Deletion within chromosome 22 is common in patients with absent pulmonary valve syndrome

Nakata index above 1500 mm2/m2 predicts death in absent pulmonary valve syndrome

OBJECTIVES

Absent pulmonary valve syndrome is a rare congenital heart disease with severe airway compression due to dilatation of the pulmonary arteries (PAs). We investigated risk factors for death and prolonged mechanical ventilation (>7 days) and a threshold PA size for these outcomes.

METHODS

This retrospective 2-centre cohort study included 68 patients with complete repair between January 1996 and December 2015.

RESULTS

Median age at repair was 3.9 months (1.3-8.7 months), and median weight was 5 kg (4-7 kg). The mortality rate before hospital discharge was 12%, and the mortality rate at last follow-up was 19%. In multivariable analysis, risk factors for death were higher Nakata index [hazard ratio (HR) 1.001, 95% confidence interval (CI) 1.001-1.002; P < 0.001] and lower SpO2 (HR 1.06, 95% CI 1.02-1.09; P = 0.002). The accuracy of the Nakata index to predict death was excellent (area under the curve at 6 months: 0.92; P = 0.010). A Nakata index above 1500 mm2/m2 predicted mortality at 6 months with a sensitivity of 98% and a specificity of 82%. Twenty-five patients (37%) had prolonged mechanical ventilation. The only multivariable risk factor for prolonged ventilation was lower weight at repair (odds ratio 2.9, 95% CI 1.3-6.7; P = 0.008). Neither PA plasty nor the LeCompte manoeuvre had a protective effect on mortality or prolonged ventilation. A Nakata index above 1500 mm2/m2 remained a risk factor for mortality (P = 0.022) in patients who had a PA plasty or the LeCompte manoeuvre.

CONCLUSIONS

In patients with absent pulmonary valve syndrome, the Nakata index predicts mortality with a cut-off of 1500 mm2/m2. Lower weight at repair is the only multivariable risk factor for prolonged ventilation. Neither PA plasty nor the LeCompte manoeuvre had a protective effect on these outcomes.

Congenital heart diseases and cardiovascular abnormalities in 22q11.2 deletion syndrome: From well-established knowledge to new frontiers

Congenital heart diseases (CHDs) and cardiovascular abnormalities are one of the pillars of clinical diagnosis of 22q11.2 deletion syndrome (22q11.2DS) and still represent the main cause of mortality in the affected children. In the past 30 years, much progress has been made in describing the anatomical patterns of CHD, in improving their diagnosis, medical treatment, and surgical procedures for these conditions, as well as in understanding the underlying genetic and developmental mechanisms. However, further studies are still needed to better determine the true prevalence of CHDs in 22q11.2DS, including data from prenatal studies and on the adult population, to further clarify the genetic mechanisms behind the high variability of phenotypic expression of 22q11.2DS, and to fully understand the mechanism responsible for the increased postoperative morbidity and for the premature death of these patients. Moreover, the increased life expectancy of persons with 22q11.2DS allowed the expansion of the adult population that poses new challenges for clinicians such as acquired cardiovascular problems and complexity related to multisystemic comorbidity. In this review, we provide a comprehensive review of the existing literature about 22q11.2DS in order to summarize the knowledge gained in the past years of clinical experience and research, as well as to identify the remaining gaps in comprehension of this syndrome and the possible future research directions.

Right-sided aortic arch and aberrant left subclavian artery with or without a left nonrecurrent inferior laryngeal nerve

Background

In thyroid surgery, preserving the recurrent laryngeal nerve (RLN) is crucial for preventing postoperative phonatory dysfunction. Right nonrecurrent laryngeal nerves (NRLNs) are not particularly rare, and they are vulnerable to injury during surgery. This anomaly is associated with a right aberrant subclavian artery. Thus, a right‐sided aortic arch with an aberrant left subclavian artery (LSA) suggests a possible left NRLN.

Methods

We report the cases of 4 patients with right‐sided aortic arch and aberrant LSA. Preoperative imaging studies revealed those anomalies, but no signs of situs inversus. During the surgeries, only 1 of the 4 cases had a left NRLN. We retrospectively evaluated the patients' imaging studies.

Results

An aortic diverticulum was found at the point at which the aberrant LSA originated in the 3 patients with left‐RLNs, but not in the patient with the left‐NRLN.

Conclusion

In right‐sided aortic arch + aberrant LSA cases, the absence of an aortic diverticulum suggests a left NRLN. © 2016 Wiley Periodicals, Inc. Head Neck 38: First–E2511, 2016

Prenatal diagnosis of 22q11.2 deletion syndrome in twin pregnancy: a case report

Chromosome 22q11.2 deletion syndrome is a common genetic disorder, also known as DiGeorge syndrome. It occurs in approximately 1:4,000 births, and the incidence is increasing due to affected parents bearing their own affected children. We report the prenatal diagnosis of 22q11.2 deletion syndrome by fluorescence in situ hybridization in twin fetuses having tetralogy of Fallot with absent pulmonary valve.

