESULTS

Normal reference values of fetal cardiovascular dimensions between 20 and 34 weeks were obtained from 4396 subjects at a single center in China. Measurements of fetal cardiac structures increase with advancing GA. It seems there is no difference in r values among linear, cubic, and quadratic model analyses (P > 0.05). However, the r values for the exponential models appear to be smaller than those of the other three models (P < 0.05). Ratios of the diameters of fetal cardiac structures were calculated in order to identify for differential changes in the growth of structures.

CONCLUSIONS

The presented data derived from 4396 normal fetuses provide the reference values of fetal echocardiography in China, which provide guidance to fetal echocardiography examinations.

Model of Human Fetal Growth in Hypoplastic Left Heart Syndrome: Reduced Ventricular Growth Due to Decreased Ventricular Filling and Altered Shape

INTRODUCTION

Hypoplastic left heart syndrome (HLHS) is a congenital condition with an underdeveloped left ventricle (LV) that provides inadequate systemic blood flow postnatally. The development of HLHS is postulated to be due to altered biomechanical stimuli during gestation. Predicting LV size at birth using mid-gestation fetal echocardiography is a clinical challenge critical to prognostic counseling.

HYPOTHESIS

We hypothesized that decreased ventricular filling in utero due to mitral stenosis may reduce LV growth in the fetal heart via mechanical growth signaling.

METHODS

We developed a novel finite element model of the human fetal heart in which cardiac myocyte growth rates are a function of fiber and cross-fiber strains, which is affected by altered ventricular filling, to simulate alterations in LV growth and remodeling. Model results were tested with echocardiogram measurements from normal and HLHS fetal hearts.

RESULTS

A strain-based fetal growth model with a normal 22-week ventricular filling (1.04 mL) was able to replicate published measurements of changes between mid-gestation to birth of mean LV end-diastolic volume (EDV) (1.1-8.3 mL) and dimensions (long-axis, 18-35 mm; short-axis, 9-18 mm) within 15% root mean squared deviation error. By decreasing volumetric load (-25%) at mid-gestation in the model, which emulates mitral stenosis in utero, a 65% reduction in LV EDV and a 46% reduction in LV wall volume were predicted at birth, similar to observations in HLHS patients. In retrospective blinded case studies for HLHS, using mid-gestation echocardiographic data, the model predicted a borderline and severe hypoplastic LV, consistent with the patients' late-gestation data in both cases. Notably, the model prediction was validated by testing for changes in LV shape in the model against clinical data for each HLHS case study.

CONCLUSION

Reduced ventricular filling and altered shape may lead to reduced LV growth and a hypoplastic phenotype by reducing myocardial strains that serve as a myocyte growth stimulus. The human fetal growth model presented here may lead to a clinical tool that can help predict LV size and shape at birth based on mid-gestation LV echocardiographic measurements.

Nomograms for Fetal Cardiac Ventricular Width and Right-to-Left Ventricular Ratio

OBJECTIVES

To establish nomograms for right ventricular (RV) and left ventricular (LV) widths and their ratio from 16 to 38 gestational weeks.

METHODS

We conducted a retrospective evaluation of 1242 fetal echocardiographic examinations with normal findings in a single referral medical center between 2007 and 2013. We excluded all echocardiographic examinations with abnormal findings. The RV and LV widths, measured in end diastole from inner to inner line below the valves' insertion at the 4-chamber view, were obtained. Nomograms for the RV and LV widths and RV/LV ratio from 16 to 38 gestational weeks were constructed by using separate best-fitted regression models for estimation of mean and standard deviation at each gestational age (GA).

RESULTS

Regression models for the RV and LV widths and RV/LV ratio were best fit by different-degree polynomial regression. The mean RV and LV widths and RV/LV ratio (±2 SD) increased statistically with GA from 16 to 38 weeks: 4.13 (3.00-5.44) to 16.68 (12.98-20.83) mm, 4.21 (3.18-5.49) to 15.17 (11.60-19.56) mm, and 1.03 (0.87-1.23) to 1.06 (0.87-1.30), respectively. Although the width increments in the RV and LV were both statistically and clinically significant, the ratio increment seemed to fall into the error of measurement and thus has no clinical significance.

CONCLUSIONS

Reference values for cardiac ventricle widths and their ratio throughout gestation were established. The RV/LV ratio increases with GA, although without clinical significance. These reference values will be useful in objective assessment of RV-to-LV disproportion.

Longitudinal systolic left ventricular function in preterm and term neonates: reference values of the mitral annular plane systolic excursion (MAPSE) and calculation of z-scores

The mitral annular plane systolic excursion (MAPSE) is a quick and reliable echocardiographic tool for assessing longitudinal left ventricular (LV) systolic function in children and adults. Because this parameter is affected by the LV longitudinal dimension, pediatric and adult normal values are not suitable for preterm and term neonates. A prospective study investigated a large group of preterm and term neonates [gestational age (GA), 26/0-6 to 40/0-6; birth weight (BW), 670-4,140 g]. The growth- and BW-related changes in MAPSE were determined to establish normal z-score values for preterm and term neonates. The MAPSE ranged from a mean of 0.36 ± 0.05 cm in preterm neonates with a GA of 26/0-6 to 0.56 ± 0.08 cm in term neonates with a GA of 40/0-6. The findings showed MAPSE, GA, and BW to be moderately correlated. Pearson's correlation coefficient was 0.56 for GA (MAPSE; p < 0.001) and 0.58 for BW (MAPSE; p < 0.001). The normal MAPSE values did not differ significantly between females and males (p = 0.946). The absolute values and z-scores of normal MAPSE values in healthy preterm and term neonates within the first 48 h of life were calculated, and percentile charts were established. Determination of LV function using MAPSE might be useful for vulnerable infants for whom a prolonged examination is inappropriate and for neonates with suboptimal visualization of the endocardium.

Screening for hemoglobin Bart's disease among fetuses at risk at mid-pregnancy using the fetal cardiac diameter to biparietal diameter ratio

Background

All sonomarkers used to screen for fetal hemoglobin (Hb) Bart’s disease need high expertise, preventing them from being widely used. Fetal cardiac diameter to biparietal diameter (C/B) ratio is a simple marker which has never been evaluated for its effectiveness. Therefore, we conducted this study to evaluate the effectiveness of C/B ratio in predicting fetal Hb Bart’s disease among fetuses at risk.

