Changes in topographical relation between the ductus arteriosus and left subclavian artery in human embryos: a study using serial sections.

At birth, the ductus arteriosus (DA) merges with the aortic arch in the caudal side of the origin of the left subclavian artery (ltSCA). Since the SCA (seventh segmental arteries) were fixed on the levels of the seventh cervical-first thoracic vertebral bodies, the confluence of the DA should migrate caudally toward the lower level. We aimed to describe the changing topographical anatomy of the DA and SCA using serial sections. First, we examined serial sagittal sections of 11 embryos (Carnegie stage 15-18), but the specimens were clearly divided into 2 groups with and without the lower confluence of the DA. Next, we examined serial horizontal sections of 40 specimens (Carnegie stage 14-16) and we chose 5 specimens (CRL 11 mm, 3 specimen; 1, 14 mm; 1, 15 mm) including the DA near (within 1-vertebral segment from) the ltSCA. The final approach of the DA occurred during the heart descent in which the apex of the heart migrated from the level of the first to the fourth thoracic vertebral body. Thus, the DA reached the SCA level before establishment of the heart descent. The right aortic arch maintained its entire course in 2 of the 5 specimens. Therefore, the positioning of the DA along the left aortic arch might occur independently of degeneration of the right arch. Notably, the tracheal bifurcation level was higher when the DA-ltSCA distance was greater. A contribution of the increased pulmonary volume was suggested for the final approach of the DA.

Clinical discussion of the arteria lusoria: a case report / Discussão clínica a respeito da artéria lusória: um relato de caso

Abstract The right subclavian artery may originate from the left portion of the aortic arch. This aberrant vessel is known as the arteria lusoria. Its course to its usual site runs behind the esophagus, which may cause a disease known as dysphagia lusoria, responsible for symptoms of discomfort. This artery is often associated with other anomalies, such as the non-recurrent laryngeal nerve and the bicarotid trunk, and with diseases such as aneurysms, congenital heart defects, and even genetic syndromes. During routine dissection of a male cadaver fixed in 10% formalin solution, an arteria lusoria was found. This article reports the variation and discusses its embryological, clinical and surgical aspects.

Resumo Em alguns casos, a artéria subclávia direita pode se originar da porção esquerda do arco aórtico. Esse vaso aberrante é conhecido como artéria lusória. Para chegar em sua região, essa artéria passa posteriormente ao esôfago, e pode ser, portanto, causa de uma doença conhecida como disfagia lusória, desencadeando sintomas desconfortantes. A artéria lusória está frequentemente associada com outras anomalias, como o nervo laríngeo não recorrente e o tronco bicarotídeo, assim como pode estar em associação com aneurismas, defeitos cardíacos congênitos e até síndromes genéticas. Durante dissecação cadavérica de rotina, foi observada a presença dessa artéria em um cadáver do sexo masculino fixado em uma solução de formalina a 10%. O objetivo deste trabalho é relatar a variação conhecida como artéria lusória e trazer destaque para seus aspectos embriológicos, clínicos e cirúrgicos.

Incidence of an Aberrant Right Subclavian Artery on Second-Trimester Sonography in an Unselected Population.

OBJECTIVES: The aim of this study was to assess the incidence of an aberrant right subclavian artery (ARSA) among an unselected population during second-trimester sonography and to review the importance of this conotruncal variant as a marker of Down syndrome. METHODS: The presence or absence of an ARSA was assessed in an unselected population of 1913 second-trimester fetuses. RESULTS: Among the 1913 patients, an ARSA was detected in 20 fetuses (1.04%), all with a normal karyotype. Thirteen of 20 fetuses had an isolated ARSA, and 7 of them were nonisolated. Associated abnormal sonographic findings were an intracardiac echogenic focus (n = 3), a choroid plexus cyst (n = 1), pyelectasis (n = 1) and tetralogy of Fallot (n = 2). One of the cases of tetralogy of Fallot was also associated with a persistent left superior vena cava, a persistent right umbilical vein, hydrocephalus, rhombencephalosynapsis, and unilateral renal agenesis. There were only 2 fetuses with Down syndrome in this group, and both of them had a normal origin of the right subclavian artery. CONCLUSIONS: In an unselected population, an ARSA may be seen less frequently than in a high-risk population and may not be related to Down syndrome. An isolated ARSA is not a sufficient indication for karyotype analysis; it can be managed with noninvasive prenatal testing rather than invasive testing.