Variation in prevalence of chromosome 22q11 deletion in subtypes of conotruncal defect in 254 children

AIM

To determine the frequency of chromosomal aberrations particularly 22q11 deletion in Indian children ≤2 years with different types of conotruncal malformations and their association with abnormal aortic arch. Additionally, extracardiac features were also studied.

METHODS

Conventional cytogenetic and fluorescence in situ hybridization analyses were performed in 254 patients with conotruncal defects. Multivariable logistic regression analysis was performed to ascertain extracardiac features helpful in identifying high-risk patients with deletion.

RESULTS

Chromosomal abnormalities were identified in 52 (21%) children, of whom 49 (94%) showed 22q11 deletion and 3 (6%) had abnormalities of chromosome 6, 2 and X. None of the 11/254 children with tetralogy of Fallot with absent pulmonary valve showed deletion. The association of 22q11 deletion with right sidedness of the aortic arch varied with the type of conotruncal defect. The eight extracardiac features in combination showed 93.5% agreement with the presence of deletion.

CONCLUSION

The extracardiac features along with specific type of conotruncal defect and associated cardiovascular anomaly should alert the clinician for 22q11 deletion testing. However, if deletion analysis is not possible, specific extracardiac features (six dysmorphic facial features, thin long fingers and hypocalcemia) can help to identify an increased risk of 22q11 deletion in patients with conotruncal defect.

Cardiovascular anomalies associated with chromosome 22q11.2 deletion syndrome

Cardiovascular anomalies are present in 80% of neonates with 22q11.2 deletion syndrome. Three genes in chromosome 22q11.2 (TBX1, CRKL, and ERK2) have been identified whose haploinsufficiency causes dysfunction of the neural crest cell and anterior heart field and anomalies of 22q11.2 deletion syndrome. The most common diseases are conotruncal anomalies, which include tetralogy of Fallot (TF), TF with pulmonary atresia, truncus arteriosus, and interrupted aortic arch. A high prevalence of the deletion is noted in patients with TF with absent pulmonary valve, TF associated with pulmonary atresia and major aortopulmonary collateral arteries, truncus arteriosus, and type B interruption of aortic arch. Right aortic arch, aberrant subclavian artery, cervical origin of the subclavian artery, crossing pulmonary arteries, and major aortopulmonary collateral arteries are frequently associated with cardiovascular anomalies associated with 22q11.2 deletion syndrome. Virtually every type of congenital heart defect has been described early in the context of a 22q11.2 deletion. In conclusion, conotruncal anomaly associated with aortic arch and ductus arteriosus anomalies should increase the suspicion of 22q11.2 deletion.

Absent pulmonary valve, intact interventricular septum, rudimentary aortic non-coronary cusp and ascending aortic aneurysm in a single patient

Absent pulmonary valve (APV) is a relatively rare congenital heart disease, and is mostly associated with tetralogy of Fallot phenotype or ventricular septal defect. APV with intact interventricular septum (IVS) is even less common with case reports or very small series in the literature. Congenital aortic regurgitation with a rudimentary non-coronary cusp is also by itself a rare congenital anomaly and to our knowledge this is the first report of the combination of APV, intact IVS, abnormal aortic valve and ascending aortic aneurysm. The clinical course, possible etiologies and management are discussed.

Chromosomal abnormalities among children born with conotruncal cardiac defects

BACKGROUND

Conotruncal heart defects compose 25% to 30% of nonsyndromic congenital heart defects. This study describes the frequency of chromosome abnormalities and microdeletion of 22q11 associated among infants and fetuses delivered with conotruncal heart malformations.

METHODS

From a population base of 974,579 infants/fetuses delivered, 622 California infants/fetuses were ascertained with a defect of aortopulmonary septation. Infants whose primary cardiac defect was tetralogy of Fallot (n = 296) or d-transposition of the great arteries (n = 189) were screened for microdeletion of 22q11.

RESULTS

Of the infants who had routine karyotypes, 5% had chromosomal abnormalities, including four with extra sex chromosomes. Thirty infants had chromosome 22q11 microdeletions, providing a cause for 10% of infants whose primary defect was tetralogy of Fallot. Right aortic arch, abnormal branching patterns of the major arteries arising from the thoracic aorta, and pulmonary artery abnormalities were observed more frequently among infants with tetralogy of Fallot caused by 22q11 microdeletion.