Methods

Fetuses at risk of Hb Bart’s disease scheduled for diagnostic cordocentesis at 18 to 22 weeks of pregnancy were prospectively enrolled. All underwent ultrasound for fetal biometry and cardio-STIC acquisition for subsequent off-line analysis. Cardio-STIC volume datasets (VDS) were analyzed for cardiac diameter measurement and C/B ratio was calculated by the authors who did not know the fetal diagnosis. Final diagnosis of Hb Bart’s disease was based on fetal blood Hb typing.

Results

Of 131 pregnancies enrolled to the study, 11 were excluded because of poor quality VDS. The remaining 120 were available for analysis. C/B ratio was significantly higher in the fetuses with Hb Bart’s disease than that in the unaffected ones (53.16% vs 41.68%, P < 0.001). C/B ratio could detect fetuses with Hb Bart’s disease with sensitivity of 91.5% and specificity of 77.6% (AUC ROC 0.929), using a cut-off point of greater than 45%.

Conclusions

Among fetuses at risk, C/B ratio measurement at mid-pregnancy, using cut-off point of 45%, could effectively differentiate fetuses with Hb Bart’s disease from unaffected fetuses.

Prenatal diagnosis of prevalence of the right heart: associated anomalies and outcome predictors

OBJECTIVES

To analyze the characteristics, associations, and outcomes of prevalence of the right heart and to evaluate the use of sonography to predict the risk of a poor prognosis in fetuses with this condition.

METHODS

We conducted a retrospective cohort study of 182 fetuses with prevalence of the right heart. At the initial evaluation, the left ventricle (LV) and right ventricle (RV) sizes, left atrium and right atrium sizes, great artery diameters, appearance of the aortic arch and ductus arteriosus arch, and flow direction across the foramen ovale and aortic arch were documented. Malformations were documented in fetuses with intracardiac anomalies, who were divided into groups with and without coexisting extracardiac defects. The RV-LV diameter ratio and main pulmonary artery-to-aortic root diameter ratio were calculated and compared. The following variables were analyzed: coexisting intracardiac anomalies, associated extracardiac anomalies, diagnosis before 24 gestational weeks, fetal growth restriction, reversed flow across the foramen ovale, reversed flow in the aortic arch, and RV-LV ratio greater than 2.0. Relationships between these sonographic findings and the prognosis were evaluated by multivariable logistic regression.

RESULTS

Of the 182 fetuses, 1 (0.5%) had intrauterine death, and 25 (13.7%) had neonatal death; 1 (0.5%) had selective reduction, and 106 (58.2%) underwent termination of pregnancy; 49 (26.9%) survived at this writing. The mean RV-LV ratio was 1.67. Multivariable logistic regression revealed that only 2 sonographic parameters, coexisting intracardiac anomalies (odds ratio, 17.75; 95% confidence interval, 4.18-75.26) and diagnosis before 24 weeks (odds ratio, 17.26; 95% confidence interval, 1.80-165.39) were significantly associated with a poor prognosis.

CONCLUSIONS

The sonographic parameters of coexisting intracardiac anomalies and diagnosis before 24 gestational weeks are significant independent predictors of a poor prognosis in fetuses with prevalence of the right heart. Combinations of these risk factors may be useful in prenatal consultation.

Fetal left ventricular mass determination on 2-dimensional echocardiography using area-length calculation methods

OBJECTIVES

Fetal cardiac examination is an important part of fetal malformation screening. The purposes of this study were to describe the left ventricular (LV) mass in the second and third trimesters by 2-dimensional echocardiography using area-length calculation methods and to examine the clinical usefulness of this procedure in evaluation of gestational age (GA)- and fetal weight-related LV mass changes.

METHODS

Five hundred healthy fetuses were divided into 2 groups (250 participants per group): second- and third-trimester groups. The estimated fetal weight (EFW) was computed according to the Hadlock formula (Radiology 1984; 150:535-540). The LV mass at end diastole (LVd mass) and LV mass at end systole (LVs mass) were measured, and the difference between the LVd mass and LVs mass [LV(d-s) mass], LVd mass/EFW ratio, and LVs mass/EFW ratio were calculated.

RESULTS

The EFW, LVd mass, LVs mass, and LV(d-s) mass were all significantly greater in the third-trimester group than the second-trimester group (P < .05), whereas the LVd mass/EFW and LVs mass/EFW ratios did not differ between the groups (P > .05). The LVd mass, LVs mass, and LV(d-s) mass all significantly correlated with GA and weight (P< .001), but the LVd mass/EFW and LVs mass/EFW ratios did not (P > .05).

CONCLUSIONS

Two-dimensional echocardiography using area-length calculation methods can effectively provide measurements for LV mass and can sensitively indicate fetal weight- and GA -related changes in LV mass. Fetal cardiac mass measurement is a useful parameter for evaluation of fetal heart development.

Right ventricular performance in preterm and term neonates: reference values of the tricuspid annular peak systolic velocity measured by tissue Doppler imaging

BACKGROUND

The tricuspid annular peak systolic velocity (S') is an echocardiographic measurement to assess systolic right ventricular function in adults and children.

OBJECTIVE

We determined growth and birth weight-related changes of S' to establish reference values in preterm and term neonates.

METHODS

A prospective study was conducted in a group of 290 preterm and term neonates (gestational age 26 + 0 to 40 + 6 weeks of gestation; birth weight 660-4,460 g). A correlation of S' values with established tricuspid annular plane systolic excursion (TAPSE) values was performed.

RESULTS

The S' ranged from a mean of 4.5 cm/s (Z-score ± 2 SD: 3.6-5.5 cm/s) in preterm neonates in week 26(0-6) of gestation to 7.8 cm/s (Z-score ± 2 SD: 5.5-10.1 cm/s) in term neonates in week 40(0-6) of gestation. The S' values increased from 26 to 40 weeks of gestation. S' and week of gestation are strongly correlated: Pearson's correlation coefficient was 0.66 for week of gestation - S' (p < 0.001). A significant correlation was found between S' and TAPSE values (r = 0.67; p < 0.001).

CONCLUSION

Z-scores of S' values were calculated and percentile charts were established to serve as reference data for preterm and term neonates with structurally normal hearts.

