Heparan sulfate expression in the neural crest is essential for mouse cardiogenesis

Impaired heparan sulfate (HS) synthesis in vertebrate development causes complex malformations due to the functional disruption of multiple HS-binding growth factors and morphogens. Here, we report developmental heart defects in mice bearing a targeted disruption of the HS-generating enzyme GlcNAc N-deacetylase/GlcN N-sulfotransferase 1 (NDST1), including ventricular septal defects (VSD), persistent truncus arteriosus (PTA), double outlet right ventricle (DORV), and retroesophageal right subclavian artery (RERSC). These defects closely resemble cardiac anomalies observed in mice made deficient in the cardiogenic regulator fibroblast growth factor 8 (FGF8). Consistent with this, we show that HS-dependent FGF8/FGF-receptor2C assembly and FGF8-dependent ERK-phosphorylation are strongly reduced in NDST1^−/− embryonic cells and tissues. Moreover, WNT1-Cre/LoxP-mediated conditional targeting of NDST function in neural crest cells (NCCs) revealed that their impaired HS-dependent development contributes strongly to the observed cardiac defects. These findings raise the possibility that defects in HS biosynthesis may contribute to congenital heart defects in humans that represent the most common type of birth defect.     

Myocardial deletion of Smad4 using a novel α skeletal muscle actin Cre recombinase transgenic mouse causes misalignment of the cardiac outflow tract

SMAD4 acts as the converging point for TGFβ and BMP signaling in heart development. Here, we investigated the role of SMAD4 in heart development using a novel α skeletal muscle actin Cre recombinase (MuCre) transgenic mouse strain. Lineage tracing using MuCre/ROSA26^LacZ reporter mice indicated strong Cre-recombinase expression in developing and adult heart and skeletal muscles. In heart development, significant MuCre expression was noted at E11.5 in the atrial, ventricular, outflow tract and atrioventricular canal myocardium, but not in the endocardial cushions. MuCre-driven conditional deletion of Smad4 in mice caused double outlet right ventricle (DORV), ventricular septal defect (VSD), impaired trabeculation and thinning of ventricular myocardium, and mid-gestational embryonic lethality. In conclusion, MuCre mice effectively delete genes in both heart and skeletal muscles, thus enabling the discovery that myocardial Smad4 deletion causes misalignment of the outflow tract and DORV.     

Cardiovascular anomalies produced by nimustine hydrochloride in the rat fetus

The cardiovascular teratogenicity of nimustine hydrochloride (ACNU) was studied in rat fetuses. This drug is a nitrosourea derivative anticancer agent and produces alkylation of DNA. Pregnant Donryu rats were treated with single doses of 10, 11 or 13 mg/kg of the teratogen at various stages during gestation. Examination of the hearts was performed by microdissection after sacrificing the animals on the 20th day of gestation. The highest frequency of cardiovascular anomalies was found in the groups treated on the 8th day of gestation, but there was no difference in the rates induced by the three dosages of ACNU administered. The most common cardiovascular anomalies observed were ventricular septal defect (76.8%) and double outlet right ventricle (10.3%). A considerable number of affected fetuses (37/263) showed complex cardiac anomalies with atrioventricular (AV) malalignment and other AV valve anomalies. These anomalies include: double inlet left ventricle, straddling AV valve, atresia or stenosis of the AV valve, and dysplastic AV valve. ACNU appears to be a useful teratogenic agent for inducing complexes of cardiac anomalies which include AV malalignment.     

Evaluation of a ventricular septal defect in an orangutan: a case report

A 15-year-old male Sumatran orangutan (Pongo pymaeus abeli) with a history of an interventricular septal defect was evaluated with cardiac catheterization and two-dimensional echocardiography. Results demonstrated that by Homo sapiens standards the right heart pressures were normal. The oxygen saturations were consistent with a small ventricular septal defect. Echocardiography demonstrated a slight enlargement of the right ventricle.     

