Fetal aortic arch measurements between 14 and 38 weeks' gestation: in-utero ultrasonographic study

Fetal cardiac evaluation in HIV-positive women under HAART therapy in a Romanian hospital

Human immunodeficiency virus (HIV) is an RNA (ribonucleic acid) virus that causes acquired immunodeficiency syndrome (AIDS). This disease has a major socioeconomical impact. The aim of the present study was to assess the fetal heart structure and function in HIV-positive pregnant women on highly active antiretroviral therapy (HAART). This is a prospective study conducted between January, 2018 and December, 2019. The hearts of fetuses from 14 HIV-positive pregnant women on HAART were assessed. Statistically significant sex-related cardiac changes in HIV-exposed uninfected fetuses of pregnant women on HAART were found. A narrow aorta was detected in female fetuses and a smaller left ventricular transverse diameter in male fetuses. Overall, the myocardial performance index remained unaltered. The impact of antiretroviral therapy on fetal heart seems to be sex-related. Accurate and complete information about the risks and benefits of antiretroviral treatment and management strategies to improve fetal outcomes may also ensure better compliance of the mothers to this treatment.

Prenatal Diagnosis of Aortopulmonary Window by 2-Dimensional Echocardiography: Summary of 8 Cases

Aortopulmonary window (APW) is a rare congenital heart anomaly. A total of 8 cases with APW confirmed by echocardiography and surgery were retrospectively reviewed and the echocardiographic features analyzed. Among the 8 APW cases, 5 were type II and 3 were type III, the latter of which includes 2 cases complicated with Berry syndrome. Prenatal echocardiography can provide accurate information for the diagnosis of fetal APW. The prognosis depends on the timing of surgery and the nature of the associated cardiac anomalies.

Prenatal Sonographic Predictors of Neonatal Coarctation of the Aorta

OBJECTIVES

To identify practical prenatal sonographic markers for the postnatal diagnosis of coarctation of the aorta.

METHODS

We reviewed the fetal echocardiograms and postnatal outcomes of fetal cases of suspected coarctation of the aorta seen at a single institution between 2010 and 2014. True- and false-positive cases were compared. Logistic regression analysis was used to determine echocardiographic predictors of coarctation of the aorta. Optimal cutoffs for these markers and a multivariable threshold scoring system were derived to discriminate fetuses with coarctation of the aorta from those without coarctation of the aorta.

RESULTS

Among 35 patients with prenatal suspicion of coarctation of the aorta, the diagnosis was confirmed postnatally in 9 neonates (25.7% true-positive rate). Significant predictors identified from multivariate analysis were as follows: Z score for the ascending aorta diameter of -2 or less (P = < .001), Z score for the mitral valve annulus of -2 or less (P= .033), Zscore for the transverse aortic arch diameter of -2 or less (P= .028), and abnormal aortic valve morphologic features (P= .026). Among all variables studied, the ascending aortic Z score had the highest sensitivity (78%) and specificity (92%) for detection of coarctation of the aorta. A multivariable threshold scoring system identified fetuses with coarctation of the aorta with still greater sensitivity (89%) and only mildly decreased specificity (88%).

CONCLUSIONS

The finding of a diminutive ascending aorta represents a powerful and practical prenatal predictor of neonatal coarctation of the aorta. A multivariable scoring system, including dimensions of the ascending and transverse aortas, mitral valve annulus, and morphologic features of the aortic valve, provides excellent sensitivity and specificity. The use of these practical sonographic markers may improve prenatal detection of coarctation of the aorta.

Gestational age-specific scoring systems for the prediction of coarctation of the aorta

OBJECTIVES

To determine which combination of cardiac parameters provides the best prenatal prediction of coarctation of aorta (CoAo).

METHODS

We selected all cases of simple cardiac asymmetry prenatally diagnosed in 2003-2013. Logistic regression was used to select the best predictors of CoAo.