Preterm heart in adult life: cardiovascular magnetic resonance reveals distinct differences in left ventricular mass, geometry, and function

BACKGROUND

Preterm birth leads to an early switch from fetal to postnatal circulation before completion of left ventricular in utero development. In animal studies, this results in an adversely remodeled left ventricle. We determined whether preterm birth is associated with a distinct left ventricular structure and function in humans.

METHODS AND RESULTS

A total of 234 individuals 20 to 39 years of age underwent cardiovascular magnetic resonance. One hundred two had been followed prospectively since preterm birth (gestational age=30.3±2.5 week; birth weight=1.3±0.3 kg), and 132 were born at term to uncomplicated pregnancies. Longitudinal and short-axis cine images were used to quantify left ventricular mass, 3-dimensional geometric variation by creation of a unique computational cardiac atlas, and myocardial function. We then determined whether perinatal factors modify these left ventricular parameters. Individuals born preterm had increased left ventricular mass (66.5±10.9 versus 55.4±11.4 g/m(2); P<0.001) with greater prematurity associated with greater mass (r = -0.22, P=0.03). Preterm-born individuals had short left ventricles with small internal diameters and a displaced apex. Ejection fraction was preserved (P>0.99), but both longitudinal systolic (peak strain, strain rate, and velocity, P<0.001) and diastolic (peak strain rate and velocity, P<0.001) function and rotational (apical and basal peak systolic rotation rate, P =0.05 and P =0.006; net twist angle, P=0.02) movement were significantly reduced. A diagnosis of preeclampsia during the pregnancy was associated with further reductions in longitudinal peak systolic strain in the offspring (P=0.02, n=29).

CONCLUSIONS

Individuals born preterm have increased left ventricular mass in adult life. Furthermore, they exhibit a unique 3-dimensional left ventricular geometry and significant reductions in systolic and diastolic functional parameters.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT01487824.

Accuracy, agreement, and reliability of fetal cardiac measurements using 4-dimensional spatiotemporal image correlation

OBJECTIVES

The purpose of this study was to evaluate the accuracy, agreement, and reliability of 4-dimensional sonography using spatiotemporal image correlation (STIC) in fetal cardiac measurements during the second and third trimesters.

METHODS

Four-dimensional cardiac STIC volumes were acquired from 150 low-risk singleton pregnancies at gestational ages of 18 to 38 weeks. A total of 11 dimensions of the fetal heart and great vessels were analyzed by two different observers. Accuracy was assessed by comparing the measurements acquired by 4-dimensional STIC with those determined by 2-dimensional echocardiography by calculating the mean error and mean percent error and depicted by Bland-Altman plots. Absolute agreement and reliability of STIC-based measurements were evaluated on the basis of an intraclass correlation coefficient (ICC).

RESULTS

For STIC-based measurements of cardiac dimensions, good accuracy was achieved by the two experienced observers (mean percent error, -3.10% to 0.87% for observer A; -2.49% to -0.33% for observer B), and absolute agreement was almost perfect (ICC, 95% confidence interval, 0.916-0.993 for observer A; 0.957-0.990 for observer B). Interobserver ICCs among the two observers were between 0.909 and 0.990 (95% confidence interval), whereas intraobserver ICCs for observer A were between 0.894 and 0.989, and those for observer B were between 0.893 and 0.985, showing no significant differences in the reliability of SITC with regard to observers.

CONCLUSIONS

Four-dimensional sonography with STIC is a feasible and accurate method for fetal cardiac dimension measurements in the second and third trimesters. It is in good agreement with 2-dimensional echocardiography and can be performed by different observers.

Right ventricular performance in congenital heart disease: a physiologic and pathophysiologic perspective

Underappreciated is the fact that the right ventricle is often the primary determinant of long-term morbidity and mortality in patients with congenital heart disease. Right ventricular performance in these patients depends on a unique set of physiologic and pathophysiologic factors that are rarely considered in acquired heart disease. This article explores this unique physiology and pathophysiology in the hope that it will enhance understanding of a wide variety of congenital cardiac anomalies.

Fetal cardiac dimensions at 14-40 weeks' gestation obtained using cardio-STIC-M

OBJECTIVES

To establish normative reference ranges of fetal cardiac dimensions derived from volume datasets acquired using spatiotemporal image correlation with M-mode display (cardio-STIC-M).

METHODS

A cross-sectional study was undertaken on singleton pregnancies with normal fetuses and accurate gestational ages. Cardio-STIC volume datasets were acquired by experienced operators using a high-resolution ultrasound machine; these were maneuvered to obtain a four chamber-view with exactly horizontal interventricular septum (IVS). Cardiac dimensions were measured in STIC-M-mode using 4D View software.

RESULTS

A total of 657 measurements, at a rate of between 15 and 37 per week, were obtained. Normal reference ranges for biventricular outer diameter, left and right ventricular inner diameter, left and right ventricular wall thickness, IVS thickness, left to right ventricular diameter ratio and left and right ventricular shortening fractions were constructed based on best-fit equations as a function of gestational age, fetal head circumference and biparietal diameter. Thirty-four volume datasets of abnormal fetal hearts were also separately assessed, many of which showed abnormal cardiac dimensions.

CONCLUSIONS

This is the first report on normal ranges of fetal cardiac dimensions constructed using the new cardio-STIC-M technology. Preliminary evaluation suggests that these reference ranges may be a useful tool in the assessment of fetal cardiac abnormalities.

Systolic right ventricular function in preterm and term neonates: reference values of the tricuspid annular plane systolic excursion (TAPSE) in 258 patients and calculation of Z-score values

BACKGROUND

The tricuspid annular plane systolic excursion (TAPSE) is an echocardiographic measurement to assess right ventricular systolic function in adults and children.

OBJECTIVE

We determined growth- and birth weight-related changes of TAPSE to establish reference values in preterm and term neonates.

METHODS

A prospective study was conducted in a group of 258 preterm and term neonates (age: 25+0 to 40+6 weeks of gestation, birth weight: 530-4200 g).