CONCLUSIONS

We found an unusual number of infants with an extra sex chromosome and a conotruncal defect. Infants with tetralogy of Fallot owing to 22q11 microdeletion showed more associated vascular anomalies than infants with tetralogy without a 22q11 microdeletion. Although these associated vascular anomalies provide clues as to which infants with tetralogy of Fallot are more likely to carry the microdeletion, the overall risk of 10% among infants with tetralogy of Fallot warrants chromosome analysis and fluorescent in situ hybridization (FISH) testing routinely, which may be supplanted by genome-wide copy number testing as it becomes more widely utilized.

Prenatal diagnosis and postnatal outcome in patients with absent pulmonary valve syndrome not associated with tetralogy of Fallot: report of one case and review of the literature

Echocardiographic diagnosis of absent pulmonary valve syndrome and muscular ventricular septal defect was made in a fetus of gestational age 25 weeks referred for marked dilation of the right ventricle at obstetric ultrasound examination. Delivery was planned in a tertiary-level center. The neonate became severely symptomatic for respiratory distress and heart failure during the second day of life. His clinical condition dramatically improved after surgical closure of a large ductus arteriosus. The child is still asymptomatic 30 months later. In the minority of cases with absent pulmonary valve not associated with tetralogy of Fallot, irrespective of the presence of muscular ventricular septal defect, early closure of the ductus may be crucial to improve hemodynamic conditions and postpone surgical correction.

Cardiac defects and results of cardiac surgery in 22q11.2 deletion syndrome

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.

Peri-operative management of paediatric patients undergoing cardiac surgery--focus on respiratory aspects of care

Children requiring cardiac surgery present particular challenges in peri-operative respiratory management. The wide variety of conditions and operations and their varied impact on respiratory function makes dialogue with related medical staff essential. In most circumstances, cardiac performance is the main determinant of respiratory outcomes. Changing cardiologic and surgical approaches have combined to diminish the severity and frequency of pulmonary hypertensive issues and new treatment modalities are simplifying the intensive care approach. Patients with Down's syndrome and 22q11 deletion syndrome present particular issues related to anatomy, physiology and respiratory function. Certain conditions, including tetralogy of Fallot and cavopulmonary connections, present unique circumstances where respiratory management, sometimes including extubation, may assist in optimisation of cardiac performance. These and other conditions highlight the complexities of cardiopulmonary interactions. Cardiac performance remains the principal determinant of outcome after paediatric cardiac surgery and has the biggest impact on respiratory function.

Genetic basis for congenital heart defects: current knowledge: a scientific statement from the American Heart Association Congenital Cardiac Defects Committee, Council on Cardiovascular Disease in the Young: endorsed by the American Academy of Pediatrics

The intent of this review is to provide the clinician with a summary of what is currently known about the contribution of genetics to the origin of congenital heart disease. Techniques are discussed to evaluate children with heart disease for genetic alterations. Many of these techniques are now available on a clinical basis. Information on the genetic and clinical evaluation of children with cardiac disease is presented, and several tables have been constructed to aid the clinician in the assessment of children with different types of heart disease. Genetic algorithms for cardiac defects have been constructed and are available in an appendix. It is anticipated that this summary will update a wide range of medical personnel, including pediatric cardiologists and pediatricians, adult cardiologists, internists, obstetricians, nurses, and thoracic surgeons, about the genetic aspects of congenital heart disease and will encourage an interdisciplinary approach to the child and adult with congenital heart disease.

Genetics of congenital heart diseases in syndromic and non-syndromic patients: new advances and clinical implications

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.

Correction of Tetralogy of Fallot with Absent Pulmonary Valve Syndrome in a Young Infant Using a Bicuspid Equine Pericardial Tube

Absent pulmonary valve syndrome (APVS) is an uncommon variant of tetralogy of Fallot (TOF), which manifests morphologically as vestigial pulmonary valve cusps at the right ventricle-pulmonary trunk junction. The aneurysmally dilated pulmonary arteries may compress the tracheobronchial tree and cause severe respiratory distress in the neonatal or infant stage. Early surgical correction in these patients is necessary despite the high operative mortality rate. A 1-day-old male neonate suffered from progressive shortness of breath after birth. Echocardiography confirmed the diagnosis of TOF with APVS. The marked dilatation of pulmonary arteries resulted in airway compression in addition to heart failure. Total surgical correction was performed at 40 days of age, using a homemade bicuspid equine pericardial tube for right ventricular outflow reconstruction. The short-term follow-up echocardiogram demonstrated good motility of the pericardial leaflet. However, patients receiving this type of valved conduit require meticulous long-term follow-up.

Prenatal diagnosis of membranous ventricular septal aneurysms and their association with absence of atrioventricular valve 'offsetting'

Congenital aneurysm of the membranous portion of the ventricular septum in association with absence of atrioventricular valve 'offsetting' was diagnosed in two fetuses at 29 and 34 weeks. In the first case the fetus had a normal karyotype and no other structural heart defects, whereas in the second case there was a partial deletion of the long arm of chromosome 5 and an absent pulmonary valve syndrome. The association of absence of 'offsetting' with aneurysms of the membranous ventricular septum may represent spontaneous closure of ventricular septal defects initially extended to the inlet.