RESULTS

The study population included 115 fetuses. CoAo was confirmed in 52 neonates (45%). The sample was divided in two groups according to the gestational age (GA) at diagnosis: early group (EG) ≤28 weeks (n = 57), and late group (LG) >28 weeks (n = 58). CoAo was confirmed in 75% and 16% of cases, respectively. GA-specific scoring systems with maximum two parameters were made, and the pairwise combination with the best diagnostic performance for each group was selected. In EG, the z-score of ascending aorta (AAo) and aortic isthmus (three vessels and trachea view) showed the best diagnostic accuracy [area under receiver-operating curve (AUC) 0.98, 95% confidence interval (CI) 0.94-1.00]. In the LG, the best results were provided by the tricuspid valve/mitral valve ratio with the main pulmonary artery/AAo ratio (AUC 0.84, 95% CI 0.67-1.00).

CONCLUSIONS

Gestational age-specific scoring systems combining size-based cardiac parameters may improve the accuracy of fetal echocardiography to stratify the risk of CoAo. The objectivity and simplicity of its components may facilitate its implementation in fetal cardiology units.

Extracranial Segments of the Vertebral Artery: Insight in the Developmental Changes up to the 21st Year of Life

The vertebral artery (VA) bilaterally arises usually from the subclavian artery and courses within the bony canals of cervical vertebrae, and then it reverses directions on the first vertebra before piercing the dura to enter the cranium.The aim was to follow (ab)normal developmental changes of extracranial VA from prenatal status to age 21. This chapter included a brief description of the arterial embryology and morphofunctional specificity of the VA in prevertebral, cervical, and atlantic parts, during prenatal and postnatal period.The authors concluded that the subclavian origin of the VA was in most of fetal and adult cases. The incidences of variable VA origins and domination of one of the VAs were different from one series of human specimens to the second one. Although in most of cases, anomalous origin and/or variable course of the extracranial VA had little or did not result in clinical symptoms in infants and young adults, the true value of their discovery is in the diagnostic gain before vascular surgery of supra-aortic arteries.

Quantitative anatomy of the growing abdominal aorta in human fetuses: an anatomical, digital and statistical study

Background

Advances in perinatal medicine have required an extensive knowledge of fetal aorto-iliac measurements. The present study was performed to compile reference data for dimensions of the abdominal aorta at varying gestational ages.

Material/Methods

Using the methods of anatomical dissection, digital-image analysis (Leica QWin Pro 16 system), and statistical analysis (Student’s t-test, one-way ANOVA, post-hoc RIR Tukey test, regression analysis, and Wilcoxon signed-rank test), the growth of length (mm), proximal and distal external diameters (mm), and volume (mm³) of the abdominal aorta in 124 (60 male, 64 female) spontaneously aborted human fetuses aged 15–34 weeks was examined.

Results

No significant male-female differences were found. The length ranged from 9.35±1.24 to 36.29±4.98 mm, according to the linear function y=−14.596+1.519 × Age ±2.639 (R²=0.92; p<0.0001). The proximal external diameter varied from 1.18±0.25 to 5.19±0.49 mm, according to the linear pattern y=−2.065+0.212 × Age ±0.348 (R²=0.92; p<0.0001). The distal external diameter increased from 1.03±0.23 to 4.92±0.46 mm, in accordance with the linear model y=−2.097+0.203 × Age ±0.351 (R²=0.92; p<0.0001). Both length and proximal external diameter of the abdominal aorta indicated a proportionate evolution, because the length-to-proximal external diameter ratio was stable, following the linear function y=7.724–0.017 × Age ±0.925. The abdominal aorta volume ranged from 9.6±4.5 to 740.5±201.8 mm³, given by the quadratic function y=911–101 × Age +2.838 × Age² ±78 (R²=0.89; p<0.0001).

Conclusions

There are no significant differences between males and females for morphometric parameters of the abdominal aorta. The abdominal aorta grows linearly in both length and diameters, and parabolically in volume. These detailed morphometric data of the abdominal aorta provide a database for intra-uterine echographic examinations in the early diagnosis, monitoring and management of aorto-iliac malformations.

The normal growth of cross-sectional areas of the aorto-iliac segment in human fetuses - an anatomical, digital, and statistical study

BACKGROUND

The intraluminal size of the aorto-iliac segment is relevant in both the clinical and echographic settings. The aim of this study was to compile both the absolute and relative age-specific reference intervals for cross-sectional areas (CSAs) of the aorto-iliac segment.