RESULTS

The TAPSE ranged from a mean of 0.44 cm (Z-score ±2: 0.30-0.59 cm) in preterm neonates in the 26th week of gestation to 1.03 cm (Z-score ±2: 0.85-1.21 cm) in term neonates in the 41st week of gestation. The TAPSE values increased in a linear way from the 26th to 41st week of gestation. TAPSE, week of gestation and weight are strongly correlated: Pearson's correlation coefficient was 0.93 for week of gestation - TAPSE (p < 0.001), 0.93 for week of gestation - birth weight (p < 0.001), and 0.89 for birth weight - TAPSE (p < 0.001). There was no statistically significant difference of normal TAPSE values between female and male patients (p = 0.987).

CONCLUSION

Z-scores of TAPSE values were calculated and percentile charts were established to serve as reference data for ready application in preterm and term neonates with structurally normal hearts and with congenital heart disease in the future.

Assessment of cardiomyopathy in fetuses of women with false positive oral glucose loading test

OBJECTIVE

To evaluate fetal asymmetric septal hypertrophy in women with a false positive oral glucose loading test (OGL).

STUDY DESIGN

OGL was applied to 79 pregnant women at gestational age between 24 and 28 weeks. The first study group consisted of patients with a normal OGL. Cases having glucose levels above 130 mg/dL after 50 g OGL but a normal 100g oral glucose tolerance test (OGTT) formed a second group. M-mode echocardiography was then performed. Fetal septal and left ventricular posterior wall (LVPW) thicknesses in Group 1 and Group 2 were compared.

RESULTS

Mean septal and LVPW thickness was slightly higher in the second group but there was no statistically significant difference between the two groups.

CONCLUSIONS

Although statistically not significant, there is some increase in septal and ventricular wall thickness in cases with high OGL but normal OGTT. The study also provides evidence of the absence of prominent septal and ventricular thickening in these cases with minimal glucose intolerance.

Cardiac remodelling as a result of pre-term birth: implications for future cardiovascular disease

AIMS

Pre-term birth affects 10-12% of live births and occurs when the myocardium is still developing; therefore, the final structure of the myocardium could be altered. We hypothesized that, in response to pre-term birth, structural remodelling occurs within the myocardium which enables the immature heart muscle to adapt to the haemodynamic transition at birth but results in persistent alterations in its structure. Our objective was to determine how pre-term birth alters the final structure of the myocardium.

METHODS AND RESULTS

Using sheep, pre-term birth was induced at 0.9 of term; hearts were examined at 9 weeks after term-equivalent age, when cardiomyocyte proliferation and maturation have ceased. In pre-term lambs, we found that cardiomyocytes of both ventricles and the interventricular septum were hypertrophied. Cardiomyocyte maturation in pre-term lambs was altered in that there was a greater proportion of mononucleated, polyploid (4n) cardiomyocytes in both ventricles compared with controls; importantly, induction of polyploidy is associated with irreversible stress-related changes in DNA. We also found a six- to seven-fold increase in collagen deposition, usually accompanied by lymphocytic infiltration.

CONCLUSION

We conclude that pre-term birth leads to remodelling of the myocardium that alters its final structure. This may programme for long-term cardiac vulnerability.

Morphometric study of the ventricular segment of the human fetal heart between 13 and 20 weeks' gestation

Our objective was to determine the normal dimensions of the ventricular segment of the human fetal heart between 13 and 20 weeks' gestation.

STUDY DESIGN

103 hearts obtained by necropsy were dissected and measurements of different portions of ventricles were determined under stereoscopic magnification. In each ventricle were measured anteroposterior and lateral diameters, inlet and outlet length, and thickness of walls at different levels. Our results showed the cardiac apex was constituted by the left ventricle in 68.9% of the hearts. Both ventricles showed linear growth during this period of fetal development. Ranges in median values of external and internal ventricular measurements were determined. The left ventricular wall was thicker than the right, and the right ventricular cavity was larger. This study provides morphometric reference information concerning the dimensions and growth of both ventricles of the fetal heart, which may be useful in pediatric cardiac surgery and echocardiography.

Estudo morfométrico do coração fetal: sua utilização como parâmetro para análise ecocardiográfica

OBJETIVO: Avaliar o diâmetro, o perímetro e a área das valvas atrioventriculares do coração fetal, bem como a espessura das paredes ventriculares e os diâmetros das cavidades ventriculares. MATERIAIS E MÉTODOS: Foram dissecados 20 corações de fetos com idade gestacional entre 28 e 36 semanas. Em seguida foram medidos os diâmetros ântero-posterior e transverso e aferidos as áreas e os perímetros das valvas mitral e tricúspide, bem como foram medidas as espessuras das paredes ventriculares e os diâmetros de suas cavidades, utilizando-se um paquímetro com acurácia de1/10 mm. RESULTADOS: Os diâmetros ântero-posterior e transverso da valva atrioventricular esquerda mediram, em média, 10,35 ± 1,62 mm e 9,90 ± 1,79 mm, respectivamente, e os diâmetros ântero-posterior e transverso da valva atrioventricular direita, 10,98 ± 1,90 mm e 9,51 ± 1,81 mm, respectivamente. A área e o perímetro da valva mitral foram de 84,06 ± 25,09 mm² e 29,87 ± 3,96 mm, respectivamente. A área e o perímetro da valva tricúspide mediram, respectivamente, 84,49 ± 26,79 mm² e 28,44 ± 3,85 mm. No ventrículo direito a espessura da parede anterior foi de 5,00 ± 1,70 mm e a da parede posterior foi de 3,83 ± 0,91 mm; no ventrículo esquerdo a espessura da parede anterior foi de 4,25 ± 0,87 mm e a da parede posterior foi de 4,14 ± 0,89 mm. O septo interventricular teve espessura de 4,10 ± 1,13 mm. O ventrículo direito teve como diâmetro ântero-posterior 9,25 ± 0,85 mm, e como diâmetro transverso 8,24 ± 0,42 mm. O ventrículo esquerdo mediu 9,95 ± 0,37 mm para o diâmetro ântero-posterior e 9,20 ± 0,40 mm para o diâmetro transverso. CONCLUSÃO: O conhecimento dos dados morfométricos do coração do feto é de grande importância para o diagnóstico ecocardiográfico de possíveis malformações cardíacas.

Fetal myocardial performance in pregnancies complicated by gestational impaired glucose tolerance

OBJECTIVE

To determine fetal myocardial performance in pregnancies complicated by mild gestational impaired glucose tolerance (GIGT).