Aberrant Right Subclavian Artery: Correlation Between Fetal and Neonatal Abnormalities and Abnormal Genetic Screening or Testing.

OBJECTIVES: To determine whether fetuses with an isolated aberrant course of the right subclavian artery (ARSA) have increased risk for chromosomal abnormalities, including trisomy 21 or 22q11 deletion. METHODS: We performed a retrospective chart review of all fetuses with antenatally diagnosed ARSA. Data were collected from fetal anatomic surveys, fetal echocardiograms, noninvasive trisomy 21 screening programs, invasive genetic studies, and neonatal records. RESULTS: Seventy-nine fetuses with ARSA were identified at 20.3 ± 3.8 weeks' gestation. Forty-eight fetuses underwent chromosomal evaluation. Of those, seven had trisomy 21. Four other fetuses had unusual karyotype abnormalities. All fetuses with genetic anomalies had additional aberrant ultrasound findings. There were three spontaneous fetal deaths (trisomy 21-2 and Wolf-Hirshhorn-1). Nine pregnancies were terminated because of abnormalities and one died as a result of hypoplastic left heart syndrome. No neonate was found or suspected to have 22q11.2 deletion. The ARSA was isolated in 43 fetuses; all had unremarkable neonatal outcomes, and none were readmitted within 6 months after discharge. CONCLUSIONS: As an apparently isolated finding, ARSA is benign and not associated with trisomy 21 or 22q11.2 deletion. The finding of ARSA, however, warrants a detailed fetal ultrasound. All fetuses with ARSA and genetic anomalies had additional ultrasound findings.

Congenital vascular rings: a clinical challenge for the pediatrician.

Vascular rings are congenital anomalies that lead to variable degrees of respiratory problems or feeding difficulties by forming a complete or partial ring compressing the trachea, the bronchi, and the esophagus. The clinical diagnosis of vascular rings is often challenging for the pediatrician because the clinical manifestations are heterogeneous and nonspecific. Symptoms can vary from wheezing, stridor, dyspnea, and/or dysphagia to life-threatening conditions; however, they may not be present. The aim of this study is to review the recent literature on this subject and describe new developments in diagnostics and imaging.

[Aberrant right subclavian artery (ARSA)--a new sonographic marker for chromosomal aberrations in the second trimester--preliminary observations]. / Bladzaca prawa tetnica podobojczykowa--nowy marker aberracji chromosomowych w badaniu USG drugiego trymestru--wstepne obserwacje na materiale wlasnym.

OBJECTIVES: Presentation of our own, preliminary experiences in the assessment of the right subclavian artery's (RSA) position during the second trimester scan. MATERIAL AND METHODS: Since January 2012 our center has started to conduct the assessment of the position of the right subclavian artery in the second trimester scan. Patients who were diagnosed with an aberrant right subclavian artery (ARSA) were referred to invasive method of prenatal diagnosis. Abnormal karyotype and microdeletion 22q11 were analyzed. Detailed echocardiography was conducted in each case. RESULTS: Between January 2012 and September 2013 we diagnosed 19 cases of ARSA. There were three cases of congenital heart defect (15.8%; 3/19) (ventricular septal defect--VSD, n=2, atrioventricular septal defect--AVSD, n=1). Two out of 17 cases showed an abnormal karyotype (11.8%; 2/17)--46,XY del(5) (q15q31) and 47,XX+18. No 22q11.2 deletions were observed. Two patients did not consent to invasive methods of prenatal diagnosis. CONCLUSIONS: The position of the right subclavian artery (RSA) should be routinely assessed during the second trimester of ultrasound screening. The presence of ARSA increases the risk for abnormal karyotype in the fetus and therefore, all patients who are diagnosed with ARSA should be referred to the reference center.

Arterial supply to the thyroid gland and the relationship between the recurrent laryngeal nerve and the inferior thyroid artery in human fetal cadavers.

