Introduction
With the popularization and application of the three-vessel-tracheal view in fetal ultrasonic cardiogram (UCG), the right aortic arch often has been reported antenatally and sorted according to the routing of cephalic and cervical vessels. Among those sorts, the right aortic with the left subclavian vagus and the mirroring carotid artery branch are very common types, which have been reported. Until now, the type of the right aortic with the isolated left subclavian artery (ILSCA) or the isolated left brachiocephalic trunk (ILBCT) has not been reported antenatally yet. It is the first time that they are reported. The prenatal ultrasound features of right aortic arch with ILSCA and ILBCT in our study were analyzed. In addition, we also analyzed the prognosis of two cases in our study and 12 cases in children or adults reported in Pubmed, in order to increase the prenatal diagnosis rate, and improve prognosis.
Materials and Methods
From March 2015 to March 2017, cases who received routine ultrasound scan in our hospital and cases referred to our hospital because of suspicious abnormality were included. With the method of continuously horizontal scanning, following section was observed, it was the abdominal transverse section, the four-chamber view, the left ventricular outflow tract view, the right ventricular outflow tract view and the three-vessel-tracheal view. Then, the origin and routing of cephalic and cervical vessels were examined in cases with the right aortic arch or the right arterial duct arch. Moreover, the spectrum features of the left common carotid artery and the left subclavian artery were analyzed when the ILSCA or the ILBCT was doubted.
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All fetuses were followed up for 3 months after birth or autopsies after induction of labor. Fetuses that failed to be followed up were not included into this study. The literatures of the ILBCT and ILSCA in Pubmed were reviewed to analyze their clinical presentation and prognosis.
Results
General Information
A total of 85 cases were diagnosed with the right aortic arch during the study, in which 73 cases had right aortic arch with the left arterial duct, and 12 cases had right aortic arch with right arterial duct. Among the 85 cases, 45 cases had left subclavian vagus, 38 cases with mirroring carotid artery branch, one case of ILBCT, and one of ILSCA. Among them, 14 cases were accompanied with other congenital cardiac malformations: seven of cases had tetralogy of Fallot, five cases with endocardial cushion defect and two cases had the Persistent truncus arteriosus. Seventy-one cases were not accompanied with congenital cardiac malformation.
Two cases with ILBCT and ILSCA in our study were both the right aortic arch and right arterial duct, and not accompanied by other congenital cardiac malformations.
Among these 85 cases, 69 cases were normal term infant, six cases were preterm, ten cases were labor induction, which were three cases of tetralogy of Fallot, five cases of endocardial cushion defect, and two cases of persistent truncus arteriosus respectively.
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All cases received UCG during the neonatal period, or autopsy was carried out after induced abortion, and these diagnosis results are consistent with the prenatal diagnosis.
Ultrasound Features of the Right Aortic Arch Accompanied with ILSCA and ILBCT
Two cases of were both right aortic arch and right arterial duct in our study. In fetuses with ILBCT, the aortic arch successively branched off the right common carotid artery and right subclavian artery from front to back, the left brachiocephalic trunk originated from the main pulmonary artery (Figs. 1, 2). In fetuses with the ILSCA, the aortic arch successively branched off the left common carotid artery, the right common carotid artery and the right subclavian artery from front to back, left subclavian artery originated from the main pulmonary artery (Figs. 3, 4).
