Journal of Pediatric Cardiology and Cardiac Surgery 8(2): 87‒91 (2024)

Case Report

An Unusual Form of Anomalous Origin of the Right Pulmonary
Artery from the Ascending Aorta, or Aorto-Pulmonary Window?
Toshi Maeda, MD1), Keiichi Fujiwara, MD, PhD1), Kotaro Inaguma, MD2),
Kosuke Yoshizawa, MD1), Otohime Mori, MD1), and Hisanori Sakazaki, MD, PhD2)
1) Department of Cardiovascular Surgery, Hyogo Prefectural Amagasaki General Medical Center, Hyogo, Japan
2) Department of Pediatric Cardiology, Hyogo Prefectural Amagasaki General Medical Center, Hyogo, JapanAnomalous origin of the right pulmonary artery from the ascending aorta is characterized by the right pulmonary artery arising from the right or posterior aspect of the ascending aorta. The anomalous right pulmonary
artery is seldom connected to the pulmonary trunk. A premature baby was diagnosed with this malformation.
The right pulmonary artery arose from the left aspect of the ascending aorta and additionally communicatedwith the pulmonary trunk via a small lumen just distal to its aortic origin. She underwent reimplantation of theright pulmonary artery to the pulmonary trunk at 13 days old. She remained asymptomatic at five years postoperatively. There were only three cases reported describing continuous tissues between the right pulmonary arteryand the pulmonary trunk. In embryogenesis, imbalanced and incomplete septation of the aortic sac may resultin this rare circumstance.

Keywords: anomalous origin of the right pulmonary artery, premature, hemitruncus, congenital heartdiseaseIntroduction
Anomalous origin of a unilateral pulmonary arteryfrom the ascending aorta (AAo) is a rare congenital
malformation, which is characterized by the right or theleft pulmonary artery originating from the AAo withseparate semilunar valves. The contralateral pulmonary
artery is normally connected to the pulmonary trunk(PT) arising from the right ventricle. It accounts for
0.1% of all congenital heart diseases.1) The anomalouspulmonary artery is more frequently on the right thanleft.1, 2) The anomalous pulmonary artery does not usually have a direct connection to the PT. Only three cases
have been reported with continuity between the anomalous right pulmonary artery (RPA) and the PT.3‒5) Theirmorphological diagnosis is still controversial, whether
anomalous origin of the RPA from the AAo (AORPA) or

aorto-pulmonary window (APW).6) We herein report apremature baby with AORPA or APW whose RPA communicating with the PT via a small lumen.

Case Presentation
A female baby was delivered by an emergent cesarean
section secondary to fetal bradycardia at a gestationof 33 weeks and 4 days. She weighed 1,700 g, and was
eventually referred to our hospital at 12 days old. During
pregnancy, her mother was doing well without detectionof any congenital anomaly including heart disease on
routine fetal ultrasonograms. She had no family history
regarding congenital heart disease. She was sufferingfrom progressive respiratory distress and congestive
heart failure. Levine 2/6 continuous murmur was heard
at the left sternal border of the second intercostal space.
Her heart rate, respiratory rate and blood pressure

Received: July 12, 2023; Accepted: December 26, 2023
J-STAGE Advance Published Online: June 24, 2024
Corresponding author: Toshi Maeda, MD, Department of Cardiovascular Surgery, Hyogo Prefectural Amagasaki General MedicalCenter, 2‒17‒77, Higashinaniwa-cho, Amagasaki-shi, Hyogo 660‒8550, Japan
E-mail: tmsirius825@gmail.com
Toshi Maeda ( https://orcid.org/0000-0002-9639-7000)
doi: 10.24509/jpccs.23-013© 2024 Japanese Society of Pediatric Cardiology and Cardiac Surgery
This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/)

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were 164 beats/min, 70 breaths/min and 60/30 mmHg,
respectively. Oxygen saturation was 99% on room air.
Chest X-ray showed cardiomegaly with right pulmonary
plethora (Fig. 1). An electrocardiogram showed biatrial
overload. Her serum B-type natriuretic peptide level was3,383 pg/mL. The RPA originated from the left posterior
aspect of the proximal AAo. The orifice of the RPA atthe proximal AAo was 5.0 mm. Moreover, the RPA wasFig. 1 Preoperative chest X-ray showed cardiomegaly and right pulmonary plethora

connected to the PT via a 2.0 mm-diameter lumen at
the intrapericardial portion adjacent to its aortic origin.
She was diagnosed as having AORPA, left aortic arch,patent ductus arteriosus bridging normally between theFig. 2 Preoperative echocardiogram showed that theRPA arose from the left aspect of the AAo andconnected to the PT via a small lumen (whitearrow)
AAo, ascending aorta; PT, pulmonary trunk; RPA,
right pulmonary artery

Fig. 3 Preoperative computed tomography
Axial views (A, B), and an anterior (C) and a posterior views (D) on three-dimensional computed tomography. The RPA originated from the proximal AAo (A and D, blue arrows and white arrowheads, respectively) and had a connection to the PT
just distal to the origin of the RPA (B and C, yellow and white arrows, respectively). The oriﬁce of the RPA at the proximal
AAo was much greater than the small channel between the RPA and the PT. AAo, ascending aorta; PDA, patent ductus
arteriosus; PT, pulmonary trunk; RPA, right pulmonary artery

J Pediatr Cardiol Card Surg Vol. 8, No. 2 (2024)

