Total anomalous pulmonary venous return: familial and environmental factors. The Baltimore-Washington Infant Study Group

Total Anomalous Pulmonary Venous Connections, Human Genetics

Partial anomalous pulmonary venous connections (PAVC) have been found after abnormal gene expressions involving several syndromes. Total anomalous pulmonary venous connection (TAPVC) is found in conjunction with heterotaxia syndrome as well as several other syndromes. It has been reported with an autosomal dominance with variable expression and incomplete penetrance. The occurrence is also related to environmental factors which may superimpose on a familial susceptibility for TAPVC. Many pathways are involved in the normal development of the pulmonary venous connections and as a consequence disturbance of many genetic and epigenetic pathways lead to partial or total pulmonary venous misconnections. In this chapter, an overview of current knowledge regarding human genetics of anomalous venous connections is provided.

Outcome of obstructed total anamalous pulmonary venous connection (TAPVC) repair patients with milrinone versus milrinone and inhaled nitric oxide (INO): A prospective randomized observational study

Background

Obstructed total anomalous pulmonary venous connection (TAPVC) typically present with severe cardiovascular decompensation and requires urgent surgical management. Pulmonary arterial hypertension (PAH) is a major risk factor affecting mortality. Perioperative management focuses on providing inotropic support and managing potential pulmonary hypertensive episodes. Milrinone and inhaled nitric oxide (iNO) efficiently reduce pulmonary artery pressure (PAP) and help to improve the outcome. The aim was to determine the outcome of patients with high PAP with milrinone alone and a combination of iNO and milrinone.

Material and Method

After ethical committee approval, the study was conducted over a period of 3 years in 80 patients with obstructed TAPVC repair. A total of 80 patients having severe PAH (supra systemic arterial pressure) randomly divided into two groups with 40 patients in each (M & MN). Group M (milrinone) patients received milrinone and Group MN (milrinone & iNO) patients received both milrinone (after opening aortic cross clamp) and iNO (post operative ICU). Ventilation time, hospital stay, ICU stay, complications, in hospital mortality were compared between both groups.

Result

Ventilation time, Intensive Care Unit (ICU) stay, hospital stay for group M was 8.02 ± 5.74 days, 11.25 ± 7.33 day, 14.92 ± 8.55 days, respectively, and for group MN was 5.02 ± 1.78 days, 8.27 ± 3.24 days, 10.3 ± 3.18 days, respectively. In hospital mortality for group M and MN was 10% and 2.5%, respectively. P value for each variable was significant < 0.05 (except mortality).

Conclusion

Most of the patients with obstructed TAPVC had severe PAH. Management of severe PAH with a combination of milrinone with iNO had a better outcome than milrinone alone.

Surgical repair of an obstructed mixed-type total anomalous pulmonary venous connection

Total anomalous pulmonary venous connection is a rare congenital anomaly and has four anatomical subtypes of which the mixed type represents diagnostic and therapeutic challenge. When associated with obstruction, however, urgent surgical repair is needed. Herein, we present a rare case of obstructed mixed type total anomalous pulmonary venous connection with successful surgical repair.

TBX5 variant with the novel phenotype of mixed‑type total anomalous pulmonary venous return in Holt‑Oram Syndrome and variable intrafamilial heart defects

Variants in T‑box transcription factor 5 (TBX5) can result in a wide phenotypic spectrum, specifically in the heart and the limbs. TBX5 has been implicated in causing non‑syndromic cardiac defects and Holt‑Oram syndrome (HOS). The present study investigated the underlying molecular etiology of a family with heterogeneous heart defects. The proband had mixed‑type total anomalous pulmonary venous return (mixed‑type TAPVR), whereas her mother had an atrial septal defect. Genetic testing through trio‑based whole‑exome sequencing was used to reveal the molecular etiology. A nonsense variant was identified in TBX5 (c.577G>T; p.Gly193*) initially showing co‑segregation with a presumably non‑syndromic presentation of congenital heart disease. Subsequent genetic investigations and more complete phenotyping led to the correct diagnosis of HOS, documenting the novel association of mixed‑type TAPVR with HOS. Finally, protein modeling of the mutant TBX5 protein that harbored this pathogenic nonsense variant (p.Gly193*) revealed a substantial drop in the quantity of non‑covalent bonds. The decrease in the number of non‑covalent bonds suggested that the resultant mutant dimer was less stable compared with the wild‑type protein, consequently affecting the protein's ability to bind DNA. The present findings extended the phenotypic cardiac defects associated with HOS; to the best of our knowledge, this is the first association of mixed‑type TAPVR with TBX5. Prior to the current analysis, the molecular association of TAPVR with HOS had never been documented; hence, this is the first genetic investigation to report the association between TAPVR and HOS. Furthermore, it was demonstrated that the null‑variants reported in the T‑box domain of TBX5 were associated with a wide range of cardiac and/or skeletal anomalies on both the inter‑and intrafamilial levels. In conclusion, genetic testing was highlighted as a potentially powerful approach in the prognostication of the proper diagnosis.

Comparison of Blood Lead Concentrations in Mothers of Children with Congenital Heart Disease and Mothers of Healthy Children

Congenital heart disease (CHD) is the most prevalent congenital defect that causes several problems for patients and their families and medical specialists. It is important to investigate CHD risk factors due to their significantly destructive load on society. This study aims to determine the association between maternal lead exposure and conceiving a child with CHD. This case-control study was performed on a total of 246 mothers in the pediatric clinic of Vali-e-Asr Hospital in Birjand, Iran. One hundred forty-six mothers with CHD children were defined as the case group, and 100 age-matched mothers with healthy children were considered the control group. All the mothers were between 20 and 40 years old, and their children were under the age of 6 months. Demographic data was collected from mothers using a well-designed questionnaire. In addition, all mothers were referred to the laboratory for measuring blood lead concentrations. The mean blood lead concentration (BLC) of mothers in the group of children with heart problems was 4.11 ± 10.02 with a median of 2.50 μg/dL and in the control group was 2.66 ± 2.06 with a median of 2.30 μg/dL. The Mann-Whitney test results showed that mothers' lead concentration in the group of children with heart problems was significantly higher than the control group (z = 2.13, p = 0.03). The chi-square test results showed that lead concentrations in the two groups were significantly different from each other (χ² = 9.11, p = 0.01). The results of our study showed that mothers of children with CHD had higher blood concentrations than mothers of healthy children.

Total Anomalous Pulmonary Venous Connection and Aortopulmonary Window: Successful Management of a Rare Association

The association of total anomalous pulmonary venous connection (TAPVC) with aortopulmonary window (APW) is extremely rare. The coexistence of these two anomalies will have implications on clinical presentation, diagnosis, and pathophysiology. The lungs are exposed to pulmonary venous hypertension due to obstructed TAPVC as well as pulmonary arterial hypertension due to unrestrictive APW. We describe successful management of this unusual association in a three-month-old child.