Fig. 1
Sagittal sections of the aortic arch and ductal arch of ILBCT, Right aortic arch accompanied by a right arterial duct: RCCA and RSCA originated from the aortic arch, while the left brachiocephalic trunk derived from the main pulmonary artery. (MPA main pulmonary artery, RPA right pulmonary artery, DAO descending aorta, PD patent ductus, HV hepatic vein, RCCA right common carotid artery, RSCA right subclavian artery, LIA left innominate artery)
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Fig. 2
The coronal section of the descending aorta (DAO) in ILBCT. The right aortic arch accompanied by a right arterial duct: it can be observed that the left brachiocephalic trunk [or left innominate artery (LIA)], LPA and RPA have the same origin, namely, the main pulmonary artery. LIA successively branched off LCCA and LSCA, while the aortic arch branched off RCCA and RSCA. (RPA right pulmonary artery, LPA left pulmonary artery, DAO descending aorta, RCCA right common carotid artery, RSCA right subclavian artery, LCCA left common carotid artery, LSCA left subclavian artery, LIA left innominate artery, INV innominate vein)
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Fig. 3
The sagittal section of the aortic arch in ILSCA. The aortic arch branched off to the left common carotid artery (left *), right common carotid artery (right upper *), and right subclavian artery (right lower *), while the left subclavian artery derived from the MPA. (MPA main pulmonary artery, LPA left pulmonary artery, LPV left pulmonary vein, RVOT right ventricular outflow tract, LVOT left ventricular outflow tract, LSCA left subclavian artery, LCCA left common carotid artery, RCCA right common carotid artery, RSCA right subclavian artery)
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Fig. 4
Three-vessel-tracheal view of ILSCA. The ductal arch and aortic arch were located on the right of the fetus body, and the aortic arch branched off to the left common carotid artery (upper *), right common carotid artery (middle *) and right subclavian artery (lower *), from the front and the back. (MPA main pulmonary artery, AAO ascending aorta, ARCH aortic arch, DAO descending aorta, PD patent ductus, LSCA left subclavian artery, INV innominate vein)
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Doppler Frequency Spectrum Features of Cephalic and Cervical Vessels in Cases with the ILBCT and the ILSCA
In ILBCT fetuses, peak time of left common carotid artery and subclavian artery was prolonged (Fig. 5) compared to the right common carotid artery and subclavian artery. In fetuses with the ILSCA, peak time of left subclavian artery was prolonged compared with right subclavian artery. Peak blood flow rate mainly depends on fetus state. As we were unable to measure left and right artery’s rate simultaneously, we can not compare the exact peak blood flow rate. Although in theory, isolated left subclavian artery or common artery should have a lower blood flow rate than that of right subclavian artery or right common carotid.
Fig. 5
Blood-flow spectrum of LSCA and RSCA in ILBCT: peak time of LSCA was prolonged. (LSCA left subclavian artery, RSCA right subclavian artery)
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The Prognosis of the Two Cases of ILBCT and ILSCA in Our Study
Two cases diagnosed prenatally were both born after normal period of gestation, and no growth abnormalities were found during follow-up. Through physical examination, it was found that left radial pulsation was weakened and blood pressure of the left upper limb decreased in baby with ILSCA. In baby with ILBCT, in addition that, the left common carotid artery pulse disappearance too. The result of chromosome in ILSCA was normal. Chromosome in ILBCT was not been checked.
Literature Retrieval Result in PUBMED
1)
In Pubmed, a total of seven cases of ILSCA [1‐7] were searched, in which the youngest patient was newborn [7], and the eldest patient was 47 years old [2]. Five cases were accompanied with congenital cardiac malformation with or without chromosome abnormalities, which were as follows: TOF double outlet right ventricle accompanied with DiGeorge syndrome; main pulmonary artery window; transposition of the great arteries with right auricle apposition; left heart dysplasia; single atrium accompanied with Left heart dysplasia and Double outlet right ventricle. For the remaining two cases that were not accompanied with congenital cardiac malformation, one case was a 10-year-old boy [1], who visited a doctor due to paroxysmal atypical chest pain that lasted several minutes each time. His pulsation of the left common carotid artery and left subclavian artery disappeared during physical examination, which was diagnosed as left subclavian artery originated from the main pulmonary artery by CT angiography. Therefore, he received follow-up observation. The other case was a 47-year-old [2] male who suffered from intermittent headache, dizziness, blurry vision, and hearing loss in his left ear for the past 2 years. Although these symptoms were increasing in frequency, they were not precipitated by any upper extremity effort. Physical examination revealed a normal neuromotor response, as well as equal pulse and blood pressure in both arms. CT angiography revealed abnormal origin of the left subclavian artery and the patient received a follow-up observation.
2)
In Pubmed, a total of five cases of ILBCT [8‐12] were reviewed, and their age ranged from 23 days to 5 years old. Four cases were accompanied by congenital cardiac malformation with or without chromosome abnormality, which are as follows: Subvalvular aortic stenosis accompanied by CHARGE syndrome, atrial septal defect and ventricular septal defect accompanied by DiGeorge syndrome, ventricular septal defect accompanied by 21 trisomy, and ventricular septal defect. The remaining one case was a 5-year-old boy [8] without other malformation, he was found with radial pulsation that disappeared and occasional left upper limb weakness during his physical examination at school. Right upper limb blood pressure was 90/50 mm Hg, and left upper limb systolic blood pressure was 40 mm Hg (diastolic was not recordable). Postoperatively, the patient had good left upper limb pulsation and a good pulse. Postoperative CT angiography revealed normal branching pattern of right aortic arch. The patient was free of symptoms and doing well at 4 months of follow-up.
