Echocardiographic features and outcomes of fetuses with isolated restrictive foramen ovale or redundant foramen ovale flap using atrial septum excursion index.

PURPOSE: This study was designed to investigate the application value of the atrial septum excursion index (ASEI) in fetuses with isolated restrictive foramen ovale (RFO) or redundant foramen ovale flap (RFOF) and the outcomes of these fetuses. METHODS: This was a retrospective study. Healthy pregnant women who were examined by antenatal fetal echocardiography from January 1, 2019 to December 31, 2021, at Sir Run Run Shaw Hospital were enrolled. One hundred seventy-seven (177) fetuses were categorized into three groups by diagnosis: (1) RFOF (n = 33), (2) RFO (n = 21), and (3) normal (n = 123). Fetal echocardiographic features and postnatal outcomes were collected. RESULTS: The median ASEIs were 0.50 (range, 0.41-0.65) in the control group, 0.76 (range, 0.67-0.88) in the RFOF group and 0.31 (range, 0.14-0.35) in the RFO group, and the differences were significant (p < 0.001). The ratios of right atrium/left atrium, right ventricle/left ventricle, and pulmonary artery diameter to aorta diameter (PA/AO) and the pulmonary annulus Z-scores were greater in fetuses with RFOF and RFO than in the controls (p < 0.05). Twenty-seven of 33 fetuses (87.9%) with RFOF and 19 of 21 fetuses (90.5%) with RFO had good outcomes after birth. CONCLUSION: The ASEI may be a new tool for quantitatively assessing the mobility of foramen ovale flaps in fetuses with isolated RFOF or RFO.

Fetal echocardiographic predictors of biventricular circulation in hypoplastic left heart complex.

OBJECTIVES: To determine which echocardiographic features of hypoplastic left heart complex (HLHC) in the fetal period are predictive of biventricular (BV) circulation and to evaluate the long-term outcome of patients with HLHC, including rates of mortality, reintervention and development of further cardiac disease. METHODS: Echocardiograms of fetuses with HLHC obtained at 18-26 weeks and 27-36 weeks' gestation between 2004 and 2017 were included in the analysis. The primary outcome was successful BV circulation (Group 1). Group 2 included patients with single-ventricle palliation, death or transplant. Univariate analysis was performed on data obtained at 18-26 and 27-36 weeks and multivariate logistic regression was performed on data obtained at 27-36 weeks only. RESULTS: Of the 51 included cases, 44 achieved successful BV circulation (Group 1) and seven did not (Group 2). Right-to-left/bidirectional foramen ovale (FO) flow and a higher mitral valve (MV) annulus Z-score were associated with successful BV circulation on both univariate and multivariate analysis. Bidirectional or left-to-right FO flow, left ventricular length (LVL) Z-score of < -2.4 and a MV Z-score of < -4.5 correctly predicted 80% of Group 2 cases. Late follow-up was available for 41 patients. There were two late deaths in Group 2. Thirteen patients in Group 1 required reintervention, 12 developed mitral stenosis and five developed isolated subaortic stenosis. CONCLUSIONS: BV circulation is common in fetuses with HLHC. Higher MV annulus and LVL Z-scores and right to left direction of FO flow are important predictors of BV circulation. Long-term sequelae in those with BV circulation may include mitral and subaortic stenosis. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

Urgent neonatal balloon atrial septostomy in simple transposition of the great arteries: predictive value of fetal cardiac parameters.