The aim of this study was to identify the arterial supply to the thyroid gland and the relationship between the inferior thyroid artery (ITA) and the recurrent laryngeal nerve (RLN) in fetal cadavers using anatomical dissection. The anterior necks of 200 fetuses were dissected. The origins of the superior thyroid artery (STA) and the ITA and location of the ITA in relation to the entrance of the thyroid lobe were examined. The relationship between the ITA and the RLN was determined. The origins of the STA were classified as: external carotid artery, common carotid artery (CCA), and the thyrolingual trunk. The origins of the ITA were the thyrocervical trunk and the CCA. The ITA was absent on the left side in two cases. The relationship of the RLN to the ITA fell into seven different types. Type 1: the RLN lay posterior to the artery; right (42.5%), left (65%). Type 2: the RLN lay anterior to the artery; right (40.5%), left (22.5%). Type 3: the RLN lay parallel to the artery; right (11.5%), left (7%). Type 4: the RLN lay between the two branches of the artery; right (1%), left (3.5%). Type 5: The extralaryngeal branch of the RLN was detected before it crossed the ITA; right (4.5%), left (0%). Type 6: the ITA lay between the two branches of the RLN; right (0%), left (0.5%). Type 7: the branches of the RLN lay among the branches of the ITA; right (0%), left (0.5%). The results from this study would be useful in future thyroid surgeries.

Second-trimester fetal aberrant right subclavian artery: original study, systematic review and meta-analysis of performance in detection of Down syndrome.

OBJECTIVES: First, to estimate the prevalence of fetal aberrant right subclavian artery (ARSA) in our population and its association with Down syndrome. Second, to determine the feasibility of ultrasound to visualize ARSA in the three planes. Finally, to carry out a systematic review of the literature on the performance of second-trimester ARSA to identify fetuses with Down syndrome. METHODS: ARSA was assessed by ultrasound in the axial plane and confirmed in the longitudinal and coronal planes during the second half of pregnancy in women attending our unit (from February 2011 to December 2012). A search of diagnostic tests for the assessment of ARSA was carried out in international databases. Relevant studies were subjected to a critical reading, and meta-analysis was performed with Meta-DiSc. RESULTS: Of the 8781 fetuses in our population (mean gestational age: 24 ± 5.4 weeks), 22 had Down syndrome. ARSA was detected in the axial view in 60 cases (0.7%) and confirmed in the coronal view in 96.7% and in the longitudinal view in 6.7% (P < 0.001). Seven cases with ARSA had Down syndrome and all were in the non-isolated-ARSA group. The estimates of positive likelihood ratio (LR) were 0 for isolated ARSA and 199 (95% CI, 88.9-445.2) for non-isolated ARSA. In the systematic review, six studies were selected for quantitative synthesis. The pooled estimates of positive and negative LRs for global ARSA were, respectively, 35.3 (95% CI, 24.4-51.1) and 0.75 (95% CI, 0.64-0.87). For isolated ARSA, the positive and negative LRs were 0 (95% CI, 0.0-14.7) and 0.98 (95% CI, 0.94-1.02), respectively. CONCLUSIONS: The prevalence of ARSA seems close to 1%. The coronal plane is the most suitable for its confirmation after detection in the axial plane. Detection of isolated or non-isolated ARSA should guide decisions about karyotyping given that isolated ARSA shows a weak association with Down syndrome.

Origin and course of the extracranial vertebral artery: CTA findings and embryologic considerations.

PURPOSE: The aim of this study was to show the different origins and courses of the extracranial VA on CTA with special emphasis on embryological considerations. The duplicated VA is an anomaly that has been assumed to predispose for dissection and to be associated with aneurysms. We report its frequency and clinical significance. METHODS: We retrospectively reviewed CTA of 539 patients by using a contrast-enhanced CTA protocol of the VA on CT. RESULTS: Ninety-four-point-two percent of left VA originated from left subclavian artery and entered the transverse foramen at C6 in nearly all cases. Six-point-three-percent of left VA (m = 4 %, f = 10 %) originated from the aortic arch and entered the transverse foramen either at C4, C5 or C7 but never at C6. One case of an aberrant retroesophageal right VA originated from the aortic arch distal to the left subclavian artery and entered at C7 (0.19 %). All other right VA originated from the right subclavian artery (99.8 %) and entered between C4 and C6. We diagnosed four cases of duplicated VA (0.74 %) with a female predominance (1.9 %) without any signs of dissection on CTA. Two cases with VA duplication had intracranial arterial aneurysms. CONCLUSIONS: The VA is a longitudinal anastomosis of segmental metameric arteries. The level of entrance into the transverse foramen indicates which metameric artery or arteries persist. Duplication corresponds to persistence of two segmental arteries and is a rare phenomenon. VA duplication might be associated with vascular lesions.