MATERIAL/METHODS

Using the methods of anatomical dissection, digital-image analysis (Leica QWin Pro 16) and statistical analysis (Student's t test, one-way ANOVA, post-hoc RIR Tukey test, linear regression), the growth in CSA (in mm2) of the abdominal aorta, the common, external, and internal iliac arteries in 124 (60 males, 64 females) spontaneously aborted human fetuses aged 15-34 weeks was examined.

RESULTS

No significant sex differences were found. In the age range of 4-9 months, the distal CSA of the abdominal aorta ranged from 0.87±0.34 to 19.18±3.36 mm2. The CSA of the common iliac artery varied from 0.37±0.22 to 4.30±1.54 mm2 on the right, and from 0.36±0.16 to 3.80±1.44 mm2 on the left. The sum of the CSAs of the right and left common iliac arteries grew proportionately to the distal CSA of the abdominal aorta; the latter being significantly larger than the former. On both sides, however, the CSA of the internal iliac artery was approximately twice that of the external iliac artery. Between the ages of 4 and 9 months, the CSA of the external iliac artery ranged from 0.10±0.06 to 1.32±0.52 mm2 on the right, and from 0.08±0.03 to 1.19±0.42 mm2 on the left. The CSA of the internal iliac artery increased from 0.23±0.14 to 2.59±1.22 mm2 on the right, and from 0.21±0.14 to 2.27±1.11 mm2 on the left. Bilaterally, the sum of the CSAs of the internal and external iliac arteries was significantly smaller than the CSA of the common iliac artery. The relative CSA of each artery decreased until the age of 6 months, after which their values were gradually increasing until the age of 9 months.

CONCLUSIONS

The aorto-iliac segment does not reveal sex differences in its cross-sectional area. The cross-sectional area of the internal iliac artery is approximately twice the size of the external iliac artery. The aorto-iliac segment observed proximally to distally reduces its cross-sectional area, thereby resulting in an increase in blood velocity.

New quantitative patterns of the growing trachea in human fetuses

BACKGROUND

Rapid progress in perinatal medicine has resulted in numerous tracheo-bronchial interventions on fetal and neonatal airways. The present study was performed to compile normative data for tracheal dimensions at varying gestational ages.

MATERIAL/METHODS

Using anatomical dissection, digital image analysis (NIS-Elements BR 3.0) and statistical analysis (Wilcoxon signed-rank test, Student's t test, one-way ANOVA, post-hoc Bonferroni test, linear and nonlinear regression analysis) a range of the 4 variables (length in mm, middle external transverse diameter in mm, proximal internal cross-sectional area in mm², internal volume in mm³) for the trachea in 73 spontaneously aborted human fetuses (39 male, 34 female) aged 14-25 weeks was examined.

RESULTS

No significant male-female differences were found (P>0.05). The length ranged from 10.37±2.15 to 26.54±0.26 mm as y=-65.098 + 28.796 × ln (Age) ±1.794 (R²=0.82). The middle external transverse diameter varied from 2.53±0.09 to 5.09±0.42 mm with the model y=-11.020 + 5.049 × ln (Age) ±0.330 (R²=0.81). The trachea indicated a proportional evolution because the middle external transverse diameter-to-length ratio was stable (0.23±0.03). The proximal internal cross-sectional area rose from 1.46±0.04 to 5.76±1.04 mm² as y=-3.562 + 0.352 × Age ±0.519 (R²=0.76). The internal volumetric growth from 11.89±2.49 to 119.63±4.95 mm³ generated the function y=-135.248 + 9.919 × Age ±10.478 (R²=0.86).

CONCLUSIONS

The growth in both length and middle external transverse diameter of the trachea follows logarithmic functions, whereas growth of both its proximal internal cross-sectional area and internal volume follow linear functions. The length and middle external transverse diameter of the trachea develop proportionally to each other. The tracheal dimensions may be helpful in the prenatal diagnosis and monitoring of tracheal malformations and obstructive anomalies of the upper respiratory tract.

The normal growth of the common iliac arteries in human fetuses - an anatomical, digital and statistical study

BACKGROUND

The present study was carried out to compile normative data for dimensions of the common iliac arteries at varying gestational ages.