OBJECTIVES: To investigate the impact of abnormal perinatal loading conditions on cardiac geometry and function in term fetuses and neonates with transposition of the great arteries with intact interventricular septum (simple TGA), and to explore the predictive value of fetal cardiac parameters for an urgent balloon atrial septostomy (BAS) after birth. METHODS: This was a prospective longitudinal follow-up study of women delivering at term, including both uncomplicated pregnancies with normal outcome and pregnancies affected by fetal simple TGA. Conventional, spectral-tissue Doppler and speckle-tracking echocardiographic parameters were obtained within 1 week before delivery and within the first few hours after delivery. Neonates with simple TGA that required urgent BAS were assessed after the procedure and before corrective arterial switch surgery. Cardiac parameters were normalized by cardiac cycle length, ventricular end-diastolic length or end-diastolic dimension, as appropriate. Fetal and neonatal cardiac parameters were compared between simple-TGA cases and controls, and perinatal changes in the simple-TGA group were assessed. Receiver-operating-characteristics (ROC)-curve analysis was used to assess the predictive value of fetal cardiac parameters for urgent BAS after birth in the simple-TGA group. RESULTS: A total of 67 pregnant women delivering at term were included in the study (54 normal pregnancies and 13 with a diagnosis of fetal simple TGA). Compared with normal term fetuses, term fetuses with simple TGA exhibited more globular hypertrophied ventricles, increased biventricular systolic function and diastolic dysfunction (right ventricular (RV) sphericity index (SI), 0.58 vs 0.54; left ventricular (LV)-SI, 0.55 vs 0.49; combined cardiac output (CCO), 483 vs 406 mL/min/kg; LV torsion, 4.3 vs 3.0 deg/cm; RV isovolumetric relaxation time (IVRT'), 127 vs 102 ms; P < 0.01 for all). Compared with normal neonates, neonates with simple TGA demonstrated biventricular hypertrophy, a more spherical right ventricle and altered systolic and diastolic functional parameters (RV-SI, 0.61 vs 0.43; RV myocardial performance index, 0.47 vs 0.34; CCO, 697 vs 486 mL/min/kg; LV-IVRT', 100 vs 79 ms; RV-IVRT', 106 vs 71 ms; P < 0.001 for all). Paired comparison of neonatal and fetal cardiac indices in the simple-TGA group showed persistence of the fetal phenotype, increased biventricular systolic myocardial contractility and CCO, and diastolic dysfunction (RV systolic myocardial velocity (S'), 0.31 vs 0.24 cm/s; LV-S', 0.23 vs 0.18 cm/s; CCO, 697 vs 483 mL/min/kg; LV torsion, 1.1 vs 4.3 deg/cm; P < 0.001 for all). Several fetal cardiac parameters in term fetuses with simple TGA demonstrated high predictive value for an urgent BAS procedure after birth. Our proposed novel fetal cardiac index, LV rotation-to-shortening ratio, as a potential marker of subendocardial dysfunction, for a cut-off value of ≥ 0.23, had an area under the ROC curve (AUC) of 0.94, sensitivity of 100% and specificity of 83%. For RV/LV end-diastolic area ratio ≥ 1.33, pulmonary-valve-to-aortic-valve-dimension ratio ≤ 0.89, RV/LV cardiac output ratio ≥ 1.38 and foramen-ovale-dimension-to-total-interatrial-septal-length ratio ≤ 0.27, AUC was 0.93-0.98, sensitivity was 86% and specificity was 83-100% for all. CONCLUSIONS: Simple-TGA fetuses exhibited cardiac remodeling at term with more profound alterations in these cardiac parameters after birth, suggestive of adaptation to abnormal loading conditions and possible adaptive responses to hypoxemia. Perinatal adaptation in simple TGA might reflect persistence of the abnormal parallel arrangement of cardiovascular circulation and the presence of widely patent fetal shunts imposing volume load on the neonatal heart. The fetal cardiac parameters that showed high predictive value for urgent BAS after birth might reflect the impact of late-gestation pathophysiology and progressive hypoxemia on fetal cardiac geometry and function in simple TGA. If these findings are validated in larger prospective studies, detailed cardiac assessment of fetuses with simple TGA near term could facilitate improvements in perinatal management and refinement of the timing of postnatal intervention strategies to prevent adverse pregnancy outcomes. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

Redundancy of foramen ovale flap may mimic fetal aortic coarctation.