The Jing-Mai connections of the heart

BACKGROUND

The Jing-Mai (variously translated as the Channel, Vessel or Meridians), as described by traditional Chinese medicine, probably exists and has represented the connections between various parts of human body during embryonic development. According to the Chinese theories, there are 14 major Jing-Mai within the human body, of which four are directly connected with the Heart.

METHODS

The described paths of the four Jing-Mai were compared with features of congenital syndromes involving particular types of congenital heart defects.

RESULTS

Specific correlation seem to exist between such four Jing-Mai and known developmental mechanisms underlying various congenital heart defects: the Kidney Jing-Mai-ectomesenchymal tissue migration abnormalities; the Spleen Jing-Mai-situs and looping defects; the Heart Jing-Mai-abnormal cell death; the Small Intestine Jing-Mai (and the Heart Jing-Mai)-extracellular matrix anomalies.

CONCLUSIONS

The Chinese theories seem to provide some intriguing insights into the pathogeneses of congenital heart defects. The Jing-Mai seems to distinguish from, but nevertheless have a close relationship with the blood vessels. Utilization of the Jing-Mai will probably enable a better understanding and development of new treatments for cardiovascular diseases.

Prenatal diagnosis by echocardiogram and outcome of absent pulmonary valve syndrome

We reported echocardiographic findings and outcomes of fetuses with absent pulmonary valve syndrome diagnosed during fetal life. Cases were identified from a prospectively acquired computerized database of 18,308 pregnancies referred to a fetal cardiology center between January 1988 and July 2000. Twenty fetuses were identified with a median gestation of 23 weeks (range 18 to 36) at presentation. In 18 cases (90%), there was an associated ventricular septal defect. Eighteen cases (90%) had branch pulmonary artery diameters above the normal range. In four cases (20%), an arterial duct was present. A chromosome 22q11 deletion was identified in 2 of 9 cases (22%) in which this deletion was sought. There were 6 terminations of pregnancy (30%), 3 intrauterine deaths (15%), 5 neonatal deaths (25%), 3 infant deaths (15%), and 3 patients who did not die (15%). Ten of the 11 "liveborn" infants required early ventilation. The outcome of absent pulmonary valve syndrome diagnosed prenatally appears poor. The high morbidity and mortality is due to both cardiac disease and associated bronchomalacia.

Assessment of the thymus at echocardiography in fetuses at risk for 22q11.2 deletion

OBJECTIVES

An absent or hypoplastic thymus is common in patients with 22q11.2 deletion (del22q11.2). We sought to determine whether fetal echocardiography could identify absence of the thymus as a diagnostic tool in pregnancies at risk for fetal del22q11.2.

METHODS

We evaluated the fetal thymus in 16 consecutive pregnancies at risk for fetal del22q11. Fourteen of the fetuses had a conotruncal cardiac lesion, one had a twin with a conotruncal lesion, and in one the mother had a diagnosis of del22q11.2. The fetal thymus assessment was performed by an individual who was not aware of the del22q11.2 status of the fetus.

RESULTS

By 2D imaging, the thymus was identified in the anterosuperior mediastinum as a subtle hypoechogenic area. In nine cases, the thymus was demonstrated prenatally and none had del22q11.2. However, in one case the thymus was only seen on follow-up fetal echocardiography. In six cases, the thymus could not be identified and all six had del22q11.2. In one additional case, analyzed retrospectively, the thymus could not be assessed. The status of the thymus was confirmed on postnatal echocardiography or autopsy in 11 of the 15 cases assessed prenatally.

CONCLUSIONS

Our study suggests that fetal echocardiography can assess the thymus in most cases at risk for del22q11.2. This information may be useful in counseling women/couples who decline amniocentesis or who are awaiting amniocentesis results.

Progressive aortic root dilatation in adults late after repair of tetralogy of Fallot

BACKGROUND

Aortic valve or aortic root (AoRo) replacement is occasionally required because of AoRo dilatation and aortic regurgitation (AR) in repaired tetralogy of Fallot (TOF). We evaluated AoRo size and possible factors associated with its dynamic nature in adults with repaired TOF.