Myocardial overexpression of ANKRD1 causes sinus venosus defects and progressive diastolic dysfunction

AIMS

Increased Ankyrin Repeat Domain 1 (ANKRD1) levels linked to gain of function mutations have been associated to total anomalous pulmonary venous return and adult cardiomyopathy occurrence in humans. The link between increased ANKRD1 level and cardiac structural and functional disease is not understood. To get insight into this problem, we have generated a gain of function ANKRD1 mouse model by overexpressing ANKRD1 in the myocardium.

METHODS AND RESULTS

Ankrd1 is expressed non-homogeneously in the embryonic myocardium, with a dynamic nucleo-sarcomeric localization in developing cardiomyocytes. ANKRD1 transgenic mice present sinus venosus defect, which originates during development by impaired remodelling of early embryonic heart. Adult transgenic hearts develop diastolic dysfunction with preserved ejection fraction, which progressively evolves into heart failure, as shown histologically and haemodynamically. Transgenic cardiomyocyte structure, sarcomeric assembly, and stability are progressively impaired from embryonic to adult life. Postnatal transgenic myofibrils also present characteristic functional alterations: impaired compliance at neonatal stage and impaired lusitropism in adult hearts. Altogether, our combined analyses suggest that impaired embryonic remodelling and adult heart dysfunction in ANKRD1 transgenic mice present a common ground of initial cardiomyocyte defects, which are exacerbated postnatally. Molecular analysis showed transient activation of GATA4-Nkx2.5 transcription in early transgenic embryos and subsequent dynamic transcriptional modulation within titin gene.

CONCLUSIONS

ANKRD1 is a fine mediator of cardiomyocyte response to haemodynamic load in the developing and adult heart. Increased ANKRD1 levels are sufficient to initiate an altered cellular phenotype, which is progressively exacerbated into a pathological organ response by the high ventricular workload during postnatal life. Our study defines for the first time a unifying picture for ANKRD1 role in heart development and disease and provides the first mechanistic link between ANKRD1 overexpression and cardiac disease onset.

Research Progress in Pathogenesis of Total Anomalous Pulmonary Venous Connection

Congenital heart defect (CHD) is one of the most common birth defects and the leading course of infant mortality. Total anomalous pulmonary venous connection (TAPVC) is a rare type of cyanotic which accounting for approximately 1-3% of congenital heart disease cases. Based on where the anomalous veins drain, TAPVC can be divided into four subtypes: supracardiac, cardiac, infracardiac, and mixed. In TAPVC, all pulmonary veins fail to link to the left atrium correctly but make abnormal connections to the right atrium or systemic venous system. The mortality of TAPVC patients without proper intervention is nearly 80% in the first year of life and 50% of them died within 3 months after birth. However, the pathogenesis and mechanism of TAPVC remains elusive. In this chapter, we systematically review the epidemiology, anatomy, and pathophysiology of TAPVC and give an overview of the research progress of TAPVC pathogenesis.

Surgical ductal stent implantation in total anomalous pulmonary venous connection to vena porta with right pulmonary sequestration in a mature newborn

In many cases of total anomalous pulmonary venous connection (TAPVC), the four pulmonary veins (PV) join together behind the left atrium, where they form a collector. This collector can drain into the right atrium directly through the innominate vein into the superior vena cava (SVC), into the coronary sinus (CS), or through the diaphragm to the venous structures of the abdomen. In our case, a mature newborn had TAPVC draining into the vena porta along with severe pulmonary hypertension. Additionally, there were right pulmonary sequestration, dextrocardia, transposition of the great arteries, severe pulmonary stenosis, and single ventricular pathology in echocardiographic examination. Clinical signs manifested in the first 7 days of life. Diagnostic tools used were echocardiography and angiography. A ductal stent was surgically implanted into the ductus arteriosus by angiography. TAPVC was found to be nonobstructive. Therefore, we would like to emphasize the rareness and hardness to perform the surgical ductal implant technique in our particular case of TAPVC with pulmonary sequestration draining into the vena porta. The prognosis in TAPVC is poor and related mainly to the existence of pulmonary venous obstruction.

The effects of lead and aluminum exposure on congenital heart disease and the mechanism of oxidative stress

OBJECTIVES

This study aimed to analyze the association between fetal lead or aluminum exposure and congenital heart disease (CHD) occurrence as well as to explore the mechanism of oxidative stress in heart development.

METHODS

Lead and aluminum concentrations were measured by ICP-MS in umbilical serum. The oxidative stress statuses were analyzed by measuring SOD, GPx and MDA with colorimetric assays.

RESULTS

Higher concentrations of Al were seen in the CHD groups compared to the controls. The risk of CHD occurrence increased markedly in the highly elevated Al group (aOR 2.08, 95%CI 1.11-3.88). With increasing Al and Pb levels, the activity of SOD decreased, and the level of MDA increased. Significantly decreased activity of SOD and GPx were found in the CHD groups (P < 0.05).

CONCLUSION

Fetal aluminum exposure may contribute to CHD occurrence. Oxidative stress was related to the concentration of Pb and Al, which may be involved in the occurrence of CHD.

Whole-exome sequencing identifies SGCD and ACVRL1 mutations associated with total anomalous pulmonary venous return (TAPVR) in Chinese population

As a rare type of Congenital Heart Defects (CHD), the genetic mechanism of Total Anomalous Pulmonary Venous Return (TAPVR) remains unknown, although previous studies have revealed potential disease-driving regions/genes. Blood samples collected from the 6 sporadic TAPVR cases and 81 non-TAPVR controls were subjected to whole exome sequencing. All detected variations were confirmed by direct Sanger sequencing. Here, we identified 2 non-synonymous missense mutations: c.C652T, p.R218W in activin A receptor type II-like 1 (ACVRL1), c.C717G, p.D239E in sarcoglycan delta (SGCD). Our results offered the landscape of mutations for TAPVR in Chinese population firstly and are valuable in the mutation-based pre- and post-natal screening and genetic diagnosis for TAPVR.

Surgical Approaches to Total Anomalous Pulmonary Venous Connection

Total anomalous pulmonary venous connection (TAPVC) constitutes a spectrum of congenital lesions whereby the pulmonary veins remain connected to systemic venous vessels or aberrantly connect to the right atrium. Definitive management requires surgical intervention and, in patients with obstruction to pulmonary venous flow, urgent operation is required. Use of temporizing catheter-based interventions allow for optimization in hemodynamically unstable neonates. Overall, survival has significantly improved over the past decades through better perioperative management and evolution of surgical approaches to minimize post-repair pulmonary vein stenosis, which persists as a major determinant of long-term outcomes.

