Inferior phrenic artery–to–pulmonary artery fistula after surgery for catamenial pneumothorax: a case report

Systemic artery–to–pulmonary artery fistula (SAPAF) is a rare vascular anomaly, and involvement of the inferior phrenic artery is particularly uncommon. Acquired SAPAF may occur as a late postoperative complication; however, diagnosis is often challenging because of subtle imaging findings and complex hemodynamics. Four-dimensional CT angiography (4D-CTA) enables time-resolved assessment of blood flow and may facilitate accurate diagnosis and treatment planning.

A 56-year-old woman was referred to the respiratory department after a screening chest CT performed for suspected malignancy revealed a vascular abnormality in the right lower lung field. Further evaluation confirmed a history of thoracoscopic wedge resection of the right middle lobe at the site of air leakage and partial diaphragmatic resection for catamenial pneumothorax 10 years earlier; the retrieved operative record indicated that no pleural adhesion procedure or reinforcement had been performed. She was asymptomatic at presentation. Dynamic 4D-CTA demonstrated absence of opacification of the right A9 segmental pulmonary artery during the pulmonary arterial phase, followed by retrograde filling of a tortuous vessel arising from the right inferior phrenic artery during the systemic arterial phase, suggesting an inferior phrenic artery–to–pulmonary artery fistula. Digital subtraction angiography confirmed the diagnosis, and coil embolization was successfully performed, with complete angiographic occlusion of the feeder artery.

This case appears to represent a previously unreported late postoperative complication following surgery for catamenial pneumothorax and highlights the clinical utility of 4D-CTA as a noninvasive modality for hemodynamic assessment and treatment planning in SAPAF.