改良Nikaidoh手术治疗合并肺动脉瓣狭窄的右室双出口

目的：总结改良Nikaidoh手术治疗右心室双出口（DORV）患者的临床经验,以提高手术疗效。方法：2例先天性心脏病右心室双出口伴肺动脉瓣狭窄行改良Nikaidoh手术,游离主动脉根部及冠状动脉,重建左心室流出道,以带单瓣牛心包片补片重建肺动脉及右心室流出道。结果：术后患者紫绀消失,复查心脏彩超仅有轻度肺动脉瓣关闭不全,未发现左、右心室流出道梗阻,康复出院。结论：采用改良Nikaidoh手术治疗伴肺动脉瓣狭窄的右室双出口,术后可获得良好的血流动力学效果,早期临床结果满意。     

改良Nikaidoh 手术治疗合并肺动脉瓣狭窄的右室双出口

目的:总结改良Nikaidoh手术治疗右心室双出口(DORV)患者的临床经验,以提高手术疗效。方法:2例先天性心脏病右心室双出口伴肺动脉瓣狭窄行改良Nikaidoh手术,游离主动脉根部及冠状动脉,重建左心室流出道,以带单瓣牛心包片补片重建肺动脉及右心室流出道。结果:术后患者紫绀消失,复查心脏彩超仅有轻度肺动脉瓣关闭不全,未发现左、右心室流出道梗阻,康复出院。结论:采用改良Nikaidoh手术治疗伴肺动脉瓣狭窄的右室双出口,术后可获得良好的血流动力学效果,早期临床结果满意。     

Comparative assessment of hemodynamic parameters in ventricular septal defect, obtained by Doppler echocardiography and catheterization of cardiac cavities

The study was undertaken to assess hemodynamic parameters by Doppler echocardiography in patients with ventricular septal defect (VSD) and pulmonary hypertension. Seventy-two patients aged 5 months to 9 years (mean 2.5 years) who had isolated VSD were examined. The authors conclude that it is possible and necessary to assess hemodynamics in the lesser circulation by using Doppler echocardiography. The method permits monitoring the time course of changes in the right heart, which makes it possible to follow the natural history of disease without applying invasive studies.     

Heritable ventricular septal defect in Yucatan miniature swine

A heritable ventricular septal defect (VSD) was found in a strain of Yucatan miniature swine. The defect was determined to be a high membranous VSD analogous in anatomic location to the most common from of VSD in humans. Eighteen animals were studied clinically, hemodynamically and at necropsy to characterize the defect. Three mature animals developed pulmonary hypertension. Three animals were found to have a patent foramen ovale (PFO) in addition to the VSD. VSD is heritable probably due to polygenic factors. VSD in Yucatan miniature swine may be a suitable model of the human disease syndrome.     

Ethyl alcohol-induced cardiovascular malformations in the chick embryo

Chick embryos incubated for 72-80 hours were exposed to various volumes (0.20-0.40 m1/egg) of 50% ethyl alcohol. Examination of embryos at day 14 of incubation showed that higher doses of ethanol decreased the survival rate of embryos compared with control embryos. Three major categories of cardiovascular malformations were observed in this study: intracardiac anomalies characterized primarily by isolated ventricular septal defect, ventricular septal defect with overriding aorta, double outlet right ventricle or common aorticopulmonary trunk; aortic arch anomalies; and subclavian artery anomalies. Frequencies of embryos with intracardiac anomalies were equal to or greater than 64.8% in the six groups exposed to ethanol. Administration of ethanol also induced high frequencies of embryos with subclavian artery anomalies (11.2-89.1%). Absence or hypoplasia of the right and/or left secondary subclavian artery was commonly associated with persistence of the corresponding primary subclavian artery. Bilateral absence and/or hypoplasia of the secondary subclavian arteries was more common than unilateral anomalies, whereas absence of the left secondary subclavian artery was more commonly observed than an absent right secondary subclavian artery. No embryos in the two control groups combined (n = 94) demonstrated aortic arch or subclavian artery anomalies.     