Total Anomalous Pulmonary Venous Connection Draining into the Portal Vein in a 2-Month-Old Infant: Multidetector Computed Tomography Angiography Diagnosis

Total anomalous pulmonary venous connection (TAPVC) is a rare congenital cardiac anomaly in which the pulmonary veins fail to connect with the left atrium and connect directly to the right atrium or to one of the systemic veins. Early diagnosis and surgical correction is highly important for survival. In the evaluation of TAPVC, imaging methods such as echocardiography, computed tomography (CT) angiography, magnetic resonance (MR) angiography, and catheter angiography have been used. We reported a rare case of infracardiac type of TAPVC draining into the portal vein at 2-mounth-old infant who was admitted to the hospital with shortness of breath and mild cyanosis. The images demonstrating TAPVC between the portal vein and the pulmonary veins with multidetector computed tomography (MDCT) angiography were also shown.

Prenatal diagnoses of an uncommon isolated obstructed supracardiac total anomalous pulmonary venous connection: Case report and review of the literature (CARE compliant)

INTRODUCTION

Total anomalous pulmonary venous connection is an uncommon congenital heart disease. Four types are described based on the site of pulmonary venous drainage: supracardiac, cardiac, infradiaphragmathic, and mixed connection. In most cases of supracardiac type, the common venous confluence drains through an ascending left vertical vein into the brachiocephalic vein, right superior vena cava, and then into the right atrium. Anomalous connection of the pulmonary venous confluence directly to the right SVC, especially the obstructed form is an unusual and severe supracardiac variant. The prenatal diagnosis is challenging.

PATIENT CONCERNS

We present a case report of a fetus diagnosed with TAPVC at 23 gestational weeks.

DIAGNOSIS INTERVENTIONS

The 4-chamber view showed a small left atrium, with a "smooth" posterior wall and the absence of pulmonary vein connection. This is the first case of prenatally diagnosed isolated, obstructed supracardiac type with drainage directly into the right superior vena cava.

CONCLUSION

The obstetrician and fetal cardiologist should be cautious at the direct and indirect echocardiographic signs of this condition. A prenatal diagnose of isolated, obstructed form is important for adequate planning of delivery and postnatal surgery in a tertiary center.

Total Anomalous Pulmonary Venous Connection: Preoperative Anatomy, Physiology, Imaging, and Interventional Management of Postoperative Pulmonary Venous Obstruction

Total anomalous pulmonary venous connection refers to a spectrum of cardiac anomalies where the pulmonary veins fail to return to the left atrium and the pulmonary venous blood returns through a systemic vein or directly to the right atrium. There is a wide anatomical variety of venous connections and degrees of pulmonary venous obstruction that affect the presentation, surgical repair, and outcomes. In this review, we explore the preoperative physiology, echocardiographic diagnosis, and approach to postoperative complications.

Maternal Chlamydia Infection During Pregnancy and Risk of Cyanotic Congenital Heart Defects in the Offspring

OBJECTIVES

Genital Chlamydia is a common bacterial sexually-transmitted infection among reproductive aged women, particularly younger populations. Cyanotic congenital heart defects (CCHDs) constitute about one quarter of all cardiac malformations at birth, and are associated with high rate of morbidity and mortality. Epidemiological research on the association between maternal Chlamydia during pregnancy and CCHDs in the offspring is lacking.

METHODS

Using data from the 2012 United States birth certificates, we examined the association between CCHDs and prenatal exposure to Chlamydia among live singleton births with CCHDs (n = 2487) and unaffected singleton births (n = 3,334,424). We estimated adjusted odds ratios (aORs) and 95% confidence intervals (CIs) using unconditional logistic regression analysis for all CCHDs combined, and isolated CCHDs (without other major congenital malformations).

RESULTS

Overall 1.7% of case and 1.7% of control women reported having Chlamydia during their pregnancies. After controlling for potential confounders, we found a weak positive association between maternal Chlamydia during pregnancy and all CCHDs combined (aOR = 1.39; 95% CI 1.02-1.90). The positive association persisted for isolated CCHD cases, but with marginal significance (aOR = 1.34; 95% CI 0.96-1.74). Subgroup analyses for younger women showed an increased risk for CCHDs; however, the associations were not statistically significant.

CONCLUSIONS

Maternal exposure to Chlamydia during pregnancy was weakly associated with a higher risk of CCHDs in the offspring. The finding should be interpreted with caution due to limitations of birth certificate data. Future studies using more robust data sources are warranted to further study the association between maternal Chlamydia during pregnancy and CCHDs in the offspring.

Anomalous Pulmonary Venous Return: Insights Into Prenatal Detection

OBJECTIVES

To review all cases of total anomalous pulmonary venous return (TAPVR) or partial anomalous pulmonary venous return (PAPVR) identified prenatally or postnatally at a single institution and to identify factors that may lead to a correct or missed diagnosis in both high- and low-risk fetuses on screening examinations.

METHODS

Fetal images from 16 cases of prenatally or postnatally diagnosed T/PAPVR were retrospectively reviewed to analyze factors that influenced interpretations and diagnoses.

RESULTS

Sixteen diagnoses of T/PAPVR were made, with a final number of 10 confirmed cases, 1 of which was PAPVR. Ten fetuses with a presumptive diagnosis of T/PAPVR before delivery were at an average gestational age of 24.7 weeks, with 5 cases diagnosed postnatally. None of the diagnoses of isolated TAPVR were made during a screening examination. Twelve of the pregnancies were complicated by complex cardiac defects, including 6 with heterotaxy syndromes. Of the 5 abnormal cases identified in the postpartum period, 3 had isolated TAPVR. In the 3 patients with isolated defects, prenatal echocardiography was not performed; the anatomy scan interpretations were confounded by multiple factors. In retrospect, there was no obvious sonographic evidence of TAPVR in these patients; however, color flow Doppler imaging of the pulmonary veins was not performed on any of them.

CONCLUSIONS

Although fetal echocardiography has improved the overall detection of TAPVR or PAPVR, this abnormality continues to elude prenatal diagnosis during screening in both low- and high-risk patients. We hypothesize that the use of color flow Doppler imaging in the 4-chamber view may assist in diagnosing TAPVR in screening low-risk patients, especially in those with difficult scans.

Maternal occupational pesticide exposure and risk of congenital heart defects in the National Birth Defects Prevention Study

BACKGROUND

Congenital heart defects (CHDs) are common birth defects, affecting approximately 1% of live births. Pesticide exposure has been suggested as an etiologic factor for CHDs, but previous results were inconsistent.

METHODS

We examined maternal occupational exposure to fungicides, insecticides, and herbicides for 3328 infants with CHDs and 2988 unaffected control infants of employed mothers using data for 1997 through 2002 births from the National Birth Defects Prevention Study, a population-based multisite case-control study. Potential pesticide exposure from 1 month before conception through the first trimester of pregnancy was assigned by an expert-guided task-exposure matrix and job history details self-reported by mothers. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using multivariable logistic regression.