OBJECTIVES: To assess the relationship between presence of a redundant foramen ovale flap (RFOF), in the absence of a clearly restrictive foramen ovale, and ventricular disproportion, in three groups of fetuses: (1) those with a final diagnosis of aortic coarctation (CoA); (2) those referred for suspicion of ventricular disproportion and/or CoA which did not develop CoA postnatally; and (3) normal fetuses. METHODS: This was a retrospective study including 73 fetuses: 12 with a final diagnosis of isolated CoA; 30 referred for suspicion of ventricular disproportion and/or CoA, which did not develop CoA postnatally; and 31 normal fetuses. Four-dimensional volume datasets and clips were assessed offline. Maximum diameters of the FOF (FOFD), left atrium (LAD), right atrium, left and right ventricles and, when available, aortic isthmus, were measured, as were areas of the FOF (FOFA), left atrium (LAA) and right atrium. The left/right ratios for all segments of the heart, as well as the FOFD/LAD ratio and FOFA/LAA ratio, were calculated. Regression analysis was performed to assess the relationship between RFOF and ventricular disproportion and means were compared by ANOVA. RESULTS: Repeatability was fair, with all variables having an intraclass correlation coefficient ≥ 83%. In the pooled group of fetuses with no CoA found at birth (normal fetuses plus those with ventricular disproportion (n = 61)), there was a significant linear correlation between redundancy of the FOF and degree of ventricular disproportion (P < 0.01 and P < 0.05 for diameter and area ratios, respectively). Categorizing the FOF redundancy, FOFD/LAD ratio ≥ 0.65 was significantly associated with ventricular disproportion (P = 0.006). Based on the degree of FOF prominence, we described four categories of redundancy, ranging from no redundancy/ventricular disproportion (Stage 0) to severe redundancy/ventricular disproportion with transient obstruction of the foramen ovale or mitral orifice (Stage III). Comparing cases without neonatal evidence of coarctation but FOFD/LAD ratio ≥ 0.65 vs those with neonatal evidence of coarctation, there was no statistically significant difference in the degree of ventricular disproportion or in the Z-score of the aortic isthmus maximum diameter. CONCLUSIONS: This study demonstrates that: (1) there is an association between RFOF and ventricular disproportion, independent of the association with a restrictive foramen ovale, and (2) the presence of a RFOF may mimic CoA. In fact, it causes both ventricular disproportion and a significant reduction in the diameter of the aortic isthmus, associated in some cases also with reversed isthmic flow. Future prospective studies are needed to evaluate whether focusing the sonologist's attention on the appearance of the foramen ovale may reduce the rate of false-positive diagnosis of CoA. Copyright © 2020 ISUOG. Published by John Wiley & Sons Ltd.

Induction of left ventricular hypoplasia by occluding the foramen ovale in the fetal lamb.

Disturbed fetal haemodynamics often affects cardiac development and leads to congenital cardiac defects. Reduced left ventricular (LV) preload in the fetus may result in hypoplastic LV, mitral and aortic valve, mimicking a moderate form of hypoplastic left heart complex. We aimed to induce LV hypoplasia by occluding the foramen ovale (FO) to reduce LV preload in the fetal sheep heart, using percutaneous trans-hepatic catheterisation. Under maternal anaesthesia and ultrasound guidance, hepatic venous puncture was performed in six fetal lambs (0.7-0.75 gestation). A coronary guidewire was advanced into the fetal inferior vena cava, right and left atrium. A self-expandable stent was positioned across the FO. An Amplatzer Duct Occluder was anchored within the stent for FO occlusion. Euthanasia and post-mortem examination was performed after 3 weeks. Nine fetuses were used as age-matched controls. Morphometric measurements and cardiac histopathology were performed. Compared with controls, fetal hearts with occluded FO had smaller LV chamber, smaller mitral and aortic valves, lower LV-to-RV ratio in ventricular weight and wall volume, and lower number of LV cardiomyocyte nuclei. We conclude that fetal FO occlusion leads to a phenotype simulating LV hypoplasia. This large animal model may be useful for understanding and devising therapies for LV hypoplasia.

Flap valve of the heart foramen ovale revisited: macroscopic and histologic observations of human near-term fetuses.

We assessed the flap valve of the foramen ovale (FO valve) by examining 30 hearts from human fetuses of gestational age 30-40 weeks. We dissected the hearts, examined their macroscopic morphology, and then prepared semiserial sagittal sections across the valve. Although the primary septum is expected to extend along the left atrial face, eight hearts had a superior rim of the fossa ovalis on the left atrial face that was too thick and high, so there was no smooth continuation with the valve. Moreover, three of these eight hearts each had a flap valve that was fused with a long and narrow plate arising from the caval orifice. Histological analysis indicated that 21 specimens each had a candidate primary septum that contained myocardium, although the left sinuatrial valve (LSAV) contained fibrous tissue, but little or no myocardium. In each of 17 hearts, a candidate primary septum was attached to the left atrial face of the fossa, and parts of the LSAV extended to and approached the right atrial face. However, seven of these 17 hearts each had a folded small primary septum. Another four of these 17 hearts each had an LSAV that extended widely to the fossa, and a candidate primary septum (which might be a remnant) attached to the left atrial side of the LSAV. These variations suggest that the LSAV makes a major contribution to the FO valve in some fetal hearts. Consequently, the fetal FO valve appears to have heterogeneous morphology and origin.