METHODS AND RESULTS

Of 216 patients with TOF repair who underwent echocardiography in 1997, we identified 32 patients (mean age, 36+/-8.0 years) with AoRo dilatation, defined as ratio of observed to expected AoRo size by standard nomogram >1.5 (group A), and 54 TOF controls, matched for age with AoRo ratio <1.5 (group B), who underwent at least 1 previous echocardiogram in the preceding 10 years. Mean indexed AoRo size (cm/m2) in 1997 was 2.5+/-0.5 in group A and 1.7+/-0.2 in group B (P<0.0001). AoRo rate of change (mm/year) from the first to 1997 study (mean interval, 5.2+/-3.8 years) was 1.7+/-3.8 in group A and 0.03+/-1.6 in group B (P=0.001). Patients from group A had a longer shunt-to-repair interval (P=0.048) with a higher prevalence of pulmonary atresia (P<0.0001), right aortic arch (P=0.03), moderate to severe AR (P=0.002), aortic valve replacement (P=0.02), larger cardiothoracic ratio (P=0.02), and increased left ventricular end-diastolic dimensions (P=0.002).

CONCLUSIONS

A subset of adult TOF exhibits ongoing dilatation of AoRo late after repair. This dilatation relates to previous long-standing volume overload of AoRo and possibly to intrinsic properties of AoRo and may lead to AR. Meticulous follow-up of AoRo after TOF repair is recommended.

The molecular basis of congenital cardiac disease

Today, congenital cardiovascular disease is virtually always amenable to corrective or palliative surgical interventions. However, the mechanisms causing developmental anomalies of the heart and vessels have remained obscure until recently. This review presents genetic defects causing the pediatric vasculopathies; Marfan's syndrome, inherited supravalvar aortic stenosis, and Williams' syndrome. A synopsis of known mutations causing human cardiomyopathies in nuclear genes encoding contractile proteins, cardiomyocyte structural proteins, and mitochondrial proteins essential for cardiac energy production is provided. The molecular genetic evidence implicating single gene mutations in the pathogenesis of conotruncal anomalies (the 22q11 monosomy or "cardiac defects, abnormal facies, thymic hypoplasia, cleft palate, and hypocalcemia with deletions on chromosome 22" [CATCH-22] syndrome), heterotaxy syndromes, trisomies and atrioventricular canal defects, and secundum atrial septal defects is presented. The consequences of these genetic causes for diagnostic evaluation and perioperative care are emphasized. Single gene defects are a common cause of congenital cardiac disease. Copyright 1998 by W.B. Saunders Company

Anatomic patterns of conotruncal defects associated with deletion 22q11

PURPOSE

Patients with cardiovascular malformations (CVMs) and deletion 22q11 from our series were studied in order to (1) analyze the association with dysmorphic features and noncardiac anomalies, (2) identify specific cardiac patterns and the distinctive association with additional CVMs.

METHODS

From 1993 to 2000, 931 patients with CVM (95 with a clinical diagnosis of DiGeorge/velocardiofacial syndrome (DG/VCFS), 208 with different genetic syndromes, 628 without dysmorphic features) underwent accurate cardiac assessment, clinical and phenotypical examination, and screening for deletion 22q11 by fluorescence in situ hybridization (FISH).

RESULTS

Deletion 22q11 was detected in 88 of the total patients, and in 87 of the 95 patients with a clinical diagnosis of DG/VCFS. Only one patient among the 628 without dysmorphic features had deletion 22q11. Conotruncal heart defects were the most common CVMs, often presenting in association with additional anomalies in four areas of the cardiovascular system: (1) the aortic arch can be right sided, cervical, double, and the subclavian artery can be aberrant, (2) the pulmonary arteries can present discontinuity, diffuse hypoplasia, discrete stenosis, defect of arborization and major aortopulmonary collateral arteries (MAPCA), (3) the infundibular septum can be malaligned, hypoplastic, or absent, (4) the semilunar valves can be bicuspid, severely dysplastic, insufficient, or stenotic.

CONCLUSION

In subjects with deletion 22q11 CVM is virtually always associated with one or more noncardiac anomalies. Deletion 22q11 is exceptionally rare in children with nonsyndromic CVMs. Specific patterns of CVMs are observed in patients with deletion 22q11, including (1) anomalies of the aortic arch, (2) anomalies of the pulmonary arteries and of the pulmonary blood supply, (3) defects of the infundibular septum, (4) malformations of the semilunar valves. These additional CVMs may influence the surgical treatment of these patients.

Familial absent pulmonary valve syndrome without deletions of chromosome 22q11

Deletions of chromosome 22q11 are common in patients with tetralogy of Fallot, and in those with absent pulmonary valve syndrome. In this report, we describe a pair of siblings with absent pulmonary valve syndrome, neither of whom had deletions of chromosome 22q11. The finding of familial absent pulmonary valve syndrome without deletion of 22q11 in our patients suggests an alternative genetic basis for this rare condition.

