Chronic perinatal hypoxia delays cardiac maturation in a mouse model for cyanotic congenital heart disease.

Compared with acyanotic congenital heart disease (CHD), cyanotic CHD has an increased risk of lifelong mortality and morbidity. These adverse outcomes may be attributed to delayed cardiomyocyte maturation, since the transition from a hypoxic fetal milieu to oxygen-rich postnatal environment is disrupted. We established a rodent model to replicate hypoxic myocardial conditions spanning perinatal development, and tested the hypothesis that chronic hypoxia impairs cardiac development.

Ultrahigh-Frequency Echocardiography of Autonomic Devoid Phox2B Homozygous Embryos Does Not Reveal a Significant Cardiac Phenotype before Embryo Death.

In vivo micro-imaging of mice is useful in studying the genetic basis of cardiac development in mutant embryos. We examined Phox2b mutant mice, which lack autonomic innervation to the heart and die in utero, and investigated whether this lack of innervation causes cardiac dysfunction during embryogenesis. A VisualSonics Vevo 2100 ultrahigh-frequency linear array ultrasound machine with 30- and 40-MHz probes was used to analyze embryo size, gross characteristics, ventricular contractility and rhythm.

The ubiquitin ligase HECTD1 promotes retinoic acid signaling required for development of the aortic arch.

The development of the aortic arch is a complex process that involves remodeling of the bilaterally symmetrical pharyngeal arch arteries (PAAs) into the mature asymmetric aortic arch. Retinoic acid signaling is a key regulator of this process by directing patterning of the second heart field (SHF), formation of the caudal PAAs and subsequent remodeling of the PAAs to form the aortic arch. Here, we identify the HECTD1 ubiquitin ligase as a novel modulator of retinoic acid signaling during this process.

DNAH6 and Its Interactions with PCD Genes in Heterotaxy and Primary Ciliary Dyskinesia.

Heterotaxy, a birth defect involving left-right patterning defects, and primary ciliary dyskinesia (PCD), a sinopulmonary disease with dyskinetic/immotile cilia in the airway are seemingly disparate diseases. However, they have an overlapping genetic etiology involving mutations in cilia genes, a reflection of the common requirement for motile cilia in left-right patterning and airway clearance. While PCD is a monogenic recessive disorder, heterotaxy has a more complex, largely non-monogenic etiology.

Characterizing the angiogenic activity of patients with single ventricle physiology and aortopulmonary collateral vessels.

Objectives: Patients with single ventricle congenital heart disease often form aortopulmonary collateral vessels via an unclear mechanism. To gain insights into the pathogenesis of aortopulmonary collateral vessels, we correlated angiogenic factor levels with in vitro activity and angiographic aortopulmonary collateral assessment and examined whether patients with single ventricle physiology have increased angiogenic factors that can stimulate endothelial cell sprouting in vitro.

Methods: In patients with single ventricle physiology (n = 27) and biventricular acyanotic control patients (n = 21), hypoxia-inducible angiogenic factor levels were measured in femoral venous and arterial plasma at cardiac catheterization.

Establishing normative nasal nitric oxide values in infants.

Introduction: Primary ciliary dyskinesia (PCD), a disease of impaired respiratory cilia motility, is often difficult to diagnose. Recent studies show low nasal nitric oxide (nNO) is closely linked to PCD, allowing the use of nNO measurement for PCD assessments. Nasal NO cutoff values for PCD are stratified by age, given nNO levels normally increase with age.

Global genetic analysis in mice unveils central role for cilia in congenital heart disease.

Congenital heart disease (CHD) is the most prevalent birth defect, affecting nearly 1% of live births; the incidence of CHD is up to tenfold higher in human fetuses. A genetic contribution is strongly suggested by the association of CHD with chromosome abnormalities and high recurrence risk. Here we report findings from a recessive forward genetic screen in fetal mice, showing that cilia and cilia-transduced cell signalling have important roles in the pathogenesis of CHD.

Airway ciliary dysfunction and sinopulmonary symptoms in patients with congenital heart disease.

Rationale: Patients with congenital heart disease with heterotaxy exhibit a high prevalence of abnormal airway ciliary motion and low nasal nitric oxide, characteristics associated with primary ciliary dyskinesia, a reflection of the role of motile cilia in airway clearance and left-right patterning.

Objectives: To assess the potential broader clinical significance of airway ciliary dysfunction in congenital heart disease, we assessed the prevalence of ciliary dysfunction versus respiratory symptoms in patients with congenital heart disease with or without heterotaxy.

Methods: Patients with a broad spectrum of congenital heart disease were recruited (n = 218), 39 with heterotaxy.

A detailed comparison of mouse and human cardiac development.

Background: Mouse mutants are used to model human congenital cardiovascular disease. Few studies exist comparing normal cardiovascular development in mice vs. humans.

Interrogating congenital heart defects with noninvasive fetal echocardiography in a mouse forward genetic screen.