Echocardiographic features of PFOs and paradoxical embolism: a complicated puzzle.

Patent foramen ovale (PFO) is a residual, oblique, slit or tunnel like communication in the atrial septum that persists into adulthood. It is usually an incidental finding with no clinical repercussions. Nevertheless, recent evidence supports the association between the presence of a PFO and a number of clinical conditions, most notably cryptogenic stroke (CS). There is enough evidence that paradoxical embolism is a mechanism which can explain this association. Patient characteristics and certain echocardiography-derived anatomical and hemodynamic features of PFO provide great assistance in estimating the probability of paradoxical embolism. In this review, we initially describe PFO embryology and anatomy. We extensively present the available data on clinical, anatomical and hemodynamic features of PFOs which have been correlated with increased likelihood of paradoxical embolism and recent evidence of therapeutic management.

Isolated premature restriction or closure of foramen ovale in fetuses: Echocardiographic characteristics and outcome.

BACKGROUND: Premature restriction or closure of foramen ovale (FO) in otherwise structurally normal hearts may be associated with right ventricular dilation, tricuspid regurgitation, pericardial effusion, heart failure, even poor perinatal outcomes. Data about these rare conditions are lacking. METHODS: We retrospectively reviewed the echocardiographic records of 9704 fetuses seen from 2010 to 2014 in Beijing Anzhen Hospital, a regional and national referral center, to ascertain the presence of restriction or closure of FO. We collected the fetal echocardiography and perinatal outcome data for this group of fetuses with restriction or closure of FO. RESULTS: In this large, single-institution cohort (n = 9704), 6707 fetuses seen between 23 and 37 weeks of gestation had normal heart structures; of these, 60 (0.89%) had restrictive FO (rFO) and 5 (0.07%) had closure of FO (cFO). Fetal echocardiographic images showed right atrial dilation in 48 (73.84%), right ventricular dilation in 38 (58.46%), tricuspid regurgitation in 19 (29.23%), and pericardial effusion in 10 (15.38%). Also in this group, 50 (83.3%) with rFO and 4 (80.0%) with cFO had follow-up data. No prenatal deaths occurred in either the rFO or the cFO group, but the neonatal mortality included 1 in the rFO group and 2 in the cFO group. CONCLUSION: Premature rFO/cFO are rare in fetuses with otherwise structurally normal hearts. The fetal echocardiographic characteristics include right atrial and ventricular dilated, tricuspid regurgitation, and pericardial effusion. Most fetuses had a good outcome, although there was an association between rFO, especially cFO, with neonatal morality and complications (prematurity, maternal preeclampsia and placental abruption, hydrops fetalis, and necrotizing enterocolitis with perforation).

Right heart dilatation in a fetus with an abnormal foramen ovale valve: an indicator of interatrial communication restriction.

AIMS: Foramen ovale (FO) valve with a shape or motion abnormality is frequently detected during routine obstetric ultrasonic examinations. However, the hemodynamics mechanism of this entity remains unclear. The purpose of the study is to determine the relevance of interatrial communication restriction and resultant morphological modifications. MATERIALS AND METHODS: We reviewed the echocardiographic records of fetuses with isolated abnormal FO valve evaluated between January of 2010 and december of 2016. The size (DFO) of the FO orifice, opening angle (α) of the FO valve, and dimensions of cardiac chambers, FO channel outlet (DOUT) and inferior vena cava (DIVC) were measured. We evaluated their (DFO, DOUT, α) relationships to the diameters of RA and DIVC. Five hundred and seventy normal fetuses were selected to establish the normal range of the DOUT/DIVC ratio so as to provide a criterion for restriction. RESULTS: An abnormal FO valve was identified in 89 fetuses without congenital heart disease, with restriction noted in 62 fetuses (45 fetuses with RA dilatation, 12 fetuses with RA and RV dilatation, and 5 fetuses with no RA dilatation). There were no significant correlations between RA/LA and DFO/DIVC, RA/ LA and α. RA/LA was negatively correlated with DOUT/DIVC (R2=0.97, p<0.01). CONCLUSIONS: For a fetus with an abnormal FO valve, right heart dilatation could be considered as an indicator of interatrial communication restriction, which could be assessed by evaluating the FO channel outlet. The degree of right atrium dilatation indicates the severity of the restriction.