Aberrant right subclavian artery (ARSA) in unselected population at first and second trimester ultrasonography.

OBJECTIVES: To evaluate the feasibility of examining aberrant right subclavian artery (ARSA) at first and second trimester gestation, its prevalence and associations in an unselected population. METHODS: Right subclavian artery (RSA) was prospectively evaluated in 6617 routine patients. When ARSA was detected, fetal echocardiography was offered and fetal karyotyping was discussed. If invasive testing was performed with normal karyotype, fluorescence in situ hybridization for 22q11.2 microdeletion and additionally, in case of nuchal translucency (NT) measurement above the 99(th) centile, oligo array-based comparative genomic hybridization, were offered. In all aneuploidies, NT and first trimester additional ultrasonographic (US) markers assessment (nasal bone, tricuspid valve, ductus venosus) were recorded. RESULTS: RSA assessment was feasible in 85.3% and 98% of first and second trimester examinations, respectively (overall feasibility 94%). There were detected 89 ARSA (1.42% of the feasible cases), of which 66 in the first trimester. More than 20% were associated to other abnormalities: 10 aneuploidies; 2 microdeletions (15q11.2 and 22q11.2); in the euploid fetuses, 8 associated abnormalities were observed, 4 of which were cardiac defects. In the case of 22q11.2 microdeletion, ARSA was associated only with increased NT. CONCLUSION: Prenatal routine US assessment of the RSA is feasible by highly experienced operators in first trimester screening. There is an important association of ARSA detected in unselected population with fetal abnormalities, including aneuploidies, cardiac defects and genetic anomalies. In trisomy 21 fetuses, ARSA can be the only first trimester US marker or, when associated to increased NT, it can represent the only 'additional' marker.

Aberrant right subclavian artery: incidence and correlation with other markers of Down syndrome in second-trimester fetuses.

OBJECTIVE: To assess the incidence of aberrant right subclavian artery (ARSA) and other strong markers of Down syndrome and their correlation in a large population of second-trimester Down syndrome fetuses assessed in a tertiary referral center. METHODS: Presence or absence of ARSA and other major ultrasound markers of Down syndrome was assessed in a population of 106 second-trimester Down syndrome fetuses referred to our unit for expert assessment and/or termination of pregnancy after karyotyping performed for positive first- or second-trimester screening or advanced maternal age or on maternal request. All cases in which the diagnosis of Down syndrome followed the ultrasound detection of major anomalies or soft markers were excluded from the study, as were all cases with a gestational age less than 14 + 0 weeks. We searched for the ARSA on the three vessels and trachea view using color or power Doppler. All fetuses underwent a thorough anatomic assessment and fetal echocardiography. The other Down syndrome markers assessed were: absent or hypoplastic nasal bone (NB-), defined as length < 5(th) centile; nuchal fold ≥ 5 mm; and mild pyelectasis (> 5 mm). In addition, the presence of major cardiac and extracardiac defects was recorded. A correlation analysis was then performed in order to investigate possible associations between markers and/or major anomalies. Postmortem or postnatal diagnostic confirmation was available in all cases. RESULTS: The mean (SD) gestational age at ultrasound assessment was 20.4 (4.1) weeks. The incidence of the various variables in the population of Down syndrome fetuses was: ARSA, 25%; NB-, 43%; nuchal fold ≥ 5 mm, 16%; pyelectasis, 17%; major heart defects, 41%; atrioventricular septal defect, 25%; and extracardiac anomaly, 24%. The presence of ARSA did not correlate with any of the other variables. The only positive correlations (P < 0.05) were between NB- and pyelectasis, and between cardiac and extracardiac defects. CONCLUSIONS: This represents the largest Down syndrome population assessed for ARSA. In this series, the incidence of ARSA was 25%, lower than previously reported in much smaller series. Its presence did not correlate with the presence of any other marker or major anomaly, including heart defects.