Tetralogy of Fallot with absent pulmonary valve. A continuing challenge

Absent pulmonary valve syndrome (APVS); the combination of tetralogy of Fallot (TOF) with agenesis of the pulmonary valve, is a relatively rare cardiac malformation. Despite the anatomic similarity with classic TOF, the pathophysiology is strikingly different. Data on 10 patients (3 male, 7 female) with APVS, treated between January 1978 and December 1995, were retrospectively reviewed. During this period a total of 2920 children underwent correction of a variety of congenital cardiac anomalies, of which 246 patients (8%) had a correction for TOF. Two patients with APVS presented within the first four months of life with severe cardiorespiratory distress and required several operative procedures. The remaining eight patients had only mild to moderate respiratory and/or cardiac symptoms and elective intracardiac repair was performed on those between the ages of 10 months and 9.5 years. Associated cardiac anomalies seen in five patients included aberrant coronary artery, absent or interrupted left pulmonary artery, partial AVSD and aberrant azygos continuation. In those electively corrected, the strategies used were ventriculotomy (7), pulmonary homograft (3) and aneurysmorrhaphy (2). There were two deaths, one in each group of patients, as a result of progressive respiratory insufficiency and cardiac tamponade, respectively. The follow-up of the eight survivors ranged from 2 to 11 years (median 6.75). All have a normal effort tolerance; only one child is on digoxin therapy, and one child continues to suffer bronchospastis episodes. Our experience with infants with this lesion is limited but underlines the different approaches required, depending on the age of presentation.

Congenital heart defects and 22q11 deletions: which genes count?

Hemizygous deletions on the long arm of chromosome 22 (del22q11) are a relatively common cause of congenital heart disease. For some specific heart defects such as interrupted aortic arch type B and tetralogy of Fallot with absent pulmonary valve, del22q11 is probably the most frequent genetic cause. Although extensive gene searches have been successful in discovering many novel genes in the deleted segment, standard positional cloning has so far failed to demonstrate a role for any of these genes in the disease. We show how the use of experimental animal models is beginning to provide an insight into the developmental role of some of these genes, while novel genome manipulation technologies promise to dissect the genetic aspects of this complex syndrome.

Frequency of 22q11 deletions in patients with conotruncal defects

OBJECTIVES

This study was designed to determine the frequency of 22q11 deletions in a large, prospectively ascertained sample of patients with conotruncal defects and to evaluate the deletion frequency when additional cardiac findings are also considered.

BACKGROUND

Chromosome 22q11 deletions are present in the majority of patients with DiGeorge, velocardiofacial and conotruncal anomaly face syndromes in which conotruncal defects are a cardinal feature. Previous studies suggest that a substantial number of patients with congenital heart disease have a 22q11 deletion.

METHODS

Two hundred fifty-one patients with conotruncal defects were prospectively enrolled into the study and screened for the presence of a 22q11 deletion.

RESULTS

Deletions were found in 50.0% with interrupted aortic arch (IAA), 34.5% of patients with truncus arteriosus (TA), and 15.9% with tetralogy of Fallot (TOF). Two of 6 patients with a posterior malalignment type ventricular septal defect (PMVSD) and only 1 of 20 patients with double outlet right ventricle were found to have a 22q11 deletion. None of the 45 patients with transposition of the great arteries had a deletion. The frequency of 22q11 deletions was higher in patients with anomalies of the pulmonary arteries, aortic arch or its major branches as compared to patients with a normal left aortic arch regardless of intracardiac anatomy.

CONCLUSIONS

A substantial proportion of patients with IAA, TA, TOF and PMVSD have a deletion of chromosome 22q11. Deletions are more common in patients with aortic arch or vessel anomalies. These results begin to define guidelines for deletion screening of patients with conotruncal defects.

Absent pulmonary valve syndrome with interrupted aortic arch

A surgically treated case of absent pulmonary valve syndrome associated with type B interrupted aortic arch is presented. The presence of a restrictive ductus arteriosus promoted the development of a collateral circulation between ascending and descending thoracic aorta, allowing the child to remain clinically stable after birth.

Truncus arteriosus communis associated with chromosome 22q11 deletion

OBJECTIVES

The purpose of this study was to clarify characteristics of truncus arteriosus communis associated with chromosome 22q11 deletion (del 22q11).

BACKGROUND

DiGeorge syndrome and conotruncal anomaly face syndrome are associated with del 22q11 (hemizygosity). In 30% of cases, truncus arteriosus communis is associated with the deletion.

METHODS

Fifteen consecutive patients with truncus arteriosus communis were checked for 22q11 with fluorescent in situ hybridization using an N25 probe (Oncor). Cardiovascular anomalies were studied with cardiac catheterization, cineangiography and echocardiography.