New method to predict need for Rashkind procedure in fetuses with dextro-transposition of the great arteries.

OBJECTIVE: Prenatal congenital heart disease classification systems distinguish between critical dextro-transposition of the great arteries (d-TGA) with restriction of the foramen ovale (FO) (which requires a Rashkind procedure within the first 24 h following delivery) and d-TGA for which surgery is planned (after prostaglandin perfusion or Rashkind procedure later than 24 h after delivery). However, current prenatal diagnostic criteria for postnatal FO restriction in d-TGA are inadequate, resulting in a high false-negative rate. We aimed to identify echocardiographic features to predict the urgent need for Rashkind procedure. METHODS: We identified retrospectively 98 patients with singleton pregnancy diagnosed prenatally with fetal d-TGA at two European centers from 2006 to 2013. Two groups were compared: (1) those in whom the Rashkind procedure was performed within the first 24 h postnatally; and (2) those who did not undergo a Rashkind procedure before cardiac surgery. Exclusion criteria were: (1) no fetal echocardiography within 3 weeks prior to delivery (n = 18); (2) delivery before 37 weeks of gestation (n = 6); (3) improper or lack of measurement of pulmonary vein maximum flow velocity (n = 10); (4) lack of neonatal follow-up data (n = 9); (5) Rashkind procedure performed more than 24 h after delivery (n = 4). RESULTS: Fifty-one patients met the inclusion criteria: 29 who underwent the Rashkind procedure and 22 who did not. There were no differences between these two study groups in terms of maternal age, gestational age at time of fetal echocardiography, fetal biometric measurements, estimated fetal weight, rate of Cesarean delivery, newborn weight or Apgar score at 1 min. There were also no differences during prenatal life between the two groups in terms of fetal cardiac size (heart area/chest area ratio), rate of disproportion between left and right ventricle, FO diameter and maximum velocity of flow through the FO. However, the pulmonary vein maximum velocity was significantly higher in the group requiring a Rashkind procedure (47.62 ± 7.48 vs 32.21 ± 5.47 cm/s; P < 0.001). The cut-off value of 41 cm/s provided maximum specificity (100%) and positive predictive value (100%) at only a slight cost of sensitivity (82%) and NPV (86%). The prenatal appearance of the FO also differed between the groups, the FO valve being flat in 52% of those requiring a Rashkind procedure. CONCLUSIONS: In fetuses with d-TGA, prenatal sonographic findings of increased pulmonary venous blood flow and flattened FO valve were associated with the need for a Rashkind procedure within the first 24 h postnatally; these echocardiographic features could be used to predict prenatally a need for the procedure following delivery. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Prenatal Echocardiographic Assessment of Foramen Ovale Appearance in Fetuses with D-Transposition of the Great Arteries and Impact on Neonatal Outcome.

INTRODUCTION: Neonates with D-transposition of the great arteries (dTGA) may die at birth because of the inadequate intracardiac mixing due to a misdiagnosed restrictive foramen ovale. We reviewed our experience in echocardiographic assessment and perinatal management of fetuses with dTGA searching for new features that may predict the need for urgent balloon atrial septostomy (BAS) immediately after birth. PATIENTS AND METHODS: We included fetuses diagnosed with dTGA between January 2000 and December 2014. We assessed pre- and postnatal appearance of the foramen ovale, ductus arteriosus and pulmonary veins. Both the diagnostic findings at the time of last prenatal echocardiogram and those findings deriving from a retrospective reevaluation of stored videos were considered. BAS was defined as urgent if performed in neonates with restrictive foramen ovale and severe hypoxemia. RESULTS: We reviewed 40 fetuses with dTGA. 20/40 fetuses received urgent BAS at birth. Not only the restrictive but also the hypermobile and the redundant appearance of the foramen ovale was significantly associated with urgent BAS (p < 0.0001, p = 0.002 and p = 0.0001, respectively). CONCLUSIONS: Prenatal evaluation of the foramen ovale appearance in fetuses with dTGA is still challenging. Based on our experience, also the redundant foramen ovale appearance may need urgent BAS at birth.