RESULTS

Maternal occupational exposure to pesticides was not associated with CHDs overall. In examining specific CHD subtypes compared with controls, some novel associations were observed with higher estimated pesticide exposure: insecticides only and secundum atrial septal defect (OR = 1.8; 95% CI, 1.3-2.7, 40 exposed cases); both insecticides and herbicides and hypoplastic left heart syndrome (OR = 5.1; 95% CI, 1.7-15.3, 4 exposed cases), as well as pulmonary valve stenosis (OR = 3.6; 95% CI, 1.3-10.1, 5 exposed cases); and insecticides, herbicides, and fungicides and tetralogy of Fallot (TOF) (OR = 2.2; 95% CI, 1.2-4.0, 13 exposed cases).

CONCLUSION

Broad pesticide exposure categories were not associated with CHDs overall, but examining specific CHD subtypes revealed some increased odds ratios. These results highlight the importance of examining specific CHDs separately. Because of multiple comparisons, additional work is needed to verify these associations.

Shared Segment Analysis and Next-Generation Sequencing Implicates the Retinoic Acid Signaling Pathway in Total Anomalous Pulmonary Venous Return (TAPVR)

Most isolated congenital heart defects are thought to be sporadic and are often ascribed to multifactorial mechanisms with poorly understood genetics. Total Anomalous Pulmonary Venous Return (TAPVR) occurs in 1 in 15,000 live-born infants and occurs either in isolation or as part of a syndrome involving aberrant left-right development. Previously, we reported causative links between TAVPR and the PDGFRA gene. TAPVR has also been linked to the ANKRD1/CARP genes. However, these genes only explain a small fraction of the heritability of the condition. By examination of phased single nucleotide polymorphism genotype data from 5 distantly related TAPVR patients we identified a single 25 cM shared, Identical by Descent genomic segment on the short arm of chromosome 12 shared by 3 of the patients and their obligate-carrier parents. Whole genome sequence (WGS) analysis identified a non-synonymous variant within the shared segment in the retinol binding protein 5 (RBP5) gene. The RBP5 variant is predicted to be deleterious and is overrepresented in the TAPVR population. Gene expression and functional analysis of the zebrafish orthologue, rbp7, supports the notion that RBP5 is a TAPVR susceptibility gene. Additional sequence analysis also uncovered deleterious variants in genes associated with retinoic acid signaling, including NODAL and retinol dehydrogenase 10. These data indicate that genetic variation in the retinoic acid signaling pathway confers, in part, susceptibility to TAPVR.

Total anomalous pulmonary venous connection : Autopsy considerations

Total anomalous pulmonary venous connection (TAPVC), where the pulmonary venous circulation drains into the systemic venous circulation rather than into the left atrium, may present a number of problems at autopsy. A 5-week-old infant is reported who died suddenly and unexpectedly who was found at autopsy to have infradiaphragmatic TAPVC into the portal vein. The only associated anomalies were a tri-lobed left lung, a patent ductus arteriosus, and drainage of the inferior vena cava into the both the right and left atria. This case demonstrates particular features that may lead to difficulties in establishing the diagnosis of TAPVC. Sudden death in the absence of symptoms in this age group raises the possibilities of sudden infant death syndrome (SIDS) and inflicted injury, both of which were discounted in this case. An autopsy approach is outlined to maximize chances of diagnosing this entity that includes meticulous inspection and dissection of cardiac vascular connections before evisceration, with photographic documentation of findings. Concurrent cardiovascular abnormalities, including valve atresias, septal defects, and left heart hypoplasia are likely in the presence of asplenia/polysplenia syndrome. Extracardiac anomalies may be present in the form of Holt-Oram, Ellis-van Creveld, and cat eye syndromes. Careful examination of the common draining vein for obstructive features is an important part of the postmortem assessment. The possibility of heritable cases requires referral of the family for genetic evaluation.

Total anomalous pulmonary venous return in siblings

Total anomalous pulmonary venous return (TAPVR) is a rare and critical congenital vascular anomaly that requires an early operation. However, initial symptoms of TAPVR may be non-specific, and cardiovascular findings may be minimal. The heart may not be enlarged and there is often no cardiac murmur. Without cardiac murmur, these symptoms are similar to those of respiratory distress syndrome in newborns. Therefore, a high degree of suspicion and an early diagnosis of TAPVR are important. This condition generally occurs without a family history and has a low recurrence rate, but several familial cases, including siblings, have been reported worldwide. Additionally, several chromosomal or gene abnormalities associated with TAPVR have been reported. In the case presented here, two brothers with a 6-year age gap were diagnosed with TAPVR. Surgery was performed without cardiac or neurological complications. This is the first report on TAPVR in siblings in Korea.

Maternal lead exposure and risk of congenital heart defects occurrence in offspring

Maternal lead exposure may be harmful to fetal development. However, sufficient evidence was lacked about the risk on cardiac development in offspring. To explore the association between maternal lead exposure and risks of congenital heart defects (CHDs) occurrence in fetuses, a case-control study was adopted during pregnant women making antenatal examinations. The maternal hair lead levels were measured by using inductively coupled plasma mass spectrometry (ICP-MS), and logistic regression analysis was used to calculate the odds ratio (OR). Three hundred and sixteen cases and 348 controls were eligible to the study. The median level of lead in maternal hair of case (0.670ng/mg) was significantly higher (AOR 3.07, 95% CI 2.00-4.72) than that of the control (0.461ng/mg), including the CHD cases with or without extracardiac malformations (AOR 3.55, 2.94, respectively). Maternal lead exposure is associated with the risk of some subtypes of CHDs occurrence in offspring. The potential dose-response relationship is also presented.

Residential agricultural pesticide exposures and risk of selected congenital heart defects among offspring in the San Joaquin Valley of California

BACKGROUND

Pesticide exposures are ubiquitous and of substantial public concern. We examined the potential association of congenital heart defects with residential proximity to commercial agricultural pesticide applications in the San Joaquin Valley, California.

METHODS

Study subjects included 569 heart defect cases and 785 non-malformed controls born from 1997 to 2006 whose mothers participated in a population-based case-control study. Associations with any versus no exposure to physicochemical groups of pesticides and specific chemicals were assessed using logistic regression adjusted for relevant covariates, for 8 heart defect phenotypes that included ≥ 50 cases and pesticide exposures with ≥ 5 exposed cases and controls, which resulted in 235 comparisons.

RESULTS

38% of cases and controls were classified as exposed to pesticides within a 500 m radius of mother's address during a 3-month periconceptional window. Adjusted odds ratios (AORs) with 95% CIs excluding 1.0 were observed for 18 comparisons; all were >1 and ranged from 1.9 to 7.1. They included tetralogy of Fallot (n=101 cases) and neonicotinoids; hypoplastic left heart syndrome (n=59) and strobins; coarctation of the aorta (n=74) and pyridazinones; pulmonary valve stenosis (n=53) and bipyridyliums and organophosphates; ventricular septal defects (n=93) and avermectins and pyrethroids; and atrial septal defects (n=132) and dichlorphenoxy acid or esters, organophosphates, organotins, and pyrethroids. No AORs met both of these criteria for d-transposition of the great arteries (n=58) or heterotaxia (n=53).

