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Right aortic arch is a relatively rare congenital anomaly. The combination of a right aortic arch, a right patent ductus arteriosus, and an aberrant left subclavian artery in a child with an otherwise structurally normal heart is very uncommon. We report the successful transcatheter coil occlusion of a right-sided patent ductus arteriosus in a child with the above-mentioned anatomy. To our knowledge, such a case has not been reported in the English-language medical literature to date.
Right aortic arch occurs in approximately 0.1% of the population and is generally classified by its course, ramification pattern, and ductal position.1 This classification is of particular importance when one is attempting to determine the existence of a vascular ring. Moreover, the possibility of an asymptomatic vascular ring adds to the risk of performing transcatheter intervention in patients who have a right aortic arch and patent ductus arteriosus (PDA).
Transcatheter coil and device occlusion of the PDA have become commonplace in pediatric cardiology. Most of the patients have a left aortic arch with a normally positioned PDA. Due to the rare occurrence of a right aortic arch and the variability in anatomic positioning of the head and neck vessels and the duct, it is important for interventionalists to consider these factors before beginning any interventional procedure. We describe our treatment of a young patient with a right aortic arch, right PDA, and aberrant (retroesophageal) left subclavian artery.
An asymptomatic 5-year-old girl, who was normal in growth and development, was referred to our hospital with a murmur. An echocardiogram revealed a right aortic arch and a small, right-sided PDA that originated from the descending aorta. The PDA had left-to-right flow, and the right and left ventricles were normal in size and function. The branching pattern of the right arch could not be fully delineated due to the patient's movement. She was referred to the cardiac catheterization laboratory for further evaluation of the aortic arch anatomy and for possible transcatheter occlusion of the PDA.
In the cardiac catheterization laboratory, the patient was placed under general anesthesia. A prograde right and left heart catheterization was performed. The intracardiac pressures were normal, with the exception of a small gradient of 10 to 12 mmHg from the right ventricle to the branch pulmonary arteries. This gradient corresponded with the echocardiographic findings of mild branch-pulmonary-artery stenosis. The pulmonary-to-systemic flow ratio was calculated to be 1.3:1, and the pulmonary artery resistance was normal at 0.5 Wood units.
Left ventricular angiography was performed to further delineate the aortic arch. A right aortic arch was clearly identified: the 1st branch was the left common carotid artery, followed by the right carotid artery, and then the right subclavian artery. The left subclavian artery originated from the distal transverse arch with a cephalad course (Fig. 1). A right-sided PDA was noted to arise from the descending aorta, distal to the takeoff of the aberrant left subclavian artery. The duct was connected to the right pulmonary artery and stayed to the right of the trachea and esophagus throughout its entire course (Fig. 2). There was no evidence of a vascular ring. A retrograde approach was then undertaken, and further angiograms were obtained to define the size and shape of the PDA. After confirmation of adequate positioning of the catheter across the duct, a 0.038-in × 8-cm × 5-mm Cook embolization coil (Cook Medical Inc.; Bloomington, Ind) was advanced through a 4F 100-cm JB-1 Glidecath™ (Medi-Tech, Boston Scientific; Quincy, Mass). Approximately three fourths of a loop was advanced out of the catheter into the right pulmonary artery just distal to the insertion of the PDA. The catheter was slowly pulled back through the duct and into the aorta with gradual release of the remainder of the coil. A repeat angiogram revealed no flow of contrast medium from the aorta into the pulmonary artery (Fig. 3).
The patient tolerated the procedure well. A chest radiograph performed during the recovery period showed stable positioning of the coil. She was discharged from the hospital the day of the procedure. She was seen in our cardiology clinic at 1 and 14 months after the procedure. Her clinical course and echocardiographic findings have been uneventful.
This patient underwent successful transcatheter coil occlusion of a right-sided PDA from a right aortic arch with an aberrant left subclavian artery, which to our knowledge has not been reported in the English-language medical literature to date. A previous case report described this particular anatomic variant and the successful surgical ligation of the PDA in 2 instances.2 Another report presented the successful coil occlusion of a left PDA from an aberrant left subclavian artery with a right aortic arch and successful coil occlusion of a right PDA from a right aortic arch with mirror-image branching.3
In children referred to major cardiac centers and in those with congenital heart disease, right aortic arch is more common than it is in the general pediatric population and is associated with tetralogy of Fallot, pulmonary atresia, and truncus arteriosus.1 Many of these patients undergo surgical intervention and therefore are not routinely referred to the cardiac catheterization laboratory for PDA coil or device occlusion. Consequently, it is less likely that children who have right aortic arch variants will present for PDA transcatheter intervention, as evidenced by the relative paucity of case reports in the literature.
Our patient had a right aortic arch with a right PDA and an aberrant left subclavian artery. According to one source, only 0.3% of patients in a large catheterization series were found to have this anomaly, and all but one of these patients had a conotruncal abnormality.4 In the absence of a right PDA, the incidence of congenital heart disease in patients with a right aortic arch and aberrant left subclavian artery is low.5,6
Four right arch variants have the potential to cause vascular rings. The most common ring is due to a retroesophageal diverticulum of Kommerell.7 Rao and colleagues reported the successful transcatheter coil occlusion of a PDA with right aortic arch and retroesophageal diverticulum of Kommerell.3 In such cases, the potential exists for creation of a symptomatic ring with coil or device occlusion.
The 2nd-most-common form of vascular ring associated with a right aortic arch occurs in the presence of a left ligamentum arteriosum or ductus arteriosus (arising from the right-sided descending aorta) with a mirror-image branching pattern.7 Two other right aortic arch anomalies have the potential to cause vascular rings, and both are uncommon. The first is a right aortic arch with a retroesophageal brachiocephalic artery, and the second is a right arch with a left descending aorta and left ductus or ligamentum.4 The aforementioned anomalies do not encompass all of the possible anatomic variants of the right aortic arch and arterial ductus or ligamentum. For further details regarding these variations, the reader is encouraged to review the previously referenced case report by Rao and co-authors.3
In summary, a right aortic arch is a rare phenomenon and may be accompanied by common or extremely rare variations in anatomy. Several varieties of right arch anatomy, when combined with a PDA, will result in a vascular ring, either symptomatic or asymptomatic. In patients with a right arch who are referred to the cardiac catheterization laboratory for possible PDA occlusion, the anatomy of the arch must be clearly defined. In our patient, the anatomic variant did not cause a vascular ring, but the variant was rare enough for us to pause and consider the anatomy before pursuing any intervention. From the results of our case and a review of the literature, it appears as though transcatheter occlusion of PDA variants from right aortic arches is a safe and effective procedure, provided that the substrate for a vascular ring is not present. Only a single case of transcatheter coil occlusion has been reported in a patient who had a PDA that produced a ring, albeit a loose one.3 Although that intervention was successful, the evidence for the safety of this approach is not conclusive.
Address for reprints: Michael R. Carr, MD, Pediatric Cardiology, Texas Children's Hospital, MC 19345C, 6621 Fannin, Houston, TX 77030. E-mail: ude.cmt.mcb@rrac
Dr. Leonard is now at the Department of Pediatric Cardiology, Duke University Medical Center, Durham, NC 27710
This article was written while LCDR Michael R. Carr, MC, USNR, was a fellow training in Pediatric Cardiology at Texas Children's Hospital. The views expressed in this article are those of the authors and do not necessarily reflect the official policy or position of the Department of the Navy, Department of Defense, or the U.S. Government