METHODS

Ultrasound examinations were performed in 37 pregnant women with mild GIGT (36 did not require insulin) and in 44 controls at 18-24, 26-30 and 34-37 weeks of gestation. The thickness of the fetal ventricular walls and interventricular septum were measured by M-mode echocardiography. Using conventional Doppler echocardiography, the mitral and tricuspid early (E) and late (A) diastolic velocities and the ventricular myocardial performance index (MPI) were determined.

RESULTS

The fetuses of women with GIGT had a greater abdominal circumference (P = 0.02), a larger amniotic fluid index (P = 0.03), and a tendency to be heavier (P = 0.058) at the third scan. There were no significant differences in myocardial thickness, mitral and tricuspid E and A velocities, and E/A ratios between study and control groups. The left and right ventricular MPIs, while similar between the two groups in the first and second scans, had decreased significantly by late gestation in the GIGT fetuses (P for trend = 0.018 and 0.014, respectively) and were significantly lower than those of the control group (P = 0.002 and 0.0008, respectively).

CONCLUSIONS

Fetuses of women with mild GIGT lack the ventricular hypertrophy and diastolic dysfunction that is common in fetuses of diabetic mothers, and they have a decreased MPI late in gestation. Published by John Wiley & Sons, Ltd.

Gender-related changes in magnetocardiographically determined fetal cardiac time intervals in intrauterine growth retardation

Prenatal growth deficiencies as well as gender have been associated with cardiovascular disease in later life. It is also known that the duration of fetal cardiac time intervals (CTI) are dependent on fetal development. The aim of this work was to examine the relationship between fetal CTI in healthy and intrauterine growth retardation (IUGR) fetuses, taking gender into account. A total of 269 magnetocardiograms (MCG) were obtained in 47 healthy and 27 IUGR pregnancies. In each signal-averaged MCG, durations of CTI were determined. Age- and heart rate-corrected values were compared between normal and IUGR fetuses separately with respect to gender. Overall, there was an association between atrial and ventricular conduction times and estimated fetal body weight. In female fetuses, IUGR was associated with shorter P WAVE, PQ segment, PR interval, and QRS complex and longer STT and QT intervals. For males, this was so only for P wave, QRS complex, and STT interval. The shortening of conduction times in IUGR may be explained by reduced cardiac muscle mass associated with lower body weight. On the other hand, the gender-specific differences, particularly in the IUGR fetuses may be due to hormonal factors.

Assessing fetal cardiac ventricular function

Fetal echocardiography has been used primarily to identify fetuses with structural malformations of the heart. Evaluation of fetal ventricular function, however, has received minimal attention since the inception of fetal echocardiography in the early 1980s. This communication reviews the use of M-mode, B-mode and pulsed Doppler ultrasound to examine cardiac function. M-mode ultrasound is used to determine the size of the fetal heart, the end-diastolic and end-systolic dimensions of the ventricular chambers, and the thickness of the ventricular walls and the interventricular septum, and to measure the diameter of the mitral and tricuspid valves as well as the diameter of the aorta and pulmonary artery. B-mode evaluation of the fetal heart includes measurement of atrial and ventricular dimensions as well as dimensions of the outflow tracts. This modality is useful when M-mode measurements cannot be made due to fetal position. Once measurements of cardiac structures are obtained using either M-mode or B-mode ultrasound, pulsed Doppler recording of mitral valve, tricuspid valve, aortic valve and pulmonary artery waveforms can be used to compute cardiac output as well as stroke volume. In addition, pulsed Doppler can be used to evaluate diastolic and systolic cardiac functions by examining the components of each waveform.

Development of Z-scores for fetal cardiac dimensions from echocardiography

OBJECTIVES

Z-scores for cardiac dimensions are well established in postnatal life, but have yet to be developed for fetal cardiac dimensions. These would be of real advantage to the clinician in accurately quantifying size and growth of cardiac dimensions and to the researcher by allowing mathematical comparison of growth in differing subgroups of a disease. The purpose of this observational study, conducted at tertiary fetal medicine and cardiology units, was to produce formulae and nomograms allowing computation of Z-scores for fetal cardiac dimensions from knowledge of femur length (FL), biparietal diameter (BPD) or gestational age (GA) using fetal echocardiography.

METHODS

Seventeen fetal cardiac dimensions were measured in 130 pregnant women with singleton fetuses of gestational age 15-39 weeks. Regression equations were derived relating all dimensions to FL, BPD and GA. From the calculations, formulae were then developed allowing fetal cardiac Z-score computation.

RESULTS

The relationships between cardiac dimensions and FL, BPD or GA were described following natural log transformation. From this analysis, FL (taken as an expression of fetal size) had the highest correlation to fetal cardiac dimensions. From the developed nomograms, Z-scores of specific fetal cardiac structures could be estimated from knowledge of the FL, BPD or GA and echocardiographically derived measurements.

CONCLUSIONS

This study allowed computation of Z-scores in fetal life for 17 cardiac dimensions from FL, BPD or GA. Previous studies of normal data allowed qualitative assessment of where abnormal cardiac dimensions lay with regard to the normal range. Z-scores from this study allow quantitative analysis of where such dimensions lie relative to the mean. This permits exact assessment of growth of fetal cardiac structures in normal hearts and particularly in congenitally abnormal hearts where quantitative assessment of the growth of cardiac structures is important in analyzing and planning treatment strategies.

Three-dimensional and four-dimensional fetal echocardiography: a new frontier

PURPOSE OF REVIEW

One of the difficulties of conventional two-dimensional cardiac imaging is the inability to examine fetal cardiac anatomy from multiple angle planes. Three-dimensional and four-dimensional ultrasound allows the fetal examiner to more accurately accomplish this task. Currently, multiple disciplines may be involved in the examination of the fetal heart (pediatric cardiologists, obstetricians, maternal-fetal medicine specialists, and radiologists). The three-dimensional and four-dimensional imaging equipment used by these specialty physicians varies greatly. The purpose of this communication is to review techniques using three-dimensional and four-dimensional imaging that the pediatric cardiologist may not be exposed to in the clinical environment, however, in consulting with colleagues needs to have an understanding of these imaging modalities.

