Specific types and subtypes of cardiac defects have been described in children with 22q11.2 deletion syndrome as well as in other genetic syndromes. The conotruncal heart defects occurring in patients with 22q11.2 deletion syndrome include tetralogy of Fallot, pulmonary atresia with ventricular septal defect, truncus arteriosus, interrupted aortic arch, isolated anomalies of the aortic arch, and ventricular septal defect. These conotruncal heart defects are frequently associated in this syndrome with additional cardiovascular anomalies of the aortic arch, pulmonary arteries, infundibular septum, and semilunar valves complicating cardiac anatomy and surgical treatment. In this review we describe the surgical anatomy, the operative treatment, and the prognostic results of the cardiac defects associated with 22q11.2 deletion syndrome. According to the current literature, in patients with tetralogy of Fallot with/without pulmonary atresia and truncus arteriosus, in spite of the complex cardiac anatomy, the presence of 22q11.2 deletion syndrome does not worsen the surgical prognosis. On the contrary in children with pulmonary atresia with ventricular septal defect and probably in those with interrupted aortic arch the association with 22q11.2 deletion syndrome is probably a risk factor for the operative treatment. The complex cardiovascular anatomy in association with depressed immunological status, pulmonary vascular reactivity, neonatal hypocalcemia, bronchomalacia and broncospasm, laryngeal web, and tendency to airway bleeding must be considered at the time of diagnosis and surgical procedure. Specific diagnostic, surgical, and perioperative protocols should be applied in order to provide appropriate treatment and to reduce surgical mortality and morbidity.

The population of neonates and children with congenital heart defects presents about a 30% prevalence of associated genetic syndrome or additional extracardiac anomalies and may show an increased risk of death or major complication at cardiac surgery. Since a well-defined pattern of combined cardiac and extracardiac anomalies may be found in relation to specific genetic defects, correct understanding of the genetic issues may help improving diagnosis, surgical approach and final outcome of these patients. Hereby we review the medical and surgical issues correlated to the genetic asset in patients with congenital heart defects and genetic syndromes, including trisomy 21, deletion 22q11, Noonan/LEOPARD, Turner, Marfan and Williams syndromes. Recognition of specific surgical risk factors can lead to the preparation of specific diagnostic and perioperative protocols in order to reduce operative mortality and morbidity.

A review concerning some embryogenetic aspects of the cardiac outflow tract is presented. Two main topics are discussed: the truncal septation and the secondary heart field. In the context of the septation of the truncus arteriosus, the development of the arterial valves is largely discussed, particularly in reference to the sinuses of Valsalva. Emphasis is also given to the fate of the external myocardial wall of the truncus arteriosus, as this primordial myocardial surface disappears later in the development. Molecular genetics data concerning Sox4 and NF-Atc transcription factors are correlated in the present review with rare forms of truncus malformations encountered in human pathology. The roles exerted by the secondary heart field and the neural crest on the development and growth of the conotruncal musculature are largely discussed. Reported experimental ablations of both secondary heart field and neural crest, showed conotruncal defects such as persistent truncus arteriosus, tetralogy of Fallot, and double-outlet right ventricle, which were considered as the result of a short outflow tract causing, ultimately, a lack of conotruncal rotation. In this regard, some morphologic correlations are carried out, in the present review, between these experimental animal models and human malformations, and it is thought that this sort of conotruncal defects cannot be explained always in terms of conotruncal hypoplasia. Finally, influence of Pitx2c, a left-right laterality signaling gene, on the modulation of the conotruncal rotation, as most recently reported, is emphasized in terms of very likely multifactorial contributions in the embryogenesis of the conotruncal region of the heart. Anat Rec Part A, 288A: 936-943, 2006