CONCLUSIONS

Most pesticides were not associated with increased risk of specific heart defect phenotypes. For the few that were associated, results should be interpreted with caution until replicated in other study populations.

Total anomalous pulmonary venous connection in a chicken

This report describes a case of total anomalous pulmonary venous connection (TAPVC) in a 5-wk-old male white leghorn chicken that presented with growth retardation. This chicken was a specific-pathogen-free chicken bred in an isolator. At 5 wk of age, the chicken was euthanatized and autopsied. Macroscopically, the right ventricle and right atrium were significantly enlarged whereas the left atrium was small and blind-ending with no connection to the pulmonary veins. The pulmonary veins were connected directly to the right atrium. The above abnormality was accompanied by an ostium secundum-type atrial septal defect. No other malformations were observed. TAPVC is a very rare congenital cardiac abnormality that has not been reported in avian species to date.

Possible association between complex congenital heart defects and 11p15 hypomethylation in three patients with severe Silver-Russell syndrome

Silver-Russell syndrome (SRS) is characterized by pre- and post-natal growth restriction that spares head growth, feeding difficulties, and variable dysmorphic facial features without major malformations. Hypomethylation of the paternal 11p15 imprinting control region 1 (ICR1) and maternal uniparental disomy of chromosome 7 are found in 50-60% and in 5-10% of SRS patients, respectively. We report on the pre- and post-natal features of three unrelated SRS patients with unusual congenital heart defects (CHDs). Two patients born prematurely had total anomalous pulmonary venous return and died shortly after birth, and a third patient, now 4 years old, had cor triatriatum sinistrum, which was surgically corrected. In all three patients, the underlying molecular defect was 11p15 ICR1 hypomethylation. Based on a large cohort with molecularly proven SRS, the prevalence of CHD in SRS is estimated at 5.5%. We suggest that the occurrence of CHD in SRS with 11p15 ICR1 hypomethylation is not coincidental, but specific to this genotype.

Successful surgical intervention of total anomalous pulmonary venous drainage in the third decade of life

Total anomalous pulmonary venous drainage (TAPVD) accounts for approximately 1.5% of all congenital heart diseases. It is usually diagnosed in the neonatal period and is rarely seen in adults. We report an unusual case of a patient with TAPVD who was successfully treated at the age of 28 years. We believe that this is the oldest person in the South Asian literature to undergo surgical correction of TAPVD.

Total anomalous pulmonary venous connection: impact of prenatal diagnosis

OBJECTIVES

To investigate whether prenatal screening is effective in the detection of total anomalous pulmonary venous connection (TAPVC) and to identify common prenatal features.

METHODS

This was a retrospective collaborative study involving 19 pediatric cardiac centers in the UK, Ireland and Sweden. Cases with TAPVC born between January 1, 1998 and December 31, 2004, and prenatally diagnosed cases whose estimated dates of delivery were within this time frame, were identified. Cases with functionally univentricular circulation or atrial isomerism were excluded. All available data and stored images were reviewed.

RESULTS

Four-hundred and twenty-four cases with TAPVC were identified prenatally or postnatally, of whom eight (1.9%) had a prenatal diagnosis of TAPVC. Median gestational age at fetal diagnosis was 26 + 6 (range, 22 + 4 to 32 + 0) weeks. Six further fetuses with TAPVC had an abnormality diagnosed on prenatal ultrasound, but not the TAPVC. This included other congenital heart defects (four cases) and isolated pleural effusion (two cases). Seventeen (4.0%) of the 422 liveborn infants had a first-degree relative with congenital heart disease; and six of 17 had a sibling with TAPVC. Two died in utero. Of the liveborn infants diagnosed prenatally with TAPVC, none required urgent intervention for pulmonary venous obstruction and all were alive and well at a median of 2.3 (range, 1.0-7.0) years after surgical repair.

CONCLUSION

Prenatal diagnosis of TAPVC is infrequent using current screening methods. Where there is a family history of TAPVC, specialized fetal echocardiography at 20 and 28 weeks' gestation may be indicated.

Association between maternal occupational exposure to organic solvents and congenital heart defects, National Birth Defects Prevention Study, 1997-2002

OBJECTIVE

To examine the relation between congenital heart defects (CHDs) in offspring and estimated maternal occupational exposure to chlorinated solvents, aromatic solvents and Stoddard solvent during the period from 1 month before conception through the first trimester.

METHODS

The study population included mothers of infants with simple isolated CHDs and mothers of control infants who delivered from 1997 through 2002 and participated in the National Birth Defects Prevention Study. Two methods to assess occupational solvent exposure were employed: an expert consensus-based approach and a literature-based approach. Multiple logistic regression was used to calculate adjusted ORs and 95% CIs for the association between solvent classes and CHDs.

RESULTS

2951 control mothers and 2047 CHD case mothers were included. Using the consensus-based approach, associations were observed for exposure to any solvent and any chlorinated solvent with perimembranous ventricular septal defects (OR 1.6, 95% CI 1.0 to 2.6 and OR 1.7, 95% CI 1.0 to 2.8, respectively). Using the literature-based approach, associations were observed for: any solvent exposure with aortic stenosis (OR 2.1, 95% CI 1.1 to 4.1) and Stoddard solvent exposure with d-transposition of the great arteries (OR 2.0, 95% CI 1.0 to 4.2), right ventricular outflow tract obstruction defects (OR 1.9, 95% CI 1.1 to 3.3) and pulmonary valve stenosis (OR 2.1, 95% CI 1.1 to 3.8).

CONCLUSIONS

The authors found evidence of associations between occupational exposure to solvents and several types of CHDs. These results should be interpreted in light of the potential for misclassification of exposure.

Familial recurrence of congenital heart diseases

Familial recurrence of congenital heart disease (CHD), in particular, d-transposition of great arteries (d-TGA) is rare. However, there have been several reports in the literature of sibling recurrence of total anomalous pulmonary venous return (TAPVR). This is the first case report in the literature, describing mother to offspring recurrence of d-TGA. We describe two cases of non-syndromic CHD with mother to offspring and sibling recurrence. The first case is an antenatally diagnosed d-TGA on fetal echocardiogram at 25 weeks of gestational age in the offspring of a 30-year-old mother with d-TGA. The second case is a sibling reoccurrence of TAPVR diagnosed antenatally at 30 weeks of gestational age, with supradiaphragmatic TAPVR on fetal echocardiogram in a mother, whose first child was diagnosed with infradiaphragmatic TAPVR in infancy.

Total Anomalous Pulmonary Venous Connection

Background—

Late mortality after repair of total anomalous pulmonary venous connection is frequently associated with pulmonary venous obstruction (PVO). We aimed to describe the morphological spectrum of total anomalous pulmonary venous connection and identify risk factors for death and postoperative PVO.

