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.