Arch of aorta with bi-carotid trunk, left subclavian artery, and retroesophageal right subclavian artery.

We report a case of left sided aortic arch with three branches - a bi-carotid trunk, left subclavian, artery and right subclavian artery. The anomalous right subclavian artery presented a retroesophageal course. A right non-recurrent laryngeal nerve was noticed. The embryonic development of this branching pattern is discussed.

Aberrant right subclavian artery at 16 to 23 + 6 weeks of gestation: a marker for chromosomal abnormality.

OBJECTIVES: This study was carried out to determine the feasibility of defining the position of the right subclavian artery (RSA) by fetal echocardiography between 16 and 23 weeks of gestation, and the association between an aberrant right subclavian artery (ARSA) and chromosomal and cardiac defects. METHODS: We examined the position of the RSA in all patients who attended our unit for a fetal cardiac scan. The assessment was carried out using a transverse view of the fetal chest sweeping up from the level of the aortic arch, using color flow mapping. An ARSA was diagnosed when this vessel was not seen in the normal position and an arterial vessel was seen crossing behind the trachea towards the right arm, arising as a fourth branch of the aortic arch, at a lower level than normal. RESULTS: The course of the RSA could be identified in more than 95% of the 2799 fetuses examined between 16 and 23 + 6 weeks of gestation. An ARSA was found in 43 fetuses. The incidence was 1.5% in normal fetuses, 28.6% in fetuses with trisomy 21, 18.2% in fetuses with trisomy 18 and 8% in fetuses with other chromosomal defects. There was an association between an ARSA and cardiac defects in seven of the 43 fetuses (16%), and three of these seven fetuses had a normal karyotype. CONCLUSIONS: Assessment of the RSA by a fetal cardiologist is possible in almost all cases. The finding of an ARSA is much more common in fetuses with chromosomal defects, in particular trisomy 21 (where the prevalence of an ARSA was 29%), compared with euploid fetuses. Moreover, the presence of an ARSA may be associated with an increased incidence of intracardiac malformations. Examination of the position of the RSA is likely to become a routine ultrasound marker for chromosomal abnormalities in the second trimester of pregnancy.

Quantitative morphology of the left subclavian artery in human fetuses.

PURPOSE: The present study was performed to compile normative data for dimensions of the left subclavian artery at varying gestational age. MATERIAL AND METHODS: Using anatomical dissection, digital image analysis (Leica Q Win Pro 16 system) and statistical analysis (ANOVA, regression analysis) a range of measurements (length, original external diameter, volume) for the left subclavian artery in 128 spontaneously aborted human fetuses aged 15-34 weeks was examined. RESULTS: No significant gender differences were found (P>0.05). The length ranged from 4.62 +/- 0.49 to 12.28 +/- 1.25 mm, according to the linear function y = -2.1482 + 0.4302 x +/- 0.9972 (r = 0.93 P<0.001). The original external diameter increased from 0.68 +/- 0.16 to 2.89 +/- 0.29 mm, according to the linear model y = -1.2169 + 0.1233 x +/- 0.2389 (r = 0.95 P<0.001). The left subclavian artery-to-aortic root diameter ratio increased from 0.337 +/- 0.064 to 0.423 +/- 0.103. Distance between the left common carotid and left subclavian arteries increased from 0.57 +/- 0.17 to 3.92 +/- 0.91 mm. Aortic arch diameter to distance between the left common carotid and left subclavian arteries decreased with advanced fetal age, from 2.82 +/- 0.51 to 1.56 +/- 0.27. The volume ranged from 1.77 +/- 0.89 to 80.60 +/-; 22.18 mm3, in accordance with the quadratic function y = 76.0 - 8.956 x + 0.031 x2 +/- 10.945 (R2 = 0.85). CONCLUSIONS: The developmental dynamic of the length and diameter of the left subclavian artery follows a linear regression, whereas its volumetric dynamic follows a quadratic regression. The ratio of the aortic arch diameter to the distance between the left common carotid and left subclavian arteries has clinical application in the early recognition of aortic coarctation.

