3 | Discussion
The most common CVR is right aortic arch (RAA) and double aortic arch(DAA). RAA includes aberrant left subclavian arteries (ALSA) and mirror-image branching pattern, while ALSA is common3,4. The RAA with ALSA can have a Kommerell’s diverticulum closely related to 22q11.2 chromosome microdeletion. RAA with mirror-image branching is usually complicated by congenital cardiac anomalies and cases without anomalies are quite rare5. DAA has been reported as an association with upper airway obstruction1.
An accurate diagnosis of CVRs can be made prenatally by fetal echocardiography6. The three-vessel and tracheal(3VT) view are the ‘gold standard’ to observe arch anomalies7. Fetal CVRs can be assessed by a four-dimensional (4D) spatiotemporal image correlation (STIC) technique with high-definition(HD) flow imaging8. Once an aortic arch anomaly is diagnosed, a comprehensive ultrasound examination, including fetal echocardiography is recommended to finding potential structural malformation9,10. According to the type of VR,prenatal counseling on chromosome examination and postnatal airway assessment are recommended11,12.
RAA with ALSA can be accurate diagnosed by ”U”-shaped VR and ALSA. The RAA with mirror branch is often mistaken for a DAA when the arterial ductus flows into the descend aorta and forms an ”U”-shaped VR. The color blood flow is likely to mistaking the cross relationship between the left innocent artery(LINA) and the arterial ductus for anatomy connection which may lead to misdiagnosis. Although most of the infants with the RAA mirror branch are asymptomatic, DAA is often related to compression symptoms of esophagus or trachea. If the RAA with mirror branch is misdiagnosed as a DAA, it may lead to excessive abortion or unnecessary worry of pregnant women. The author believes that the RAA with mirror branch should be diagnosed by following criteria: 1): 3VT view shows RAA and the left side ductus arch forming a ”U”-shaped VR, without a ALSA; 2): the first branch of the aortic arch begins with the LINA and the LINA straightly moves to the left. 3): Continuous scanning of the aortic arch view and the long axis view of the ductus arch show that the LINA is not connected to the descend aorta or arterial ductus and is not formation of VR.
In addition, DAA is usually combined with the right arch dominant type and it is common to misdiagnose DAA as an RAA with mirror branch when the left arch is thin or the arterial duct is thick because of the left arch is not easy to display, as in our third case. The authors believe that the DAA should be diagnosed by following criteria: 1): 3VT view shows that the left and right aortic arches form an ”O”-shaped VR encircling the trachea and esophagus; 2): The arterial ductus is located on the left side of the left aortic arch, 3) DAA and the left ductus are all connected to the descend aorta.
Ethical approval
This study has been granted an exemption from the Medical Ethics Committee of Gansu Provincial Maternity and Child-care Hospital. The pregnant mothers provided their written informed consent to publish their cases (including publication of images).
Acknowledgments:
Not applicable
Consent for publication
Written informed consent was obtained from the patient for publication of this case report and any accompanying images.
CONFLICTS OF INTEREST
The authors have no conflicts of interest.
Funding
This work is supported by National Key Research and Development Program of China (grant 2018YFC1002504), Lanzhou Science and Technology Program (grant 2017-4-53)
ORCID
Tian-gang Li. https://orcid.org/0000-0003-4384-9701
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