[Fetal cardiac interventions - are we ready for them?]. / Interwencyjne zabiegi kardiologiczne u plodów - czy jestesmy do nich przygotowani?

OBJECTIVE: The aim of the study was to analyze types and methods of intrauterine fetal cardiac interventions performed between June 2011 and December 2013, and to assess the perinatal management of the neonates. METHODS: The program was developed after analysis of the available literature, practical individual training in Linz, Austria, and simulation of the procedure in a dissecting-room. The rules for anesthesia in pregnant women and their fetuses were developed. The interventions were performed in fetuses with critical cardiac defects, in the operating room, under ultrasonographic control. The protocol was approved by the Local Bioethics Committee at the Centre of Postgraduate Medical Education. MATERIAL: We included fetuses with critical aortic stenosis (n=29), critical pulmonary stenosis (n=2), and closed or extremely restricted foramen ovale (n=7). Between June 2011 and December 2013, the team comprised of JD, MD and AK conducted 42 interventions in 35 fetuses, including 32 balloon aortic valvuloplasties (in 29 fetuses), 2 pulmonary valvuloplasties, 4 balloon atrial septostomies and 4 atrial septal stent placement. Three fetuses required both, aortic valvuloplasty and fenestration of the atrial septum. RESULTS: Out of the 42 procedures, 41 (97%) were technically successful. We recorded 3 cases of fetal demise associated with the intervention. We modulated the protocol of anesthesia given to pregnant women, switching from general to local anesthesia with intravenous sedation. We always provided additional fetal anesthesia with fentanyl and atracurium via the umbilical vein. CONCLUSIONS: Based on our 2.5-year experience, it seems safe to conclude that all types of fetal cardiac interventions may be successfully conducted at Polish centers. The procedures are safe for the pregnant women and improve fetal status. Most of the neonates treated prenatally were referred in good general condition to a tertiary pediatric cardiology and cardiac surgery center

Fetal critical aortic stenosis with natural improvement of hydrops fetalis due to spontaneous relief of severe restrictive atrial communication.

We describe a rare case of fetal critical aortic stenosis with spontaneous relief of severe restrictive atrial communication, resulting in complete resolution of hydrops fetalis in utero. Fetal ultrasonography showed hydrops fetalis caused by critical aortic stenosis with a severely restrictive foramen ovale and severe mitral regurgitation at 23 weeks of gestation. Hydrops fetalis, however, spontaneously resolved, showing an obvious increase of flow through the foramen ovale and pulmonary vein at 26 weeks of gestation. The neonate required balloon dilation of the aortic valve and balloon atrioseptostomy immediately after birth and also received bilateral pulmonary artery banding and arterial duct stenting 1 week later. The patient was in good condition after conversion to biventricular circulation via Ross procedure at 8 months old. The present case suggests that atrioseptostomy as a fetal intervention may improve outcome in even a hydropic condition.

Reference ranges for fetal septum primum excursion from 14 to 40 weeks' gestation.

OBJECTIVES: The purpose of this study was to establish reference ranges for septum primum excursion and the septum primum excursion index. METHODS: Normal singleton pregnancies with certain dates from 14 to 40 weeks' gestation were enrolled to acquire spatiotemporal image correlation volume data sets. The stored data sets were subsequently displayed offline to measure septum primum excursion and the left atrium diameter. The measured values were regressed to identify the best-fitted model as a function of gestational age and biparietal diameter. RESULTS: A total of 624 volumes were successfully measured, and normal reference ranges for predicting means and standard deviations of septum primum excursion and the septum primum excursion index were established based on best-fitted equations. The septum primum excursion index was relatively constant throughout pregnancy (mean ± SD, 0.474 ± 0.082), whereas septum primum excursion increased with gestational age and biparietal diameter as follows: (1) septum primum excursion = -6.30 + 0.667 × gestational age - 0.009 × gestational age(2); SD of septum primum excursion = 0.219 + 0.02 × gestational age; and (2) septum primum excursion = -3.342 + 1.933 × biparietal diameter - 0.102 × biparietal diameter(2); SD of septum primum excursion = 0.330 + 0.065 × biparietal diameter. Percentile charts for predicting septum primum excursion and equations for Z score calculation were also provided. CONCLUSIONS: Normal reference ranges for fetal septum primum excursion and the septum primum excursion index have been provided. These normative data may be useful tools for assessment of hemodynamics through the foramen ovale or left ventricular diastolic function.