Mophometric study of the aortic arch and its major branches in rat fetuses on the 21st day of gestation.

The anatomy and embryology of the aortic arch and its branching tributaries (brachiocephalic trunk, left common carotid artery and left subclavian artery) in man and animals are well substantiated. However, the anatomical variations and morphometry of the aortic arch and its branching tributaries in rat fetus at the 21st gestation day have not been studied. Pregnant rats were hysterectomized and the arterial systems of 114 fetuses were injected with a polymerisable resin through the umbilical artery. After maceration, the vascular casts were dissected out and prepared for observations under a scanning electron microscope (SEM). The resulting SEM pictures were studied with a picture analyser and different vessel parameters (diameters, lengths and angles) were measured. The success rate of the microvascular cast injection was 46.5%. Out of the 53 observed aortic arch casts, 98.1% showed the classical branching pattern and one (1.9%) had no brachiocephalic trunk. Morphological analysis showed many differences, which were not linked to the litter. The statistical processing of the measurements enabled us to determine that the aorta diameter after the branching of the left subclavian artery was the most replicable parameter. Moreover, the results revealed some strong correlations between different parameters. There are probably no discrete categories among the various observed parameters as diameters and angles. Some parameters show very little variability and can thus be used as reference points for further studies such as the comparison of a control population with a population treated with a relevant xenobiotic.

Common origins of carotid and subclavian arterial systems: report of a rare aortic arch variant.

An aberrant right subclavian artery (aSA) arising from the proximal descending aorta is one of the most common anomalies of the aortic arch. We present our experience with an asymptomatic atypical aSA variant found during routine anatomic dissection. This aortic arch variant had two branches, the first being a bicarotid trunk and the second being a common trunk for both subclavian arteries. The right subclavian artery traveled behind the esophagus to reach the right upper extremity, thus forming an incomplete vascular ring around the trachea and the esophagus. The literature has been silent about the existence of this exact aSA variation. A plausible embryologic explanation is provided. An aSA is rarely symptomatic, but when symptoms do occur and intervention is warranted, it is important for surgeons and radiologists alike to be aware of the vascular anomalies that may potentially coexist with this entity. The surgical and endovascular options associated with this unique vascular anomaly are also discussed.

Transforming growth factor beta-SMAD2 signaling regulates aortic arch innervation and development.

Aortic arch interruptions in humans and animal models are mainly caused by aberrant development of the fourth pharyngeal arch artery. Little is known about the maturation of this vessel during normal and abnormal development, which is the subject of this study. Tgfbeta2 knockout mice that present with fourth artery defects have been associated with defective neural crest cell migration. In this study, we concentrated on pharyngeal arch artery development during developmental days 12.5 to 18.5, focusing on neural crest cell migration using a Wnt1-Cre by R26R neural crest cell reporter mouse. Fourth arch artery maturation was studied with antibodies directed against smooth muscle alpha-actin and neural NCAM-1 and RMO-270. For diminished transforming growth factor beta (TGF-beta) signaling, SMAD2 and fibronectin have been analyzed. Neural crest migration and differentiation into smooth muscle cells is unaltered in mutants, regardless of the cardiovascular defect found; however, innervation of the fourth arch artery is affected. Absent staining for nuclear SMAD2, NCAM-1, and RMO-270 in the fourth artery in mutant coincides with severe defects of this segment. Likewise, fibronectin expression is diminished in these cases. From these data we conclude the following: (1) neural crest cell migration is not a common denominator in cardiovascular defects of Tgfbeta2-/- mice; (2) fourth arch artery maturation is a complex process involving innervation; and (3) TGF-beta2 depletion diminishes SMAD2-signaling in the fourth arch artery and coincides with reduced vascular NCAM-1 expression and neural innervation of this artery. We hypothesize that disturbed maturation of the fourth pharyngeal arch artery, and especially abrogated vascular innervation, will result in fourth arch interruptions.