MATERIAL/METHODS

We used anatomical dissection, digital-image analysis (system of Leica QWin Pro 16) and statistical analysis (Student T test, one-way ANOVA, post-hoc RIR Tukey test, and regression analysis) to examine the increase in length (mm), proximal external diameter (mm), and volume (mm³) of the common iliac arteries in 124 (60 males, 64 females) spontaneously aborted human fetuses aged 15-34 weeks.

RESULTS

Neither sex nor right-left significant differences were found (P>0.05). The length ranged from 4.76 ± 1.05 to 15.38 ± 1.60 mm on the right, and from 4.92 ± 1.33 to 14.91 ± 1.25 mm on the left, according to the linear functions y=-3.598+0.585 × Age ± 1.522 (R²=0.83) and y=-3.107+0.554 × Age ± 1.444 (R²=0.83). The proximal external diameter increased from 0.66 ± 0.19 to 2.30 ± 0.42 mm on the right, and from 0.66 ± 0.14 to 2.16 ± 0.42 mm on the left, according to the quadratic models y=1.392-0.110 × Age + 0.004 × Age² ± 0.285 (R²=0.77) and y=1.283-0.099 × Age + 0.004 × Age² ± 0.238 (R²=0.81). The volumes were increasing from 1.93 ± 1.74 to 66.95 ± 29.31 mm³ on the right, and from 1.91 ± 1.65 to 56.86 ± 25.17 mm³ on the left, given by the quadratic functions: y=99.69-10.60 × Age+0.28 7 × Age² ± 14.40 (R²=0.67) and y=82.62-8.86 × Age + 0.242 × Age² ± 11.60 (R²=0.71).

CONCLUSIONS

The common iliac arteries grow linearly in length, and parabolically in both diameter and volume. The right common iliac artery constitutes a predominant vessel in relation to its length, external diameter and volume. The morphometric data on the common iliac arteries may serve as a useful reference in the prenatal diagnosis and monitoring of congenital aorto-iliac abnormalities.

Aortic isthmus and cardiac monitoring of the growth-restricted fetus

Aortic isthmus acts as an arterial watershed between the cerebral and placental circulations, connecting 2 parallel fetal ventricular pumps. It plays a crucial role in the fetal circulatory dynamics. Information about aortic isthmus blood flow may improve the management of sick fetuses. However, perceived technical difficulties limit the clinical use of aortic isthmus Doppler for fetal hemodynamic monitoring. Changes in aortic isthmus blood flow pattern seem to reflect fetal cardiovascular status accurately and predict perinatal and long-term neurodevelopmental outcome in intrauterine growth restriction. This review evaluates the available scientific information and discusses the role of aortic isthmus in fetal circulation.

Fetal aortic arch measurements at 14 to 40 weeks' gestation derived by spatiotemporal image correlation volume data sets

OBJECTIVE

The purpose of this study was to establish reference ranges for the transverse aortic arch diameter (TAD) and distal aortic isthmus diameter (DAID) in normal singleton pregnancies (14-40 weeks) based on the 3-vessel/trachea (3VT) view of cardio-spatiotemporal image correlation (STIC) volume data sets.

METHODS

A prospective descriptive study was conducted on uncomplicated singleton pregnancies with healthy fetuses and an accurate gestational age (GA). Cardio-STIC examinations were performed by experienced sonographers using a high-resolution ultrasound machine, and the volume data sets were manipulated to obtain the 3VT view and measured for the TAD and DAID.

RESULTS

A total of 554 measurements were performed, ranging from 13 to 30 for each gestational week. The best regression models were as follows: TAD (in millimeters) = -1.01 + 1.69 (GA, in weeks) (r(2) = 0.93; P < .001), and DAID (in millimeters) = -0.85 + 1.54 (GA, in weeks) (r(2) = 0.92; P < .001). A table of nomograms for 5th, 50th, and 95th percentile ranges was constructed.

CONCLUSIONS

Normative data for the TAD and DAID at each gestational week from 14 to 40 weeks were constructed by a new technique of measurement based on cardio-STIC. These reference ranges may be useful tools for assessment of fetal aortic arch abnormalities.

Fetal aortic isthmus blood flow and the fraction of cardiac output distributed to the upper body and brain at 11-20 weeks of gestation

OBJECTIVE

To measure serial changes in fetal aortic isthmus (AI) blood flow and estimate the fraction of fetal cardiac output distributed to the upper body, including the brain, at 11-20 weeks of gestation.