22q11.2 deletion mosaicism in patients with conotruncal heart defects

BACKGROUND: Some patients with conotruncal heart defects (CTDs) have a chromosome 22q11.2 deletion, but we do not know whether patients with CTDs who are missing the peripheral blood-cell chromosome 22q11.2 deletion are also missing the 22q11.2 deletion in myocardial cells, and whether patients with the 22q11.2 deletion can show a different 22q11.2 deletion in peripheral blood cells and myocardial cells due to a postzygotic mutation during the embryonic period. METHODS: A total of 32 Chinese pediatric nonsyndromic CTD patients (21 with tetralogy of fallot [TOF], 9 with double outlet right ventricle [DORV], 1 with pulmonary artery atresia with ventricular septal defect [PAA/VSD], and 1 with congenitally corrected transposition of the great arteries [CCTGA]), 12 females and 20 males ranging in age from 5 months to 7 years, were included in our study. We used fluorescence in situ hybridization (FISH) to find the chromosome 22q11.2 deletion in peripheral blood cells and compared genotypes of 15 short tandem repeat (STR) markers within 22q11.2 between peripheral blood cells and myocardial cells to search for genetic mosaicism of the chromosome 22q11.2 deletion. RESULTS: Three patients, 2 with TOF and 1 with DORV, were determined to have the peripheral blood cell chromosome 22q11.2 deletion. There was no STR genotypic difference observed between peripheral blood cells and myocardial cells in patients with or without the chromosome 22q11.2 deletion. CONCLUSIONS: Genetic mosaicism may not play a major role in the etiology of isolated CTDs.     

BMP type II receptor regulates positioning of outflow tract and remodeling of atrioventricular cushion during cardiogenesis

Signaling of bone morphogenetic protein (BMP) via type I and type II receptors is involved in multiple processes contributing to cardiogenesis. To investigate the role of the BMP type II receptor (BMPRII) in heart development, the BMPRII gene was deleted throughout the embryo during gastrulation using a Mox2-Cre transgene. BMPRII^flox/−;Mox2-Cre mice exhibited cardiac defects including double-outlet right ventricle, ventricular septal defect (VSD), atrioventricular (AV) cushion defects, and thickened valve leaflets. To characterize the tissue-specific functions of BMPRII in cardiogenesis, a series of Cre transgenes (αMHC-, Tie2-, Wnt1-, and SM22α-Cre) was employed. Interestingly, myocardial development was normal when the BMPRII gene was deleted in myocardial cells using Mox2-Cre, αMHC-Cre, or SM22α-Cre transgenes, suggesting that signaling by other BMP type II receptors may compensate for the absence of BMPRII in the myocardial cells. AV cushion defects including atrial septal defect, membranous VSD, and thickened valve leaflets were found in BMPRII^flox/−;Tie2-Cre mice. Abnormal positioning of the aorta was observed in BMPRII^flox/−;Wnt1-Cre and BMPRII^flox/−;SM22α-Cre mice. Taken together, these results demonstrate that endocardial BMPRII expression is required for septal formation and valvulogenesis. Moreover, mesenchymal BMPRII expression in the outflow tract cushion is required for proper positioning of the aorta.     

Parathenar palmar pattern: a dermatoglyphic sign of possible clinical significance.

The frequency of a 'double proximal axial triradius' (DPAT), which results in a palmar parathenar pattern, has been reported to be increased in those with ventricular septal defect (BSD). We scored the presence of this pattern in 313 patients with congenital heart defects (including 86 with isolated VSD), 176 with cystic fibrosis (CF) or relatives of those with CF, and 333 with no known clinical disease who were unrelated to individuals with CF. The frequencies in these three groups were 1.6, 2.3, and 0.6%, respectively. None of those with isolated VSD defect had a DPAT. All five individuals in the heart defect group with a DPAT had pulmonic stenosis. Of the total of eleven individuals in our series with DPAT patterns, eight were affected only on the right hand. The frequency of DPAT in individuals with no known disease in this series was 4/406=1.0%, more than double the frequency in a control series, published previously by DAVID, 5/1,129=0.4%. If the 73 relatives of those with CF are excluded from our own 'control' group, the frequency of DPAT in this group is then 0.6%, closer to the results in DAVID's control series.     