RESULTS

Five patients had del 22q11. Two had a rare type of truncus arteriosus: type A3 of Van Praagh and Van Praagh with major aortopulmonary collateral arteries and pulmonary ostial stenosis. The other three had type A1 truncus arteriosus and pulmonary artery stenosis. One of them had major aortopulmonary collateral arteries. Ten patients with truncus arteriosus had no del 22q11. The types of truncus arteriosus in these 10 patients were type A1 in 7, type A2 in 2 and type A3 with closed ductus in 1. None of nine patients with type 1 or type 2 truncus arteriosus had pulmonary stenosis.

CONCLUSIONS

In truncus arteriosus communis, the rare type A3 with major aortopulmonary collateral arteries and pulmonary ostial stenosis and type A1 with pulmonary artery stenosis are associated with del 22q11.

Absent pulmonary valve syndrome with intact ventricular septum: role of ductus arteriosus revisited

We report two patients (four and twelve days old respectively) with heart failure due to absent pulmonary valve and patent ductus arteriosus. The ductus arteriosus in both patients had unusual course arising early from the aortic arch and maintaining an acute angle with the aortic arch. The etiology of absent pulmonary valve syndrome is still not clear. We speculate on the role of arterial duct in the development of absent pulmonary valve syndrome.

A genetic etiology for interruption of the aortic arch type B

Interrupted aortic arch (IAA) type B is a congenital heart defect believed to be caused by an anomaly of bronchial arch mesenchymal development. IAA type B has been associated with DiGeorge syndrome (DGS), which includes conotruncal heart defects, T-cell immunodeficiency, hypocalcemia, and facial abnormalities. The great majority of DGS cases are associated with hemizygous deletions at the chromosome 22q11 locus. The present study was designed to establish the involvement of the 22q11 locus in the etiology of IAA type B, independently from the typical DGS phenotype. An evaluation was performed on 73 patients with conotruncal heart defects using fluorescence in situ hybridization (FISH) analysis with probes from the 22q11 DGS locus. From this group, 7 patients were deleted (including 4 of the 11 patients with IAA type B). FISH analysis was extended to a total of 22 patients with IAA type B and 11 of these (50%) were deleted. FISH and Southern blot analyses using additional markers within the DiGeorge chromosomal region were performed on patients found not to be deleted in the initial FISH screening. No small deletions or rearrangements were detected. In our patient population, a single, specific genetic defect is the basis for one half of the IAA type B cases. These data suggest that IAA type B is one of the most etiologically homogeneous congenital heart defects. A 22q11 deletion in IAA type B may or may not be associated with the typical DGS phenotype. Therefore, IAA type B, per se, should be an indication for 22q11 deletion testing.

Chromosome abnormalities in congenital heart disease

Refinements in cytogenetic techniques have promoted progress in understanding the role that chromosome abnormalities play in the cause of congenital heart disease. To determine if mutations at specific loci cause congenital heart disease, irrespective of the presence of other defects, and to estimate the prevalence of chromosome abnormalities in selected conotruncal cardiac defects, we reviewed retrospectively cytogenetic and clinical databases at St. Louis Children's Hospital. Patients with known 7q11.23 deletion (Williams syndrome), Ullrich-Turner syndrome (UTS), and most autosomal trisomies were excluded from this analysis. Two groups of patients were studied. Over a 6.5-year period, 57 patients with chromosomal abnormalities and congenital heart disease were identified. Of these, 37 had 22q11 deletions; 5 had abnormalities of 8p; and 15 had several other chromosome abnormalities. The prevalence of chromosome abnormalities in selected conotruncal or aortic arch defects was estimated by analysis of a subgroup of patients from a recent 22-month period. Chromosome abnormalities were present in 12% of patients with tetralogy of Fallot, 26% in tetralogy of Fallot/pulmonary atresia, 44% in interrupted aortic arch, 12% in truncus arteriosus, 5% in double outlet right ventricle, and 60% in absent pulmonary valve. We conclude that chromosome analysis should be considered in patients with certain cardiac defects. Specifically, fluorescent in situ hybridization (FISH) analysis of 22q11 is indicated in patients with conotruncal defects or interrupted aortic arch. High resolution analysis should include careful evaluation of the 8p region in patients with either conotruncal or endocardial cushion defects.

Genetic disorders of cardiac morphogenesis. The DiGeorge and velocardiofacial syndromes

The phenotype associated with a 22q11 deletion is highly variable and still under investigation. Of particular interest to cardiologists and cardiac developmental biologists is the finding that many patients with a 22q11 deletion have conotruncal cardiac defects and aortic arch anomalies. Despite the phenotypic variability, the vast majority of patients have a similar large deletion spanning approximately 2 megabases. The low-frequency repeated sequences at either end of the commonly deleted region may be responsible for the size of the deletion and account for the instability of this chromosomal region. Molecular studies of patients with the DGS/VCFS phenotype and unique chromosomal rearrangements have allowed a minimal critical region for the disease to be defined. Multiple genes have been identified in the minimal critical and larger deleted region. These genes are being investigated for their potential role in the disease pathophysiology by screening for mutations in nondeleted patients with the phenotype and by analysis of the pattern of expression in the developing mouse embryo. Further experimentation in the mouse mammalian model system will be of great utility to help determine whether haploinsufficiency of one critical gene or several genes within the DGCR results in the disease phenotype. Modifying factors, both genetic and environmental, must also be considered. Further investigation into the disease mechanism leading to the DGS/VCFS phenotype will hopefully further our understanding of cardiac development and disease.