METHODS

Using pulsed-wave Doppler and two-dimensional ultrasound, blood flow velocities and inner diameter of the AI, aortic valve (AV) and pulmonary valve (PV) were measured longitudinally in 143 fetuses and volume blood flows (Q) were calculated for each site using the formula: Q (mL/min) = pix (diameter/2)(2) x velocity time integral x heart rate x 60. The sum of Q(av) and Q(pv) constituted the combined cardiac output (CCO) and the fraction (%) of the upper body (including brain) blood flow was calculated as: (Q(av)-Q(ai))x100/CCO.

RESULTS

AI blood velocities as well as the vessel diameter increased with advancing gestation, resulting in a significant increase in Q(ai) from 1.9 to 40.5 mL/min during weeks 11 to 20. The AI peak systolic velocity increased from 29 to 63 cm/s, end-diastolic velocity from 1.2 to 5.2 cm/s, and the time-averaged maximum velocity from 11 to 22 cm/s, resulting in a fairly stable pulsatility index (PI) of 2.4-2.6 and resistance index (RI) of 0.91-0.94. On average, 75% of blood ejected by the left ventricle (which represented about 35% of the CCO) passed through the AI to the descending aorta. The fraction of CCO distributed to the upper body, including the brain, was estimated as approximately 13%.

CONCLUSION

We have established longitudinal reference ranges for fetal AI diameter, blood flow velocities, PI, RI and volume blood flow at 11-20 weeks of gestation. The human fetus appears to direct a relatively small fraction (13%) of its CCO to the upper body, including the brain, during this period of pregnancy.

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.

In vitro hemodynamic investigation of the embryonic aortic arch at late gestation

This study focuses on the dynamic flow through the fetal aortic arch driven by the concurrent action of right and left ventricles. We created a parametric pulsatile computational fluid dynamics (CFD) model of the fetal aortic junction with physiologic vessel geometries. To gain a better biophysical understanding, an in vitro experimental fetal flow loop for flow visualization was constructed for identical CFD conditions. CFD and in vitro experimental results were comparable. Swirling flow during the acceleration phase of the cardiac cycle and unidirectional flow following mid-deceleration phase were observed in pulmonary arteries (PA), head-neck vessels, and descending aorta. Right-to-left (oxygenated) blood flowed through the ductus arteriosus (DA) posterior relative to the antegrade left ventricular outflow tract (LVOT) stream and resembled jet flow. LVOT and right ventricular outflow tract flow mixing had not completed until approximately 3.5 descending aorta diameters downstream of the DA insertion into the aortic arch. Normal arch model flow patterns were then compared to flow patterns of four common congenital heart malformations that include aortic arch anomalies. Weak oscillatory reversing flow through the DA junction was observed only for the Tetralogy of Fallot configuration. PA and hypoplastic left heart syndrome configurations demonstrated complex, abnormal flow patterns in the PAs and head-neck vessels. Aortic coarctation resulted in large-scale recirculating flow in the aortic arch proximal to the DA. Intravascular flow patterns spatially correlated with abnormal vascular structures consistent with the paradigm that abnormal intravascular flow patterns associated with congenital heart disease influence vascular growth and function.

Morphometric study of the ascending aorta in human fetuses

The present study was performed on 128 spontaneously aborted human fetuses, aged 15-34 weeks, to compile normative data for ascending aorta dimensions at varying gestational age. Using anatomical dissection, digital-image analysis (system of Leica QWin Pro 16) and statistical analysis (ANOVA, regression analysis) a range of measurements (Length, original and terminal external diameters, volume) for the ascending aorta during gestation was examined. No significant gender differences were found (P > 0.05). The growth curves of the best fit for the plot for each morphometric feature against gestational age were generated. Both the Length and external diameters of the ascending aorta were found to increase in a linear fashion throughout gestation. The Length ranged from 2.63 +/- 0.42 to 10.80 +/- 1.49mm, according to the linear function y = -4.678 + 0.4647x +/- 0.8447 (r = 0.95). The original external diameter ranged from 2.02 +/- 0.26 to 6.84 +/- 0.63 mm, according to the linear model y = -2.103 + 0.2684x +/- 0.3958 (r = 0.97). The terminal external diameter ranged from 1.73 +/- 0.20 to 6.29 +/- 0.52 mm, with accordance to the linear function y = -2.354 + 0.2567x +/- 0.3826 (r = 0.97). The ascending aorta volume ranged from 7.56 +/- 2.65 to 370.99 +/- 105.42 mm3, according to the quadratic function y = 373.1 - 43.38x + 1.30x(2) +/- 24.51 (R2 = 0.89). The growth curves generated from my data might be useful as a reference for fetal echocardiographers in the detection of some congenital cardiovascular abnormalities.