Identification of differentially expressed genes in human heart with ventricular septal defect using suppression subtractive hybridization

Ventricular septal defect (VSD) accounts for the largest number of birth congenital heart defects in human, but the genetic programs that control ventricular septation are poorly understood. To identify differentially expressed genes between ventricular septal defect and normal ventricular septum myocardium, we have undertaken suppression subtractive hybridization (SSH) and generated reciprocal cDNA collections of representative mRNAs specific to human heart with ventricular septal defect versus normal control. Following SSH, 1378 clones were sequenced and found to derive from 551 different genes. These predominately expressed genes included genes involved in energy metabolism, cell cycle and growth, cytoskeleton and cell adhesion, LIM protein, zinc finger protein, and development. It is anticipated that further study of genes identified will provide insights into their specific roles in the etiology of VSD, even in cardiac development, aging, and disease.     

TOTAL PHYSIOLOGIC CORRECTION OF TRICUSPID ATRESIA WITH ATRIAL SEPTAL DEFECT-VENTRICULAR SEPTAL DEFECT CLOSURE AND A RIGHT ATRIUM-RIGHT VENTRICLE NON-VALVED CONDUIT: CASE REPORT

An 18-year-old woman underwent total physiologic correction of tricuspid atresia (atrial septal defect-ventricular septal defect closure and a right atrium-right ventricle non-valved conduit). Postoperative studies documented excellent hemodynamic results. The patient remains asymptomatic 6 months after surgery.     

Antemortem diagnosis of a ventricular septal defect in a California sea lion Zalophus californianus

A yearling California sea lion Zalophus californianus stranded in poor body condition, and on physical examination a heart murmur was audible bilaterally. The sea lion was diagnosed with a left-to-right shunting membranous ventricular septal defect (VSD) using B-mode, color-flow Doppler and continuous-wave Doppler echocardiography. A left-to-right intracardiac shunting lesion was confirmed during cardiac angiographic computed tomography. The VSD defect was verified during the necropsy examination. On histologic examination concurrent mild multifocal myocarditis with focal mild ventricular free-wall myocardial necrosis were identified. A specific cause for the myocarditis and myocardial necrosis was not found, and association with the VSD and resultant myocardial dysfunction was presumed. This is the first report of the antemortem diagnosis of a VSD in a marine mammal and the first report of a VSD in a California sea lion.     

Cardiovascular malformations induced by bromodeoxyuridine in the chick embryo

For the study of morphogenesis and early embryonic development, 5-bromodeoxyuridine (BUdR), a halogenated analogue of thymidine, is incorporated into replicating DNA and serves as a valuable tool. To study the teratogenicity of BUdR on the developing chick cardiovascular system, we topically administered graded doses of BUdR (32.6-325.6 nmol) in ovo during Hamburger-Hamilton stages 15 to 16. We also administered to a parallel group of embryos corresponding nanomole doses of thymidine during identical stages of development. In the thymidine-treated group, survival rates and cardiovascular anomaly rates did not differ statistically from those in the chick Ringer's control group. Both survival rates and cardiovascular anomaly rates in the BudR-treated group were dose-responsive. Among 78 embryos with cardiovascular anomalies induced by BUdR, vascular malformations were found in 96%. These anomalies included interruption of the right fourth aortic arch, absence or hypoplasia of the right and/or left sixth aortic arch, and persistence of the left fourth aortic arch. Interruption of the right fourth aortic arch was always associated with intracardiac anomalies. Intracardiac anomalies were found in 54% of the embryos; these included ventricular septal defect, double outlet right ventricle, and persistent truncus arteriosus. Subclavian artery malformations were noted in 95% of the embryos. Possible mechanisms for BUdR-induced malformations in the cardiovascular system of the chick are discussed.     

