An 8-year-old girl was admitted to our hospital for delayed development. Physical examination revealed a marked discrepancy in limb length, with the left upper limb and hand significantly shorter than the right (Fig. 1A). Blood pressure in the left upper limb was measured to be 20 mm Hg lower than that in the right upper limb.
Figure 1.
Clinical, echocardiography, computed tomography angiography (CTA), and intraoperative findings of the anomalous origin of the left subclavian artery from the main pulmonary artery. (A) Physical examination revealed left upper limb hypoplasia and reduced blood pressure in the affected arm. (B, C) Echocardiography demonstrated continuous left-to-right shunting from the left subclavian artery (LSA) to the main pulmonary artery, visualized by colour Doppler imaging and confirmed by spectral Doppler analysis. (D, E) Thoracic CTA identified an anomalous origin of the LSA from the pulmonary artery without residual vascular stump formation. In addition, a right-sided patent ductus arteriosus (PDA) was observed. (F) Intraoperative exploration definitively confirmed the abnormal connection between the LSA and the pulmonary artery. The white arrow highlights the left subclavian artery, the arrowhead marks the main pulmonary artery, and the white triangle denotes the patent ductus arteriosus.
Echocardiographic assessment showed the proximal segment of the left subclavian artery originating from the anterior wall of the main pulmonary artery (Fig. 1B), with a junction diameter of 3.7 mm and a left-to-right peak flow velocity of 1.8 m/s (Fig. 1C), along with reversed blood flow in the left vertebral artery. Chest computed tomography angiography (CTA) confirmed the diagnosis of an anomalous left subclavian artery originating from the main pulmonary artery (Fig. 1D), with no evidence of any residual connection or blind end formation between the left subclavian artery and the aortic arch (Fig. 1E).
The patient subsequently underwent surgical correction, involving ligation of the right patent ductus arteriosus and an end-to-side anastomosis with the left common carotid artery (Fig. 1F). Postoperatively, the patient demonstrated satisfactory recovery, with normalized and equalized blood pressures in both upper limbs. Follow-up echocardiography indicated unobstructed blood flow through the anastomosis between the left subclavian artery and left common carotid artery (Video 1
, view video online).
Discussion
We report a rare case of congenital left subclavian artery (LSA) origin from the pulmonary artery (isolated LSA), observed in 0.8% of right aortic arches.1 Although often associated with conotruncal anomalies (eg, tetralogy of Fallot), our case lacked intracardiac defects. The LSA connected to the pulmonary artery via a patent ductus arteriosus (PDA), with post-PDA closure causing aortic disconnection. Shuford’s classification2 identifies 3 right aortic arch subtypes, the rarest being subclavian-pulmonary artery anomalies. Embryologically, this results from abnormal regression in a double aortic arch system: aberrant left common carotid-LSA regression combined with a persistent vascular bridge linking the LSA to the left ductus arteriosus.3 Although 22q11 microdeletion (DiGeorge syndrome) is implicated,4 our patient showed no syndromic features, and genetic testing was declined.
Clinical manifestations depend on PDA patency.5 Most patients are asymptomatic, diagnosed incidentally via limb ischemia or weak pulses. Subclavian steal syndrome (vertebral flow reversal) and pulmonary steal (left-to-right shunting causing congestion) are key hemodynamic features. Elevated pulmonary resistance may reverse shunting, inducing cyanosis. Our patient exhibited left upper limb hypoplasia from congenital steal, exacerbated by pulmonary steal, yet avoided overt vertebrobasilar insufficiency caused by compensatory mechanisms.
Management remains controversial. Options include LSA ligation, PDA closure, reimplantation, or observation. Asymptomatic cases may benefit from early ligation, whereas symptomatic steal warrants LSA reimplantation to the aortic arch or left common carotid artery (LCCA). For our 8-year-old patient, prioritizing anatomic correction and growth potential, we performed direct LSA-LCCA anastomosis.
Novel Teaching Points.
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An anomalous origin of the LSA from the pulmonary artery—termed isolated left subclavian artery—is a rare variant of right-sided aortic arch, resulting from abnormal regression of specific segments during embryonic development of the double aortic arch system.
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This anomaly may occur with or without associated intracardiac defects, particularly conotruncal anomalies such as tetralogy of Fallot, and is commonly linked to DiGeorge syndrome (22q11 microdeletion), although syndromic features are not universally present.
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Clinical manifestations depend on the patency of the PDA, with hemodynamic features including subclavian steal syndrome (vertebrobasilar insufficiency) and pulmonary steal (left-to-right shunting). Asymptomatic patients in childhood may develop progressive left upper limb ischemia or vertebrobasilar insufficiency with age.
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Upper limb ischemia typically presents with pain, diminished pulses, limb hypoplasia, and symptom exacerbation during physical exertion.
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Although LSA ligation or PDA closure may suffice in select cases, anatomic correction through LSA reimplantation to the left common carotid artery remains the optimal surgical strategy for long-term outcomes.
Acknowledgments
Ethics Statement
This study and report have been approved by the Ethics Committee of Wuhan Children's hospital and obtained informed consent from patients after hiding their personal information.
Patient Consent
The authors confirm that written consent for submission and publication of this case report including images and associated text has been obtained from the patient’s next of kin in line with COPE guidance.
Funding Sources
No funding was provided for this article.
Disclosures
The authors have no conflicts of interest to disclose.
Footnotes
See page 808 for disclosure information.
To access the supplementary material accompanying this article, visit CJC Open at https://www.cjcopen.ca/and at https://doi.org/10.1016/j.cjco.2025.03.010.
Supplementary Material
Echocardiography indicated unobstructed blood flow from left common carotid artery to left subclavian artery in postoperation follow-up.
References
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Echocardiography indicated unobstructed blood flow from left common carotid artery to left subclavian artery in postoperation follow-up.