89aortic arch and the PT, and patent fossa ovale by transthoracic echocardiography and computed tomography(Figs. 2, 3). Nitrogen inhalation therapy was started totreat high pulmonary flow.
Surgical treatment was performed at 13 days of age.
The heart was exposed through a median full sternotomy. The RPA originated from the left posterior aspectof the AAo just above the sinus of Valsalva, and wasconnected to the PT (Fig. 4) as shown preoperatively.
The RPA was dissected and snared between the superior
vena cava and the AAo. Cardiopulmonary bypass wasestablished via cannulations into the distal AAo and theright atrium. The patent ductus arteriosus was ligatedand divided. The connection between the RPA and thePT was 3 mm in external diameter. After cardioplegicarrest, the RPA was detached from the AAo and the PT.
The incised wall of the AAo was directly oversewn. TheRPA was reimplanted to the PT, also directly, using 7-0
Prolene® (Johnson & Johnson Services, Inc., New Brunswick, New Jersey, USA) running suture. Weaning fromcardiopulmonary bypass was smooth. Cardiopulmonary
bypass time and aortic cross-clamp time were 89 and35 minutes, respectively. Pulmonary arterial and aorticpressure was 26/18 (22) and 85/49 (63) mm Hg, respectively. Primary sternal closure was achieved. The postoperative course was uneventful. She was discharged on
the postoperative day 39 (body weight of 2,146 g). She
is asymptomatic with normal growth. The RPA showedno stenosis or deformity at five years postoperatively(Fig. 5).

Discussion

Fig. 4 An intraoperative picture. The RPA was connected to the PT (yellow arrow)
AAo, ascending aorta; PT, pulmonary trunk; RPA,right pulmonary artery

AORPA has two patterns morphologically: the proximal and the distal types.1, 2) The former is characterized by an anomalous RPA that usually arises from theposterior or right lateral aspect of the AAo close to theaortic valve. Its orifice is widely open in the majority.
As for the distal type, the morphological feature is theanomalous RPA usually originating from the AAo close
to the brachiocephalic artery, or much less frequently
from the brachiocephalic artery. Its orifice is likely
surrounded by a ductal tissue, and becomes stenotic inmany instances.1) AORPA is often associated with patentductus arteriosus, bridging between the aortic arch andthe PT as usual. Occasionally, an aortopulmonary septal
defect or interrupted aortic arch coexists.

Fig. 5 Echocardiography ﬁve years postoperatively. No pulmonary arterial stenosis is seen.
AAo, ascending aorta; PT, pulmonary trunk; RPA, right pulmonary artery© 2024 Japanese Society of Pediatric Cardiology and Cardiac Surgery

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In embryogenesis, the AAo and the PT separate
from the initial aortic sac. Also, the right sixth pharyngeal arch migrates leftward and fuses to the left sixth
pharyngeal arch, forming the distal part of the PT. It
is hypothesized that the proximal type of AORPA is a
result of insufficient leftward migration of the right sixth
arch and imbalanced septation of the aortic sac.7) The
RPA is rarely in continuity with the PT. To the best ofour knowledge, only three reports have described continuity between the RPA and the PT.3‒5) These cases did
not have luminal continuity. Our case had communication through a small lumen between the RPA and thePT, which has never been reported. The proximal RPA
was clearly identified as seen in the previous cases.3‒5)
The orifice of the RPA at the proximal AAo was muchgreater than the additional channel between the RPA
and the PT. We diagnosed her malformation, therefore,
as unusual form of AORPA. An alternative diagnosis
may be AORPA together with APW. Ho et al. reported
that these abnormalities can coexist.6) The present casecan sit within this spectrum of morphological variations. Somebody would argue that the diagnostic entity
remains controversial. We contemplate that imbalanced
and incomplete septation of the aortic sac could haveresulted in the unusual pathway between the RPA andthe PT.5)
Congestive heart failure with high pulmonary flowusually progresses rapidly in patients with the proximal
type of AORPA. Severe pulmonary hypertension andpulmonary vascular obstructive disease also develop
early in life.8) In this respect, early surgical repair ispertinent, even during the neonatal period.2) The resultof palliative surgery was disappointing.2) Direct anastomosis of the RPA to the PT is recommended as far
as feasible.2, 9, 10) Nonetheless, the distance between themobilized RPA and the PT varied. Stretching and/or
kinking of the reconstructed RPA should be avoided interms of future stenosis. When direct reimplantation
was unapplicable, some surgical techniques have been
described, such as use of a flap of the aortic or the pulmonary arterial wall and graft interposition.10, 11) In ourpatient, the RPA had particular features; originatingfrom the left posterior aspect of the proximal AAo andbeing unusually connected to the PT. Thanks to these,
the RPA could be directly reimplanted to the PT withoutcausing stenosis.
In conclusion, we encountered a premature girl,
J Pediatr Cardiol Card Surg Vol. 8, No. 2 (2024)

weighing 1,700 g, who had an unusual form of AORPA.
The RPA communicated with the PT via a small lumen.
Direct reimplantation to the PT was successfully established. She remained asymptomatic with no RPA stenosis in the longer term at five years postoperatively.
FundingNone.
Conﬂicts of Interest
The authors declare that they have no competing interests.
Author Contribution
TM contributed to study concept and design and was amajor contributor to writing the manuscript. KF, KY andOM contributed to study concept and design, and madecontributions to revising the manuscript. KI and HS performed clinical examinations and interpreted the patientdata. All authors read and approved the final manuscript.
Ethical Declarations
Ethics approval and consent to participate: This study has
been approved by the institutional review board (Hyogo
Prefectural Amagasaki General Medical Center, ID: 4-58).
Written informed consent to participate was obtained fromthe parents of the patient.

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