RECENT FINDINGS

The reconstruction of cardiac structures using this technology allows the examiner to view cardiac anatomy in a manner that was limited by previous two-dimensional imaging. Volume datasets are obtained in the three-dimensional static mode (no cardiac motion) or using four-dimensional - the three-dimensional heart is observed contracting during one or multiple cardiac cycles. Therefore, the fourth dimension is time. Using either three-dimensional or four-dimensional technology datasets are acquired, followed by image reconstruction. The image reconstruction enables the examiner to evaluate a two-dimensional image using multiple views, evaluate intracardiac anatomy at different depth planes, and recreate casts of blood flow of the chambers and great vessels.

SUMMARY

This new technology has enhanced the ability of the examiner to identify normal and complex fetal heart anatomy during the early second to the late third trimesters of pregnancy.

Estimation of right ventricular mass by two-dimensional echocardiography

BACKGROUND

This report describes two original echocardiographic approaches to measure right ventricular (RV) mass (RVM).

METHODS

In the bullet formula (5/24 pi D1 D2 L), where D1 and D2 are short axes and L the log axis, the RVM is obtained by subtracting the cavity volume from the RV total volume and subsequently multiplying the difference by myocardium density. The second method uses 3 endocardium segments measured at: (1) short axis plane of the aortic valve and left atrium (b1); (2) short axis plane at the midpoint between the tricuspid valve annulus and the apex (b2); and (3) 4-chamber view (h). Those segment lengths are applying in the formula A = [(b1 + b2)/2] x h. The result is multiplied by the wall thickness and by myocardium density.

RESULTS

Both formulas were primarily tested in 30 mongrel dogs and have shown good correlation with the true mass ( r = 0.869 with the segments formula and r = 0.819 with the bullet formula). The same method was used in 20 human patients before heart transplant with similar results ( r = 0.810 with the segments formula and r = 0.836 with the bullet formula).

CONCLUSIONS

The RVM can be satisfactorily estimated by 2-dimensional echocardiography. The linear regression between the calculated mass (using the smoothest and thinner myocardium thickness) and the actual mass may provide the correction factor for the RVM calculation. Two echocardiographic methods were used to measure right ventricular mass. One of them used a bullet formula variant (5/24 pi D1 D2 L). The second method used 3 endocardium segments measured in 3 2-dimensional echocardiographic planes (short axis of aortic valve and left ventricle, and 4-chamber view), and applied in the formula A = [(b1 + b2)/2] x h. Both formulas have shown good correlation with the true mass in 30 mongrel dogs ( r = 0.869 with the segments formula and r = 0.819 with the bullet formula) and in 20 human patients before heart transplant ( r = 0.810 and r = 0.836, respectively).

Fetal magnetocardiographic mapping using independent component analysis

Fetal magnetocardiography (fMCG) is the only noninvasive technique allowing effective assessment of fetal cardiac electrical activity during the prenatal period. The reconstruction of reliable magnetic field mapping associated with fetal heart activity would allow three-dimensional source localization. The efficiency of independent component analysis (ICA) in restoring reliable fetal traces from multichannel fMCG has already been demonstrated. In this paper, we describe a method of reconstructing a complete set of fetal signals hidden in multichannel fMCG preserving their correct spatial distribution, waveform, polarity and amplitude. Fetal independent components, retrieved with an ICA algorithm (FastICA), were interpolated (fICI method) using information gathered during FastICA iterations. The restored fetal signals were used to reconstruct accurate magnetic mapping for every millisecond during the average beat. The procedure was validated on fMCG recorded from the 22nd gestational week onward with a multichannel MCG system working in a shielded room. The interpolated traces were compared with those obtained with a standard technique, and the consistency of fetal mapping was checked evaluating source localizations relative to fetal echocardiographic information. Good magnetic field distributions during the P-QRS-T waves were attained with fICI for all gestational periods; their reliability was confirmed by three-dimensional source localizations.

Time course reconstruction of fetal cardiac signals from fMCG: independent component analysis versus adaptive maternal beat subtraction

M-mode and pulsed Doppler echocardiography, cardiotocography and transabdominal fetal ECG are available in clinical practice to monitor fetal cardiac activity during advancing gestation, but none of these methods allows the direct measurement of morphological and temporal parameters for fetal rhythm assessment. Fetal magnetocardiograms (fMCGs) are noninvasive recordings of magnetic field variations associated with electrical activity of the fetal heart obtained with superconducting sensors positioned over the maternal abdomen inside a shielded room. Because of maternal cardiac activity, fMCGs are contaminated by maternal components that need to be eliminated to reconstruct fetal cardiac traces. The aim of the present work was to use two methods working in the time domain, an independent component analysis algorithm (FastICA) and an adaptive maternal beat subtraction technique (AMBS), for the retrieval of fetal cardiac signals from fMCGs. Detection rates of both methods were calculated, and FastICA and AMBS performances were compared in the context of clinical applications by estimating several temporal and morphological characteristics of the retrieved fetal traces, such as the shape and duration P-QRS-T waves, arrhythmic beat detection and classification, and noise reduction. Quantitative and qualitative comparison produced figures that always suggested that FastICA was superior to AMBS from the perspective of clinical use of the recovered fetal signals.

Ventricular myocardial thicknesses in anencephalic fetuses

The heart of an anencephalic baby can be used as a donor after death. There exists insufficient information in literature, however, for the possible morphological differences in anencephalic hearts. This study compares ventricular myocardial thicknesses of anencephalic fetuses with normal fetuses in the same gestational age group. The comparison was made histologically on the slices taken from three levels of anterior and posterior walls of the left and right ventricles and from two levels of the interventricular septum. When each level was taken into account separately, the middle part of the left ventricular anterior wall was detected thinner in anencephalics (P = 0.010). When the mean value for each wall (anterior and posterior) was taken into account, left ventricular anterior wall was found thinner in anencephalics (P = 0.005). When the mean value for each ventricle was compared, the left ventricular wall was detected thinner in anencephalics (P = 0.025). These results support the idea that absence of the cerebral cortex results in modifications of the fetal heart. Because differences were limited to the left ventricular anterior wall non-homogenously, factors other than the decrease in the heart load (e.g., changes in intrathoracic anatomy) might also affect the myocardial features. When the mean value of right ventricle was compared to the left within the normal and anencephalic groups separately, the left ventricle was thicker than the right in normal fetuses (P = 0.016). In anencephalics the difference between two ventricular walls was insignificant (P = 0.084). This supports the left ventricular dominance in normal fetuses but not in anencephalics for the 27-34 weeks of age group. We suggest that when an anencephalic heart is intended to use as a donor, possible alterations presented in this article should be taken into account.