Targeted deletion of Hand2 in cardiac neural crest-derived cells influences cardiac gene expression and outflow tract development

The basic helix-loop-helix DNA binding protein Hand2 has critical functions in cardiac development both in neural crest-derived and mesoderm-derived structures. Targeted deletion of Hand2 in the neural crest has allowed us to genetically dissect Hand2-dependent defects specifically in outflow tract and cardiac cushion independent of Hand2 functions in mesoderm-derived structures. Targeted deletion of Hand2 in the neural crest results in misalignment of the aortic arch arteries and outflow tract, contributing to development of double outlet right ventricle (DORV) and ventricular septal defects (VSD). These neural crest-derived developmental anomalies are associated with altered expression of Hand2-target genes we have identified by gene profiling. A number of Hand2 direct target genes have been identified using ChIP and ChIP-on-chip analyses. We have identified and validated a number of genes related to cell migration, proliferation/cell cycle and intracellular signaling whose expression is affected by Hand2 deletion in the neural crest and which are associated with development of VSD and DORV. Our data suggest that Hand2 is a multifunctional DNA binding protein affecting expression of target genes associated with a number of functional interactions in neural crest-derived cells required for proper patterning of the outflow tract, generation of the appropriate number of neural crest-derived cells for elongation of the conotruncus and cardiac cushion organization. Our genetic model has made it possible to investigate the molecular genetics of neural crest contributions to outflow tract morphogenesis and cell differentiation.     

USE OF AN EXTRACARDIAC CONDUIT IN THE REPAIR OF l-TRANSPOSITION WITH l-LOOPING ASSOCIATED WITH SEVERE SUBVALVULAR PULMONIC STENOSIS AND A VENTRICULAR SEPTAL DEFECT

Total correction was performed in a child with l-transposition of the great arteries, severe subpulmonic stenosis, and a ventricular septal defect. The subpulmonic obstruction was bypassed with an extra-cardiac valved conduit. This alternate method of relieving ventricular outflow obstruction should be considered when conventional techniques cannot be employed because of complex intracardiac anatomy. Proper placement of the pulmonary ventriculotomy is important in order to avoid injury to coronary arteries on the upper and lower ventricular wall and to papillary muscles in the mid-portion of the ventricle.     

Right ventricular collagen and fibronectin levels in patients with pulmonary atresia and ventricular septal defect

Pulmonary atresia (PA) with ventricular septal defect (VSD) is an extreme form of tetralogy of Fallot with characteristic right ventricular hypertrophy. To reduce the right ventricular overload, these children have to undergo staged corrective surgery to restore physiological pulmonary perfusion. We studied the degree of fibrosis by analysing the myocardial expression pattern (at mRNA and protein level) of the extracellular matrix proteins, collagen and fibronectin in biopsies taken at corrective surgery from 14 patients affected by PA,VSD. Expression analysis by RT-PCR showed significantly higher levels for collagen III (p = 0.03), whereas collagen I (p = 0.31) and fibronectin (p = 0.47) mRNA levels remained unaltered in PA, VSD patients as compared to age matched controls. Video image analysis of immunohistochemical staining showed unchanged interstitial levels for total collagen (p = 0.17) as well as for fibronectin (p = 0.13) in the patients with PA, VSD. However, peri-vascular staining for collagen (p < 0.01) and fibronectin (p = 0.02) represented as the peri-vascular stained area corrected for the vessel lumen area showed significantly decreased levels in the PA,VSD group as compared to controls. Our results indicate that the patients with PA, VSD have inadequate extracellular matrix support for their coronary blood vessels and perhaps due to an altered biosynthesis of collagen and fibronectin network.