Background: Congenital heart disease (CHD) has a multifactorial pathogenesis, but a genetic contribution is indicated by heritability studies. To investigate the spectrum of CHD with a genetic pathogenesis, we conducted a forward genetic screen in inbred mice using fetal echocardiography to recover mutants with CHD. Mice are ideally suited for these studies given that they have the same four-chamber cardiac anatomy that is the substrate for CHD.

Increased postoperative respiratory complications in heterotaxy congenital heart disease patients with respiratory ciliary dysfunction.

Objective(s): Congenital heart disease (CHD) and heterotaxy patients have increased postoperative and respiratory complications. We recently showed CHD-heterotaxy patients can have respiratory ciliary dysfunction (CD) similar to that associated with primary ciliary dyskinesia, including low nasal nitric oxide and abnormal ciliary motion. In this study, we investigated whether CHD-heterotaxy patients with CD may have worse postsurgical outcomes.

Microcomputed tomography provides high accuracy congenital heart disease diagnosis in neonatal and fetal mice.

Background: Mice are well suited for modeling human congenital heart disease (CHD), given their 4-chamber cardiac anatomy. However, mice with CHD invariably die prenatally/neonatally, causing CHD phenotypes to be missed. Therefore, we investigated the efficacy of noninvasive microcomputed tomography (micro-CT) to screen for CHD in stillborn/fetal mice.

High prevalence of respiratory ciliary dysfunction in congenital heart disease patients with heterotaxy.

Background: Patients with congenital heart disease (CHD) and heterotaxy show high postsurgical morbidity/mortality, with some developing respiratory complications. Although this finding is often attributed to the CHD, airway clearance and left-right patterning both require motile cilia function. Thus, airway ciliary dysfunction (CD) similar to that of primary ciliary dyskinesia (PCD) may contribute to increased respiratory complications in heterotaxy patients.

Increased postoperative and respiratory complications in patients with congenital heart disease associated with heterotaxy.

Objective: Patients with heterotaxy and complex congenital heart disease underwent cardiac surgery with high mortality and morbidity. Recent studies have revealed an association among heterotaxy, congenital heart disease, and primary ciliary dyskinesia. We undertook a retrospective review of patients undergoing cardiac surgery at Children's National Medical Center between 2004 and 2008 to explore the hypothesis that there is increased mortality and respiratory complications in heterotaxy patients.

Ventricular rotation is independent of cardiac looping: a study in mice with situs inversus totalis using speckle-tracking echocardiography.

Background: The authors conducted an ultrasound interrogation of a mutant mouse model with a Dnah5 mutation to determine whether cardiac mechanics may be affected by reversal of cardiac situs. This mutant is a bona fide model of primary ciliary dyskinesia, with surviving homozygous mice showing either situs solitus (SS) or situs inversus totalis (SI).

Methods: High-frequency ultrasound interrogations of 27 neonatal and infant Dnah5 mutant mice, 16 with SS and 11 with SI, were conducted using an ultra-high-frequency biomicroscope.

Cardiovascular assessment of fetal mice by in utero echocardiography.

To establish a developmental profile of fetal mouse cardiovascular parameters, we analyzed a large body of ultrasound measurements obtained by in utero echocardiography of C57BL/6J fetal mice from embryonic day 12.5 to 19.5 (term).

Mouse model of heterotaxy with single ventricle spectrum of cardiac anomalies.

Heterotaxy arises from a failure of the embryo to establish normal left-right asymmetry and is known to affect 3% of infants with congenital heart disease. A recessive mutation causing heterotaxy was recovered in a mouse mutagenesis screen focused on congenital heart defects. Homozygote mutants exhibit abnormal situs in the thoracic and abdominal cavities.

Heterotaxy and complex structural heart defects in a mutant mouse model of primary ciliary dyskinesia.

Primary ciliary dyskinesia (PCD) is a genetically heterogeneous disorder associated with ciliary defects and situs inversus totalis, the complete mirror image reversal of internal organ situs (positioning). A variable incidence of heterotaxy, or irregular organ situs, also has been reported in PCD patients, but it is not known whether this is elicited by the PCD-causing genetic lesion. We studied a mouse model of PCD with a recessive mutation in Dnahc5, a dynein gene commonly mutated in PCD.

Fetal mouse imaging using echocardiography: a review of current technology.

Advances in genetic research have led to the need for phenotypic analysis of small animal models. However, often these genetic alterations, especially when affecting the cardiovascular system, can result in fetal or perinatal death. Noninvasive ultrasound imaging is an ideal method for detecting and studying such congenital malformations, as it allows early recognition of abnormalities in the living fetus and the progression of disease can be followed in utero with longitudinal studies.

ENU induced mutations causing congenital cardiovascular anomalies.

We used non-invasive high frequency ultrasound to screen N-ethyl-N-nitrosourea mutagenized mouse fetuses for congenital cardiovascular anomalies. We ultrasound scanned 7546 mouse fetuses from 262 mutagenized families, and identified 124 families with cardiovascular defects. Represented were most of the major congenital cardiovascular anomalies seen clinically.

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

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

Methods: C57BL/6J fetal mice were scanned in utero using an ultrasound system with a 15-MHz linear phased-array transducer.