High-frequency ultrasound database profiling growth, development, and cardiovascular function in C57BL/6J mouse fetuses

BACKGROUND

High-frequency ultrasound is effective for noninvasive phenotypic analysis of cardiovascular development and function in mutagenized fetal mice. However, lacking is a normative database of echocardiographic variables for monitoring growth and cardiovascular function.

METHODS

C57BL/6J fetal mice were scanned in utero using an ultrasound system with a 15-MHz linear phased-array transducer. Pregnant mothers were anesthetized with 1% isoflurane mixed with 100% oxygen. Quantitative variables for monitoring fetal growth and cardiac function were obtained in several imaging planes and modalities.

RESULTS

Fetal growth measurements increased linearly. Inflow velocities showed significant A-wave dominance. The E wave progressively increased during development. Cardiac function was best assessed through M-mode analysis, but short-axis images were difficult to obtain. Spectral Doppler was readily obtained and the myocardial performance index was calculated.

CONCLUSIONS

These results provide an essential foundation for the evaluation of cardiovascular defects in mutagenized and transgenic mice.

Major abdominal surgery of the neonate: anaesthetic considerations

The anaesthetic handling of neonates scheduled for major abdominal surgical procedures is one of the most demanding tasks that can confront an anaesthesiologist. This chapter will review the specific physiological characteristics of the newborn with relevance to anaesthesia and will also provide robust guidelines for the anaesthetic handling of the most frequent diagnoses that need major abdominal surgery during the neonatal period.

Dependency of magnetocardiographically determined fetal cardiac time intervals on gestational age, gender and postnatal biometrics in healthy pregnancies

Background

Magnetocardiography enables the precise determination of fetal cardiac time intervals (CTI) as early as the second trimester of pregnancy. It has been shown that fetal CTI change in course of gestation. The aim of this work was to investigate the dependency of fetal CTI on gestational age, gender and postnatal biometric data in a substantial sample of subjects during normal pregnancy.

Methods

A total of 230 fetal magnetocardiograms were obtained in 47 healthy fetuses between the 15^th and 42^nd week of gestation. In each recording, after subtraction of the maternal cardiac artifact and the identification of fetal beats, fetal PQRST courses were signal averaged. On the basis of therein detected wave onsets and ends, the following CTI were determined: P wave, PR interval, PQ interval, QRS complex, ST segment, T wave, QT and QTc interval. Using regression analysis, the dependency of the CTI were examined with respect to gestational age, gender and postnatal biometric data.

Results

Atrioventricular conduction and ventricular depolarization times could be determined dependably whereas the T wave was often difficult to detect. Linear and nonlinear regression analysis established strong dependency on age for the P wave and QRS complex (r² = 0.67, p < 0.001 and r² = 0.66, p < 0.001) as well as an identifiable trend for the PR and PQ intervals (r² = 0.21, p < 0.001 and r² = 0.13, p < 0.001). Gender differences were found only for the QRS complex from the 31^st week onward (p < 0.05). The influence on the P wave or QRS complex of biometric data, collected in a subgroup in whom recordings were available within 1 week of birth, did not display statistical significance.

Conclusion

We conclude that 1) from approximately the 18^th week to term, fetal CTI which quantify depolarization times can be reliably determined using magnetocardiography, 2) the P wave and QRS complex duration show a high dependency on age which to a large part reflects fetal growth and 3) fetal gender plays a role in QRS complex duration in the third trimester. Fetal development is thus in part reflected in the CTI and may be useful in the identification of intrauterine growth retardation.

Echocardiographic evaluation of cardiac function in the fetus

The development of high-resolution ultrasound has allowed detailed examination of the fetal heart. The accuracy of fetal echocardiography in the diagnosis of malformations of the fetal heart has been established in the second trimester and, more recently, at a much earlier stage in gestation (Allan et al., 1980; Allan et al., 1981; Simpson, 2000; Huggon et al., 2002). Confirmation of structural abnormalities has usually been by autopsy or by postnatal investigation. This is certainly sufficient for confirmation of structural malformations, but functional evaluation of the fetal heart is far more difficult to validate. Post-mortem studies, by their very nature give little insight into cardiac function and postnatal studies, whilst permitting functional evaluation of the heart, do so under entirely different conditions compared to the circulation in utero. Prior to the advent of ultrasound, fetal data was drawn from invasive animal studies (Pohlman, 1909; Dawes et al., 1954; Barcroft, 1936; Rudolph, 1985). There have been very few invasive studies in the human fetus including some conducted on exteriorised fetuses undergoing termination by hysterotomy (Nyberg and Westin, 1962; Rudolph et al., 1971). Pressure data has been obtained from the human fetus for normal human hearts and in cardiac disease (Johnson et al., 2000; Johnson et al., 1992; Johnson, 1992). However, the vast majority of cardiac functional data in the human fetus has been obtained by non-invasive means, which has almost exclusively been by echocardiography. This article will review some of the techniques that may be used to evaluate fetal cardiac function and will also emphasise some of the limitations of such techniques.

Na(+)-channel modulation, a new principle of inotropic intervention: effects on hemodynamic and myocardial energetics in the immature rabbit heart

Na+-channel modulators exert their positive inotropic action without affecting the adenylate-cyclase pathway by an increase in the open probability of the sarcolemmal Na+ channels. Although inotropic effects in neonatal hearts are less pronounced compared with adult hearts, the Na+-channel modulator BDF 9148 increases contractility and relaxation velocity in immature myocardium. Effects on hemodynamics and myocardial energetics are not known. Therefore, we studied the Na+-channel modulator BDF 9148 in isolated antegrade perfused rabbit hearts of different ages (2-28 d) and compared the effects with isoproterenol, enoximone, and ouabain. ANOVA showed significant effects in the concentration response curves for heart rate, stroke volume, cardiac output, and oxygen consumption but not for myocardial efficiency (p = 0.06). Age-dependent differences were observed for heart rate and stroke volume. Administration of BDF 9148 resulted in a maximal increase in stroke volume and cardiac output up to 25% in neonatal and 40% to 60% in adult preparations. Heart rate decreased by 15% in adult hearts only. Myocardial oxygen consumption was increased in a concentration-dependent manner between 25% in neonatal and 50% in adult hearts. Myocardial efficiency was increased by 35% in adult and by 10% in neonatal preparations. Although positive hemodynamic and energetic effects were less pronounced in immature compared with adult hearts, neonatal hearts also profited from the administration of the Na+-channel modulator BDF 9148. Further studies are necessary to clarify the risk of arrhythmia during application of Na+-channel modulators such as BDF 9148.