Morphological basis for the study of the interatrial septum in the human fetus.

OBJECTIVE: To describe morphological features of the interatrial septum in normal fetuses, especially foramen ovale (FO) and septum primum (SP), in order to compare septum primum excursion with foramen ovale diameter. METHODS: Septum primum excursion (SPE) toward the left atrium (LA) and foramen ovale diameter (FOD) were measured in the hearts of ten formaldehyde-fixed human fetuses ranging from 28 to 36 weeks of gestation. Histological sections were obtained from the foramen ovale (FO), septum primum (SP), septum secundum (SS), left atrium (LA), and right atrium (RA). RESULTS: FOD and SPE measurements were the following: FOD 3.1-3.5 mm and SPE 2.8-3.1 mm in three fetuses with presumed gestational age (GA) of 28 weeks; FOD 3.3-3.5 mm, and SP excursion 4.0-5.0 mm in four fetuses with presumed GA of 34 weeks, plus FOD 3.3-4.5 mm and SPE 6.0-9.0 in three fetuses with presumed GA of 36 weeks. Cardiac muscular fibers were identified in both the septum primum and secundum. CONCLUSION: Based on its muscular components, it may be suggested that SP is active in character, influencing blood flow through the FO, SP mobility, and its excursion into the LA.

Bases morfológicas para o estudo do septo interatrial no feto humano / Morphological basis for the study of the interatrial septum in the human fetus

OBJETIVO: Descrever observações morfológicas sobre o septo interatrial em fetos normais, especialmente o forame oval e o septo primeiro, de forma a comparar a excursão do septo primeiro com o diâmetro do forame oval. MÉTODOS: As medidas da excursão do septo primeiro (ESP) em direção ao átrio esquerdo (AE) e do diâmetro do forame oval (DFO) foram realizadas em corações de dez fetos humanos formolizados com 28 a 36 semanas. Os cortes histológicos foram feitos no FO, SP, septo segundo e nos AE e AD. RESULTADOS: Os resultados da análise anatômica estão expressos em amplitude das medidas do DFO e da ESP: 3 fetos com idade gestacional (IG) presumida de 28 semanas, DFO (3,1-3,5 mm) e ESP (2,8-3,1 mm); 4 fetos com IG presumida de 34 semanas, DFO (3,3-3,5 mm) e ESP (4,0-5,0 mm); e 3 fetos com IG presumida de 36 semanas, DFO (3,3-4,5 mm) e ESP (6,0-9,0). Foram identificadas fibras musculares cardíacas no SP e no segundo. CONCLUSÃO: Pode-se sugerir que o SP apresenta caráter ativo devido às fibras musculares que o constituem, influenciando o fluxo sangüíneo através do FO, a mobilidade do SP e a sua excursão para o interior do AE.

OBJECTIVE: To describe morphological features of the interatrial septum in normal fetuses, especially foramen ovale (FO) and septum primum (SP), in order to compare septum primum excursion with foramen ovale diameter. METHODS: Septum primum excursion (SPE) toward the left atrium (LA) and foramen ovale diameter (FOD) were measured in the hearts of ten formaldehyde-fixed human fetuses ranging from 28 to 36 weeks of gestation. Histological sections were obtained from the foramen ovale (FO), septum primum (SP), septum secundum (SS), left atrium (LA), and right atrium (RA). RESULTS: FOD and SPE measurements were the following: FOD 3.1-3.5 mm and SPE 2.8-3.1 mm in three fetuses with presumed gestational age (GA) of 28 weeks; FOD 3.3-3.5 mm, and SP excursion 4.0-5.0 mm in four fetuses with presumed GA of 34 weeks, plus FOD 3.3-4.5 mm and SPE 6.0-9.0 in three fetuses with presumed GA of 36 weeks. Cardiac muscular fibers were identified in both the septum primum and secundum. CONCLUSION: Based on its muscular components, it may be suggested that SP is active in character, influencing blood flow through the FO, SP mobility, and its excursion into the LA.