There are many variations of right aortic arch,Reference Hanneman, Newman and Chan1 but the association with coarctation of the aorta is very rare with a prevalence of 0.1%.Reference Kanne and Godwin2 Chromosome 22q11.2 deletion is associated with congenital heart disease and aortic arch anomalies,Reference Momma, Matsuoka and Takao3 and 24% of them are only with arch anomalies.
We report an infant with chromosome 22q11.2 deletion, who had the right aortic arch with a very rare branching variation with a vascular ring. In addition, the infant had a coarctation of the aorta in the transverse arch, which was prostaglandin dependent.
Case report
A male newborn with 37 weeks of gestation and birth weight of 2996 g was referred to our hospital at third day of life with prostaglandin E1 infusion, due to tachypnea and metabolic acidosis. At arrival, the patient had a blood pressure gradient of 20 mmHg between upper and lower extremities. A quick transthoracic echocardiogram showed right aortic arch with flow obstruction in the aortic arch, left patent ductus arteriosus, and no intracardiac anomaly. By increasing prostaglandin E1 dosage, the patient had improvement in metabolic acidosis without signs of malperfusion. A chest CT showed right aortic arch, aberrant left subclavian artery and left internal carotid artery with retroesophageal diverticulum, bovine branch of left external carotid artery and right common carotid artery from ascending aorta, and left ductus forming a vascular ring (Fig 1a). As the patient had a very complex social situation, we were unable to obtain operative consent for a month. The patient’s hemodynamics had been stable over the period with increasing prostaglandin E1 dosage; however, the follow-up echocardiogram revealed increasing peak velocity at the aortic arch with no flow at PDA. Repeat CT showed evident coarctation of the aorta in the transverse arch (Fig 1b). Despite this situation, the blood pressure gradient between the upper and lower extremities in this patient stayed approximately 20 mmHg with sufficient urine output.
Figure 1. The chest CT taken at day 2 of life (a) and day 35 of life (b). CoA, coarctation of the aorta; LDA, left ductus arteriosus; LECA, left external carotid artery; LICA, left internal carotid artery; LSCA, left subclavian artery; RCCA, right common carotid artery; RSCA, right subclavian artery.
An operation was performed at 40 days of life. The patch augmentation of the aortic arch and the division of ductus was completed under the use of cardiopulmonary bypass, aortic cross clamp placement, and regional cerebral perfusion via the right common carotid artery. Postoperative course was uneventful, and the patient was discharged to go home.
Genetic testing reported postoperatively showed he had chromosome 22q11.2 deletion.
Comments
Chromosome 22q11.2 deletion is suggested to have developmentally insufficient migration of the cephalic and cranial neural crest and responsible for aortic arch anomalies.Reference Momma, Matsuoka and Takao3 Various arch anomalies, including right aortic arch, cervical aortic arch, aberrant and isolated subclavian artery, and interrupted aortic arch, have been associated with chromosome 22q11.2 deletion. This patient’s anomaly is similar to the right aortic arch with aberrant left brachiocephalic artery, which is a rare anomaly with the left common carotid and left subclavian artery running behind the esophagus and forming a vascular ring.Reference Frederic Moes and Freedom4 It is caused by the involution of the left fourth embryonic aortic arch between the ascending aorta and left common carotid artery. For the carotid arteries, an unusual origin of internal carotid artery and external carotid artery results from persistence of the left carotid duct, which is often associated with the cervical aortic arch. Therefore, we postulate that in addition to the mechanism of aberrant brachiocephalic artery, regression of dorsal end of the third aortic arch between the left external carotid artery and the left internal carotid artery with persistence of the left carotid duct may contribute to this rare anomaly. To the best of our knowledge, there are no reports on such variance of the right aortic arch.
Ectopic ductal tissue theory is one of the main theories of etiology of coarctation of the aorta. Russell et al reported that circumferential sling of ductal tissue was identified in 22 of the 23 patients of coarctation of the aorta.Reference Russell, Berry and Watterson5 In this patient, even the left ductus arteriosus was distant from coarctation of the aorta site and right ductus arteriosus was not evident, and there was hemodynamic improvement after increasing prostaglandin E1 dosage, which supports the ectopic ductal tissue theory.
In conclusion, we report a case of chromosome 22q11.2 deletion with prostaglandin-dependent right aortic arch and a rare neck vessel variation.
Acknowledgements
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Financial support
This research received no specific grant from any funding agency and commercial or not-for-profit sectors.
Conflict of interest
None.
Ethical standards
The authors assert that all procedures contributing to this work comply with the ethical standards of the relevant national guidelines on human experimentation and with the Helsinki Declaration of 1975, as revised in 2008, and has been approved by the institutional committees of the Tokyo Women’s Medical University.