Multicentre study of fetal cardiac time intervals using magnetocardiography

OBJECTIVE

A database with reference values of the durations of the various waveforms in a magnetocardiogram of fetuses in uncomplicated pregnancies is assessed. This database will be of help to discriminate between pathologic and healthy fetuses. A fetal magnetocardiogram is a recording of the magnetic field in a location near the maternal abdomen and reflects the electric activity within the fetal heart. It is a non-invasive method, which can be used with nearly 100% reliability from the 20th week of gestation onward.

DESIGN

Durations of the waveforms were assembled from averaged magnetocardiograms and statistically processed.

SETTING

Fetal magnetocardiograms were measured with different magnetocardiographs. All measurements were carried out in magnetically shielded rooms.

SAMPLE

Fetal magnetocardiograms were obtained for 582 healthy patients.

METHOD

The durations of the waveforms were extracted from fetal magnetocardiograms measured at the cooperating centres. The variables collected included the duration of the P-wave, the PR interval, the PQ interval, the QRS complex, the QT interval and the T-wave and QTc value. The results were compared with values extracted from electrocardiograms of fetuses measured via electrodes attached to the maternal abdomen, from electrocardiograms measured during labour using a scalp electrode, and from electrocardiograms recorded in newborns, that were found in the literature.

MAIN OUTCOME MEASURES

Values of the durations are given as a function of gestational age including the regression line as well as the bounds marking the 90%, 95% and 98% prediction interval.

RESULTS

The durations of the P-wave, the PR interval, the QRS complex, the QT interval and QTc value increase linearly with gestational age. The durations of the PQ interval and the T-wave are independent of fetal age.

CONCLUSION

The values found agree with those found in the literature. The scatter of the data is wide due to the variation in normal physiology, the measuring system and signal processing and the subjectivity of the researcher. However, the system can define normal ranges and may be used in diagnosis.

Measurement of right ventricular volume in healthy term and preterm neonates

BACKGROUND

Pulmonary hypertension is associated with worse perinatal outcomes in infants with respiratory disorders. In such infants right ventricular dysfunction may result in poor pulmonary blood flow.

OBJECTIVE

To evaluate the practicability and repeatability of echocardiographic measurements of right ventricular volume in healthy term and preterm neonates, and to follow changes in right ventricular volume over the first 2 days of life.

METHODS

Serial echocardiographic examinations were performed on day 0, 1, and 2 on healthy term and preterm neonates. Two methods of estimating right ventricular volume were assessed: the ellipsoid approximation and Simpson's stacked discs methods. Systolic and diastolic volumes on days 1 and 2 were compared with baseline values on day 0. Term and preterm volumes were compared at the same time points.

RESULTS

Thirty five infants were recruited, 18 term and 17 preterm. Right ventricular volumes were significantly lower on day 1 and day 2 than baseline in both term and preterm infants. Median (interquartile range) end systolic and diastolic volumes for term infants on days 0, 1, and 2 were 1.04 (0.88-1.44), 0.82 (0.70-1.03), 0.92 (0.72-0.97) ml/kg and 2.21 (2.10-2.75), 2.05 (1.81-2.38), 1.91 (1.81-2.13) ml/kg respectively. In preterm infants the values were 1.09 (0.91-1.16), 0.72 (0.54-0.91), 0.61 (0.54-0.76) ml/kg and 2.09 (1.71-2.25), 1.47 (1.23-1.98), 1.43 (1.22-1.78) ml/kg respectively.

CONCLUSION

Right ventricular volume decreases over the first 2 days of life in healthy term and preterm infants.

Severe pulmonary hypertension without right ventricular failure: the unique hearts of patients with Eisenmenger syndrome

Why adults with the Eisenmenger syndrome fare so much better than other patients with severe pulmonary hypertension is not known, but may be related to unique hemodynamics found only in these patients and in normal fetuses. We used echocardiography to evaluate ventricular morphology and function in 80 subjects: 45 cyanotic adults and 5 cyanotic adolescents with Eisenmenger syndrome, 10 infants with nonrestrictive ventricular septal defect and left-to-right shunt flow (pre-Eisenmenger phase), and 20 fetuses with structurally normal hearts. Cross-sectional morphology of the hearts was the same in all 4 groups with a flat ventricular septum throughout the cardiac cycle and equal thickness of the right and left ventricular free walls (regression slope 0.98, r = 0.97, p <0.0001). This morphology was the same in patients independent of age, defect type, and ventricular function. Right ventricular fractional area change was slightly inferior to that of the left ventricle but normal in most patients with Eisenmenger syndrome (0.47 +/- 0.14 vs 0.51 +/- 0.13, p <0.01). Overall, there was a highly significant linear relation between right and left ventricular function (r = 0.81, p <0.0001). The hearts of patients with Eisenmenger syndrome are more like normal fetal hearts than normal adult hearts. Because of the unique cardiovascular hemodynamics, regression of right ventricular wall thickness does not occur and is likely the reason that patients with Eisenmenger syndrome fare so much better than other adults with severe pulmonary hypertension.

Fetal cardiac effects of doxorubicin therapy for carcinoma of the breast during pregnancy: case report and review of the literature

Cardiotoxicity is a recognized complication of anthracycline drugs given as part of chemotherapy; however, the pre- and postnatal cardiac effects of in utero exposure are not well documented. In this report we present a case of gestational breast cancer with initiation of four cycles of doxorubicin/cyclophosphamide chemotherapy after modified radical mastectomy and axilla dissection during the early second trimester. Serial echocardiographic measurements of the ventricular shortening fraction and biometry of the ventricular cavities were performed. Allowing for the individual variability of these values in the fetus no myocardial dysfunction was observed. The literature was reviewed in an attempt to delineate the possible role of prenatal echocardiography in the diagnosis of doxorubicin-induced cardiotoxicity in the fetus.