Methods and Results—

We conducted a retrospective, international, collaborative, population-based study involving all 19 pediatric cardiac centers in the United Kingdom, Ireland, and Sweden. All infants with total anomalous pulmonary venous connection born between 1998 and 2004 were identified. Cases with functionally univentricular circulations or atrial isomerism were excluded. All available data and imaging were reviewed. Of 422 live-born cases, 205 (48.6%) had supracardiac, 110 (26.1%) had infracardiac, 67 (15.9%) had cardiac, and 37 (8.8%) had mixed connections. There were 2 cases (0.5%) of common pulmonary vein atresia. Some patients had extremely hypoplastic veins or, rarely, discrete stenosis of the individual veins. Sixty (14.2%) had associated cardiac anomalies. Sixteen died before intervention. Three-year survival for surgically treated patients was 85.2% (95% confidence interval 81.3% to 88.4%). Risk factors for death in multivariable analysis comprised earlier age at surgery, hypoplastic/stenotic pulmonary veins, associated complex cardiac lesions, postoperative pulmonary hypertension, and postoperative PVO. Sixty (14.8%) of the 406 patients undergoing total anomalous pulmonary venous connection repair had postoperative PVO that required reintervention. Three-year survival after initial surgery for patients with postoperative PVO was 58.7% (95% confidence interval 46.2% to 69.2%). Risk factors for postoperative PVO comprised preoperative hypoplastic/stenotic pulmonary veins and absence of a common confluence.

Conclusions—

Preoperative clinical and morphological features are important risk factors for postoperative PVO and survival.

The fetal venous system, Part II: ultrasound evaluation of the fetus with congenital venous system malformation or developing circulatory compromise

The human fetal venous system is well-recognized as a target for investigation in cases of circulatory compromise, and a broad spectrum of malformations affecting this system has been described. In Part I of this review, we described the normal embryology, anatomy and physiology of this system, essential to the understanding of structural anomalies and the sequential changes encountered in intrauterine growth restriction and other developmental disorders. In Part II we review the etiology and sonographic appearance of malformations of the human fetal venous system, discuss the pathophysiology of the system and describe venous Doppler investigation in the fetus with circulatory compromise.

Association of congenital cardiovascular malformations with 33 single nucleotide polymorphisms of selected cardiovascular disease-related genes

INTRODUCTION

Clark (1996) proposed that abnormal blood flow is related to some congenital cardiovascular malformations (CCVMs), particularly CCVM with obstruction to blood flow. Our hypothesis is that CCVMs may relate to genes that affect blood coagulation or flow. We studied whether polymorphisms of such genes are related to CCVMs; previous association of these SNPs to conotruncal CCVMs is described.

METHODS

We assessed risk of pulmonary stenosis (PS, N = 120), atrial septal defect (ASD, N = 108), aortic stenosis (AS, N = 36), and coarctation of the aorta (CoAo, N = 64), associated with 33 candidate genes, selected for their relationship to blood flow affected by homocysteine metabolism, coagulation, cell-cell interaction, inflammation, or blood pressure regulation.

RESULTS

Effects were specific to cardiac phenotype and race. CoAo was associated with MTHFR (-667) C>T (odds ratio [OR] for TT 3.5, 95% confidence limits [CI] 1.4-8.6). AS was associated with a polymorphism of SERPINE1, G5>G4, OR = 5.6 for the homozygote with 95% CI 1.4-22.9. Unique polymorphisms were associated with increased risk of ASD and PS: NPPA 664G>A with ASD (OR of 2.4, 95%CI 1.3-4.4) and NOS3 (-690) C>T with PS (OR 6.1; 95% CI 1.6-22.6 in the African American population only). For ASD, the NPPA (-664) G>A SNP there was increased risk from the variant genotype only in maternal smokers (OR 2.6; 95% CI 1.0-7.2).

CONCLUSIONS

Genes affecting vascular function and coagulation appear to be promising candidates for the etiology of cardiac malformations and warrant further study.

Dysregulation of the PDGFRA gene causes inflow tract anomalies including TAPVR: integrating evidence from human genetics and model organisms

Total anomalous pulmonary venous return (TAPVR) is a congenital heart defect inherited via complex genetic and/or environmental factors. We report detailed mapping in extended TAPVR kindreds and mutation analysis in TAPVR patients that implicate the PDGFRA gene in the development of TAPVR. Gene expression studies in mouse and chick embryos for both the Pdgfra receptor and its ligand Pdgf-a show temporal and spatial patterns consistent with a role in pulmonary vein (PV) development. We used an in ovo function blocking assay in chick and a conditional knockout approach in mouse to knock down Pdgfra expression in the developing venous pole during the period of PV formation. We observed that loss of PDGFRA function in both organisms causes TAPVR with low penetrance (approximately 7%) reminiscent of that observed in our human TAPVR kindreds. Intermediate inflow tract anomalies occurred in a higher percentage of embryos (approximately 30%), suggesting that TAPVR occurs at one end of a spectrum of defects. We show that the anomalous pulmonary venous connection seen in chick and mouse is highly similar to TAPVR discovered in an abnormal early stage embryo from the Kyoto human embryo collection. Whereas the embryology of the normal venous pole and PV is becoming understood, little is known about the embryogenesis or molecular pathogenesis of TAPVR. These models of TAPVR provide important insight into the pathogenesis of PV defects. Taken together, these data from human genetics and animal models support a role for PDGF-signaling in normal PV development, and in the pathogenesis of TAPVR.

64-slice CT imaging in a case of total anomalous pulmonary venous circulation

For long, catheter angiography has been the investigation of choice for the diagnosis of congenital anomalies of the heart such as total anomalous pulmonary venous circulation (TAPVC). In the last few years, MRI and multislice CT scan have also been introduced for this purpose. We report a case where 64-slice CT scan was found very useful in the evaluation of TAPVC.

Intracellular ANKRD1 protein levels are regulated by 26S proteasome-mediated degradation

The ANKRD1/CARP gene encodes a muscle-specific protein which has been implicated in transcriptional regulation and myofibrillar assembly. Several features at both the mRNA and protein levels define ANKRD1 as a gene whose expression is tightly regulated, and deregulated expression of this protein has been recently associated to human congenital heart disease. It is therefore crucial to define the intracellular pathways that regulate the ANKRD1 protein's steady-state levels. Here, we show that ANKRD1 is a short-lived protein whose levels are tightly regulated by the 26S proteasome. In addition, a critical role for a putative PEST motif was established, although other degrons within the ANKRD1 protein are likely implicated in the control of its intracellular levels.

Successful surgical correction of total anomalous pulmonary venous drainage in the sixth decade

We report an unusual case of total anomalous pulmonary venous drainage (TAPVD), who was successfully treated by surgery at the age of 56 years. We believe that this is the oldest person in the English literature to undergo surgical correction of TAPVD. The pathophysiology and factors for prolonged survival are further discussed.