Z-scores of the fetal aortic isthmus and duct: an aid to assessing arch hypoplasia

OBJECTIVE

Prenatal diagnosis of isolated coarctation of the aorta suffers from high false positive and false negative rates. The aim of our study was to develop Z-scores for the aortic isthmus in normal fetuses as a reference for fetuses with suspected coarctation.

METHODS

The aortic isthmal diameter, immediately proximal to the insertion of the arterial duct, was measured prospectively in the transverse (three vessel and trachea) and sagittal views in 221 normal fetuses at 18 to 37 weeks' gestation. The ductal diameter was measured immediately before it entered the descending aorta in the same view. All measurements were repeated three times by a single investigator and averaged. A second investigator re-measured the images of 50 cases to assess interobserver variability. Z-scores were created relating isthmal and ductal diameters to femur length and gestational age. The ratio between the isthmal and ductal diameters was calculated.

RESULTS

The formula used to calculate Z-scores for the three diameters was: [ln(measured isthmal diameter) - (m ln(femur length or gestational age) + c)]/root MSE, where c is the intercept, m is a multiplier and MSE is the mean squared error. The ratio between isthmal and ductal diameters was close to a constant value of 1 (95% CI 0.97-1.01), regardless of the value of femur length or gestational age.

CONCLUSION

We have defined Z-scores for the fetal aortic isthmus and arterial duct measured in the three vessels and trachea view and for the isthmus in the sagittal plane. In suspected coarctation, these Z-scores and the isthmal to ductal ratio may help in longitudinal assessment of the aortic arch and aid in the prenatal diagnosis of coarctation.

Morphometric study of the ductus arteriosus during human development

During prenatal life, the ductus arteriosus connects the left pulmonary artery and the descending aorta. Morphometric features (length, external diameter, volume) of the ductus arteriosus in 131 human fetuses (65 males, 66 females) were studied by means of anatomical, digital and statistical methods. Regression analysis was used to investigate the growth of the ductus arteriosus during gestation. The values of the length of the ductus arteriosus ranged from 3.95 mm for the 15 week gestational group to 12.20 mm for the 34th week of gestation. The length of the ductus arteriosus related to fetal age (x) increased according to the linear function y = -3.0726 + 0.4381x. The mean values of the diameter of the ductus arteriosus ranged from 1.34 to 3.49mm for the 15 and 34 week gestational groups, respectively. The growth of the ductus arteriosus diameter followed in accordance with the linear function y = 0.2072 + 0.0935x. The mean values of the ductus arteriosus volume ranged from 5.08 mm3 for the 15 week group to 117.30 mm3 of the 34 week gestation group. The volume growth increased according to the function y = 0.0007x3.3782. Positive correlation coefficients between arterial parameters and fetal age were statistically significant (P < or = 0.01) and reached the following values: r1 = 0.98 for Length, r2 = 0.90 for diameter and r3 = 0.94 for volume. Despite the increase in absolute diameter, the relative diameter of the ductus arteriosus (ductus arteriosus-to-aortic bulb diameter ratio) decreased from 0.80 to 0.48.

Quantitative evaluation of aortic arch development using digital-image analysis

This study was performed on 80 spontaneously aborted human fetuses of a gestational period of between 17 and 27 weeks. The procedure was based on latex filled arteries, which were preserved in formalin, and then later dissected. Data collection was accomplished using digital imaging. The specific measurements of the aortic arch diameter, length and volume were obtained using a computer program, written solely for the purpose of this study. Results indicated that the collected figures correlated with the fetal age through 3 sets of 4-week intervals. Diameter and length of the aortic arch varied from 2.5 to 4.1 mm and from 6.7 to 10.3 mm, respectively. Both parameters showed statistically significant (p<0.05) linear growth and differences between age groups. The volumetric growth of the aortic arch followed a square root function with its values ranging from 35.7 to 136.8 mm3, which were also statistically significant (p < 0.05). The diameter of the aortic isthmus was measured and compared to the diameters of the ascending and descending aorta thus allowing an estimation ratio between those parameters. Concluding analyses suggest that the aortic isthmus becomes narrower during fetal development.