Absent Pulmonary Valve: Echocardiographic Features

Congenital absence of the pulmonary valve, a rare anomaly, is characterized by absent or rudimentary pulmonary valve, often with annular stenosis, and aneurysmal dilatation of the pulmonary arteries. This defect is most commonly an accompaniment of tetralogy of Fallot but occasionally occurs alone. Four patients with this abnormality were examined by two-dimensional echocardiography at the Mayo Clinic. Doppler echocardiography provided hemodynamic assessment of the magnitude of outflow obstruction and valve regurgitation. The two-dimensional echocardiographic and Doppler features of absent or rudimentary pulmonary valve provided diagnostic information sufficient to proceed directly to surgical correction.

Neural tube defects and deletions of 22q11

Recently we reported on three unrelated children with neural tube defects (NTDs) and deletion of 22q11. Two of these children have velo-cardio-facial syndrome and the third DiGeorge sequence. Thus, NTDs appear to be part of the clinical picture due to 22q11 deletion. To further explore this association and to clarify what findings should prompt testing for this deletion in individuals with NTDs, we have reviewed all patients in a large regional spina bifida clinic population. Two hundred ninety-five patients with NTDs were identified by chart review. Charts were reviewed for congenital heart defect, minor facial anomalies, thymic hypoplasia, cleft lip and/or palate, hypocalcemia, and a family history of a NTD, congenital heart defect, or cleft lip and/or palate. A total of 22 patients was identified with NTD and at least one more clinical trait and/or a positive family history. Sixteen children received cytogenetic and molecular testing including the three previously reported patients diagnosed with a 22q11 deletion. Results of cytogenetic and molecular studies of the remaining 13 patients were normal. Deletion of 22q11 is an infrequent cause of NTDs. We recommend testing for the 22q11 deletion in patients with a NTD and conotruncal heart defect. Testing should be considered in patients with a NTD who have a first degree relative with a conotruncal heart defect or have additional clinical findings of VCFS or DGS.

Size of 22q deletions in four previously reported patients with conotruncal anomaly face syndrome

Conotruncal anomaly face syndrome (CTAFS) was distinguished from velo-cardio-facial syndrome (VCFS) in a bind study, yet shared the finding of 22q11.2 deletions. This work has been extended to show that the 22q11.2 deletions in CTAFS greatly overlap those found in VCFS and many DiGeorge patients. The reason for dissimilar phenotypes with apparently similar 22q11.2 deletions is not yet known.

Cardiac anomalies associated with a chromosome 22q11 deletion in patients with conotruncal anomaly face syndrome

Among 114 cardiac patients with conotruncal anomaly face syndrome and DiGeorge syndrome, 100 patients were found to have a chromosome 22q11 deletion. Those with the deletion included 73 patients with tetralogy of Fallot, 12 with ventricular septal defect, 5 with aortic arch anomalies without intracardiac anomaly, 4 with interrupted aortic arch, 2 with double-outlet right ventricle, 2 with truncus arteriosus, 1 with complete transposition, and 1 with atrial septal defect.

Associated cardiac anomalies in isolated and syndromic patients with tetralogy of Fallot

To detect in children with tetralogy of Fallot (ToF) the prevalence of associated cardiac anomalies in syndromic and isolated cases, the additional cardiac defects of 150 consecutive patients with ToF (102 isolated and 48 syndromic cases) were evaluated by review of echocardiographic, angiocardiographic, and surgical reports. Syndromic patients were classified into groups with branchial arch defects, Down syndrome, and other genetic conditions. ToF is significantly associated with additional cardiac malformations in patients with branchial arch (11 of 21, p <0.01) and Down (10 of 20, p <0.0001) syndromes. The subarterial ventricular septal defect with deficiency of the infundibular septum (4 of 21, p <0.01) and the right aortic arch (6 of 21, p <0.05) were prevalent in patients with branchial arch syndromes, whereas atrioventricular canal (10 of 20, p <0.0001) was associated with ToF in patients with Down syndrome. Peculiar anatomic cardiac patterns are present in children with ToF and may alert the cardiologist to look at additional cardiac anomalies. Moreover, the presence of some associated cardiac anomalies may suggest careful clinical evaluation for genetic syndromes.