All reported cases in Pubmed that had ILBCT and ILSCA were diagnosed postnatally; among them, eight cases were of right aortic arch without arterial duct location descriptions; one case was diagnosed with right aortic arch accompanied by double arterial duct; one case of left aortic arch accompanied with right arterial duct; the remaining two cases did not have aortic arc and ductal arch location descriptions; four cases were accompanied with chromosome abnormalities.
Discussion
Prognostic Analysis of ILSCA and ILBCT Malformations
In the present study, there was a total of 14 cases ILSCA or ILBCT. Two of them were prenatally diagnosed. Twelve cases were reported postnatally. Nine of them were accompanied by other congenital cardiac malformations or chromosome abnormalities, and the prognosis of these cases was related to the severity of accompanied malformations. Five cases were not accompanied by other structural abnormalities or chromosome abnormalities, which are clinically hidden and short of representativeness. Intermittent headache, dizziness, blurry vision, and hearing loss may be related to the blood flow retrograded to left cerebral and left upper limb through wills circle after birth. And these symptoms gradually degrades as people age.
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Although such deformity surgery is simple and has a satisfactory effect, the stealthiness of the clinical symptoms tends to cause the exacerbation of the disease due to the delay in the diagnosis and treatment of these patients. However, With the continuous improvement of fetal UCG, Prenatal diagnosis can contribute to timely of treatment and enhance quality of life of young children.
Prenatal Ultrasound Diagnosis of ILSCA and ILBCT and Feasibility Analysis
During fetal period, there is no interference of the lung qi and the acoustic shadow of the rib and sternum compared with the neonatal period and childhood. Therefore, it was easier to detect the aortic arch and branches. For fetus with right aortic arch and right arterial duct or double arterial duct, the cephalic and cervical vessels derived from aortic arch should carefully be observed, when the cephalic and cervical vessels disconnected with the aortic arch, it needs to be highly vigilant ILSCA or IlBCT.
During ultrasound scan process of ILBCT, only two branches of cephalic and cervical vessels deriving from the aortic arch were observed on sagittal section, which were right common carotid artery and right subclavian artery from front to back. Meanwhile, it was found that the left truncus brachiocephalicus originated from main pulmonary artery. Compared with ILBCT, The ILSCA was easily missed because of the “normal” number of the cephalic and cervical vessels. They are the left common carotid artery, right common carotid artery, and right subclavian artery from front to back.
The spectrum morphology of left subclavian artery and left common carotid artery are helpful in further identifying the diagnosis. However, the peak blood flow rate mainly depends on fetus state, and we were unable to measure left and right artery’s blood rate simultaneously, hence we can not compare them exactly. Although in theory, isolated left subclavian artery or common artery should have a lower blood flow rate than that of right subclavian artery or right common carotid artery.
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Correlation Analysis Between ILSCA or ILBCT and Variation of the Aortic Arch and the Ductal Arch
Among 12 cases with ILSCA and ILBCT reported in pubmed, eight cases were of right aortic arch; one case was diagnosed with right aortic arch accompanied by double arterial duct; one case of left aortic arch accompanied with right arterial duct. In our two cases, both were right aortic arch accompanied by right ductal arch. It is inferred that the ILBCT and ILSCA are closely correlated with abnormal position or quantity of aortic arch or ductal arch. But further studies are needed to verify whether ILSCA or ILBCT is more closely correlated with the right aortic arch accompanied with the right arterial duct.
Conclusion
ILBCT or ILSCA is commonly seen in right aortic arch. Prenatal diagnosis can improve the prognosis and subsequently quality of life. For fetuses with abnormal position or quantity of aortic arch or ductal arch, origin of cephalic and cervical vessels should be tracked, which is the key to improve prenatal diagnosis rate. Moreover, spectrum of abnormal common carotid artery or subclavian artery is helpful for further confirming the diagnosis.
Acknowledgements
This study was supported by the Capital Project of Fund Development (No. 2011-4022-07), the Zika Special Project of the MOST (Ministry of Science and Technology) Reform and Development Project.
Compliance with Ethical Standards
Conflict of interest
The authors declare that they have no conflicts of interest of relationships to disclose.
Ethical Approval
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and its later amendments or comparable ethical standards.
Informed Consent
Informed consent was obtained from all individual participants included in the study.