Morphometric study of the aortic and great pulmonary arterial pathways in human foetuses

In prenatal and pediatric cardiovascular surgery knowledge of luminal diameters of the aortic and great pulmonary pathways is essential. The internal diameters of the aortic and great pulmonary pathways in 131 human foetuses (65 male, 66 female) were studied by means of anatomical, digital and statistical methods. During foetal development the absolute diameters revealed a linear increase. Correlation coefficients between these diameters and foetal age were statistically significant (P< or =0.05) for each age group and reached following values: r1 = 0.70 for the aortic bulb, r2 = 0.79 for the ascending aorta, r3 = 0.77 for the aortic isthmus, r4 = 0.79 for the descending aorta, r5 = 0.63 for the pulmonary trunk, r6 = 0.36 for the arterial duct, r7 = 0.46 for the right pulmonary artery and r8 = 0.49 for the left one. Diameters of the aorta and the pulmonary trunk indicated the relative increase in the values. A different tendency was observed for the internal diameters of the arterial duct and both pulmonary arteries, which were relatively decreased with increased foetal age. The largest diameter was observed in the arterial duct, the intermediate--in the right pulmonary artery and the smallest--in the left pulmonary artery. The cross-sectional area of the descending aorta was equal to the sums of the sectional areas of the aortic isthmus and the arterial duct (r9 = 0.97). The cross-sectional area of the pulmonary trunk was equal to the sums of the sectional areas of the both pulmonary arteries and the arterial duct (r10 = 0.91).

Doppler assessment of fetal aortic isthmus blood flow in two different sonographic planes during the second half of gestation

OBJECTIVE

To compare the reliability of Doppler blood flow measurements of the fetal aortic isthmus (AoI) according to whether the sampling plane is obtained from the traditional longitudinal aortic arch (LAA) view or the more recently described three vessels and trachea (3VT) view of the fetal upper mediastinum.

METHODS

Doppler blood flow measurements of pulsatility index (PI), resistance index (RI), peak systolic (PSV), end-diastolic (EDV) and time-averaged maximum (TAMXV) velocities were performed in the AoI of 40 fetuses between 24 and 36 weeks of gestation. All measurements were sampled in two different sonographic planes of the AoI: the LAA view, at a few millimeters beyond the origin of the left subclavian artery, and the 3VT view, just before the V-shaped junction of the aortic and ductal arches. All scans were performed by the same observer. The reliability of Doppler blood flow measurements was assessed by calculating intraclass correlation coefficients (ICCs) and limits of agreement between the two different sonographic sites evaluating the AoI.

RESULTS

Mean values of PI, RI, PSV, EDV and TAMXV were similar in the LAA and 3VT views. The PI and vascular velocities were reliably measured from both sonographic sites. ICCs for variability of measurements were 0.78, 0.63, 0.63, 0.60 and 0.55 for PI, RI, PSV, EDV and TAMXV, respectively. Limits of agreement revealed minimal disagreement between the two sites of evaluation of the AoI for all measurements.

CONCLUSIONS

On the basis of our observations, Doppler blood flow measurements across the fetal AoI can be reliably obtained from both the 3VT and the traditional LAA sonographic views. Since the transverse upper thoracic 3VT plane is achievable in most fetal positions, Doppler study of the AoI appears to be easier than expected.