Familial recurrence of congenitally corrected transposition of the great arteries (CCTGA) is considered uncommon. Most of the previous familial studies involved a small number of patients and referred to all situs and looping anomalies including single ventricle, heterotaxia, and other cardiac defects different from CCTGA. We performed a large, consecutive clinical case series study in order to detect the recurrence of congenital heart defects in families of children with the classic form of CCTGA. From January 1997 through December 2004, 102 consecutive patients with CCTGA were evaluated in four institutions. There were 59 male (57.8%) and 43 female (42.2%). Mean age was 8.6 +/- 7.8 years. Eighty-eight patients (86.3%) had situs solitus of the atria, 14 (13.7%) situs inversus. The cardiac and extracardiac anomalies among relatives and the patterns of familial recurrence were investigated. Relatives with congenital heart defects were found in 16/102 families (15.7%). Transposition of the great arteries (TGA) was the most common recurrent defect (6/102 families). Consanguinity was identified in the parents of three probands. Six probands had an unaffected twin-sib. Recurrence risks for congenital heart defects were calculated at 5.2% (6/116) for siblings. In conclusion, CCTGA is not always sporadic in families. The pattern of inheritance, the presence of consanguinity among parents and the recurrence of situs inversus could suggest, in some families, an autosomal recessive mechanism with similarities with that occurring in some pedigrees with heterotaxia. The recurrence of TGA and CCTGA in the same family suggests a pathogenetic link between these two anatomically different malformations.

Fetal Nuchal fluid collections can manifest with two distinct presentations attributable to the same phenotypic spectrum: increased nuchal translucency (iNT) and cystic hygroma. The prenatal detection of these findings should prompt an accurate assessment through genetic counseling and testing, including karyotype, chromosomal microarray analysis (CMA) and multigene RASopathy panel. We performed a systematic review of the literature and meta-analysis, to calculate diagnostic yields of genetic testing in fetuses with iNT and cystic hygroma. We compared the results with a cohort of 96 fetuses with these isolated findings. Fetuses with isolated NT ≥ 2.5 mm showed karyotype anomalies in 22.76% of cases and CMA presented an incremental detection rate of 2.35%. Fetuses with isolated NT ≥ 3 mm presented aneuploidies in 14.36% of cases and CMA had an incremental detection rate of 3.89%. When the isolated NT measured at least 3.5 mm the diagnostic yield of karyotyping was 34.35%, the incremental CMA detection rate was 4.1%, the incremental diagnostic rate of the RASopathy panel was 1.44% and it was 2.44% for exome sequencing. Interestingly, CMA presents a considerable diagnostic yield in the group of fetuses with NT ≥ 3.5 mm. Similarly, exome sequencing appears to show promising results and could be considered after a negative CMA result.

Congenital heart defects (CHDs) are the most common birth defects in humans and over the last 20 years significant progress has been made in the understanding of the molecular and genetic determinants of an increasing number of CHDs. Fundamental to this progress has been the contribution of five fields of research: the epidemiological results of the Baltimore-Washington Infant Study (BWIS); the pathogenetic classification introduced by Clark; the Human Genome Project; genotype-phenotype correlation and familial recurrence studies; and transgenic animals. The recently advanced cytogenetic techniques can now detect subtle rearrangements in chromosomes, which may be overlooked by standard methods and, more recently, molecular instruments such as linkage analysis and positional cloning are being used to identify genes causing Mendelian monogenic syndromes with CHDs, such as Holt-Oram, Ellis-van Creveld and Noonan/LEOPARD syndromes. Finally, useful information is yet available with regard to genes causing isolated CHDs in individuals who do not have a genetic syndrome (an example is the mutation of NKX2.5 and GATA4 genes causing atrial septal defect). The future perspectives for the genetics of CHDs will involve three fields of interest: diagnosis; therapy; and prognosis.

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Transient episodes of fetal bradycardia (heart rate less than 110 bpm) are usually benign and typically result from increased vagal stimulation in the fetus. Causes of sustained fetal bradycardia include sinus bradycardia, blocked atrial bigeminy/trigeminy, high-degree atrioventricular block, and long QT syndrome. We present the case of a 34-year-old Caucasian patient referred to our department for “blocked atrial bigeminy with pseudobradycardia” detected elsewhere at 33 weeks of gestation. A fetal echocardiography showed during all the examination a blocked atrial trigeminy with a mean fetal heart rate of 100 bpm. After birth three subsequent ECGs until day 3 showed no evidence of atrial extrasystoles, confirming the well-known frequent regression of this kind of fetal benign arrhythmia, but on day 11 recurrence of supraventricular trigeminy and development of episodes of paroxystic supraventricular tachycardia were observed. On the basis of this observation, we recommend that fetuses with complex atrial ectopic beats should be closely monitored before and after birth for evidence of new arrhythmias.