Left Pulmonary Artery

arteria pulmonalis sinistra

The left pulmonary artery is the shorter of the two main pulmonary arteries, arching over the left main bronchus and the left superior pulmonary vein to enter the left hilum. The ligamentum arteriosum (remnant of the ductus arteriosus) connects its superior surface to the undersurface of the aortic arch. It divides into upper and lower lobe branches supplying the left lung.

Region: Chest

Clinical Relevance

Clinical Notes

The left pulmonary artery and the ligamentum arteriosum are key surgical landmarks at the left hilum. The left recurrent laryngeal nerve loops under the aortic arch at the ligamentum arteriosum, making dissection in this area during left hilar surgery risky for recurrent laryngeal nerve injury. Pulmonary artery sarcoma, rare but highly aggressive, commonly involves the left pulmonary artery. In patent ductus arteriosus repair, the ligamentum arteriosum junction with the left pulmonary artery is the operative target.

Pathology

Common Injuries & Conditions

Left Hilar Lymphadenopathy Compression

Enlarged left hilar lymph nodes from sarcoidosis, lymphoma, or metastatic malignancy compress the left pulmonary artery, producing reduced perfusion of the left lung visible as a perfusion defect on V/Q scan, distinguishable from pulmonary embolism by the absence of ventilation mismatch.

Patent Ductus Arteriosus

Failure of the ductus arteriosus to close at birth maintains a left-to-right shunt between the aortic arch and the left pulmonary artery, producing a continuous machinery murmur, left heart volume overload, and pulmonary hypertension if uncorrected; treated by surgical ligation or transcatheter device closure.