Morphometric study of the human fetal heart I. Arterial segment

This study measured the dimensions of the great arteries of normal human fetal hearts at an early fetal stage (between 13-20 weeks post-fertilization) in 103 fetuses obtained by necropsy. Different segments of the aorta and the pulmonary artery were dissected and their external diameters measured under stereoscopic magnification. All segments showed linear growth during this period of fetal development. Ranges in median values of external diameters associated with the pulmonary artery were: 2.1-4.2 mm for the valve ring; 2.2-4.2 mm for the main pulmonary trunk; 1.2-2.5 mm for the right pulmonary artery; 0.9-2.18 mm for the left pulmonary artery; and 4.0-8.0 mm for the length of the main pulmonary trunk. Similarly, in the aorta, median diameters were: 2.1-4.2 mm for the ascending aorta; 1.92-3.8 mm for the aortic arch; 1.45-3.0 mm for the aortic isthmus; and 1.75 -3.35 mm for the descending aorta. The diameter of the ductus arteriosus ranged between 1.2-2.45 mm. The growth rates of the pulmonary artery and the aorta were similar. The diameter of the ascending aorta was found to be greater than that of the descending aorta and the right pulmonary artery was wider than the left pulmonary artery. In addition, the magnitude of growth in the various aortic segments was different and the ratios obtained between the aortic isthmus and the ascending and descending aortae, ranged between 0.66-0.93. This study provides important morphometric reference information concerning the dimensions and growth of the great arteries of the fetal heart and has clinical application in pediatric cardiac surgery and echocardiography.

Anomalies of the fetal aortic arch: a novel sonographic approach to in-utero diagnosis

OBJECTIVE

To describe a novel, sonographic approach for in-utero evaluation of normal and abnormal aortic arch.

METHODS

Aortic arch was evaluated by imaging of the axial view of the upper fetal mediastinum. The normal left aortic arch was defined by the V-shaped appearance of the junction between the ductus arteriosus and aortic arch, with the trachea situated posteriorly. Right and double aortic arches were diagnosed when the great vessels appeared U-shaped, with intermediate location of the trachea.

RESULTS

Between 1997 and 1999, 18 347 women were scanned in three prenatal centers, and pathological findings were prospectively recorded. In a retrospective analysis of the records, we identified 19 fetuses (0.1%) with atypical, U-shaped appearance, and no other structural abnormalities present. With the exception of one fetus with a ventricular septal defect, no congenital cardiac defects were present. Right aortic arch was found in 18 cases, while color Doppler made it possible to diagnose one case with double aortic arch, and one fetus was demonstrated as having Kommerell's diverticulum. In all 18 cases, a left descending aorta and left ductus arteriosus were present, the latter coursing to the left of the trachea, forming a loose partial vascular ring. All were asymptomatic at birth and early infancy. The fetus with double aortic arch that had a true vascular ring underwent early infantile correction.

CONCLUSIONS

It is possible to diagnose right and double fetal aortic arch using prenatal ultrasound. The use of color Doppler facilitated in-utero evaluation of possible complications, such as true vascular ring.

Fetal aortic isthmus growth and morphology in late gestation

OBJECTIVE

To establish normal values for fetal aortic isthmus diameter in late gestation and to identify any changes in aortic isthmus dimensions and morphology in pathological conditions.

METHODS

In this prospective study, the fetal aortic isthmus was evaluated in 110 low-risk pregnant women at between 30 and 40 weeks of gestation and 42 pregnant women who were at high risk for congenital heart defects. From coronal echocardiographic images of the connection between the aorta and ductus arteriosus, the internal diameter of the aorta was measured at the middle of the isthmus, at the point of the isthmus just proximal to the entry of the ductus arteriosus and at the descending aorta below the entry of the ductus arteriosus.

RESULTS

Correlation coefficients for the diameter of each aortic segment when related to gestational age varied from r = 0.60 to r = 0.80 (P < 0.001 for each), and growth curves were derived from the third and 97th percentiles about each linear regression analysis. The mean and the third percentile for the ratio of the isthmus just proximal to the entry of the ductus arteriosus to the middle of the isthmus were 1 and 0.81. In one fetus of the high-risk patients, a contraductal shelf and the accompanying area of tubular isthmic hypoplasia were suspected and a diagnosis of coarctation of the aorta was subsequently confirmed after birth. In two fetuses with growth restriction and one fetus with intestinal atresia, the isthmus diameters were below the third percentile but the ratios of the isthmus end to the middle of the aortic isthmus were all normal and no cardiac anomalies were detected after birth.

CONCLUSIONS

We could establish normal values for aortic isthmus diameters in late gestation from a coronal view and identify even minimal changes in aortic isthmus dimensions and morphology in pathological conditions.