Epidemiologic evidence of relationships between reproductive and child health outcomes and environmental chemical contaminants

This review summarizes the level of epidemiologic evidence for relationships between prenatal and/or early life exposure to environmental chemical contaminants and fetal, child, and adult health. Discussion focuses on fetal loss, intrauterine growth restriction, preterm birth, birth defects, respiratory and other childhood diseases, neuropsychological deficits, premature or delayed sexual maturation, and certain adult cancers linked to fetal or childhood exposures. Environmental exposures considered here include chemical toxicants in air, water, soil/house dust and foods (including human breast milk), and consumer products. Reports reviewed here included original epidemiologic studies (with at least basic descriptions of methods and results), literature reviews, expert group reports, meta-analyses, and pooled analyses. Levels of evidence for causal relationships were categorized as sufficient, limited, or inadequate according to predefined criteria. There was sufficient epidemiological evidence for causal relationships between several adverse pregnancy or child health outcomes and prenatal or childhood exposure to environmental chemical contaminants. These included prenatal high-level methylmercury (CH(3)Hg) exposure (delayed developmental milestones and cognitive, motor, auditory, and visual deficits), high-level prenatal exposure to polychlorinated biphenyls (PCBs), polychlorinated dibenzofurans (PCDFs), and related toxicants (neonatal tooth abnormalities, cognitive and motor deficits), maternal active smoking (delayed conception, preterm birth, fetal growth deficit [FGD] and sudden infant death syndrome [SIDS]) and prenatal environmental tobacco smoke (ETS) exposure (preterm birth), low-level childhood lead exposure (cognitive deficits and renal tubular damage), high-level childhood CH(3)Hg exposure (visual deficits), high-level childhood exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) (chloracne), childhood ETS exposure (SIDS, new-onset asthma, increased asthma severity, lung and middle ear infections, and adult breast and lung cancer), childhood exposure to biomass smoke (lung infections), and childhood exposure to outdoor air pollutants (increased asthma severity). Evidence for some proven relationships came from investigation of relatively small numbers of children with high-dose prenatal or early childhood exposures, e.g., CH(3)Hg poisoning episodes in Japan and Iraq. In contrast, consensus on a causal relationship between incident asthma and ETS exposure came only recently after many studies and prolonged debate. There were many relationships supported by limited epidemiologic evidence, ranging from several studies with fairly consistent findings and evidence of dose-response relationships to those where 20 or more studies provided inconsistent or otherwise less than convincing evidence of an association. The latter included childhood cancer and parental or childhood exposures to pesticides. In most cases, relationships supported by inadequate epidemiologic evidence reflect scarcity of evidence as opposed to strong evidence of no effect. This summary points to three main needs: (1) Where relationships between child health and environmental exposures are supported by sufficient evidence of causal relationships, there is a need for (a) policies and programs to minimize population exposures and (b) population-based biomonitoring to track exposure levels, i.e., through ongoing or periodic surveys with measurements of contaminant levels in blood, urine and other samples. (2) For relationships supported by limited evidence, there is a need for targeted research and policy options ranging from ongoing evaluation of evidence to proactive actions. (3) There is a great need for population-based, multidisciplinary and collaborative research on the many relationships supported by inadequate evidence, as these represent major knowledge gaps. Expert groups faced with evaluating epidemiologic evidence of potential causal relationships repeatedly encounter problems in summarizing the available data. A major driver for undertaking such summaries is the need to compensate for the limited sample sizes of individual epidemiologic studies. Sample size limitations are major obstacles to exploration of prenatal, paternal, and childhood exposures during specific time windows, exposure intensity, exposure-exposure or exposure-gene interactions, and relatively rare health outcomes such as childhood cancer. Such research needs call for investments in research infrastructure, including human resources and methods development (standardized protocols, biomarker research, validated exposure metrics, reference analytic laboratories). These are needed to generate research findings that can be compared and subjected to pooled analyses aimed at knowledge synthesis.

Transcriptional deregulation and a missense mutation define ANKRD1 as a candidate gene for total anomalous pulmonary venous return

Total anomalous pulmonary venous return (TAPVR) is a congenital heart defect in which the pulmonary veins fail to enter the left atrium and drain instead into the right atrium or one of its venous tributaries. Although a genetic basis for TAPVR has long been recognized, no single gene involved in the pathogenesis of this disease has been identified to date. We previously reported a TAPVR patient bearing a de novo 10;21 balanced translocation. In this work, we cloned both translocation breakpoints from this patient and mapped the ANKRD1 gene, encoding a cardiac transcriptional regulator, 130 kb proximally to the breakpoint on chromosome 10. In situ hybridization analysis performed on murine embryos showed ANKRD1 expression in the developing pulmonary veins, suggesting a possible role for this gene in TAPVR pathogenesis. Moreover, ANKRD1 expression levels were found to be highly increased in lymphoblastoid cell lines derived from both the translocation-bearing proband and a second independent sporadic TAPVR patient, suggesting that disruption of the normal ANKRD1 expression pattern is associated with TAPVR. Finally, a nonconservative missense mutation in the ANKRD1 gene was found in a third sporadic TAPVR patient. In vitro calpain-mediated degradation assays, coupled to reporter gene analysis in transfected HeLa cells, strongly suggested that this mutation enhances both the stability of the ANKRD1/CARP protein and its transcriptional repression activity upon the cardiac-specific atrial natriuretic factor (ANF) promoter. Taken together, these results define ANKRD1 as a possible candidate gene for TAPVR pathogenesis.

Two- and four-dimensional echocardiography with B-flow imaging and spatiotemporal image correlation in prenatal diagnosis of isolated total anomalous pulmonary venous connection

OBJECTIVES

To explore whether the use of four dimensional (4D) ultrasound examination with B-flow imaging and spatiotemporal image correlation (STIC) can supply additional information with respect to two-dimensional (2D) gray-scale and color Doppler echocardiography in the prenatal characterization of isolated total anomalous pulmonary venous connection (TAPVC).

METHODS

The study population comprised a group of three TAPVC fetuses that had been examined exclusively by conventional echocardiography, and a group of four additional cases initially identified by conventional echocardiography and examined further by 4D ultrasonography; a thorough postnatal work-up was available for all fetuses.

RESULTS

At our center, isolated TAPVC was found in seven of 1040 fetuses with cardiac defects (0.67%). Anomalous drainage was supracardiac to the innominate vein in three cases, cardiac to the coronary sinus in two, and infracardiac to the portal vein in the remaining two cases. An evident asymmetry between left heart and right heart structures was observed in 4/7 cases. The confluence of the anomalous pulmonary veins (PVs) was visualized in 4/7 cases and the connecting vertical vein was identified in 3/5 cases at 2D echocardiography. 4D ultrasound imaging with B-flow imaging and STIC clearly visualized the anomalous PV confluence and the draining vertical vein in all four cases examined.

