Introduction
Unilateral absence of the pulmonary artery is a rare congenital heart disease. Although its exact incidence in the general population is unknown, it has been reported in approximately 0.3–0.6% of all congenital heart defects. It may occur in isolation or in association with other anomalies such as tetralogy of Fallot or ventricular septal defect. This anomaly results from developmental abnormalities of the sixth aortic arch during the prenatal period, leading to the affected pulmonary artery being supplied by the aortic arch or other collateral vessels.
The clinical presentation of unilateral pulmonary artery absence varies widely. While some cases remain asymptomatic until adulthood, others may present with cough, haemoptysis, recurrent pulmonary infections, or pulmonary hypertension. Diagnosis can be challenging and relies heavily on advanced imaging modalities such as computed tomography and catheter angiography. Early diagnosis and treatment are essential to prevent long-term complications and to salvage the anomalously originating pulmonary artery.
Treatment options include pulmonary artery stenting to promote growth, reconstructive surgery, and anastomosis. In this report, we present two cases followed in our clinic where the left pulmonary artery was supplied via a patent ductus arteriosus, and we discuss the interventional approaches utilised.
Case presentations
Case 1
A 14-year-old girl with no known prior disease was referred to our clinic following the detection of left pulmonary artery absence on cardiac CT, which was performed due to exertional fatigue and frequent pulmonary infections. Transthoracic echocardiography revealed a right aortic arch, a patent ductus arteriosus-like structure, and an absent left pulmonary artery. Catheter angiography was performed for further assessment.
Angiography showed continuation of the main pulmonary artery into the right pulmonary artery, with no visible left pulmonary artery. Aortic root injection revealed a right aortic arch with mirror image branching, and flow to the left pulmonary artery via a patent ductus arteriosus originating from the left innominate artery. Pulmonary venous wedge injection showed sufficient distribution and calibre of the left pulmonary artery, making it suitable for recanalisation. Measurements were as follows: main pulmonary artery 19.7 mm (z-score: 0), right pulmonary artery 15.3 mm (z-score: +1.1), and left pulmonary artery 4.2 mm (z-score: –4.8). A successful patent ductus arteriosus stenting was performed, establishing continuity with the left pulmonary artery.
At three-month follow-up, control catheter angiography and cardiac CT showed good flow through the stent and significant growth of the left pulmonary artery to 9.7 mm (z-score: –0.82). The patient was evaluated by a multidisciplinary team, and a surgical main pulmonary artery-left pulmonary artery anastomosis with left pulmonary artery reconstruction was successfully performed (Figure 1).
( a ) Continuity between the MPA and the RPA, with absence of the LPA. ( b ) Visualisation of the remnant of the PDA originating from the innominate artery. ( c ) Establishment of PDA–LPA continuity following PDA stent placement. ( d ) Hypoplastic appearance of the LPA on injection (4.2 mm; z-score: –4.8). ( e ) LPA appearance at 3-month follow-up angiography (9.7 mm; z-score: –0.82). ( f ) Pulmonary artery appearance on follow-up echocardiography after LPA reconstruction.
Case 2
An 11-year-old girl with no prior known condition was referred to our clinic after left pulmonary artery absence was incidentally noted during pneumonia evaluation. Transthoracic echocardiography confirmed the absence of the left pulmonary artery, prompting catheter angiography.
Angiography revealed main pulmonary artery continuation into the right pulmonary artery and no visible left pulmonary artery. Aortic root injection demonstrated a right aortic arch with mirror image branching and flow to the left pulmonary artery via a patent ductus arteriosus originating from the left subclavian artery. Pulmonary venous wedge injection showed contrast filling the left pulmonary artery stump up to the patent ductus arteriosus site. Measurements were: main pulmonary artery 24.7 mm (z-score: +2.4), right pulmonary artery 17.6 mm (z-score: +3.1), and left pulmonary artery 5.2 mm (z-score: –3.4). Following successful patent ductus arteriosus stenting, angiography confirmed reestablished flow to the left pulmonary artery.
At four-month follow-up, catheter angiography showed sufficient stent flow and satisfactory left pulmonary artery growth (9.7 mm, z-score: –0.8). Surgical main pulmonary artery-left pulmonary artery anastomosis and left pulmonary artery reconstruction were successfully performed (Figure 2).
( a ) Continuity between the MPA and the RPA, with absence of the LPA. (b) Visualisation of the remnant of the PDA originating from the left subclavian artery. ( c ) Establishment of PDA–LPA continuity following PDA stent placement ( d ) Hypoplastic appearance of the LPA on injection (5.2 mm; z-score: –3.4). ( e ) LPA appearance at 3-month follow-up angiography (9.7 mm; z-score: –0.8) ( f ) Pulmonary artery appearance on follow-up echocardiography after LPA reconstruction.
Discussion
Unilateral absence of the pulmonary artery arises from a developmental defect in the connection between the sixth aortic arch and the pulmonary artery during embryogenesis. Reference Pfefferkorn, Löser and Pech1 As a result, distal pulmonary blood flow is often supplied via collateral vessels such as a persistent ductus arteriosus, bronchial arteries, intercostal arteries, or internal mammary arteries. Reference Bockeria, Makhachev and TKh2–Reference Kadir, Thekudan and Dheodar3
While isolated cases may remain asymptomatic, long-term complications like pulmonary hypertension and congestive heart failure can occur. Early diagnosis and treatment are crucial to reduce morbidity and mortality. Reference Yan, Cen and Luo4
In both of our cases, a patent ductus arteriosus remnant was identified and successfully stented. This approach provides time for pulmonary artery growth and enables later surgical repair, making it a valuable strategy in selected patients.