CONCLUSION

2D and color Doppler echocardiography appears to diagnose reliably TAPVC, albeit with some limitations in thorough assessment of the pathology, depending on the anatomy of the defect, on the technical adequacy of the equipment used and on the experience of the operator. 4D ultrasound examination with B-flow imaging and STIC is apparently able to facilitate identification of the anatomical features of TAPVC, thus supplying additional information over that provided by 2D fetal sonography.

Noninherited risk factors and congenital cardiovascular defects: current knowledge: a scientific statement from the American Heart Association Council on Cardiovascular Disease in the Young: endorsed by the American Academy of Pediatrics

Prevention of congenital cardiovascular defects has been hampered by a lack of information about modifiable risk factors for abnormalities in cardiac development. Over the past decade, there have been major breakthroughs in the understanding of inherited causes of congenital heart disease, including the identification of specific genetic abnormalities for some types of malformations. Although relatively less information has been available on noninherited modifiable factors that may have an adverse effect on the fetal heart, there is a growing body of epidemiological literature on this topic. This statement summarizes the currently available literature on potential fetal exposures that might alter risk for cardiovascular defects. Information is summarized for periconceptional multivitamin or folic acid intake, which may reduce the risk of cardiac disease in the fetus, and for additional types of potential exposures that may increase the risk, including maternal illnesses, maternal therapeutic and nontherapeutic drug exposures, environmental exposures, and paternal exposures. Information is highlighted regarding definitive risk factors such as maternal rubella; phenylketonuria; pregestational diabetes; exposure to thalidomide, vitamin A cogeners, or retinoids; and indomethacin tocolysis. Caveats regarding interpretation of possible exposure-outcome relationships from case-control studies are given because this type of study has provided most of the available information. Guidelines for prospective parents that could reduce the likelihood that their child will have a major cardiac malformation are given. Issues related to pregnancy monitoring are discussed. Knowledge gaps and future sources of new information on risk factors are described.

Total Anomalous Pulmonary Venous Connection

Total anomalous pulmonary venous connection (TAPVC) is a congenital heart defect in which there is no connection between the pulmonary veins and the left atrium. An anomalous connection is established that allows the pulmonary veins to deliver pulmonary venous blood to the right side of the heart rather than to the left side. A patent foramen ovale or an atrial septal defect develops in utero, allowing a right-to-left shunting of blood without which the infant would die. This article describes normal embryology, abnormal embryology that results in TAPVC, types of anomalous connections, how TAPVC is diagnosed, surgical correction, and nursing interventions when caring for patients with TAPVC and dealing with the concerns of their family members.

Inter-rater agreement of assessed prenatal maternal occupational exposures to lead

BACKGROUND

Industrial hygienists' assessments of prenatal occupational exposures based on parental job histories is a promising approach for population-based case-control studies of birth defects and other perinatal outcomes. However, evaluations of inter-rater agreement of such assessments have been limited.

METHODS

We examined inter-rater agreement of occupational lead exposure assessments of maternal job reports by industrial hygienists in a population-based case-control study of parental occupational lead exposure and low birth weight. A total of 178 jobs with potential exposure to lead during the 6 months before pregnancy to the end of pregnancy were examined. Three industrial hygienists evaluated these jobs independently for exposure to lead including probability of exposure, type of exposure, route of entry, exposure frequency, duration, and intensity. Inter-rater agreement of these assessments beyond chance was evaluated using the kappa statistic (kappa).

RESULTS

In general, inter-rater agreement was greater for assessment of direct exposures than assessment of indirect exposures. However, inter-rater agreement varied with the lead exposure metric under consideration, being: 1) fair to good for type of direct exposure (i.e., inorganic or organic), respiratory exposure and frequency of exposure to direct inorganic lead, hours per day of direct (i.e., inorganic or organic), and intensity of direct inorganic exposure; 2) poor for probability and type of indirect exposure (inorganic or organic); and 3) indeterminate for frequency of direct organic exposure, frequency of indirect exposures (organic or inorganic), and intensity of direct exposures (organic or inorganic).

CONCLUSION

Retrospective assessment of maternal prenatal exposures to lead by industrial hygienists can provide some reliable metrics of exposure for studies of perinatal outcomes. Reliability studies of such exposure assessments may be useful for: quantifying the reliability of derived exposure metrics; identifying exposure metrics for exposure-outcome analyses; and determining the reliability of prenatal occupational exposures to other agents of interest.

Pesticide exposures and developmental outcomes: the epidemiological evidence

Since the advent of DDT as an insecticide in the late 1930s, billions of kilograms of pesticide active ingredient have been sold in North America and around the world. In recent years, there has been a heightened public awareness of pesticides and child health and a number of epidemiologic studies linked pre- and postnatal exposures to pesticides to a number of adverse developmental outcomes, including fetal death, intrauterine growth restriction, preterm birth, and birth defects. Given this, it was felt prudent to critically appraise the evidence for periconceptual pesticide exposures and developmental outcomes. The epidemiological evidence for specific pesticide classes, families, and active ingredients were examined and summarized and recommendations were made for how to improve future studies in order to address the current pitfalls and gaps in the studies in this area. Many of the studies suffered from poor exposure estimation, relying on job title only and/or the exposure category "any pesticide" as a measure of exposure, and there was limited or inadequate evidence to support causality for all associations examined.

Pesticide exposure: the hormonal function of the female reproductive system disrupted?

Some pesticides may interfere with the female hormonal function, which may lead to negative effects on the reproductive system through disruption of the hormonal balance necessary for proper functioning. Previous studies primarily focused on interference with the estrogen and/or androgen receptor, but the hormonal function may be disrupted in many more ways through pesticide exposure. The aim of this review is to give an overview of the various ways in which pesticides may disrupt the hormonal function of the female reproductive system and in particular the ovarian cycle. Disruption can occur in all stages of hormonal regulation: 1. hormone synthesis; 2. hormone release and storage; 3. hormone transport and clearance; 4. hormone receptor recognition and binding; 5. hormone postreceptor activation; 6. the thyroid function; and 7. the central nervous system. These mechanisms are described for effects of pesticide exposure in vitro and on experimental animals in vivo. For the latter, potential effects of endocrine disrupting pesticides on the female reproductive system, i.e. modulation of hormone concentrations, ovarian cycle irregularities, and impaired fertility, are also reviewed. In epidemiological studies, exposure to pesticides has been associated with menstrual cycle disturbances, reduced fertility, prolonged time-to-pregnancy, spontaneous abortion, stillbirths, and developmental defects, which may or may not be due to disruption of the female hormonal function. Because pesticides comprise a large number of distinct substances with dissimilar structures and diverse toxicity, it is most likely that several of the above-mentioned mechanisms are involved in the pathophysiological pathways explaining the role of pesticide exposure in ovarian cycle disturbances, ultimately leading to fertility problems and other reproductive effects. In future research, information on the ways in which pesticides may disrupt the hormonal function as described in this review, can be used to generate specific hypotheses for studies on the effects of pesticides on the ovarian cycle, both in toxicological and epidemiological settings.